Disable the AUX when on the generator

[WaterBoyz]

My Trane heat pump has the huge meter-spinning toaster coils as AUX heat. The generator is not large enough to power those when the outdoor unit goes into defrost mode. I need to stop the toaster from turning on.

I realize that there will be some amount of chilled air coming from the air handler during the defrost period, which I will have to tolerate.

I plan to install a simple manual toggle switch that disables the toaster ONLY when on the generator. My Ecobee thermostat has been programmed to never turn on the AUX, but I do want to be sure it does not sneak in an AUX call.

Thanks........

The generator is for backup only, so I'm not an off-the-grid lifestyle.

 

[PCustoms]

Isn't there a setting in the control/thermostat?

 

[PoorUB]

If you want to put in a switch, put it here, in the blue wire. (red circle) Make certain you get the correct blue wire, the one that goes to the over load, not the other heat relay. This will kill both heating coils.

 

[larry4406]

How is your heat pump system breakered?

The ones I am familiar with have (3) 2-pole breakers - one for the heat pack (your "toaster"), one for the air handler, and one for the outdoor unit.

If yours is breakered this way, why not just turn the breaker for the heat pack off?

 

[Notgrownup]

Mine is all on the same breaker

 

[mike93lx]

Isn't there a setting in the control/thermostat?

There may be something buried in the settings, but at least on my thermostats (April aire) my only front screen options are heat (which enables both the heat pump and backup, controlled by the setpoint) and emergency heat (which forces the backup to run). I don't have an easy way to disable the backup source.

Maybe other thermostats are different though.

 

[fitter30]

If your low voltage board has a humidifier terminal should drop out 24 vac when unit goes into defrost. 24 vac relay with N.O. contact in series with aux heat wire.

 

[WaterBoyz]

Isn't there a setting in the control/thermostat?

The Ecobee has AUX settings but mainly for when to engage it. Today, the outside temp was at 3º, so the Ecobee turned on the AUX to heat, knowing the heat pump can't do it. If I did the switch-out today, the system would run and run since the Ecobee would not know the AUX was disabled.

 

[WaterBoyz]

If you want to put in a switch, put it here, in the blue wire. (red circle) Make certain you get the correct blue wire, the one that goes to the over load, not the other heat relay. This will kill both heating coils.

That is where I was going to go, but wanted additional input since I'm not an official HVAC ....just an overqualified tinkerer.

 

[WaterBoyz]

How is your heat pump system breakered?

The ones I am familiar with have (3) 2-pole breakers - one for the heat pack (your "toaster"), one for the air handler, and one for the outdoor unit.

If yours is breakered this way, why not just turn the breaker for the heat pack off?

I do have two circuit breakers. One feeds just the single heat pack. The other feeds the double heat pack and the air handler. If I'm reading the drawing correctly.

 

[WaterBoyz]

There may be something buried in the settings, but at least on my thermostats (April aire) my only front screen options are heat (which enables both the heat pump and backup, controlled by the setpoint) and emergency heat (which forces the backup to run). I don't have an easy way to disable the backup source.

Maybe other thermostats are different though.

My Ecobee has an AUX setting, but mainly when to turn it on. Not really a setting to turn completely off.

 

[WaterBoyz]

If your low voltage board has a humidifier terminal should drop out 24 vac when unit goes into defrost. 24 vac relay with N.O. contact in series with aux heat wire.

I glanced at the drawing for the air handler and did not see a humidifier. I'll have to look better later. Great idea.

 

[PCustoms]

My Ecobee has an AUX setting, but mainly when to turn it on. Not really a setting to turn completely off.

Adjust the setting to a ridiculous value so it never comes on?

 

[mike93lx]

My Ecobee has an AUX setting, but mainly when to turn it on. Not really a setting to turn completely off.

That's normal and what I described.

 

[mike93lx]

Adjust the setting tona ridic value so it never comes on?

Aux heat gets triggered by a couple things, one is outdoor temp, another is how far off the interior set point is from actual interior temp. So if I click my tstat up by 10 degrees, it will trigger the Aux regardless of the outdoor temp.

There should be settings for all this, but it may mean making a bunch of changes and it may mean there is something that can't be fully overridden

 

[PCustoms]

Aux heat gets triggered by a couple things, one is outdoor temp, another is how far off the interior set point is from actual interior temp. So if I click my tstat up by 10 degrees, it will trigger the Aux regardless of the outdoor temp.

There should be settings for all this, but it may mean making a bunch of changes and it may mean there is something that can't be fully overridden

I did a bit of reading and see the aux heat comes on automatically during defrost too, regardless of settings.

Sounds like he has to physically disconnect it to prevent it from kicking on and tripping the genny

 

[theoldwizard1]

If you want to put in a switch, put it here, in the blue wire. (red circle) Make certain you get the correct blue wire, the one that goes to the over load, not the other heat relay. This will kill both heating coils.

Correct answer !

 

[PoorUB]

That is where I was going to go, but wanted additional input since I'm not an official HVAC ....just an overqualified tinkerer.

Plus, it is low voltage, 24 volts at that point so just a cheap toggle switch will do.

I can understand what you are trying to do, but some of the sugestions don't get it! I can see not changing the settings i nthe thermostat and just walking over and flipping the switch. Changing the settings means you have to enter the code to the set up menu, change some setting and then change it back and hope you don't accidentally screw something else up.

I would go with the switch!

I have a two stage furnace. The furnace is a bit over sized and will heat the house fine on low fire until -30F. (I tested it once, unintentionally, when the out door temps dropped a bit lower than -30F and the furnace didn't keep up!) My thermostat has a control board mounted near the furnace and I unscrew the second stage wire so it never runs unless I hook the wire back up. I should put a switch on the second stage wire, but I have run second stage one time in ten years, so it isn't much of an issue!

 

[WaterBoyz]

Adjust the setting to a ridiculous value so it never comes on?

Currently, it is set to disable the heat pump and use AUX when calling for heat when the outside temp is 10º.

 

[WaterBoyz]

That's normal and what I described.

 

[WaterBoyz]

I did a bit of reading and see the aux heat comes on automatically during defrost too, regardless of settings.

Sounds like he has to physically disconnect it to prevent it from kicking on and tripping the genny

The AUX is triggered by the outside unit when it goes into defrost mode. The Ecobee is not involved. That is why I'm going to put a switch on the blue wire route. It is only a concern during the winter AND while on the generator.

 

[PCustoms]

The AUX is triggered by the outside unit when it goes into defrost mode. The Ecobee is not involved. That is why I'm going to put a switch on the blue wire route. It is only a concern during the winter AND while on the generator.

Yes, that's what I was getting at...

 

[WaterBoyz]

Plus, it is low voltage, 24 volts at that point so just a cheap toggle switch will do.

I can understand what you are trying to do, but some of the sugestions don't get it! I can see not changing the settings i nthe thermostat and just walking over and flipping the switch. Changing the settings means you have to enter the code to the set up menu, change some setting and then change it back and hope you don't accidentally screw something else up.

I would go with the switch!

I have a two stage furnace. The furnace is a bit over sized and will heat the house fine on low fire until -30F. (I tested it once, unintentionally, when the out door temps dropped a bit lower than -30F and the furnace didn't keep up!) My thermostat has a control board mounted near the furnace and I unscrew the second stage wire so it never runs unless I hook the wire back up. I should put a switch on the second stage wire, but I have run second stage one time in ten years, so it isn't much of an issue!

Yeah, I understand the programming route. But since the only concern is during the winter AND while on the generator. So, the switch is my plan.

Thanks...........

 

[WaterBoyz]

Yes, that's what I was getting at...

Thanks.............