Heat Pump question...

[MossflowerWoods]

What is the outside temperature most of the time?

You can select the mode to run in for most heat pumps, it looks like yours is running in comfort mode, that is why the back up aux heat strips kick in. It thinks you want to get to the new set point in the shortest amount of time.

Change it to efficiency mode, this will make it heat just the heat pump, even though it might take a few hours to get the to the new set point. This is how I operate mine. In this mode, the air coming out of the vents will feel cooler, but its still warm, after all it is heating your house.

Leave your thermostat alone, if its a modern one, it will learn the heat losses of your house. It will become more efficient as time goes by.

Do NOT disconnect your aux heat. The system can NOT defrost if you turn the aux heat off.

I see a lot of bad information on here, don't follow it.

jinjimbob,

This unit is only 4-5 years old, and the thermostat is fancy digital programmable etc. But there are NO selections for "Comfort" or "Efficiency" etc. They MUST be on the heatpump unit itself. Any ideas where I can find these settings?

I live in central/northern Virginia. Winter here is mild, but we do get some cold spells. In Feb we will have days or even a couple weeks down to the teens at night.

Coldest I can recall here in VA for the last 7+ years was one morning it was 0.

Thanks,
Be Well,
David

 

[LD1]

Do NOT disconnect your aux heat. The system can NOT defrost if you turn the aux heat off.

Leave all your vents fully open. Let the system do its job as it was designed to do. Closing the vents will cause the system blower to work harder, costing more money.

I see a lot of bad information on here, don't follow it.

That may or may not be true on the OP's system.

First, not all systems run aux heat while defrosting. Mine does not. And not all systems are set-up to run both aux and HP at the same time. Just depends on how the system is designed and where the heat strips/BU heat is located.

EX: my propane BU furnace is BELOW the A-coil for the HP. So my system will NOT run both at the same time. Because blowing 150 degree propane heat across the heat exchanger (A-coil) really screws with the referigant and pressures in the system.

Second, closing vents isnt going to make anything work harder and cost more.

The set-up he is using was probabally designed to HEAT the whole house. If he does NOT want the whole house heated, closing off a few vents certainly isnt going to cost him more money. The blower could care less if EVERY vent is closed, it isnt a positive displacement blower, just a squirrel cage. I doubt there would even be a 0.1A increase in power draw to the blower if ALL the vents were closed.

But by closing vents, it does force more air out of the other outlets (where he desires more heat) and puts less heat to where he wants it cooler.

In my house, I have an unfinished basement with 6 vents. I have only 2 open. We dont live down there so there is no point in keeping it 70 like everywhere else. The vents in the interior bathroom is also closed. One fullsized vent in that small of a room makes it get MUCH warmer than the larger bedrooms with 1 vent. You get the picture:thumbsup:

 

[MossflowerWoods]

That may or may not be true on the OP's system.

First, not all systems run aux heat while defrosting.

Second, closing vents isnt going to make anything work harder and cost more.

In my house, I have an unfinished basement with 6 vents.

LD1,

The defrosting MUST be outside, and the electric resistive heat is inside, how can that possibly be used for defrost?

2nd, I agree, closing vents is not a major issue.

My unfinished basement has 2 vents. I NEVER open them in the summer because the basement is very cool regardless. But in the winter I open one or both. We have laundry, my office, and a tv/play area in the basement area.

Be well,
David

 

[kiotiken]

Before putting an addition on our house, we heated exclusively with a ground source heat pump, and it worked exactly as you described, on a significant part of the day and night. Emergency heat was triggered when the temperature in the house fell by more than 2 degrees below the thermostat setting. I believe heat pumps work much better maintaining a constant temperature all day and night.

When we added 1200 sq/ft to our house, the heat pump was no longer sized to the house. We added a fireplace that is ducted to the furnace, a room that acts as a passive solar heater, but at night we still needed the heat pump. To meet the extra demand, I added a water valve that is energized by the compressor in the heat pump. The valve opens and then triggers a small pump. The pump pushes water through a heat exchanger (water coil) that I added to the furnace above the heat pumps heat exchanger. This gives all the additional heat we need. Now, especially with all 3 heat sources going (fireplace/water coil/heat pump), the air coming out of the registers is warm to hot and much more like an oil or gas furnace. We bought a propane water heater with ports on the side as well as the top. The side ports supply the water coil, the top is tempered and supplies the domestic hot water. Propane for the water heater (hot water and home heating) and the standby generator is about $800/year (generator "exercises" once a week + outages, so a good chunk of the propane is for that).

I recommend spray foam insulation, nothing beats it. You'll cut all the air movement and your heat pump won't have to work as hard. Mine used to keep me up all night too, now it works more like a normal furnace.

 

[grsthegreat]

I know my Honeywell electronic thermostat has 2 modes. One visible to the homeowner and one programmable by the installer. The installers programs determine whether backup heat work during defrost, when aux heat kicks in, etc.

I have the code and install book with all needed codes.

It all depends on how much effort the installer put into the job.

 

[EE_Bota]

I'll tell a little about the two systems I know about in case it helps the op

My old Lennox system had wires from the thermstat to control everything in a discrete fashion*, so the thermostat itself had much to do with the way the system worked.

It originally had a mercury type thermostat. When I went with a Hunter Programmable and tried to use a programmable setback function, it would frequently turn on the strip heat, since it was more than 2 degrees behind immediately upon resuming the old temperature. I resolved that by putting a little slide switch to block that wire..one position...aux heat is allowed, the other positon, aux heat is not allowed. It was simple to do.

When the aux heat was not allowed, that meant that the aux heat could not come on when it was time to defrost either. So, during defrost, which for that unit was nothing other than going to A/C mode, the house temperature would drop (as it was being cooled by A/C mode instead of heated...thus the outdoor unit is being heated...therefore defrosted.) No big deal, since any time it could be a big deal, I always put the switch I added in the "allowed" mode. I never left for an extended period in winter without being in "allowed" mode either.

My new system uses the exact same wires (they did not replace them) but uses them in a different way. Apparently it "communicates" using those wires. Therefore, putting a switch into that wiring is not a good idea at all. A novice should not mess with that wiring in any way. Fortunately, the thermostat that came with the system allows me to select "heat pump only" therefore making the switch I had previously installed irrelevent. This system is a Carrier Infinity system.

I don't know the communication protocol for the Infinity system...and since my thermostat is more than capable, I don't care really. I don't do setbacks at night..I do them during the day..since heating the place back up around 3-4 pm is usually a much easier thing to do than trying to recover heat at 4:30 AM just so I can be comfortable for the morning rush out the door. Also, I will use some wood heat for the night, and it will help the HP considerably.

*This wire is energized...aux heat is on. This wire, cooling mode, etc.

 

[Mickey_Fx]

My Tstat is NOWHERE NEAR that complex.

I need to break out the manual nd see if I can update some settings...
David

Before getting this HP, I had no idea how high-tech these things had gotten. Has a full color display which you have control over. With the cover open, you can see all the controls & if you know the secret handshake you get access to a whole lot more functions and info.

Air handler has a variable speed blower and I can see what the air flow is at any time. Controls measure pressure drop across the filter and pops up a message any time the filter needs replacing. Can also control humidity and if you live where the air is really dry and you have the humidifier attached in the system you can really control humidity over a fairly broad range.

Yesterday someone mentioned defrost cycles. Outside humidity impacts freq of defrost cycles. Real humid here and during real cold spells, my HP freezes up to the point system has to go into defrost mode 3-4 time an hr. All aux heat comes on at that time so if you have this situation you may be better off having the lock out point set a little higher so defrost cycles don't happen so frequently. Since my aux heat comes on in stages, it may be a little more economical to have aux heat come on in the 30-35 degree range than say low to mid 20's. During the heating season, I always have a small stream of water dripping from the HP.

 

[Larry Caldwell]

The defrosting MUST be outside, and the electric resistive heat is inside, how can that possibly be used for defrost?

During the defrost cycle the heat pump unloads and the auxiliary heat warms the coils in the house. When the coils get hot, the pump reverses into AC mode and sends a charge of hot gas through the condenser coils. You should see it melt the ice and blow off a cloud of steam.

 

[grsthegreat]

During the defrost cycle the heat pump unloads and the auxiliary heat warms the coils in the house. When the coils get hot, the pump reverses into AC mode and sends a charge of hot gas through the condenser coils. You should see it melt the ice and blow off a cloud of steam.

yup..exactly. And if you done hve a system that kicks in the aux heat during this cycle, you can get a blast of cold air in the house..... i did before we got the programming figured out.

 

[LD1]

During the defrost cycle the heat pump unloads and the auxiliary heat warms the coils in the house. When the coils get hot, the pump reverses into AC mode and sends a charge of hot gas through the condenser coils. You should see it melt the ice and blow off a cloud of steam.

Not exactally how my system works. (propane aux. heat)

MossFlower (David), as others pretty much mentioned, a HP needs to defrost on ocassion. EVEN if it is above freezing outside. Because the coils outside are sub-freezing, and ice up. The heat strips dont do the defrosting, but depending on how yours is programmed, it may AIDE the defrost as larry caldwell mentioned.

BUT, not all systems do that. Just cycling in reverse (AC mode) is pleanty of heat to defrost the coils outside. Most units, mine included, have a sensor outside to detect when defrost is needed, and detect when defrost is complete.

When it isnt iced up too bad, and mine goes into defrost mode, ONLY the compressor and outdoor fan run. The blower in the house does NOT (so it isnt blowing out AC out of the vents). And the propane does NOT come on either.

If after a certain amount of time pass and that was insufficent @ defrosting the unit (iced up bad), then the indoor blower kicks on and blows AC out my vents. But it aids in defrosting because it is circulating the 70 degree inside air across the indoor coil. Which makes the freon circulating through the outside coils get even hotter to defrost.