# Honeywell VisionPro Short Cycling?



## kcrossley2 (Dec 17, 2006)

I'm having problems with a Honeywell VisionPro 8321U short cycling. It seems like as soon as the furnace cuts off, it starts right back up.

It's currently set to 5 cycles per hour, which is what's recommended for the Goodman GMH80453AN (45,000 BTU Gas Furnace, 80% Efficiency, with 2-Stage Burner and 1,200 CFM Multi-Speed Blower) it's controlling. 

Is this a problem with the Honeywell thermostat or should I simply reduce the number of cycles? If it's the latter, how many cycles per hour should I set it at?


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## hvactech126 (Nov 11, 2010)

start out lowering your cph to 3. it may be the stat location and or you may be losing heat that quickly. New stats are really built more for comfort (maintaining temp) then efficiency


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## kcrossley2 (Dec 17, 2006)

hvactech126 said:


> start out lowering your cph to 3. it may be the stat location and or you may be losing heat that quickly. New stats are really built more for comfort (maintaining temp) then efficiency


Interesting. I never considered the thermostat location, but it's right next to a 20' x 22' two story open family room that's probably sucking up all the hot air from the first floor. 

This particular house has two furnaces, one on the first floor, a smaller one on the second. How much of a temperature spread should I allow between the two units to compensate for the large family room, or is there some other secret to heating this type of floorplan?


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## hvactech126 (Nov 11, 2010)

move stat to adjoining hallway and or put fan on 24/7to circulate the aire


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## kcrossley2 (Dec 17, 2006)

hvactech126 said:


> move stat to adjoining hallway and or put fan on 24/7to circulate the aire


As opposed to using the "Circulate" feature built-in to the thermostat?


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## hvactech126 (Nov 11, 2010)

kcrossley2 said:


> As opposed to using the "Circulate" feature built-in to the thermostat?


you can use the circ function, but may not be enough to over come the space


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## kcrossley2 (Dec 17, 2006)

hvactech126 said:


> you can use the circ function, but may not be enough to over come the space


How much electricity does the furnace fan use? Also, can it handle 24/7 operation?


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## hvactech126 (Nov 11, 2010)

it uses enough to notice a difference in the electric bill. and yes it can handle 24/7


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## beenthere (Oct 11, 2008)

5 CPH is too many, I don;t care what Honeywell says in their instructions.

First, make sure its the thermostat doing this, and not your furnace shutting off on high limit or some other safety.

Next, make sure the thermostat and furnace are wired for 2 stage operation. And not just using the furnace's timer to go to second stage. Then make sure the hole in the wall where the wires come through is sealed. Then reset the thermostat's CPH to 3 for both first and second stage.


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## hvactech126 (Nov 11, 2010)

beenthere said:


> Next, make sure the thermostat and furnace are wired for 2 stage operation. And not just using the furnace's timer to go to second stage.


Been,

if I am correct this furnace only has a w1 terminal on the control and upstaging is timed. I don't know why goodman did this but you can't use a 2 stage stat with this furnace. it can be set for 10 min timer or what they call auto. I'm not sure how auto function works.


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## beenthere (Oct 11, 2008)

Your right. I missed that its a GMH.


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## LukeROttinger (Jan 16, 2011)

I think your problem is simpler than cycle rate. pull out your installation manual and check to see if in the program there is an option to change the stat from economy to comfort. Flip it over is economy, this should force the stat to reach a larger temp drop before engaging the furnace. it should also over run the temp by a degree to have fewer cycles per hour. Good Luck


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## beenthere (Oct 11, 2008)

TH8321 doesn't have a comfort setting. Its a comfort thermostat, and is CPH only.

Part of the problem is his 5 CPH. The next part is most likely that the furnace is over sized.


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## kcrossley2 (Dec 17, 2006)

HVAC tech stopped by today and said the problem is the gas valve in the furnace is sticking and needs to be replaced. The strange thing is I had another tech out here last week (from a competing company), who said nothing was wrong with the furnace. 

Does this sound on the up and up? Also, will a sticking gas valve exhibit this kind of behavior?


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## beenthere (Oct 11, 2008)

A sticking gas valve generally has nothing to do with short cycling.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> A sticking gas valve generally has nothing to do with short cycling.


So a sticking gas valve wouldn't cause the furnace to power down, then immediately start back up?


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## beenthere (Oct 11, 2008)

kcrossley2 said:


> So a sticking gas valve wouldn't cause the furnace to power down, then immediately start back up?


If its already open. Then it would be sticking open, wouldn't it?

If its stuck closed, then you wouldn't have heat coming out on the first cycle.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> If its already open. Then it would be sticking open, wouldn't it?
> 
> If its stuck closed, then you wouldn't have heat coming out on the first cycle.


I don't know. Do you think this is just some BS to make a quick buck? What worries me is this guy isn't Goodman certified, but maybe that doesn't matter. The guy said he cleaned something and it seems to be better. I haven't noticed it running right after it's shut down since he left.


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## beenthere (Oct 11, 2008)

Saying a gas valve is sticking and causing short cycling is a wild guess because he doesn't know what is causing it(and its not the problem).

May have cleaned a flame sensor, trap or drain hose. What air filter are you using?


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> Saying a gas valve is sticking and causing short cycling is a wild guess because he doesn't know what is causing it(and its not the problem).
> 
> May have cleaned a flame sensor, trap or drain hose. What air filter are you using?


3M Filtrete Filters
http://www.filtrete.com/wps/portal/...1011_nid=3JNKR6364PgsQHZF8K475Hgl85WZKW2WB2bl

So, if that's not the problem, where do I go from here? I mean, I'm not going to pay $100 for a misdiagnosis. BTW, I haven't noticed the restarts since the tech did whatever he did. It could just be coincidence though.


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## beenthere (Oct 11, 2008)

LOL... Probably cleaned the air filter.

Get a real air filter. 3M's are too restrictive.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> LOL... Probably cleaned the air filter.
> 
> Get a real air filter. 3M's are too restrictive.


Nope, he didn't do that because my air filters are located in the return vents, not in the furnace. Besides, every since we've been using the 3M filters, the occurrence of dust, allergies, and sickness have been greatly reduced.


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## beenthere (Oct 11, 2008)

kcrossley2 said:


> Nope, he didn't do that because my air filters are located in the return vents, not in the furnace. Besides, every since we've been using the 3M filters, the occurrence of dust, allergies, and sickness have been greatly reduced.


And so has the air flow of the furnace.

Look for a pleated air filter. That the pleats look more like soft curves, instead of shape edges like that 3M.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> And so has the air flow of the furnace.
> 
> Look for a pleated air filter. That the pleats look more like soft curves, instead of shape edges like that 3M.


Not sure I know what you mean. I thought the 3M's were pleated. Can you post a link? BTW, we've used the 3M filters for about 3 years and have NEVER had a short cycling problem.


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## beenthere (Oct 11, 2008)

kcrossley2 said:


> Not sure I know what you mean. I thought the 3M's were pleated. Can you post a link? BTW, we've used the 3M filters for about 3 years and have NEVER had a short cycling problem.


Yes, the 3M is pleated. look at it, and you'll see its edges are like sharp points. Get a type with soft rolls, instead of the sharp edges.

Have you had this furnace for 3 years?


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> Yes, the 3M is pleated. look at it, and you'll see its edges are like sharp points. Get a type with soft rolls, instead of the sharp edges.
> 
> Have you had this furnace for 3 years?


Yes, I've had it for 3 years.


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## beenthere (Oct 11, 2008)

Get the standard pleated air filters. Something like this. http://www.alibaba.com/product-gs/231825407/KLC_MERV_8_pleated_air_filter.html

Have them check the bottom side of the secondary heat exchanger.

You may have a high limit getting weak, or be running on the high limit near the end of the heating cycle. To test. Turn your thermostat up 6 degrees higher then room temp. See if the furnace runs continuous until the thermostat is satisfied. If it does, its not the air filter, dirty heat exchanger or dirty A/C coil. If it doesn't. then the air filters, heat exchanger or A/C coil need to be looked at.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> Get the standard pleated air filters. Something like this. http://www.alibaba.com/product-gs/231825407/KLC_MERV_8_pleated_air_filter.html
> 
> Have them check the bottom side of the secondary heat exchanger.
> 
> You may have a high limit getting weak, or be running on the high limit near the end of the heating cycle. To test. Turn your thermostat up 6 degrees higher then room temp. See if the furnace runs continuous until the thermostat is satisfied. If it does, its not the air filter, dirty heat exchanger or dirty A/C coil. If it doesn't. then the air filters, heat exchanger or A/C coil need to be looked at.


I'll give it a shot. What do you do when one HVAC company is telling you one thing, and another is telling you something entirely different?


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## beenthere (Oct 11, 2008)

kcrossley2 said:


> I'll give it a shot. What do you do when one HVAC company is telling you one thing, and another is telling you something entirely different?



I don't know, I don't call other company's. 

Try that test first. Then you have an idea what is going on. And can inform both HVAC companies and see what they say.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> Get the standard pleated air filters. Something like this. http://www.alibaba.com/product-gs/231825407/KLC_MERV_8_pleated_air_filter.html
> 
> Have them check the bottom side of the secondary heat exchanger.
> 
> You may have a high limit getting weak, or be running on the high limit near the end of the heating cycle. To test. Turn your thermostat up 6 degrees higher then room temp. See if the furnace runs continuous until the thermostat is satisfied. If it does, its not the air filter, dirty heat exchanger or dirty A/C coil. If it doesn't. then the air filters, heat exchanger or A/C coil need to be looked at.


Actually, now that I think about it, that's what HVAC company #1 did and they couldn't find a problem with the furnace. The HVAC tech from that company said all the furnace was doing was following the instructions given to it by the VisionPro, which was calling for heat, immediately after the furnace was shutting down.


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## beenthere (Oct 11, 2008)

Have you reset the CPH to 3 yet. is the hole in the wall where the wires come through sealed?

Did they actually set the stat up 6 degrees and watch it run until the house temp came up 6 degrees. Or did they just let it run for 10 or 15 minutes or so, and call it good.


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## kcrossley2 (Dec 17, 2006)

beenthere said:


> Have you reset the CPH to 3 yet. is the hole in the wall where the wires come through sealed?
> 
> Did they actually set the stat up 6 degrees and watch it run until the house temp came up 6 degrees. Or did they just let it run for 10 or 15 minutes or so, and call it good.


Sorry. Busy day. I haven't had a chance to do any of this, save setting the CPH to 3. I'll try these suggestions tomorrow. Thanks for your help.

And no, they did not let the furnace run for an extended period of time.


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## kcrossley2 (Dec 17, 2006)

As a side note, I track my household electricity use using a TED 5000. 

I've noticed that ever since the HVAC tech that diagnosed a sticking gas valve was out here, my hourly electricity use has gone down by 750-1000 watts. Does a 5-ton gas furnace use that much electricity? What could he have done that would account for such a large drop in electricity use?


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## beenthere (Oct 11, 2008)

The blower motor can use 1000 watts an hour. So even if its running less, it wouldn't be a 1000 watt an hour drop.


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