# Adding R-22 increases suction temperature???



## psehorne (Jul 29, 2012)

I am trying to understand what I am seeing on my gauges. (I have an HVAC Certification, but have never earned a living professionally in the HVAC industry).

The unit in question is a Payne Heat Pump PH10JA030. The instructions I have say that if the suction temperature is not at target adding refrigerant will lower the suction temperature and removing refrigerant will increase the temperature. I am seeing just the opposite. Can any of you shed some light on this?

Here are my measurements:
Air temperature entering the evaporator (dry bulb) ~73F. 
Wet-bulb arrived at by calculating from above and RH 45% = 62F.
Outdoor air temperature entering condenser (dry-bulb) 105F

According to the chart on the unit the above results in a superheat requirement that is off the chart to the low side. In other words, less than 5. Because of this I am concerned that the unit may be overcharged.

Other pertinent measurements:
High pressure line gauge reading PSI/temp = 270psi/122F
High pressure line actual temperature = 113F (subcooling ~9f)
Suction line gauge reading PSI/temp = 70psi/41F
Suction line actual temerature = 47F
Air exiting indoor vents = 55F
Cold air return = 73 (diff = 19F)

Thanks in advance for any help any of you can offer. 


Paul


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## turnermech (Jul 21, 2012)

is your condenser coil clean? your high side pressure looks high. your super heat is a 6 degrees if I am reading your numbers correctly which at first glance seems lower than normal. I would think more like 10. What kind of metering device do you have(txv or piston)? Are you having any prefromace problems or are you just checking the unit. If I was not an experianced tech I would not make any changes to a working unit. Try to clean the out side coil and recheck the system.


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## Doc Holliday (Mar 12, 2011)

Both high and low pressures will increase as refrigerant is added and decrease when removed. 

Here's a good formula for target superheat. Btw, superheat for fixed orifice/piston metering device and subcool for thermostatic expansion valves.

3 x's the wet bulb
- 80 
- ambient temperature (outside temperature)

divided by 2 = what your superheat (piston) should be.

You can search "calculating superheat" on Youtube as well as find that formula all over the web if you want to confirm it.


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## Doc Holliday (Mar 12, 2011)

turnermech said:


> is your condenser coil clean? your high side pressure looks high. your super heat is a 6 degrees if I am reading your numbers correctly which at first glance seems lower than normal. I would think more like 10. What kind of metering device do you have(txv or piston)? Are you having any prefromace problems or are you just checking the unit. If I was not an experianced tech I would not make any changes to a working unit. Try to clean the out side coil and recheck the system.


We all help each other out around here, tech to tech. Ask beenthere how much I bug him!


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## psehorne (Jul 29, 2012)

turnermech said:


> is your condenser coil clean? your high side pressure looks high. your super heat is a 6 degrees if I am reading your numbers correctly which at first glance seems lower than normal. I would think more like 10. What kind of metering device do you have(txv or piston)? Are you having any pereformance problems or are you just checking the unit. If I was not an experienced tech I would not make any changes to a working unit. Try to clean the out side coil and recheck the system.


Turnermech,
Thanks for your reply. Your questions answered below.

The condenser is relatively clean (it was hosed off a few weeks ago), but could be cleaner. I will clean it tomorrow.

I am not sure about the metering device. However, I think it has a piston in cooling mode and TXV in heating mode. The label on the machine gives superheat instructions for cooling mode and subcooling instructions for heat mode. (Is that a clue?). 

I had a problem a couple of days ago. Turned out to be very dirty air filter, but in the process of troubleshooing I checked the pressures and temperatures. At the time I did not know it, but I had a defective low pressure hose on my gauges/manifold. It appeared to need refrigerant; so I added some. Reading were not normal; that is when I discovered the bad hose. I received a new gauge/hose/manifold set yesterday (my old set was ~30 years old). So the measurements I posted here were done with my new gauges/hoses/manifold.

Regarding the 6 degrees superheat. It does 'seem' low, but, again, the chart on the instrument shows that with my outside temp of 105F and air entering evaporator at 62F wet-bulb, the required superheat is even less than 6. The required superheat is off the chart scale below the 5 minimum shown.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Both high and low pressures will increase as refrigerant is added and decrease when removed.
> 
> Here's a good formula for target superheat. Btw, superheat for fixed orifice/piston metering device and subcool for thermostatic expansion valves.
> 
> ...


Doc, 
Thanks for your reply.

I am not seeing any significant change in pressures when adding or removing (a small amount of) refrigerant. They are pretty stable at 70 and 270. 

But I am seeing the temperature of the suction line increase when adding refrigerant and the temperature of the high side decrease when adding refrigerant. Can you comment on this scenario?

And thanks for the formula, but I am using the manufacturer's chart. I will recalculate the superheat requirement using your formula and compare that with Payne's chart.

Thanks,
Paul


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Here's a good formula for target superheat.
> 
> 3 x's the wet bulb
> - 80
> ...


Doc, using your formula I come up with:

[(3 x 62) - 80 - 105] /2 = .5

Hmnnn.... Please comment.

Paul


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## turnermech (Jul 21, 2012)

your temp is increasing when adding refrigerant because you are affecting the pressure temp relationship. 70 psi = around 40 degrees 80= around 50. did not look it up just off top of my head might be a little off. It seems as if you have a txv by what you are describing as your suctions is staying at 70 while I guess you head press is climing. the door of your unit may have a chart for super heat and yes that would be for piston. but this could also been matched with a txv unit when installed. A txv will try to maintain the 70 psi and 40 temp to an extent when overcharging. A piston would not. Super heat is also not bad to check when charging a txv but changes can't be made based on superheat. A txv will adjust to attempt to maintain the super heat. you have to use subcooling. If you have the refrigerant to spare try to remove untill you see the low pressure just start to begain to fall below 70. observe you high side pressure and see if it falls back to a more normal pressure. retake all of your readings.


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## psehorne (Jul 29, 2012)

Pic attached of the Payne superheat-required chart. Notice that 62F wet-bulb and 105 outdoor temp is off the chart.


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## turnermech (Jul 21, 2012)

take the refrigerant out slowly. Allow it to bleed from your liq line through you red hose with the manifold valve into a reclaim cylinder. let it out in small burst allow several min to pass( some times takes as much as 10 min for a change to take place)while checking your pressures and temps between burst. as expensive as r-22 is I dont want you to waste it.


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## Doc Holliday (Mar 12, 2011)

Half a degree superheat would be way too low, even if the formula says it's correct. It would only take another one half of a degree for the vapor to change to liquid and that is the main concern when it comes to superheat and subcooling, making sure the refrigerant stays in it's designated state either to the evaporator or on it's way back from the evaporator to the compressor. It just so happens that we can also determine system charge this way.

What I would do is go back and check the system once it's about 85-90 degrees out, using that formula and see where you stand.

Too little superheat most likely does mean overcharged. What's happening is the system has too much refrigerant, might even still be some liquid on the way out which is not good. Liquid returning to the compressor will eventually kill the compressor. In this scenario liquid is most likely making it way past the piston and cap tubes, all the way into the evaporator. Saturation is most likely not occurring until a third or halfway into the evap and again, floodback would be a serious concern.

Is this an old system or a new one or what? Piston or txv?


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## turnermech (Jul 21, 2012)

psehorne said:


> Pic attached of the Payne superheat-required chart. Notice that 62F wet-bulb and 105 outdoor temp is off the chart.


 if its off the chart it means you cant use the chart. you have to change the inside condition to be able to use the chart.


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## Doc Holliday (Mar 12, 2011)

psehorne said:


> Pic attached of the Payne superheat-required chart. Notice that 62F wet-bulb and 105 outdoor temp is off the chart.


That's because they design them at a nominal operating temperature. What you have is an extreme temperature. Again, go back when it's cooler outside and check it. It'll make sense then.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Is this an old system or a new one or what? Piston or txv?


Unit was installed new in November 2002. It has never caused a problem. The reason I got to checking it is because it quit working a couple of days ago - my fault... filter was very dirty. Unit has not caused a problem, but now that I changed the charge (see previous post where I reported that a defective hose caused me to add refrigerant) I'm concerned that it might be overcharged. 

Rereading the manual I have[on PH10xx-048 (4 ton) and 060 (5 ton)] . It shows metering devices inside and outside as piston. I would assume that is also the case for the -030 (2.5 ton).


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## psehorne (Jul 29, 2012)

turnermech said:


> take the refrigerant out slowly. Allow it to bleed from your liq line through you red hose with the manifold valve into a reclaim cylinder. let it out in small burst allow several min to pass( some times takes as much as 10 min for a change to take place)while checking your pressures and temps between burst. as expensive as r-22 is I dont want you to waste it.


Will take a look at doing this tomorrow.


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## beenthere (Oct 11, 2008)

Most Paynes have a piston in heating mode. Could be piston or TXV in cooling mode. Need to verify which metering device you have before you do anything else with the charge.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> What I would do is go back and check the system once it's about 85-90 degrees out, using that formula and see where you stand.


It's 89F outside right now. I will lower the thermostat, allow the unit to stabilize, and measure the air temp entering the evaporator. I'll convert that to wet-bulb based upon the RH in the house and will consult the chart again.

My hoses are still hooked to the unit; so I can go outside and see what the pressures are and measure the temps.

Will report my findings.


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## psehorne (Jul 29, 2012)

beenthere said:


> Most Paynes have a piston in heating mode. Could be piston or TXV in cooling mode. Need to verify which metering device you have before you do anything else with the charge.


Looks like piston for both modes.


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## psehorne (Jul 29, 2012)

*New measurements with outside temp of 89F*

Here are my measurements with the outside temp now 89F:
Air temperature entering the evaporator (dry bulb) ~74F. 
Wet-bulb arrived at by calculating from above and RH 38% = 74F.
Outdoor air temperature entering condenser (dry-bulb) 89F

According to the chart on the unit the above results in a superheat requirement of 27F

Other pertinent measurements:
High pressure line gauge reading PSI/temp = 231psi/111F
High pressure line actual temperature = 107F (subcooling ~4f)
Suction line gauge reading PSI/temp = 70psi/41F
Suction line actual temperature = 50F (superheat ~9F too low)
Air exiting indoor vents = 54F
Cold air return = 74 (diff = 20F)

Bottom line: 
I am now seeing too little superheat, only 9F.
Suction temp is too low. The chart calls for 68F.
The chart says to add refrigerant. I will do that now, instead of waiting till tomorrow (when it will be 100+F again).

Thanks for everyone's help.

Paul


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## psehorne (Jul 29, 2012)

*Oops! Major mistake*



psehorne said:


> Here are my measurements with the outside temp now 89F:
> Air temperature entering the evaporator (dry bulb) ~74F.
> Wet-bulb arrived at by calculating from above and RH 38% = 74F.
> Outdoor air temperature entering condenser (dry-bulb) 89F
> ...


When I entered the barometric pressure into the wet-bulb calculator I entered 3002 instead of 30.02. The correct wet-bulb is 59F, not 74F. So, the superheat requirement is still off the chart. Darn!

What's a guy to do???


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## Doc Holliday (Mar 12, 2011)

Using the formula I provided it should be 4 degrees.


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## Doc Holliday (Mar 12, 2011)

Once you get it to 4 degrees (with your 59 wet bulb and 89 ambient) take the air temperature at the nearest supply grill to the unit and then the temperature at the return air grill. Let us know the difference between these two temps.

Do not use a laser temperature gun if you have one. Use a thermometer, even one for cooking if you have one.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Once you get it to 4 degrees (with your 59 wet bulb and 89 ambient) take the air temperature at the nearest supply grill to the unit and then the temperature at the return air grill. Let us know the difference between these two temps.
> 
> Do not use a laser temperature gun if you have one. Use a thermometer, even one for cooking if you have one.


Ah! I forgot about your formula.

I added some refrigerant before I discovered my barometric pressure / wet-bulb error.

Current measurements 


Supply vent temperature 55F. Return air 74F. = 19F diff. (Fluke digital thermocouple thermometer).
Suction gauge now 70psi/42F. Suction line temp 49. = 7F superheat
High pressure now up to 290psi.

Paul


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## Doc Holliday (Mar 12, 2011)

With a 59 wet bulb and 89 ambient 4 degrees superheat seems to fit perfectly into that chart, where 4 degrees would be if it were on there.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> With a 59 wet bulb and 89 ambient 4 degrees superheat seems to fit perfectly into that chart, where 4 degrees would be if it were on there.


Yep. I will have to make a point to remember your formula.

So I'm at 7F superheat now. Too much? Do I need to remove some R-22?

Thanks,
Paul


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## psehorne (Jul 29, 2012)

psehorne said:


> Yep. I will have to make a point to remember your formula.
> 
> So I'm at 7F superheat now. Too much? Do I need to remove some R-22?
> 
> ...


And what about the high pressure at 290psi? Too much?


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## Doc Holliday (Mar 12, 2011)

psehorne said:


> Ah! I forgot about your formula.
> 
> I added some refrigerant before I discovered my barometric pressure / wet-bulb error.
> 
> ...



I'd add a bit to get to 4 degrees. I'm not sure why your head pressure is so high but I don't like the low saturation temp, too close for comfort. 

Is your outside unit clean? Can you take a hose to it while it's running? First add a little bit of refrigerant getting it to 4 degrees of superheat and let the system stabilize there for a few minutes. Then run some water all over the heat pump coils as the unit is running, the sides, and watch your head pressure. It should lower substantially. Then watch it climb back up as the unit dries up. Then see where the pressures come to rest at once the unit is completely dry. 

After it's dry take the superheat calculation again, where it's actually at (is it still at 4?) and where it should be as the outside temperature may have cooled down a bit.


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## Doc Holliday (Mar 12, 2011)

psehorne said:


> Yep. I will have to make a point to remember your formula.
> 
> So I'm at 7F superheat now. Too much? Do I need to remove some R-22?
> 
> ...


Adding refrigerant decreases superheat. Add some to bring it down to 4.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Adding refrigerant decreases superheat. Add some to bring it down to 4.



You just cleared up one of my misconceptions mentioned in my original post. Your statement is consistent with the statement on Payen's charging procedure. "Add refrigerant to lower suction line temperature." (decreasing superheat).

I'll add some more R-22 and hose down the unit. Will report back. 

It's after midnight here in Texas. I don't know what timezone you are in, but in any event I appreciate you staying up with me. You may not hear from me again tonight. But tomorrow I will update you. Thanks for all your help.

Paul


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## Doc Holliday (Mar 12, 2011)

pse, I gotta go to sleep, work early in the morning. Try the water trick to bring down the head pressure. A high head pressure is a sign of a clogged condenser coil, may need to be taken apart and chemically cleaned. 

Good luck. I'll check back in after work tomorrow.


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## Doc Holliday (Mar 12, 2011)

psehorne said:


> You just cleared up one of my misconceptions mentioned in my original post. Your statement is consistent with the statement on Payen's charging procedure. "Add refrigerant to lower suction line temperature." (decreasing superheat).
> 
> I'll add some more R-22 and hose down the unit. Will report back.
> 
> ...


:thumbup:

I'm in Houston.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Try the water trick to bring down the head pressure. A high head pressure is a sign of a clogged condenser.


After following your instructions I have the following to report:

OUTSIDE:
Suction gauge psi/temp 70/42
Suction line temp 46
Resulting in superheat of 4F.

INSIDE:
Supply vent temp 54F
Return air temp 73F (diff 19)
Wet-bulb 58.

The above inside readings did not change from previous readings. However, outside air temp had dropped to 86F. Still your superheat formula called for 4F.

Unfortunately after adding R-22 to bring the suction line temp down the head pressure settled in at 330 PSI - even after hosing down the condenser (in the dark with a flash light; so I will take a look at it again by the morning light).


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## beenthere (Oct 11, 2008)

May have a restricting LLFD.


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## turnermech (Jul 21, 2012)

stop adding refrigerant you are overcharged 270,290 or 330 too high. it is time to start taking it out either as I earlier described or take it all out and weigh it in. Grossly overcharged systems will act strange and to all but the most experiance techs seem right or even low and cause more charging. You have most likely a flooded indoor coil. Needs to be gas not liq.


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## ben's plumbing (Oct 6, 2011)

you have a restriction....thats my call...


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## turnermech (Jul 21, 2012)

ben's plumbing said:


> you have a restriction....thats my call...


 I would not think so with 19 temp split. 

remove refrigerant unitl you drop below 70 psi suction. then carge back to 8 to 12 super heat. Recheck your data.

I think your wet buld reading is unaccurate some how.


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## ben's plumbing (Oct 6, 2011)

I don't think his reading are right somehow...but Iam not there I'll wait and see...what he comes up with...thanks ben


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## beenthere (Oct 11, 2008)

turnermech said:


> I would not think so with 19 temp split.
> 
> remove refrigerant unitl you drop below 70 psi suction. then carge back to 8 to 12 super heat. Recheck your data.
> 
> I think your wet buld reading is unaccurate some how.


A system with a restriction can be over charged enough to easily get a 19° split across the inside coil.

Of course with a 105° outdoor temp, 290 is not out of line on many systems.


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## turnermech (Jul 21, 2012)

We have had temp 95-100 here most of the summer I have not seen a modern system running correctly whit liq line press of even 270 yet alone 290/330. Really old unit yes. Panye I don't think has been around that long for me to call them old.

I could be wrong but I can't see a restriction in a refrigerant circuit still having 19 split. All I can say is I have not seen one yet. OP has been adding refrigerant wiht a dirty filter his own statement. THE UNIT IS OVERCHARGED. 

If it is overcharged, I would strongly suggest he get it out. 105 degrees 330 psi, soon he will need a compressor.


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## psehorne (Jul 29, 2012)

It is now the hottest part of the day. Head pressure has climbed to 400 PSI. I am removing R-22. Will report back.


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## beenthere (Oct 11, 2008)

turnermech said:


> We have had temp 95-100 here most of the summer I have not seen a modern system running correctly whit liq line press of even 270 yet alone 290/330. Really old unit yes. Panye I don't think has been around that long for me to call them old.
> 
> I could be wrong but I can't see a restriction in a refrigerant circuit still having 19 split. All I can say is I have not seen one yet. OP has been adding refrigerant wiht a dirty filter his own statement. THE UNIT IS OVERCHARGED.
> 
> If it is overcharged, I would strongly suggest he get it out. 105 degrees 330 psi, soon he will need a compressor.



A LLFD with a 30 PSIG PD across it will give readings like he is posting. Been to a few places where the neighbor that "use to do HVAC" topped off the charge. Only by checking suction pressure, not by looking at the whole charge.


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## beenthere (Oct 11, 2008)

psehorne said:


> It is now the hottest part of the day. Head pressure has climbed to 400 PSI. I am removing R-22. Will report back.


You should recover the entire charge. And weight it back in.


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## ben's plumbing (Oct 6, 2011)

the op should if he has the equiptment remove all freon...vac the system down weigh in the correct charge ....and start from there.....I think there is to many unanswered questions and reading don't add up... safest way ...:yes:


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## psehorne (Jul 29, 2012)

turnermech said:


> OP has been adding refrigerant wiht a dirty filter his own statement.


New, clean filter was installed a couple of days ago.


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## psehorne (Jul 29, 2012)

ben's plumbing said:


> the op should if he has the equiptment remove all freon...vac the system down weigh in the correct charge ....and start from there.....I think there is to many unanswered questions and reading don't add up... safest way ...:yes:


Thanks to all of you for your input.

My hangar was burglarized a few months ago. One of the things that was taken was my Promax RG5000. I had not replaced it until today. I have one that will ship to me tomorrow, but I won't have it for several days. So I can't entirely purge the system with what I have on hand. But I can probably bleed it down a bit.


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## psehorne (Jul 29, 2012)

BTW, the manual I have on the Payne PH10 shows a scroll compressor for the model -048 (four ton) and -060 (five ton). No mention is made of the -030 (2.5 ton) that I have. I have not found a more pertinent manual.

If this unit has a scroll compressor does it make any difference in the how the readings are interpreted. My guess is 'no'.


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## psehorne (Jul 29, 2012)

ben's plumbing said:


> the op should if he has the equiptment remove all freon...vac the system down weigh in the correct charge ....and start from there.....I think there is to many unanswered questions and reading don't add up... safest way ...:yes:





beenthere said:


> You should recover the entire charge. And weight it back in.



I'm heading in that direction, but some equipment I need will not be here for a few days.

Thanks for your input.


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## ben's plumbing (Oct 6, 2011)

psehorne said:


> Thanks to all of you for your input.
> 
> My hangar was burglarized a few months ago. One of the things that was taken was my Promax RG5000. I had not replaced it until today. I have one that will ship to me tomorrow, but I won't have it for several days. So I can't entirely purge the system with what I have on hand. But I can probably bleed it down a bit.


 you could try it ...bleed it where???...safest bet recover freon..vac it down weigh in charge.....start over:thumbsup:


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## psehorne (Jul 29, 2012)

ben's plumbing said:


> ...bleed it where???..


I'm assuming that without a recovery vacuum pump I can still get some refrigerant to flow into my recovery tank (which is totally empty at present) just from the high head pressure. Is this just wishful thinking?


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## psehorne (Jul 29, 2012)

turnermech said:


> I think your wet buld reading is unaccurate some how.


To determine wet-bulb:


I meaure the temperature of the air going into the evaporator (at the cold air return vent. I haven't seen in difference here than at the evaporator filter about six foot away) with a Fluke thermocouple thermometer that I trust.
I measure the relative humidity with two analog/dial hygrometers. Don't know how accurate they are, but they agree within a % or so. (I have a digital tool ordered.)
I use these numbers and the barometric pressure reading obtained by calling the local airport ASOS number to input on the form at http://easycalculation.com/weather/dewpoint-wetbulb-calculator.php


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## turnermech (Jul 21, 2012)

When I supect overcharged system (not saying that is it as others may disagree but that would be my guess without being there) I purge into reclaim cylinder from liq line. due it in short burst. allow at least 5 min between burst may be even 10 to be sure. check the system after waiting the 5/10 min. repeat the procedure unit your suction starts to fall. If you are overcharged you will let a lot out any suction will remain the same or near the same. you will see the high pressure drop as you let it out. Once you bring the low side down past where it should be you can then charge the system. Forget the chart as I think you wet buld is off somehow. I also supect you have a txv but you say you don't and I am not there. A piston metering device would typically increase the suction pressure as the discharge pressure increased. I think you are extreemly overcharged and your indoor coil is all liq vs gas. Once you are sure your charge is low then begain recharging slowly. Get the super heat to 8 to 12.


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## turnermech (Jul 21, 2012)

psehorne said:


> To determine wet-bulb:
> 
> 
> I meaure the temperature of the air going into the evaporator (at the cold air return vent. I haven't seen in difference here than at the evaporator filter about six foot away) with a Fluke thermocouple thermometer that I trust.
> ...


 try to wrap your same theromocouple with wet rag and stick it in the return see what you get that way


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## psehorne (Jul 29, 2012)

psehorne said:


> BTW, the manual I have on the Payne PH10 shows a scroll compressor for the model -048 (four ton) and -060 (five ton). No mention is made of the -030 (2.5 ton) that I have. I have not found a more pertinent manual.
> 
> If this unit has a scroll compressor does it make any difference in the how the readings are interpreted. My guess is 'no'.


I found a manual on the net that provides information on the -030. It has a reciprocating compressor, not scroll. 

Under Optional Equipment it list 


TXV Kits (Hard Shutoff)
TXV Kits (RPB)
I am sure this unit has no optional equipment. It did not even come with a starting capacitor which the manual says is required if TXV is installed.

Under Metering Devices the manual also list Indoor Piston Size and Outdoor Piston Size. 

Conclusion:
Metering is by piston and compressor is reciprocating.


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## turnermech (Jul 21, 2012)

psehorne said:


> I'm assuming that without a recovery vacuum pump I can still get some refrigerant to flow into my recovery tank (which is totally empty at present) just from the high head pressure. Is this just wishful thinking?


exactly how to do it. use the liq line service port. (proably what you mean by high head pressure port). you could actually empty nearly the whole thing this way.


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## beenthere (Oct 11, 2008)

Use a bathroom sale.


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## Doc Holliday (Mar 12, 2011)

Still no luck, huh? Sucks. Best bet would be what these guys have been saying, recover and weigh in charge. What is the system charge? It should say on the service panel.

And btw, that weigh in charge is good for the compressor, about 15' of line set and the evaporator. Don't be surprised if you have to add to that weight as you will most likely have to with a longer line set. You'll be dealing with superheat again.

If it were me I'd simply pump the system down, remove shraeder cores, shoot some nitrogen into the line by way of ONE side, either low or high and again, with the shraeder cores removed, and watch the other side's needle to make sure it comes up as well. Then close off the open side and open the other and back and forth to make sure there is no restriction. In other words, adding through one side the other side should rise as well. If not or noticeably too slow, restriction.

Let the nitrogen sit in there for about ten minutes to make sure there aren't any leaks which I wouldn't believe there to be at this point but still...then I'd remove the hoses from both valves and let the nitrogen fly out (taking any possible debri with it), put back in the shraeder cores, vacuum, open valves, turn system on and see what happens.

Then if still the same is when I'd get to recovering and weighing in the charge. I as well don't believe it to be overcharged but rather a restriction at this point.


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## Doc Holliday (Mar 12, 2011)

beenthere said:


> Use a bathroom sale.


You didn't tell me that, you said refrigerant scale. That was like over $200.00. 

Hmmff. :thumbup:

Best dang tool I've purchased, well worth every cent.


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## beenthere (Oct 11, 2008)

Doc Holliday said:


> You didn't tell me that, you said refrigerant scale. That was like over $200.00.
> 
> Hmmff. :thumbup:
> 
> Best dang tool I've purchased, well worth every cent.


LOL... Sometimes you gotta improvise.


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## turnermech (Jul 21, 2012)

I would guess a digital bathroom scale would be fairly cheap. And pretty good in a pinch. I was going to suggest a bathroom scale if he asked.

if you pump it all down in your empty reclaim tank weight it empty and after you pump it into the tank. that will tell you if you are overcharged and by how much. If you are not overcharged look for other problem before recharging with the scale.

let us know the amount you take out if you attempt to remve all you can by pumping the refrigeant out with your compressor through the liq line.


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## psehorne (Jul 29, 2012)

turnermech said:


> I would guess a digital bathroom scale would be fairly cheap. And pretty good in a pinch. I was going to suggest a bathroom scale if he asked.


I have digital bathroom scale but also have a Ohaus dual beam balance that goes to ~45 lbs (20+ kilos), and it is very accurate.


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## beenthere (Oct 11, 2008)

psehorne said:


> I have digital bathroom scale but also have a Ohaus dual beam balance that goes to ~45 lbs (20+ kilos), and it is very accurate.


That scale is ok if your cylinder is a small 30 pound cylinder, and you aren't over charged by a lot.


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## JJboy (Oct 12, 2010)

http://www.ebay.com/itm/New-110lbs-...-Scale-oz-Postal-Fishing-Weight-/390435321155

:thumbsup:


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## psehorne (Jul 29, 2012)

JJboy said:


> http://www.ebay.com/itm/New-110lbs-...-Scale-oz-Postal-Fishing-Weight-/390435321155
> 
> :thumbsup:


Bought it. Thank you.


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## psehorne (Jul 29, 2012)

turnermech said:


> When I supect overcharged system (not saying that is it as others may disagree but that would be my guess without being there) I purge into reclaim cylinder from liq line. due it in short burst. allow at least 5 min between burst may be even 10 to be sure. check the system after waiting the 5/10 min. repeat the procedure unit your suction starts to fall. If you are overcharged you will let a lot out any suction will remain the same or near the same. you will see the high pressure drop as you let it out. Once you bring the low side down past where it should be you can then charge the system. Forget the chart as I think you wet buld is off somehow. I also supect you have a txv but you say you don't and I am not there. A piston metering device would typically increase the suction pressure as the discharge pressure increased. I think you are extreemly overcharged and your indoor coil is all liq vs gas. Once you are sure your charge is low then begain recharging slowly. Get the super heat to 8 to 12.


After removing some refrigerant a couple of times, last evening while outside temp was still over 100 I ended up with Suction Pressure 70 and Liquid Line Pressure 285. This morning with outside temp 78, I have Suction Pressure 60 and Liquid Line Pressure 215.

Indoor wet-bulb into the evaporator is 52. Superheat is off the Payne chart and -1 using Doc's formula. 

Suction Pressure 60 equates to 36F. Measured Suction Line temp is 38, resulting in 2F Superheat. Not sure if I am under charged yet or not, but at least out of danger. My Promax RG5000 ships today. Should be here around Wednesday. So I am going leave things as they are, now that I am out of the danger zone, until the Promax arrives.

Paul 

The house is a cold 70F.


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## psehorne (Jul 29, 2012)

turnermech said:


> try to wrap your same theromocouple with wet rag and stick it in the return see what you get that way


I actually have a wet-bulb thermocouple on its way to me. Shipped last week via USPS. Should be here any day now. 

I also have a digital Temp/RH meter on its way here. Also shipped last week.

Will report my findings.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Still no luck, huh? Sucks. Best bet would be what these guys have been saying, recover and weigh in charge. What is the system charge? It should say on the service panel.
> 
> And btw, that weigh in charge is good for the compressor, about 15' of line set and the evaporator. Don't be surprised if you have to add to that weight as you will most likely have to with a longer line set. You'll be dealing with superheat again.
> 
> ...


Thanks for the suggestion Doc. Unfortunately I don't have nitrogen; and I just checked with a local welding supply store, and, although they have nitrogen and rent tanks, they don't rent the ~$125 regulator. I'll look into this to determine what other alternatives are available for nitrogen.


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## turnermech (Jul 21, 2012)

psehorne said:


> After removing some refrigerant a couple of times, last evening while outside temp was still over 100 I ended up with Suction Pressure 70 and Liquid Line Pressure 285. This morning with outside temp 78, I have Suction Pressure 60 and Liquid Line Pressure 215.
> 
> Indoor wet-bulb into the evaporator is 52. Superheat is off the Payne chart and -1 using Doc's formula.
> 
> ...


I still am having some trouble with your reading. suction pressure of 60 with line temp of 38. something seems wrong. with a suction pressure of 60 you would seem to be low on charge (but please don't add more) you would be 36 at the start of the coil but to be 38 at the suction line service valve can't in my mind be correct. are you taking this temp near the low side line set port (like with in a few feet)? 
Try to test your thermometer by placing it in a water ice mixture and see if you read 32. Test you gauges by checking the pressure in your R-22 tank and then testing the temp of the tank (once you prove your thermometer). then use P/T chart to see if you gauges are correct. test both gauges


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## psehorne (Jul 29, 2012)

turnermech said:


> I still am having some trouble with your reading. suction pressure of 60 with line temp of 38. something seems wrong. with a suction pressure of 60 you would seem to be low on charge (but please don't add more) you would be 36 at the start of the coil but to be 38 at the suction line service valve can't in my mind be correct. are you taking this temp near the low side line set port (like with in a few feet)?
> Try to test your thermometer by placing it in a water ice mixture and see if you read 32. Test you gauges by checking the pressure in your R-22 tank and then testing the temp of the tank (once you prove your thermometer). then use P/T chart to see if you gauges are correct. test both gauges


For measuring the suction line temperature I have been using a digital infrared thermometer. I couldn' seem to get good contact with a thermocouple strapped to the pipe with velcro.

I have set up a ice water bath and have three thermocouples in it connect to two instruments. The closest any of them read to 32 is 33.2. However, the infrared reads 32 when held about three inches above the water bath. It read a degree or two less when held really close; presumably because it it measuring an ice cube. At three inches away the pattern is presumably broad enough to capture the average of water and ice cubes and I believe is more likely to reflect the correct temperature.

Bottom line the infrared thermometer that I have been using appears to be accurate. However, I will fashion some type of clamp other than velcro to attache a thermocouple and see what reading I get. (Keep in mind that all three thermocouples and instruments they are attached to consistently read higher than 32. It is hard to get consistent reading. Stirring the water bath changes the readings - varying from 33.2 to ~35)

Once again. thanks for your staying power. This experience has been very educational and enjoyable - despite the wild good chase adding R-22 when the system was already overcharged. No one is at fault here. As you mentioned it is very easy to be fooled when reading are distorted when a system is overcharged.

Paul


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## psehorne (Jul 29, 2012)

My sling thermometer/psychrometer arrived today. I will compare its results against the hygrometers that I have (regarding relative humidity). As you all know up to now I have been using temp and RH to determine wet-bulb.


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## turnermech (Jul 21, 2012)

any mixture of water and ice will be 32 every drop of water and every inch of ice. this will stay constant until all ice is melted or all water is frozen. This is handy fact of science so mixing should not matter, ice temp will be same as water temp. You would need to let the two adjust to one another several min before testing temp 

What is your temp split across you evap once you have removed refrigerant? Did you attemp to check the gauges? If you decied not to remove all the charge and weigh back in, I would continue to remove refrigerant until My temp split fell below 15. then I would charge to 8 to 12 super heat.


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## turnermech (Jul 21, 2012)

psehorne said:


> My sling thermometer/psychrometer arrived today. I will compare its results against the hygrometers that I have (regarding relative humidity). As you all know up to now I have been using temp and RH to determine wet-bulb.


 I have never need to use one in my career as of yet. i bought one years ago and never used it before one thermomete broke. I fixed it and it somehow broke again.

When I need to know wet buld I put a digital thermometer in the return duct of a running system with wet cloth on the sensing probe.


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## psehorne (Jul 29, 2012)

psehorne said:


> My sling thermometer/psychrometer arrived today. I will compare its results against the hygrometers that I have (regarding relative humidity). As you all know up to now I have been using temp and RH to determine wet-bulb.


Sling psychrometer provides the following readings:


Dry bulb 25C
Wet bulb 17C
wet bulb depression is 8C

The chart says this is [EDIT:50% RH should be 44%]. I find this hard to believer. Our local airport is reporting 


Temp 31C
Dew Point 15C
Barometric Pressure 29.94
which translates to 38% RH according to http://easycalculation.com/weather/wetbulb-humidity-calculator.php and my Psychrometric Chart.

I find it hard to believe that the humidity inside my air conditioned house is higher than the outdoor humidity.

However, if I use the above 17C (63F) and the current outdoor temperature of 88F, the Payne Chart shows required superheat of ~8F.
Current measurements at the heat pump are:
Suction Line psi/temp: 65/40
Suction Line temp: 45
Superheat: 5

I think from what I have learned this indicates that I am still overcharged a bit. Correct?


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## psehorne (Jul 29, 2012)

turnermech said:


> I have never need to use one in my career as of yet. i bought one years ago and never used it before one thermomete broke. I fixed it and it somehow broke again.
> 
> When I need to know wet buld I put a digital thermometer in the return duct of a running system with wet cloth on the sensing probe.


I have a wet-bulb thermocouple on its way to me. In the mean time I can try your method, which some, perhaps you, suggested earlier in this thread. I just had not gotten around to it yet. (Besides, being fond of vintage technology, I just had to have a sling psychrometer.

I could have mentioned early on that my primary reason for venturing into this DIY HVAC journey is mostly because I have always had a thirst for knowledge and wanted to understand how these systems work. (Of course, that is not the reason I gave my wife. :thumbup I have enjoyed every minute of the time I have put into this 'hobby'. Maybe that helps you understand why I do not mind spending good money on old technology. But I also have modern equipment and cross-check things. (just the techie in me... I gotta do it.) And by the way, my wife and I have been married long enough that she has caught on.... and she knows I need a 'hit' every so often; so she now knows that all the things I buy are not necessary ... but she approves because she understands me.


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## psehorne (Jul 29, 2012)

turnermech said:


> any mixture of water and ice will be 32 every drop of water and every inch of ice. this will stay constant until all ice is melted or all water is frozen. This is handy fact of science so mixing should not matter, ice temp will be same as water temp. You would need to let the two adjust to one another several min before testing temp
> 
> What is your temp split across you evap once you have removed refrigerant? Did you attemp to check the gauges? If you decied not to remove all the charge and weigh back in, I would continue to remove refrigerant until My temp split fell below 15. then I would charge to 8 to 12 super heat.


I would think that if the temperature in my freezer is -10F, that would be the temperature of the ice until it is warmed up by the tap water I put in the container along with it.


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## psehorne (Jul 29, 2012)

turnermech said:


> What is your temp split across you evap once you have removed refrigerant? Did you attemp to check the gauges? If you decied not to remove all the charge and weigh back in, I would continue to remove refrigerant until My temp split fell below 15. then I would charge to 8 to 12 super heat.


Current split (after removing R-22) is 17F

I have checked the gauges - just a few minutes ago:
Suction Line Pressure/Temp: 65psi/40F
Suction Line Temp Measured: 45
Superheat: 5
High Side: 240 PSI
OAT: 88F
Wet-Bulb: 17C/63F


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## beenthere (Oct 11, 2008)

Yep, still sounds like its over charged.


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## Doc Holliday (Mar 12, 2011)

psehorne said:


> Current split (after removing R-22) is 17F
> 
> I have checked the gauges - just a few minutes ago:
> Suction Line Pressure/Temp: 65psi/40F
> ...


I'd have to agree with BT, overcharged. Using the formula from earlier and plugging in your newest numbers the superheat would need to be 10(.5)f. You're close, very.

63 wb x's 3 = 189
- 80 = 109
- oat 88 = 21
/ 2 = 10.5 superheat.


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## psehorne (Jul 29, 2012)

Sorry, I forgot to answer these question earlier.



turnermech said:


> Are you taking this temp near the low side line set port (like with in a few feet)?


I am taking the suction line temp about 3 inches from where the copper tubing enters the heat pump housing... about 3 inches from where the blue hose is attached.



turnermech said:


> Test you gauges by checking the pressure in your R-22 tank and then testing the temp of the tank (once you prove your thermometer). then use P/T chart to see if you gauges are correct. test both gauges


My gauge set is brand new Yellow Jacket, just received a few days ago. Of course, that doesn't mean they couldn't be reading wrong. But I really doubt that. (As mentioned in one of my earlier posts, my ~30 year old gauge set had a problem; I decided it was time for a completely new set, particularly since a set of hoses cost almost as much as the complete set up.) I will, however, do as you suggest and report back.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> I'd have to agree with BT, overcharged. Using the formula from earlier and plugging in your newest numbers the superheat would need to be 10(.5)f. You're close, very.
> 
> 63 wb x's 3 = 189
> - 80 = 109
> ...


Yes, as well as consulting Payne's chart, after my post reporting those numbers I remembered to compute superheat with your formula.


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## psehorne (Jul 29, 2012)

psehorne said:


> Sling psychrometer provides the following readings:
> 
> 
> Dry bulb 25C
> ...


I took my sling thermometer and one of my analog dial-type hygrometers outside last evening. Indoors the analog hygrometer was showing about 35% RH; outdoors it went to 42%. Although the readings on the sling thermometer changed from 25C/17C (50% RH) to 31/22 (45% RH), the RH went down instead of up! Go figure!

So I now don't trust my thermocouple or sling thermometers. The only instrument that seems to provide accurate temperature readings is my digital infrared thermometer.


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## psehorne (Jul 29, 2012)

psehorne said:


> I took my sling thermometer and one of my analog dial-type hygrometers outside last evening. Indoors the analog hygrometer was showing about 35% RH; outdoors it went to 42%. Although the readings on the sling thermometer changed from 25C/17C (50% RH) to 31/22 (45% RH), the RH went down instead of up! Go figure!
> 
> So I now don't trust my thermocouple or sling thermometers. The only instrument that seems to provide accurate temperature readings is my digital infrared thermometer.


Although I still don't know the accuracy of my analog hygrometers, at least the one I took outside moved in the correction direction; it showed an increase in humidity over indoor humidity. And both of them read a few % less than the RH being reported by the local airport ASOS. (Note: Airports report current temperature and dew point - requiring conversion to RH)


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## beenthere (Oct 11, 2008)

Not uncommon for the outdoor RH to be lower then the indoor RH in the summer.


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## psehorne (Jul 29, 2012)

beenthere said:


> Not uncommon for the outdoor RH to be lower then the indoor RH in the summer.


Hmnnn.... didn't know that. I do believe that there is little to be wrong that would cause an actual wet-bulb thermometer to read incorrectly. So things are starting to fall into place.


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## beenthere (Oct 11, 2008)

At 70°F and 50%RH, the air contains 85.2378 grains of moisture per pound. Heat that air up to 90°F with the same 85.2378 grains per pound, and the RH is now only 40.2%


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## psehorne (Jul 29, 2012)

beenthere said:


> At 70°F and 50%RH, the air contains 85.2378 grains of moisture per pound. Heat that air up to 90°F with the same 85.2378 grains per pound, and the RH is now only 40.2%


That may be... under controlled circumstances.... but...
My a/c is removing moisture from the air via the evaporate; so I suspect that my indoor humidity is lower than outdoors. In addition when taken outside my analog hygrometer showed an increase in humidity... as expected.

You and the other member of the forum have been very helpful in educating me. I don't want this to turn into a debate of scientific facts; so please don't take offense to my disagreeing with you on this topic. Your HVAC knowledge and experience are very important to me and much appreciated. 

I disagreed with turnermech on the temperature of ice. 


turnermech said:


> any mixture of water and ice will be 32 every drop of water and every inch of ice. this will stay constant until all ice is melted or all water is frozen.





psehorne said:


> I would think that if the temperature in my freezer is -10F, that would be the temperature of the ice until it is warmed up by the tap water I put in the container along with it.


I hope he didn't take offense either; again, his input has been very useful, right on target, and much appreciated.


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## turnermech (Jul 21, 2012)

no offence to disagree of water ice but your not think correctly. the water can not be lower than 32 or it will be ice. the ice can not be warmer than 32 or it will be water. the two together have to be 32 untill all ice is melted or all water is frozen. That is undisputable fact. No matter what temp the ice is when enters the water. for the ice to cool the water to even 31.99 all water would have to change state to a soild (ice in this case). for the water to increase in temp the ice would need to change state from solid to liq. The two when mixed will need very short amount of time to adjust to each other but no way around them being 32.

another problem is 65 = 37 or so degrees in the R-22 Pressure temp relationship not the 40 degrees that I think you posted. 40 = right aroulnd 68 psi. Not that big of a deal but your super heat is lower than you posted.


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## beenthere (Oct 11, 2008)

psehorne said:


> That may be... under controlled circumstances.... but...
> My a/c is removing moisture from the air via the evaporate; so I suspect that my indoor humidity is lower than outdoors. In addition when taken outside my analog hygrometer showed an increase in humidity... as expected.


Actually, thats the way it works in the real world also. 

If you take 20°f air with a RH of 70%, and heat it to 70°F, its RH will only be 9.7%.

The warmer air is, the more moisture it can hold. 

You should calibrate all of your hygrometers.


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## psehorne (Jul 29, 2012)

turnermech said:


> no offence to disagree of water ice but your not think correctly. the water can not be lower than 32 or it will be ice. the ice can not be warmer than 32 or it will be water.


This topic started because I stated that when I held the infrared thermometer very close to the surface of the ice water mix it read lower than 32 - actually 30 degrees at times and 31 at other times depending on exactly where it was pointed. What I was stating is that the infrared thermometer's pattern was tight enough when held close I could not keep from pointing at an ice cube (and thus reading the temperature of the ice cube which I still believe can be less than 32 degrees, much less) and when held further away the pattern spread out enough to read the 'average' temperature of the area that pattern was spread over (and thus was 32 degrees).


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## Doc Holliday (Mar 12, 2011)

Infrared thermometers, commonly known as lasers, refract light. They need to be within a range of something like 6 to 8 feet from the object to properly take it's temperature. If an object is dirty than that refracted temperature of the dirt is what is being tested. They can only test surface.

I never use 'em once I found that out.


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## psehorne (Jul 29, 2012)

turnermech said:


> ...another problem is 65 = 37 or so degrees in the R-22 Pressure temp relationship not the 40 degrees that I think you posted.


Ah! You are correct. I made a mistake.... imagine that, and I had such a perfect record.... Thanks for pointing that out to me.

I am finding these new gauges harder to read than my old ones, because the low pressure gauge goes all the way up to 500 PSI (to protect the gauge from damage by high pressure) while my old ones only went to 150 PSI, so the resolution is not as good with the new gauges.



turnermech said:


> Not that big of a deal but your super heat is lower than you posted.


Actually the superheat is higher than I posted.


psehorne said:


> Suction Line psi/temp: 65/40
> Suction Line temp: 45
> Superheat: 5


Should have posted


Suction Line psi/temp: 65/37
 Suction Line temp: 45
 Superheat: 8

I just checked. Current readings are:


Suction Line psi/temp: 70/42
 Suction Line temp: 50 (still using infrared thermometer)
 Superheat: 8
Wet-Bulb: 65
Required Superheat: 8 per Payne chart, 10 per the formula
OAT: 95
 So things look pretty good. However, I will do as you suggested and remove refrigerant until system is obviously undercharged and then add it back until proper superheat is obtained.


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## psehorne (Jul 29, 2012)

beenthere said:


> You should calibrate all of your hygrometers.


The hygrometers I have are the inexpensive (<$10) analog, dial-type that you might find in a cigar humidor. I have a digital one ordered. It has shipped and should be here within the next couple of days.


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## Doc Holliday (Mar 12, 2011)

psehorne said:


> Ah! You are correct. I made a mistake.... imagine that, and I had such a perfect record.... Thanks for pointing that out to me.
> 
> I am finding these new gauges harder to read than my old ones, because the low pressure gauge goes all the way up to 500 PSI (to protect the gauge from damage by high pressure) while my old ones only went to 150 PSI, so the resolution is not as good with the new gauges.
> 
> ...


You're 2 degrees off/overcharged with those numbers. Get you some real tools and quit wasting our time! 

Just messing with you.


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## psehorne (Jul 29, 2012)

Doc Holliday said:


> Get you some real tools and quit wasting our time!


Exactly what I've been thinking.

I was concerned when I started this thread that I might just be a nuisance to your pros, but I think you actually enjoy this.... at times.:yes:


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## psehorne (Jul 29, 2012)

psehorne said:


> Thanks for the suggestion Doc. Unfortunately I don't have nitrogen; and I just checked with a local welding supply store, and, although they have nitrogen and rent tanks, they don't rent the ~$125 regulator. I'll look into this to determine what other alternatives are available for nitrogen.


Ah! Guess what. I can use one of the regulator off of my oxy/acetylene tanks. I'll take a look tomorrow to determine what adapter might be needed to use it with my HVAC set up.

So this system may get a nitrogen bath after all. I can rent a tank for $6/mo and ~$20 to fill it.


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## psehorne (Jul 29, 2012)

beenthere said:


> Not uncommon for the outdoor RH to be lower then the indoor RH in the summer.





beenthere said:


> At 70°F and 50%RH, the air contains 85.2378 grains of moisture per pound. Heat that air up to 90°F with the same 85.2378 grains per pound, and the RH is now only 40.2%





beenthere said:


> Actually, thats the way it works in the real world also.
> 
> If you take 20°f air with a RH of 70%, and heat it to 70°F, its RH will only be 9.7%.
> 
> ...


I think I have not been listening to you. I've read your words but not analyzed the meaning. I think I now understand. As an exercise I made the following assumptions and consulted my psychrometric chart.



The temperature of the air passing over the evaporator is reduced to below the dew point as evidenced by condensation on the evaporator.
Therefore this air is now at 100% RH.
Using 55F (typical reading I see from my supply vent) and 100% RH, I consulted my psychrometric chart and determined that the lbs of moisture per lb of dry air would be .009.
At 75F cold air return temp .009 translates to 50% RH - agreeing with my sling thermometer - and is higher than the outdoor humidity.


I may be slow.... but (I think) I do eventually catch on.:thumbup:


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## psehorne (Jul 29, 2012)

psehorne said:


> I think I have not been listening to you. I've read your words but not analyzed the meaning. I think I now understand. As an exercise I made the following assumptions and consulted my psychrometric chart.
> 
> 
> 
> ...


Just for grins I held the sling thermometer in front of the supply vent. The readings were:


Dry Bulb: 10C
Wet Bulb: 9C

This translates to about 87% RH. Not 100% RH but pretty close.


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## beenthere (Oct 11, 2008)

psehorne said:


> Just for grins I held the sling thermometer in front of the supply vent. The readings were:
> 
> 
> Dry Bulb: 10C
> ...


80%RH+/-5% leaving the evap coil is normal. Much higher would generally indicate a low air flow problem.


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## psehorne (Jul 29, 2012)

Just reporting back in since you haven't heard from me in a couple of days.

I picked up a rebuilt Nitrogen regulator from a local supply store. I have a Nitrogen tank on its way to me. Should be here on Tuesday. So I will be taking your advice to flush out the system with Nitrogen after all.

My Promax RG5000 arrived today, replacing the one that was stolen. I installed a new filter dryer on it. I already have all the other equipment that I need (gauges, hoses, recovery tank, R22).

Since a few days ago I removed enough R22 to get the LL pressure down to a tolerable level and my compressor is now out of danger, I will not be doing anything more until the Nitrogen tank arrives. At the time I will remove all R22 and flush with Nitrogen.

_*I have one question:*_ If I decide to put in new R22 I assume that I will need to add oil separately (before adding R22) because I am under the impression that R22 does not come premixed with oil. I have a tank of R22 that is nearly full, and I haven't needed refrigerant for several years; so after the current exercise I probably won't need it again for years. So putting in new R22 instead of reinstalling the old recovered R22 is not a financial concern for me. There won't be any current out-of-pocket expense. I'm just assuming that there may be some contaminants in the old R22 (even though it will pass through the brand new filter dryer that I installed on the Promax RG5000 today) and that new would be better. Your thoughts? Should I just reinstall the recovered refrigerant, or since adding new is not a financial concern for me, should I install new R22?

Thanks,
Paul


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## beenthere (Oct 11, 2008)

Reuse the recovered R22.


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## Doc Holliday (Mar 12, 2011)

A filter drier is not a purifier. It's purpose is to it catch heavy particles to prevent your refrigerant metering device from being clogged up.


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## psehorne (Jul 29, 2012)

Reporting in:

Today I received my Nitrogen tank. I had it filled and followed your suggestions.



I recovered the R22 into my recovery tank using my Promax RG5000.
I removed the Schrader valves.
I then introduced Nitrogen into the high side of the system and confirmed pressure on the low side. I then allowed the Nitrogen to flush out the system via the low side port.
I then introduced Nitrogen into the low side and confirmed pressure on the high side, and then allowed the Nitrogen to flush out the system via the high side port.
I installed new Schrader valves.
With 89F air entering the condenser and 61F inside wet-bulb the charts called for 5-7F superheat (depending on whose chart or forula is consulted). I gradually charged the system in steps with 30 minute settling time in between steps and ended up with 6-7F superheat (70psig/41F and 47-48F pipe temperature).

I plan on checking it in a couple of days.

Thanks for all your help.


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