Dual fuel thermostat

[dan144]

During cooling season, I program the heat pump to work more in the early morning in order to make more efficient use of lower outside temps. However, when I increase the setpoint later in the morning, the HP doesn't run, and hot air collects on the 2nd story. Thought being able to run the fan intermittently during the "coasting" period might help reduce the stratification somewhat.

The 6 programming periods available with the newer RobertShaw models is asloappealing. During the winter, I program the Honeywell to be 58 overnite, 67 at 5:30, then 69 for the rest of the day while my wife and kids are home. I don't mind using the oil to warm up in the morning - I consider the HP the primary heat source in spring/fall, but only a supplement to the furnace duirng the winter - but don't want the furnace to fire mid-day if the HP can maintain the temps. Not sure how early the if the Honeywell will start a recovery, but it appears to be longer than two hours, e.g. it will begin at 2:30 for a 6:00 setpoint when outisde temps drop into the 20s. Wouldn't ever want the furnace to come on during the night, as the warm air tends to wake me.

My ideal thermostat - especially for cooling - would be able to maintain a delta below outside air temp, instead of absolute temps. I've noticed that an inside temp of 76 is quitre comfortable when it is 90+ outside, but seems warm hot when it's only 80. This leads me to increase the daytime setpoint as the spring progresses into summer, then back as fall arrives.

[wyounger]

Originally posted by dan144
My ideal thermostat - especially for cooling - would be able to maintain a delta below outside air temp, instead of absolute temps. I've noticed that an inside temp of 76 is quitre comfortable when it is 90+ outside, but seems warm hot when it's only 80. This leads me to increase the daytime setpoint as the spring progresses into summer, then back as fall arrives.

Hmm... you don't need a fancy stat for that... just undersize the equipment

Seriously, do you monitor indoor RH during cooling season? That perception you speak of is fairly common, and it's usually an indication that humidity is only well-controlled during the hottest days of summer.

[Edited by wyounger on 01-27-2006 at 05:08 PM]

[dan144]

Or I could let some charge out of the system I have. Tried that last summer.
Seriously though, I was considering a stat that had a dehumidify feature - not sure how that would work though.

[gauss66]

a dual fuel system ( propane ) that also has added elec strips for a choiee of backup .... ie heat pump during one temp range, elec back for a lower range, then propane for the lowest ... or is adding the elec strips not an advantage ... weather is in the foothills of NC ( Marion )

Thanks -Dan

[wyounger]

Let me turn the question around: If you're going to add strips, why keep using the propane? That's become a very expensive source of heat.

Based on the weather in Asheville, I'd expect that the heat pump running in conjunction with the strips would cost less than getting the same heat output from propane. It depends some on your equipment, house, etc., and your specific utility rates, but generally throughout the southeastern US that will be the case.

[gauss66]

A very valid point .... I wanted to go with a propane back up, as I am thinking of a back up generator and can scale down the size by not having a heat pump on it ... also, would add the strips to keep my options open down the line ... and just a more comfort level with gas for heat in general ... so all emotional choices.

And I will have some gas appliances - so will have gas lines ... especially if I go with a tankless hot water heater

Now Marion is more the foothills of the mountains than Ashville - so weather is more like Charlotte ( milder ) ... which would make the all heat pump argument more winning. As well as the heat pump needing to be off when the gas kicks in ...

Hence my question - can I run all three - heat pump for one range, elec strips augmenting for a lower range, then gas at the lowest range ....


"Let me turn the question around: If you're going to add strips, why keep using the propane? That's become a very expensive source of heat.

Based on the weather in Asheville, I'd expect that the heat pump running in conjunction with the strips would cost less than getting the same heat output from propane. It depends some on your equipment, house, etc., and your specific utility rates, but generally throughout the southeastern US that will be the case. "