NEST Thermostat

[IRQVET]

For the casa, not the garage. But I've had a NEST Thermostat in my house for the past 4 years with no issues. Then all of a sudden I've been getting messages from Nest stating my HVAC isn't running efficiently, and has been running on auxiliary?

Not sure what that means? Any ideas?

My house is always equipped with an emergency backup generator, but we haven't seen any power outages lately.

 

[jlv03]

You must have a heat pump, with electric strip backup?

Sounds like the heat pump isn't keeping up.

 

[mattthemuppet]

you can also change the rules about when the auxiliary heat comes on (if at all). Unless you're at below freezing for a long time and your heat pump isn't keeping up, you shouldn't need the auxiliary heat. It also costs a fortune relative to the heat pump.

With ours the default setting was a certain heat gain per time - below that the electric strips came on. Turned that feature off and it took a little longer to heat up in the morning when it was properly cold, but was still able to hit the target (usually between 68 and 70F) and maintain it.

 

[IRQVET]

you can also change the rules about when the auxiliary heat comes on (if at all). Unless you're at below freezing for a long time and your heat pump isn't keeping up, you shouldn't need the auxiliary heat. It also costs a fortune relative to the heat pump.

With ours the default setting was a certain heat gain per time - below that the electric strips came on. Turned that feature off and it took a little longer to heat up in the morning when it was properly cold, but was still able to hit the target (usually between 68 and 70F) and maintain it.

Called an HVAC tech out and he basically said the same thing you did. Said the auxiliary heat strips kick in when the heat pump cannot keep up. I went through the set up on the NEST and saw 3 energy consumption options: No auxiliary, partial auxiliary use, full auxiliary use (paraphrasing). Mine was set to partial use. But I guess with the extreme temps, air quotes (for Florida), my system is working harder than usual. Typically use the heater function of my HVAC unit maybe 3-5 weeks out of the year.

Technician said the rest of my system looked fine and checked out okay.

 

[mattthemuppet]

I set mine to No auxiliary and it coped just fine down to 25F or so (coldest we saw while living there). It probably depends a bunch on the model, how high you set your heat and how important it is to get up to that temperature quickly.

 

[IRQVET]

I set mine to no auxiliary- and my heating bill jumped by $60 bucks this month?

Is my heat pump working harder/ consuming more energy to keep pace now that the auxiliary is shut off?

Kinda experiencing the opposite effect of the intended effect . . .

Sugguestions?

 

[American Locomotive]

You cannot compare month to month without also factoring in the heating degree days and your indoor setpoint

 

[Firebrick43]

I set mine to no auxiliary- and my heating bill jumped by $60 bucks this month?

Is my heat pump working harder/ consuming more energy to keep pace now that the auxiliary is shut off?

Kinda experiencing the opposite effect of the intended effect . . .

Sugguestions?

That was bad advice given as he doesn’t mention what HP model he has and he has no idea what you have.

Some HP produce little to nothing below 35 degrees and you are wasting electricity trying to make them generate heat.

Others can extract heat down to -5 and others in between.

In Tallahassee from the 20th to the 25 of Jan you had a cold spell that was 12-15 degrees below normal and you had 142 heating degree days above the historical average for the month.

 

[mepstein]

You can set the temp where the emergency heat kicks on. Go to equipment on the nest app and set it to your desired temp.

 

[danski0224]

I set mine to no auxiliary- and my heating bill jumped by $60 bucks this month?

This is the difference between the "balance point" and the "economic balance point".

Is my heat pump working harder/ consuming more energy to keep pace now that the auxiliary is shut off?

The compressor and indoor fan are in operation.

The amount of heat output (normally) drops as the outdoor temperature drops. This is dependent on equipment choice.

Kinda experiencing the opposite effect of the intended effect . . .

Sugguestions?

Back to the need of a load calculation, yadda yadda yadda

 

[fitter30]

Standard efficient hp usually published at 17° and 47°. Can call the manufacturer and they can put up specs for different temps. Need complete model and serial numbers of outside unit, air handler and the evap coil if possible. Ask for tech. All heat pumps lose efficiency the colder the outside temp is except for hyper heat minis.