Heat pump operation

Jody Humbert · 03-07-2012, 05:28 PM

When the temperature outside is 60-65 degrees, should a heat pump be supplying the heat for the house or should the electric strip furnace be operating. HVAC tech who installed the unit states that the setpoint for the heat pump is 55-60 degrees. Anything above will call for the strip furnace. I have never heard of this and it does not sound correct. Why would the heat pump not operate from whatever high temp outside until around 32 degrees when it cannot pull enough heat from the air outside? Thank you for any comments in advance.

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**Stuart Brooks** · 03-07-2012, 05:32 PM

Originally Posted by Jody Humbert

When the temperature outside is 60-65 degrees, should a heat pump be supplying the heat for the house or should the electric strip furnace be operating. HVAC tech who installed the unit states that the setpoint for the heat pump is 55-60 degrees. Anything above will call for the strip furnace. I have never heard of this and it does not sound correct. Why would the heat pump not operate from whatever high temp outside until around 32 degrees when it cannot pull enough heat from the air outside? Thank you for any comments in advance.

When the system is cold, i.e., been off for a while, it will usually start up when in Heat mode with the auxiliary coils active as SOP.

Jody Humbert · 03-07-2012, 05:36 PM

System was run for 45 minutes with the heat pump never kicking on. A Hunter digital thermostat was installed and I am wondering if it is wired properly.

**Stuart Brooks** · 03-07-2012, 05:44 PM

Originally Posted by Jody Humbert

System was run for 45 minutes with the heat pump never kicking on. A Hunter digital thermostat was installed and I am wondering if it is wired properly.

In that case, I also would believe something was wrong. Sometimes the control panel in the air handler will give a fault code. Could be the thermostat. Could be the control system. Could be a loose wire. Calls for service by HVAC tech.

**Jim Luttrall** · 03-07-2012, 06:02 PM

Unless there is an outdoor thermostat (common only in colder climates) the indoor thermostat is simply a two stage switch that should call for heat from the heat pump first and the strip heat second. There is no advantage to energizing the strip heat during mild temperatures except to speed recovery in which case both the HP and strip heat should run simultaneously.

Either the technician is wrong or there is a misunderstanding.

Jody Humbert · 03-07-2012, 06:12 PM

Thanks guys. I can't see any advantage efficiency wise that the heat pump would not operate when the temp outside is at 60-65 degrees. I am calling for an HVAC tech.

**wayne soper** · 03-07-2012, 08:51 PM

did you test the a/c? if the a/c works, the heat will work

**Scott Patterson** · 03-08-2012, 06:23 AM

Originally Posted by Jody Humbert

When the temperature outside is 60-65 degrees, should a heat pump be supplying the heat for the house or should the electric strip furnace be operating. HVAC tech who installed the unit states that the setpoint for the heat pump is 55-60 degrees. Anything above will call for the strip furnace. I have never heard of this and it does not sound correct. Why would the heat pump not operate from whatever high temp outside until around 32 degrees when it cannot pull enough heat from the air outside? Thank you for any comments in advance.

It all depends on the type of heatpump and what sensors it has built into it.

If you turn the thermostat up by usually more than 10-15 degrees I have found that heatpumps will turn on their auxiliary heat strips to warm the house up quickly. Then as the home warms the strips turn off and the heatpump then turns on to maintain the temp.

You can always turn the heat strips on with the flick of a switch if you want.

When the outside temps gets down in the 40-30's you will find that the heatpump mode does not produce really warm air. At this point if your system is not automatic you will need to flip the switch and turn the auxiliary heat strips on. I think the HVAC tech was mistaken or you misunderstood what was being said.

Ted Menelly · 03-08-2012, 07:41 PM

Originally Posted by Scott Patterson

It all depends on the type of heatpump and what sensors it has built into it.

If you turn the thermostat up by usually more than 10-15 degrees I have found that heatpumps will turn on their auxiliary heat strips to warm the house up quickly. Then as the home warms the strips turn off and the heatpump then turns on to maintain the temp.

You can always turn the heat strips on with the flick of a switch if you want.

When the outside temps gets down in the 40-30's you will find that the heatpump mode does not produce really warm air. At this point if your system is not automatic you will need to flip the switch and turn the auxiliary heat strips on. I think the HVAC tech was mistaken or you misunderstood what was being said.

Heat pumps better be producing heat in the 40s and 30s or there is a problem the HVAC company needs to address. When it gets to the very low 30s there is limited heating going on but the new ones will produce even into the upper 20s.