HVAC guys: Phantom strip heat?

[Cameramonkey]

In the mild late November-early December of last year, the utility bill at our church more than doubled from 300 to 700 bucks. We have multiple meters, and this one covers our 9 heat pumps. So we suspect a malfunction in the HVAC.

One 2 year old system I suspect has the strip heat stuck on. The compressor runs whenever the system is on, and the stat calls for emergency heat when it starts from a setback. Except EVERY time it runs the air coming out is roasty toasty hot, not lukewarm like a heat pump typically works. Which makes me think the strips are always hot when the system is in heat mode.

Our contractor came out and looked, and he shows the strip heat is acting normally per the thermostat system history tech report. So they claim its working fine. But the more I think about it (and feel the outputs) I think he could be wrong.

Is it possible for a relay to stick or something and always fire up strip heat in heat mode, even when the stat isnt calling for it? SO the stat only reports when its calling for it?

Its a honeywell stat on a Carrier heat pump.

 

[jkaetz]

Happen to have a clamp meter available to check amp draw? It should be super obvious if the strips are powered or not with that.

 

[Mr. Habib]

Relays and contactors can and do stick. Clamp on ammeter would be a good first choice. If you don't have one, you can measure for voltage on the load side of the contactor. Check all three phases to ground, not all of the contacts may be stuck. If you have voltage on the load side contacts check for control voltage on the coil. If the voil is off your contactor is fubar. If the coil is on your problem is somewhere upstream.

 

[Mr. Habib]

I'm not too far from you down in Bloomington. If you need to borrow a clamp on or volt meter let me know.

 

[Cameramonkey]

Ive got a clamp. I'll give it a shot. I dont know why I didnt think of that.

Oh, yeah. I'm in IT, not HVAC. LOL

 

[tmschuller]

A ammeter is the answer.. or a quick and easy check is to
Flip stat over to emergency heat take a temp reading. Flip back over to the heat pump and see if there’s a difference. Or
Are there separate breakers for the heat strips and you can shut those off .. take temperature readings before and after. Just trying to help..

 

[Cameramonkey]

I may have found the issue. I have an appointment for an inspection on Wednesday, but I have a new working theory.

Over our main entrance, a gutter full of ice and giant ice daggars hanging down from what looks like a sheet of ice that had slid down the roof. Looking at the rest of the roof, it was all fully snow covered. So it appears something heated the roof deck and allowed the snow to melt.

So I climbed up in the attic. I found some minor air leaks around the main output manifold that is in that section of the church. and it was 5* warmer up there than the rest of the attic. (there is a firewall between that section and the rest of the building, so there isnt as much area to heat) . And this is an electric furnace, not a heat pump. (getting a quote to replace that unit) So I think that is a minor part of the problem.

Shortly before we noticed the jump we changed our setback schedules. Our setback got set higher for that part of the building than the adjacent unit. So I wonder if that unit was working harder to not only heat its area, but work harder because the other unit wasnt "keeping up" and its cooler air was migrating down the hall to this zone.

Ive at least temporarily changed the heat settings to be 1* lower than the newer heat pumps so that it is less likely to run. We'll see what they have to say Wednesday.

 

[tmschuller]

I believe your issue lies in the old financial records being stored too close to the return air..... sorry couldn’t resist AND it is INGO

 

[xwing]

One 2 year old system I suspect has the strip heat stuck on. The compressor runs whenever the system is on, and the stat calls for emergency heat when it starts from a setback. Except EVERY time it runs the air coming out is roasty toasty hot, not lukewarm like a heat pump typically works. Which makes me think the strips are always hot when the system is in heat mode.

Makes sense to me. I can always tell when the "emergency heat" is on because the air coming out of the register is actually hot. When that happens a lot, I know my electric usage is going to be high.

 

[Cameramonkey]

Still fighting this. Power bill has now doubled over the previous year. I think they programmed them to use strip heat too aggressively.

Take today for example. OAT of 45*. I did an override to the schedule to take it from 65 to 67. Emergency heat has kicked on. That seems bonkers to me given my experience at home with them.

At home strip heat only comes on if the compressor cant keep up due to extreme cold. Yet here strip heat seems to lead and then once at temp, it relies on the heat pump.

Is it me or does that seem overly aggressive to lead with strip heat ALL THE DAMN TIME?

Can they be reprogrammed to only go to strip when in emergency heat mode or when its too cold for the pump to keep up?

 

[wsmith1indy]

In the mild late November-early December of last year, the utility bill at our church more than doubled from 300 to 700 bucks. We have multiple meters, and this one covers our 9 heat pumps. So we suspect a malfunction in the HVAC.

One 2 year old system I suspect has the strip heat stuck on. The compressor runs whenever the system is on, and the stat calls for emergency heat when it starts from a setback. Except EVERY time it runs the air coming out is roasty toasty hot, not lukewarm like a heat pump typically works. Which makes me think the strips are always hot when the system is in heat mode.

Our contractor came out and looked, and he shows the strip heat is acting normally per the thermostat system history tech report. So they claim its working fine. But the more I think about it (and feel the outputs) I think he could be wrong.

Is it possible for a relay to stick or something and always fire up strip heat in heat mode, even when the stat isnt calling for it? SO the stat only reports when its calling for it?

Its a honeywell stat on a Carrier heat pump.

Relay's can stick on and cause this. It also could be hooked incorrectly. I am on the northside of indy. I would be happy to come take a look for you. My normal service call is $85.

 

[Cameramonkey]

Relay's can stick on and cause this. It also could be hooked incorrectly. I am on the northside of indy. I would be happy to come take a look for you. My normal service call is $85.

I appreciate the offer.

I just realized I have the direct line to the head of service at our provider, who is a former member's dad. Called him and he agreed, its not right. He'll have somebody out soon to correct what they should have fixed on the last inspection visit.

 

[jkaetz]

Still fighting this. Power bill has now doubled over the previous year. I think they programmed them to use strip heat too aggressively.

Take today for example. OAT of 45*. I did an override to the schedule to take it from 65 to 67. Emergency heat has kicked on. That seems bonkers to me given my experience at home with them.

At home strip heat only comes on if the compressor cant keep up due to extreme cold. Yet here strip heat seems to lead and then once at temp, it relies on the heat pump.

Is it me or does that seem overly aggressive to lead with strip heat ALL THE DAMN TIME?

Can they be reprogrammed to only go to strip when in emergency heat mode or when its too cold for the pump to keep up?

Yes, could be thermostat programming. For most systems the transition from HP to emergency/auxiliary heat is based on time and or delta.

I know +2 degree would trigger auxiliary heat (NG in my case) from my system as well as that is technically a large temp difference. It can be changed to a larger delta before engaging the aux heat though.

 

[DocIndy]

You need to check how the stat is set up and wired. I’ve had to “correct” plenty of homeowner installed stats were not wired correctly. If the stat is set up for a 2 stage compressor in the heat pump, they could have it wired to the electric heat. It’s not rocket science, but it helps if you know what your doing.

 

[Cameramonkey]

You need to check how the stat is set up and wired. I’ve had to “correct” plenty of homeowner installed stats were not wired correctly. If the stat is set up for a 2 stage compressor in the heat pump, they could have it wired to the electric heat. It’s not rocket science, but it helps if you know what your doing.

Good call. But wouldnt that just turn on the strips when the stat thinks its in stage 1? In this case the stat displays emergency heat.

Id expect in your suggestion that the stat would think its calling for HP and indicate HP but delivering strip instead.

 

[Brandon]

.

 

[Cameramonkey]

Yes, could be thermostat programming. For most systems the transition from HP to emergency/auxiliary heat is based on time and or delta.

I know +2 degree would trigger auxiliary heat (NG in my case) from my system as well as that is technically a large temp difference. It can be changed to a larger delta before engaging the aux heat though.

I think its programmed weird. I am babysitting window installers and working from the church today.

TOday I didnt bump it from 65 to 67. I bumped it 65 to 66. Compressor only.
It was running stable at 66 so I bumped it to 67. Emergency heat kicked in. So its apparently temperature based, not delta based.

 

[DocIndy]

I think its programmed weird. I am babysitting window installers and working from the church today.

TOday I didnt bump it from 65 to 67. I bumped it 65 to 66. Compressor only.
It was running stable at 66 so I bumped it to 67. Emergency heat kicked in. So its apparently temperature based, not delta based.

Depending on the brand of stat, the temperature separation from compressor to bringing on the electric heat can be adjusted. It’s in the installer setup options.

 

[tmschuller]

Depending on the brand of stat, the temperature separation from compressor to bringing on the electric heat can be adjusted. It’s in the installer setup options.

What brand of stat is it.. ? Helps us out and if you google the set up instructions.. tells you all you need.

 

[churchmouse]

I may have found the issue. I have an appointment for an inspection on Wednesday, but I have a new working theory.

Over our main entrance, a gutter full of ice and giant ice daggars hanging down from what looks like a sheet of ice that had slid down the roof. Looking at the rest of the roof, it was all fully snow covered. So it appears something heated the roof deck and allowed the snow to melt.

So I climbed up in the attic. I found some minor air leaks around the main output manifold that is in that section of the church. and it was 5* warmer up there than the rest of the attic. (there is a firewall between that section and the rest of the building, so there isnt as much area to heat) . And this is an electric furnace, not a heat pump. (getting a quote to replace that unit) So I think that is a minor part of the problem.

Shortly before we noticed the jump we changed our setback schedules. Our setback got set higher for that part of the building than the adjacent unit. So I wonder if that unit was working harder to not only heat its area, but work harder because the other unit wasnt "keeping up" and its cooler air was migrating down the hall to this zone.

Ive at least temporarily changed the heat settings to be 1* lower than the newer heat pumps so that it is less likely to run. We'll see what they have to say Wednesday.

You cant sert the stat back a lot to save money as you wont and yes ypu work the crap out of a heat pump making up temp. The stat will call for the resistance banks to run if the offset between stat set point and room temp is pretty wide. Depends on the stat but 2* will call for emergency heat because the stat sees this as the pump falling behind.
People make a big mistake in the search to save dollars using the set back function as it can often cost dollars.

Give me a call wild man and maybe I can talk you through this.