Auxiliary Heat Question - Lennox 12HPB24 with White-Rogers 1F89-211 thermostat

[bisowner]

I have 3 questions:

1. Will a standard Lennox 12HPB24 heat pump cause the auxiliary heat to come on by itself?

2. Will a White-Rogers 1F89-211 thermostat cause the auxiliary heat to come somehow (say after 15 minutes of heat pump only running) after the setting is moved up 2 degrees?

3. Will a Lennox Elite10 CB29M-31 cause the auxiliary heat to come on somehow (say after 15 minutes of heat pump alone running) after the setting is moved up 2 degrees?

Some other input. The FAST setting on the thermostat is set to OFF implying that auxiliary heat will not kick in unless I move the setting up by at least 10 degrees F.

The deal here is that I move the setting from 68 to 70, the heat pump comes on gets to 69 and then the auxiliary heat comes on to get the room temp to 70. I want to know what could cause this. The heat pump alone? The thermostat? The closet heater unit?

Thanks for help!

[hvacman14]

there is a deadband built in to the tstat that determines when the aux heat comes on,most are 2 degrees, the outdoor unit can demand aux on during defrost, and on some models willl if the outdoor temp is below the board setting but i cant remember if the 12 hpb does or not, there is nothing in the air handler that will demand the aux heat unless it has been modified, some lennox units have what is called "even heat" type heaters that have a discharge air sensor that will stage heaters on to temper the keep the air above a certain tempature

hope this helps answer your question


Gary

[bisowner]

Yes, the White Rogers thermostat has a FAST setting for the secondary stage. But I have it set at OFF and the manual says that moving the temp up my 10 degrees or more will kick in the secondary stage. If I had it at FAST ON, which I do not, then the secondary would kick in if I move the thermostat up my 3 or more degrees. I think that this is what you are talking about.

I guess you are also implying that the White Rogers does not have any time periods, say 15 minutes, so that the secondary is kicked in after heat pump has run 15 minutes.

[hvacman14]

im not familar with that particular stat, but i dont think that it will time the aux heat on, edit,

i went and looked up the manual for that stat, the manual stat will not time in the heat strips, only temp difference will do so, the programable stat may bring on the strip heat when in the recovery mode, the number you posted is a manual stat,

Will it bring on the strip heat every time or just randomly, if its random i would be leaning to the defrost cycle bringing them on and then after defrost you notice the warmer air blowing as the heat control is taking the back up heat offline again