programmable thermostat + heat pump

Potomac101

Questions:
1) Would you recommend my using a programmable thermostat?
2) If so, what brand/model?

The facts:

The man who installed our heat pump (York) suggested that I not get a programmable thermostat - just set the old one at one temperature and leave it alone.

My wife prefers to have the temperature lower at night.

We only use the AC about 2/3 weeks in the year.

We are both retired so we are home much of the time, and weekends and weekdays are not very different regarding schedules.

We live in the Fredericksburg, VA area.

I believe that our heat pump is multi-stage.

The backup heat is electric.

The white wire on the upper left goes to "W."

Thanks,
Potomac101
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redline

See the thread - Facts about thermostats.

bigMikeB

I don't think a programmable stat is going to save you anything in the long run with a heat pump. The discharge temps that a heat pump makes are so much lower than the typical output temps of a fossil fuel unit that you won't be able to over come the offset temp fast enough to save you any energy costs.

Potomac101

Redline - I went through that thread and didn't see where my questions were addressed. Can you be more specific?

bigMikeB - Are you taking into account the fact that the stat is getting turned back each night (and then up in the morning) for comfort's sake? Doesn't the programmable ease the temperature up and thus keep the auxiliary heat from kicking in?

Thanks,
potomac101

bigMikeB

No it doesn't, a thermostat is little different than a light switch, it's a digital device in that it is either on or off. There is no difference in you turning the heat up and down (on/off) or the stat doing it automatically, it still uses the same amount of electric.

Potomac101

This is from the U.S. Department of Energy - last update in September 2005

“Programmable thermostats are generally not recommended for heat pumps. … But when a heat pump is in its heating mode, setting back its thermostat can cause the unit to operate inefficiently, thereby canceling out any savings achieved by lowering the temperature setting. Maintaining a moderate setting is the most cost-effective practice. [ OK - I got it - if you have a heat pump don't bother with a programmable thermostat - BUT THEN] Recently, however, some companies have begun selling specially designed programmable thermostats for heat pumps, which make setting back the thermostat cost effective. These thermostats typically use special algorithms to minimize the use of backup electric resistance heat systems.”

First it states that the most cost-effective practice is to set the temperature and leave it alone. Then it says that the newly (2005) designed programmable thermostats makes setting them back cost effective.

Since my thermostat is going to get turned back at night, even if it’s not the most cost effective, wouldn’t it make sense to have the thermostat set so that the temperature is raised a degree or so at a time thus not kicking in the electric auxiliary heat?

Thanks for your patience,

potomac101

bigMikeB

Heat pumps don't do well with set backs. Thermostats are always on-off controls no matter what the algorythm is. Do yourself a favor and leave it alone.

Yes if you are going to set it back manually, don't raise it more than 3 degrees when you turn it back on to avoid electric heat.

coed

i would have to argue against what big mike said and any new readers of the original question I recommend using and to use there Programmable thermostat finder to get the right one.

so what if they are always on or off...the reason programmable thermostats work better is because you turn it down automatic in the dense hours of night where you are sleeping and under a blanket you won't notice the cold

beenthere

Your current thermostat, is for a 2 stage, not a multistage.
So hopefully, you don't have a multistage heat pump.

The right set back stat can save you money.

One with adaptive recovery.
And an outdoor sensor, so that you can lock oout the aux heat at outdoor temps, that they are not required.

dac122

Wow, haven't seen one of those tstats in a while. Actually, I have that model sitting somewhere in my box of parts.

If that baby is as old as your HP, or there abouts, you probably have just a single stage HP.

beenthere is right. A programmable model will work to give you the comfort and keep the aux from kicking on.

Maybe go with Honeywell's 7000 series to make it easy to transition from this tstat. Honeywell calls it Smart Response Technology that should slowly ramp up to set point to keep the aux from coming on. If that doesn't do it give them a call and see if one of their higher end tstats will.

pbservano

I recommend "Honeywell, 7500 series", it is available @ Home Depot for less than $100. Ensure to re-configure the thermostat to operate as Heat Pump mode. The instruction manual will guide you through the process.