Residential heat pump - seeking professional help

[Thegeek]

New construction, new installation. Bryant 215B heat pump.

Two problems:

1) When it's stupid cold, heat pumps run for their defrost interval and then go into defrost mode. During defrost, the electric backup kicks in. Rather than trying to keep track, I'd like to add an outdoor thermostat to shortcut the process.

2) When the unit kicks on (summer or winter), all the lights in the house dim. It's just annoying. My battery backup for IT stuff doesn't trip a low voltage alarm, but I'd like to eliminate this if possible. I know these units have a large capacitor to compensate for the startup draw. Is it possible to install a larger capacitor or something else that can be done here?

 

[ChristianPatriot]

1) What do you mean shortcut? Do you mean lock out the heat pump below freezing? Or something else...

2) Motors are rated for a certain microfarad, can’t change that. There could be some other system problem causing high in-rush amps.

 

[GodFearinGunTotin]

Sometimes motors are equipped with soft starts to relieve hard starts. Typically, caps are used with single phase motors to help them to turn and run. Lights dimming are typically caused by hard starting motors and/or the source unable to provide the needed starting current. The former would indicate a problem with the unit itself and might indicate a call needed to churchmouse or the HVAC guy that installed it. The latter would indicate either a problem out at your home's transformer (undersized) or a problem in your electrical system. Could be a poor connection at your breaker panel that would cause a higher than normal resistance causing your starting current to be used to be converted to heat rather than starting your motor.

 

[scott delaney]

you cam use a out door stat to lock out your heat pump at a certen temp or outdoor sensor with a smart thermostat.

a hard start on your heat pump will help with the lights dimming

 

[churchmouse]

There is a deeper issue causing the diming lights.
Not sure what you are seeking on this short cut thing.
Some pumps have a lock out stat in the system for stupid cold temps. But most manf's want the pump to run.

 

[churchmouse]

you cam use a out door stat to lock out your heat pump at a certen temp or outdoor sensor with a smart thermostat.

a hard start on your heat pump will help with the lights dimming

If it needs a start kit there is a deeper issue here.

 

[DocIndy]

There are several factory accessories that most companies don't install on heat pumps. There is a winter start kit, and crankcase heater that make compressors much happier when temps drop. The lights dimming might be a unbalanced panel that a electrician can look into.

 

[churchmouse]

There are several factory accessories that most companies don't install on heat pumps. There is a winter start kit, and crankcase heater that make compressors much happier when temps drop. The lights dimming might be a unbalanced panel that a electrician can look into.

He did say summer/winter. Wire size/panel balance/etc so on.

I am still wondering if he is trying to shorten defrost to shut of the resistance heaters.
Depending on the unit/install when we have the low teen/single digit numbers outside those are on anyway. Some units will maintain house into the mid to high 20's but that is a stretch.

 

[GodFearinGunTotin]

He did say summer/winter. Wire size/panel balance/etc so on.

I am still wondering if he is trying to shorten defrost to shut of the resistance heaters.
Depending on the unit/install when we have the low teen/single digit numbers outside those are on anyway. Some units will maintain house into the mid to high 20's but that is a stretch.

If the decision is made to put in a heat pump, if you can swing it, spring for the extra and go geo-thermal. The breakers to my auxiliary heat have been off pretty much sense we installed it.

 

[Thegeek]

Geothermal wasn't an option for this builder or location... I asked.

1) The "shortcut" is to trigger the system to not even bother with the heat pump and go straight to electric. Why run the pump if it's cold enough outside that it can't generate enough heat inside? I had a Lennox at my old house that was wired straight to the blower cabinet. It would kick in at 15F.

2) Being new construction, I'm sure the wiring is all up to code. A loose connection is probable and I can check everything but the mains. I do have way to check the temps of the connections and wires, so I'll do that to check for "heaters". It could be electrical, new stuff comes out of the box broken, etc.

Really, just need some knowledge/experience I don't have.

 

[CountryBoy19]

If the decision is made to put in a heat pump, if you can swing it, spring for the extra and go geo-thermal. The breakers to my auxiliary heat have been off pretty much sense we installed it.

+1 on geo... Mine draws ~3,000 watts running on stage-2 and maintains my house down into single-digits if it's calm, and into the teens if it's windy. I also have the backup turned off; although mine has a DIP switch on the control board that allows you to disable the resistance heat for backup, but still allow it for "emergency" heat (if the geo unit faults or stops functioning for some reason it will use resistance heat to maintain temp but it will not use resistance heat as long as the geo is functioning in normal mode).

 

[femurphy77]

If the decision is made to put in a heat pump, if you can swing it, spring for the extra and go geo-thermal. The breakers to my auxiliary heat have been off pretty much sense we installed it.

What's the ROI on a 12-20k geo thermal system nowadays?

 

[Brandon]

If you are wanting the heat pump out of the loop turn the thermostat i to aux or emergency heat. That will run your electric.

 

[churchmouse]

Geothermal wasn't an option for this builder or location... I asked.

1) The "shortcut" is to trigger the system to not even bother with the heat pump and go straight to electric. Why run the pump if it's cold enough outside that it can't generate enough heat inside? I had a Lennox at my old house that was wired straight to the blower cabinet. It would kick in at 15F.

2) Being new construction, I'm sure the wiring is all up to code. A loose connection is probable and I can check everything but the mains. I do have way to check the temps of the connections and wires, so I'll do that to check for "heaters". It could be electrical, new stuff comes out of the box broken, etc.

Really, just need some knowledge/experience I don't have.

Yes....you can just stop the pump when it gets down to a point it is no longer providing any comfort.
Shut the breakers on the unit for the heaters off. Run the pump. When it no longer can keep the house to set point ad 5*s to the outdoor temp on the stat and see how it goes. Every application is different.

 

[GodFearinGunTotin]

What's the ROI on a 12-20k geo thermal system nowadays?

Not sure... When we put ours in there was a 30% tax credit and a REMC rebate which all helped. I think I estimated something like 7-10 years but I've never gone back to see what we're actually getting. I will say this. Our max bill has historically been January. And the few times I've gone back to compare, we typically have seen a 40% or so reduction to what we saw with our old unit.

 

[Thegeek]

If you are wanting the heat pump out of the loop turn the thermostat i to aux or emergency heat. That will run your electric.

That's what I do now. When it warmed up, I forgot to set it back to auto and ran the electric heat for 4 days. Looking for an automatic solution.

Yes....you can just stop the pump when it gets down to a point it is no longer providing any comfort.
Shut the breakers on the unit for the heaters off. Run the pump. When it no longer can keep the house to set point ad 5*s to the outdoor temp on the stat and see how it goes. Every application is different.

I don't have any sort of outdoor sensing/control right now. I'm wanting to add that capability.

 

[femurphy77]

Not sure... When we put ours in there was a 30% tax credit and a REMC rebate which all helped. I think I estimated something like 7-10 years but I've never gone back to see what we're actually getting. I will say this. Our max bill has historically been January. And the few times I've gone back to compare, we typically have seen a 40% or so reduction to what we saw with our old unit.

We did the math on ours last year when considering this option and it was 15+ years using their "generous" numbers. Apparently our rates aren't as bad as we thought. Funny thing though, last year we added a 500 square foot family/living room on the back of the house and did not increase the size of our heating/cooling unit because we didn't budget to do it at the same time as we have plans to upgrade to a 95% unit in the future.

In order to optimize what we had we included 2 additional return air loops for 3 total and then balanced the return air to each one within 1 or 2% of each other. Just that simple change in spite of adding 35% more floor space and our cooling costs dropped noticeably at the same comfort level. Our heating costs have gone up a little but it's hard to tell how much since at the same time we did the room addition we removed the wood burner in the garage that was plumbed into the central heat/air. We were never really comfortable with the installation and having to buy the wood, haul it, stack it, etc. it was a break even proposition.

 

[churchmouse]

That's what I do now. When it warmed up, I forgot to set it back to auto and ran the electric heat for 4 days. Looking for an automatic solution.


I don't have any sort of outdoor sensing/control right now. I'm wanting to add that capability.

Yes I am aware and yes it is an option. Pump man. Possibly has a kit available or if you know a tech they can do this for you.

 

[GodFearinGunTotin]

We did the math on ours last year when considering this option and it was 15+ years using their "generous" numbers. Apparently our rates aren't as bad as we thought. Funny thing though, last year we added a 500 square foot family/living room on the back of the house and did not increase the size of our heating/cooling unit because we didn't budget to do it at the same time as we have plans to upgrade to a 95% unit in the future.

In order to optimize what we had we included 2 additional return air loops for 3 total and then balanced the return air to each one within 1 or 2% of each other. Just that simple change in spite of adding 35% more floor space and our cooling costs dropped noticeably at the same comfort level. Our heating costs have gone up a little but it's hard to tell how much since at the same time we did the room addition we removed the wood burner in the garage that was plumbed into the central heat/air. We were never really comfortable with the installation and having to buy the wood, haul it, stack it, etc. it was a break even proposition.

We're on a REMC. Our electrical rates "all in" were about $0.14/KWH. Seems like if you're on Duke Energy they were in the neighborhood of 9-10 cents per KWH. At the time we replaced ours, was that year LP prices were going crazy and we didn't have (and still don't) access to natural gas. So, it came down to replacing an air-to-air HP with a geo-thermal or taking a gamble on a LP system. The paybacks were about the same considering we'd have to install all the plumbing and venting needed for a LP system. The higher REMC rates helped make the geo-thermal unit more attractive though and it was a bit agonizing deciding which way to go. We're happy with our unit so far.

 

[moosehead]

We have an Ecobee thermostat, and it allows you to set an outside temperature to stop running the heat pump and just run auxiliary. It does require Internet access to work though.