# Senville miniSplit - charging procedure



## dave438 (Sep 10, 2018)

Senville minisplit relocated and needs to be fully charged, 33.6 oz.
Have digital scale and R410A. Just want to verify best technique as have charged air conditioners using pressure readings but not minisplits.

Also, what is the meaning of the SH5 (suction valve)) and SH4 (liquid valve)


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## yuri (Nov 29, 2008)

Mini splits you weigh in the charge. Check the number of feet of piping and the specs on the rating plate or in the install manual and come up with the amount of ounces of R410.

Pull a vacuum and charge it in the suction port slowly as a liquid ( flash it in ).

The 2 valves are there to put your gauges on. Use low loss fittings on your hoses as you don't want to lose a lot of R410 removing them as they are critically charged.


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## dave438 (Sep 10, 2018)

The Sh4 and SH5 caps are covering a hex valve that releases the refrigerant into the line set. The service valve (low pressure side) is where I pull a vacuum from.

When setting up a new unit, I connect the line set, nitrogen test, and then pull a vacuum (-76) and close the low pressure side of manifold gauge and turn off vacuum pump. 

If no change in pressure in 10 minutes, unscrew the cap from the packed valve (high pressure) and open the valve for 5 seconds. Then watch the pressure and makes sure it is maintained.

Then remove charge hose from the service port

Then open both the high and low pressure valves.

Does the above sound ok..

Now, if I needed to add more R410A for a longer lineset run, when would I add it to a new machine?


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## yuri (Nov 29, 2008)

You add it at startup. It can run for awhile missing a few ounces and won't be a problem so you don't have to rush. Within the first 15 minutes should be OK.


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## supers05 (May 23, 2015)

dave438 said:


> ..Then open both the high and low pressure valves....


Both are the same pressure. (low pressure for AC, high pressure for heating.) 

OP: set the unit to "powerful" or "turbo" mode. Or whatever similar on the control. Measure the temp of both lines. Yuri is right, normally your weigh the charge in. The SH4/5 are just part numbers of the caps. They mean nothing to you. 

Cheers!


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## dave438 (Sep 10, 2018)

I'm confused about the comment that both lines are the same pressure. I though the larger size was liquid / suction / low pressure and the smaller diameter line was gas / high pressure? The service valve is on the liquid side..


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## supers05 (May 23, 2015)

dave438 said:


> .... I though the larger size was liquid / suction / low pressure and the smaller diameter line was gas / high pressure? The service valve is on the liquid side..


Not on this type of unit.

Larger is suction return. Vapour only. Smaller lines is saturated, low pressure liquid. 

Cheers!


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## dave438 (Sep 10, 2018)

I'm really confused now. 

I thought that in a minisplit cooling cycle, low pressure liquid was transformed into high pressure gas by compressor. heat is dissipated into moutdoors by fan. The gas then goes to indoor evaporator and becomes a liquid and absorbs heat. The liquid is then suctioned back to the outdoor unit..

When you charge, install manual says, you charge with tank upside down (so liquid) and into the service port which is attached to the suction port (low pressure liquid)???


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## supers05 (May 23, 2015)

dave438 said:


> I'm really confused now.
> 
> I thought that in a minisplit cooling cycle, low pressure liquid was transformed into high pressure gas by compressor. heat is dissipated into moutdoors by fan. The gas then goes to indoor evaporator and becomes a liquid and absorbs heat. The liquid is then suctioned back to the outdoor unit..
> 
> When you charge, install manual says, you charge with tank upside down (so liquid) and into the service port which is attached to the suction port (low pressure liquid)???


https://espcotraining.com/wp-content/uploads/2017/01/mini-split-refridgeration-cycle1.png

https://espcotraining.com/2017/q1-2017-espco-newsletter/

Cheers!


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## carmusic (Oct 11, 2011)

here the service manual if you dont have it, they explain how to do it
http://www.quebecsales.com/images/ServiceManualForSenvilleAirConditioners.pdf


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## roughneck (Nov 28, 2014)

You say you relocated this unit. What happened to the refrigerant that was in it? Did you pump it down?


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## beenthere (Oct 11, 2008)

dave438 said:


> I'm really confused now.
> 
> I thought that in a minisplit cooling cycle, low pressure liquid was transformed into high pressure gas by compressor. heat is dissipated into moutdoors by fan. The gas then goes to indoor evaporator and becomes a liquid and absorbs heat. The liquid is then suctioned back to the outdoor unit..
> 
> When you charge, install manual says, you charge with tank upside down (so liquid) and into the service port which is attached to the suction port (low pressure liquid)???



The compressor only pumps/moves gas/vapor. The condenser coil and fan change it to liquid.


The liquid is changed to vapor by the evaporator because it absorbs heat.


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## dave438 (Sep 10, 2018)

I am trying to understand... Thank you all for your time and expertise...

Is this correct...

In a minisplit, the compressor and condenser coil / fan are located in the outside unit.

High pressure vapor enters the condenser from the compressor.

As the outside air is blown across condenser, condensation occurs and the vapor is converted to liquid. 

High pressure liquid refrigerant exists the condenser.

This is where it gets tricky... with a minisplit, the expansion valve is located at the outside unit, whereas is a central AC unit, it is at the evaporater

The expansion valve takes in the high pressure liquid refrigerant and discharges low pressure liquid / vapor refrigerant which travels to indoor evaporater via the smaller copper line.

At the evaporator, the liquid / vapor refrigerant draws heat from the room air. 

The liquid / vapor refrigerant starts to vaporize as it heats up and flows back to the compressor in the larger copper "suction" line.

This explains why a minisplit does not have the typical two service ports - suction (low pressure gas) and liquid (high pressure liquid), but only a single service valve on the suction.

As the expansion valve is contained within the outdoor unit, the only high pressure liquid is only within the outdoor unit and inaccessible (between compressor discharge and expansion valve). 

What I dont understand now is if the expansion valve is contained within the outside unit, and therefore the suction and liquid line are both low pressure vapor, why do they have a large pipe for suction and smaller copper pipe for liquid; and why do we charge through the suction (low pressure) with liquid refrigerant as that is going directly into the compressor which only pumps gas...


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## yuri (Nov 29, 2008)

A mini split is the same as a household refrigerator.

The liquid line is actually a capillary tube. There is a orifice in the outdoor unit after it leaves the condensor coil which changes the liquid pressure from high to low. It travels as liquid to the indoor unit and does not absorb heat along the way as it is insulated.

Once it gets to the indoor coil it flashes into vapor and absorbs heat.

The liquid line service port is for when you are pulling a vacuum so it goes faster and for purging the unit with nitrogen.


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## supers05 (May 23, 2015)

You got it. 

It's better to call the lines suction and saturated. This is because the refrigerant is somewhere between 60-80% liquid in the saturated line. Due to this process, the temp of that line will be 35-45*f. (corresponding to the p/t chart for that refrigerant) The seal in the cheap schrader core in the service port isn't good for this temp and likely to fail on some poor soul taking their gauges off. Between this and the confusion between where the metering device is, all the manufacturers have left them out. 

You must charge R410A as a liquid due to the change that it'll fractionate. It's composed of 2 separate refrigerants.

Cheers!


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## supers05 (May 23, 2015)

yuri said:


> The liquid line is actually a capillary tube. There is a orifice in the outdoor unit ...


Not really anymore. They use txvs or even eevs these days. The pressure drop of the saturated line is negligible. 

Cheers!


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## yuri (Nov 29, 2008)

Not literally one but readers can use it as a example of how the two compare in operation.

Pretty amazing technology we have in resi units.

In 1999 I ws working with large VFD's and Siemens BAS bdlg automation systems and DDC controls.

Now that VFD technology has filtered it's way down to a affordable price level for resi units along with electronic controls and sensors that only were in BAS systems.

Gawd help anyone troubleshoot them though.

Now more poking around looking for 24 volts AC.


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## dave438 (Sep 10, 2018)

I don't understand the sentence below... what have they left out?

Between this and the confusion between where the metering device is, all the manufacturers have left them out. 

Beginning to get it...  However, when we charge the unit into the suction line as liquid (cylinder upside down on scale), why doesn't the liquid hurt the compressor which is designed for gas returning from evaporator

And why do you add extra charge in cooling mode only... I presume in heating mode, the flow is reversed and the service suction valve would be flowing towards evaporator?


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## yuri (Nov 29, 2008)

You have to carefully flash the liquid thru your gauges which should have a viewing glass. You will see bubbles as it flashes.

Also you don't want to see the suction line frosting white as that tells you you are flashing too much in the line itself and could slug liquid to the compressor.

With a mini split only needing a few extra ounces it is not as tricky as charging several pounds into a regular split system.

I pull a deep vacuum and can flash about 3/4 or more of the charge into a empty system. Then I wait a few minutes for it t warm up and stabilize and then safely start it and top it off.


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## supers05 (May 23, 2015)

dave438 said:


> I don't understand the sentence below... what have they left out?
> 
> Between this and the confusion between where the metering device is, all the manufacturers have left them out.
> 
> ...


Sorry that was poorly worded. I was busy at the time.

I meant to say that the manufacturers wanted to avoid confusion and a potential failure point. So they only put the one service port on these units. They could have put 2 easily, but it has little benefit.

----

You have to charge in cooling, as the service port will be high pressure. You can't pull from the bottle when you're connected to high pressure. You require the low pressure. 

Cheers!


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## supers05 (May 23, 2015)

yuri said:


> I pull a deep vacuum and can flash about 3/4 or more of the charge into a empty system. Then I wait a few minutes for it t warm up and stabilize and then safely start it and top it off.


I usually put the bottle on top of the unit. Gravity helps completely fill the unit before everything equalizes. 

Cheers!


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## yuri (Nov 29, 2008)

Now why did I not think of that.

My BIL says " Let technology be your friend - don't be afraid of computers and the net ".

Now we have " Let gravity be your friend".:biggrin2:

I still use telephone banking and don't trust internet banking.


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## supers05 (May 23, 2015)

yuri said:


> Now why did I not think of that.
> 
> My BIL says " Let technology be your friend - don't be afraid of computers and the net ".
> 
> ...


Lol

Cheers!


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## LCS2029 (Mar 5, 2018)

supers05 said:


> So they only put the one service port on these units. They could have put 2 easily, but it has little benefit.
> 
> You have to charge in cooling, as the service port will be high pressure. You can't pull from the bottle when you're connected to high pressure. You require the low pressure.
> 
> Cheers!


(Sorry to res a somewhat older thread but it is totally relevant to what I am doing.) 

Is this always true though? For example In heat mode doesn't the suction line turn into the liquid line?

Couldn't you charge an evacuated system with liquid directly into this port, avoiding the whole metering the liquid in as gas using gauges and a kwikcharge device with the unit running in cool mode?

wouldn't this whole process be easier/ possible if there was a service port on the liquid line, so if you lose the factory charge you could weigh in 8lbs of liquid into an evac'ed system quickly?


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