heat pump question

[livetohunt]

My heat pump goes into defrost mode a lot, and while in this mode air keeps coming from the vents in the house. The air is not warm air and tends to cool the house down. So consequently, it is a constant battle between the defrost mode and heat mode. Is this normal? I thought in defrost mode that no air was suppose to come thru the vents in the home?

 

[PCNative]

When in defrost mode, whatever back up heat you have should be coming on. Gas or strip heat.

 

[Jim Baker]

My heat pump goes into defrost mode a lot, and while in this mode air keeps coming from the vents in the house. The air is not warm air and tends to cool the house down. So consequently, it is a constant battle between the defrost mode and heat mode. Is this normal? I thought in defrost mode that no air was suppose to come thru the vents in the home?

Have you turned the unit to EMERGENCY HEAT?

 

[livetohunt]

Have you turned the unit to EMERGENCY HEAT?

No. What will this do? Test to make sure it heats properly while in defrost mode? My knowledge on heating/air is not the best.

 

[GA native]

Emergency heat is your electric heat strips. Heat pumps can't work below 40 degrees. Not enough heat in the air, that is why your outdoor coils are icing up. So when the outside temp dips below 40, you turn your thermostat to emergency heat.

 

[NE GA Pappy]

I never move mine from heat, even when it is 10 degrees. It is suppose to be automatic adjustment from the pump to the heat strips. You are having something else go on, it sounds like. I would have a good tech come and look at it.

 

[breathe in]

i'm not an hvac guy, but what i understand, emergency heat is not for colder weather. hopefully an hvac guy will respond.

https://www.servicechampions.net/bl...y-heat-pump-thermostat-to-emergency-heat-faq/

 

[PCNative]

You don't turn your thermostat to emergency heat when the temp fall below 40 degrees. The strip heat or gas back up works with your heat pump when it can't catch up or when it's in defrost mode. My heat pumps are not the most efficient compared to most of the newer ones and my strip back up will come on occasionally when it's in the 20's or below. It's normal for a heat pump to ice up occasionally and air should still blow but it should be warm, usually warmer then the heat pump because its either strip heat or gas heat.

 

[GoldDot40]

Mine switches over to auxiliary heat when the heat pump can't keep up...does it automatically. The little flame icon on my thermostat will simply flash when it goes into "AUX" mode. It usually has to get down to ~25°F before it switches over. Emergency heat is the manual setting that I've never had to mess with.

 

[GIII]

PCNative and GoldDot are correct set it and leave be.

 

[Lukikus2]

A lot of it depends on where your ducts are located and how well it is insulated. Mine are in the attic where it's finally cold now. My unit will run continually and not feel hot but will still heat. The emergency strips are just that. Don't plan on them lasting long. Heat pumps are great and economical for cooling but lacking on heating.

 

[GA native]

You guys are right about switching to EH. I'm rusty, haven't fooled with many heat pumps, and was never a fan of them anyway.

But I can tell you that below 40 degrees, efficiency falls rapidly. Heat pumps work by pulling heat out of the air. Just like your AC, but in reverse. Below 40 degrees, there is not much heat to pull from the ambient air. The unit runs constantly, and coils can ice up.

Some units do not have a built in automatic switch when the ambient temp falls too low. Those are external switches (like Trane). And sometimes the salesman forgets to add it to the parts list. Or the installer doesn't care. Or the ambient thermostat switch is in the wrong place.

Either way, it is probably time to get an HVAC tech on it. It could be low on refrigerant. The ambient thermostat switch could be faulty. Or the ice sensor could be faulty.
Or the heat pump could be old, and in need of replacement. Or you could have dirty coils, restricting air flow, and causing them to freeze.

When was the last time you changed your air filter? Go ahead and do it, that is the first thing the service tech will do. And he'll charge you $10 for a $2 paper filter.

If you are not used to heat pumps, it is a different world from NG heat. Natural gas, you can actually feel the heat. Heat coming from the supply side of a heat pump is just barely warmer than the rest of the room.

 

[Jim Baker]

No. What will this do? Test to make sure it heats properly while in defrost mode? My knowledge on heating/air is not the best.

If your coils are icing up it it will defrost them quicker. Just a suggestion not knowing what kind of unit you have.
Had to turn on the emergency heat to thaw the one here in the office.

The air from your HP is going to feel cool unless the Aux Heat or Emergency heat is on. The air from a heat pump is around 80 to 85 degrees depending on the outside temp. So it will feel cool to your skin because you are 98 degrees. Put a thermometer in a vent and see what temp air you are getting when the HP is running normally.

If it is icing up that often might be low on freon. Best to have some one who knows what they are doing to look at it. See if refrigerant is low and if you have a leak in the system.

 

[Oldstick]

From my experience, the units I have had still run the fan on the inside of the house while the defrost mode is active. Even if the emergency heat strips activate at the same time, the net result inside the house is neutral temp air at best. You just have to wait a few minutes until the defrost finishes then you return to normal heat mode.

The ideal design is that the inside fan cuts off while defrosting, but apparently many systems are not designed that way.

 

[GoldDot40]

If you are not used to heat pumps, it is a different world from NG heat. Natural gas, you can actually feel the heat. Heat coming from the supply side of a heat pump is just barely warmer than the rest of the room.

This is why you'll find nearly zero HP's in the north. Everybody up there uses gas or electric heat. The house I sold had an air handler with electric heat. Our power bill in a typical cold month would be nearly $300. Last month my power bill in this new house (with heat pump) was $117.

 

[Jeff C.]

Most systems have eliminated the blowing of cold air through the vents that used to occur when the system temporarily switched into reverse to defrost the coils....maybe an older unit.

 

[GA native]

This is why you'll find nearly zero HP's in the north. Everybody up there uses gas or electric heat. The house I sold had an air handler with electric heat. Our power bill in a typical cold month would be nearly $300. Last month my power bill in this new house (with heat pump) was $117.

Up north, a heat pump is useless. A day like today, high of 30, those heat strips in the air handler will be cooking all day. Not enough heat in the air to pump.

But this is why you have a wood stove, oil burner, coal burner... something to supplement the heat pump. $300 dollars a month would be a back breaker.

 

[livetohunt]

Thanks for the responses. I may have a tech come out to check and make sure my heat strips are working properly..It seems to work ok for heating the house but just seems really inefficient. Maybe a when the time comes to purchase a new unit it will not blow air into the house during defrost mode. Mine is a 2008 unit.

 

[Flatlander]

Go watch the meter when AUX is running..lol

 

[tcward]

Sounds like a defrost circuit board not working properly. Have a tech check it. Mine was doing the opposite and not defrosting enough...would freeze up thick. Turned out to be a bad board.