Today’s inspection was a 1,326 sq ft townhome, 3/3, main level and upstairs, built in 2018. It had one heat pump at the rear of the unit and two thermostats ( one on the main level, one in the upstairs hallway). It had an electric air handler in the attic with heat strips.
In testing the emergency heat setting at the main level thermostat the exterior unit kicked on and there was heat coming out of the registers. When testing the heat setting with the main level thermostat the exterior unit did not come on, but there was heat coming out of the registers.
In testing the emergency heat setting at the upstairs thermostat the exterior unit did not come on, but there was heat at the registers. When testing the heat setting at the upstairs thermostat the exterior unit came on and there was heat at the registers.
Initially, to me, it sounds as though the wiring on the main level thermostat is backwards and it’s activating the wrong heating unit. But; I don’t know the intracacies of HVAC and I want to make sure there is not some scenario where you would run both different types of heating units (exterior and air handler) at the same time. This is the first time I’ve seen this setup.
Do you have a picture of the air handler. It should have some kind of zone dampers & controls.
One stat should be the primary & one will be secondary. The secondary should not override the primary on how it calls for heat. Hard to say which is which. It doesn’t make sense that they would choose the heat pump as the emergency heat source.
I agree with your assessment. Pretty simple mistake to make probably. Will just need to swap some wires on the thermostat. That said, it is one of those harder things to explain in a report, without writing a novel, lol.
I set my previous older home up like that….2 thermostats.
The thermostat on the main level kept the main level adequate but it was colder upstairs.
So, I added a thermostat upstairs, in the master bath actually. Then I set the desired temp for upstairs and the main level was somewhat above that upstairs setting.
But I was then assured that when I was gone the upstairs wouldn’t drop below my comfort level for potential freezing. It was a broken up layout where the heat was not consistent between certain areas of the home. Doing this fixed that for my comfort.
Thanks Ryan, that’s been my thinking, but again, there may be some setup I’m not familiar with. Fortunately the client showed up at the end for a brief walk through so I was able to explain it to her in a manner she would understand.
Thinking the same thing. Wiring in the thermostats. The “emergency” heat should activate the heat strips with the heat pump still running. One or the other not working in that setting, is indication of a wiring issue.
What is the backup heat and what causes it to come on?
The alternate form of heat is sometimes referred as “strip heat”, “aux heat”, or “backup heat”.
You can usually see when it is on by looking at your thermostat.
When it gets too cold outside, the heat pump can’t extract heat as normal from the outside air temperature. To heat your home, the electric coils are turned on, and is referred to as backup heat or “strip heat”.
If the backup heat comes on, the electric coils are energized.
This is a very inefficient way to heat air. It uses more electricity and costs more money.
If your thermostat calls for heat greater than about two degrees, the backup heat turns on and works with the heat pump to boost temperatures more quickly.
If your heat pump is not working properly, backup heat will become the primary heat source, and can be costly.
Seems like you are saying two diff things happened on the same thermostat - was this a typo maybe?
Regardless… if they only had ONE outdoor unit and ONE air handler AND they had two individual thermostats then they are just using a simple Split System.
I did one today and typically do at least one of these every week.
The split occurs due to an electronic board that controls the dampeners within the ductwork. You should check the corresponding lights (if installed) as this will reaffirm that the appropriate dampeners are opening / closing (also easily verified and a good value add for clients).
In testing any HEAT PUMP - it is important to understand that there is typically a delay between any change in any thermostat and the activation of the outdoor fan.
Only SOME Air handlers come with ER heat strips and these are set according to a variance of demand in temps (unless below a set temperature - then at this point they will always come on - assuming that the need will always be there in colder conditions… and it is … but is also WAY more expensive too>>> I digress…
So anyway… Again - ALL of your heat comes through your air handler. NONE of it comes directly from your outdoor unit. … Now before I am attacked for the intracasies of the way Heat Pumps work - I know that the outdoor fan still plays a role with the Condensor… am only saying this much bc you mentioned the part “Exterior and AirHandler” at the same time- which is normal -
JUST as its normal to understand that when you run EMERG Heat AND the AirHandler has the ER Heat Strips installed… then you would be getting full heat from the Air Handler and it would then be diffused according to the split system within the duct work.
One sec , Ill share a pic of the system I inspected today…
