Programmable thermostat scenarios to use minimal Aux Heating Strips in Heat Pump
I just bought my first programmable thermostat and I’m looking to use it as best I can.
It’s installed on a two stage Heat Pump with Aux heat provided by electric strips.
As it is now much colder at night (in the teens) I am wanting to use my Aux heating strips as efficiently as possible. I’m finding that if I lower the heat too much at night the heat pump just cannot raise the temp much at all without Aux heating being triggered.
We pretty much need the house warmed up every day of the week and kept warm until about 7pm. There is at least one elderly person home all day, every day of the week so a decent amount of warmth is required during the day.
The new stat has a number of changable settings.
1) Ability to vary the range (above and below) the Set temperature that the unit will wait until it shuts off and turns on. Say, it’s set at 70, it can be set for a range of 4 degrees, meaning it will run (in heat mode) til it hits 72, then stop until it hits 68, then turn on again. Adjustable in quarter degree increments.
2) Ability to control the range the temp (in quarter degrees) would have to fall below the Set temperature before the Aux heat is triggered on.
3) There is also a switch that supposedly allows the unit to anticipate the Set Temp time so as to have it reach that Set temp AT that time vs. starting to reach it at that time. (I don’t think I need this, not sure)
I’m also looking for guidance as far as using the 4 possible daily periods effectively. We have no need of an intermediary Evening Period past 7pm so I can allow it to go straight to it’s Overnite period at 7pm. That leaves 3 periods to possibly use as morning stages to hopefully gradually creep the temp up to it’s daytime set point. The Day temperature probably needs to be arrived at by 10am.
I am still experimenting, but currently it seems comfortable enough at 67 overnight and 73-74 during the day.
What I’m thinking is that with a heat pump, wide ranges of temp changes are kind of impossible and that baby steps work best. Also noticing that heat pumps really can’t raise a house’s room temp much at all when it’s below 30F, without using it’s Aux heat.
Hope this makes sense.
TF
Replies
Same thought
I live in GA and have two units for each floor. I have been researching this a bit....
Most have said, just sset it to a comfortable spot and let it run. I don't mind that but when I bump it up, having AUX hit i when I go up by 1 degree I find a bit annoying.
My unit kicks in frequently, I'd rather have it let a bit more pass and bring it up over awhile versus off and on so frequently. I have ready many articles, a Lux out there does some and another brand -
Here is one that has smart recovery but I'm not sure if that means gradual warming or just, it's warm when It supposed to start, example, 6am start, warm at 6am, not kickin.
http://www.lowes.com/pd_30683-37422-LTX9600TS-004_0__?productId=3382178&Ntt=lux&pl=1¤tURL=%2Fpl__0__s%3FNtt%3Dlux&facetInfo=
Manual - https://docs.google.com/viewer?url=http%3A%2F%2Fwww.luxproducts.com%2Fsupport%2FTX9000TS_ENG_LARGE-SIZE.pdf
This is one that had some good info on the topic but still not fully sure -
http://www.prothermostats.com/product.php?p=aprilaire_8600&product=176601
Here is another
http://www.prothermostats.com/product.php?p=white-rodgers_1f95-1277&product=110907
I am leaning towards -
http://www.prothermostats.com/product.php?p=pro1iaq_t925&product=172829
http://www.pro1iaq.com/homeowner/thermostats_t925.html
You both should
look into "strip heat lockout". Around here, the efficient systems are set up so that the strip heat cannot come on with exterior air temps above (usually) 35F. If the strip heat comes on every time you kick up the stat, you are getting screwed out of the efficiency you paid for. A good installer should be able to tell you what works locally.
One more thing - the manual talks about swings, it doesn't kick in stage 2 (Aux) until the temp goes double below the setting. Example set for 1 degree, it would have to be 2 below for it to kick in, with a max of 2 for stage 1 and 4 for stage 2.
https://docs.google.com/viewer?url=http%3A%2F%2Fwww.pro1iaq.com%2Fresources%2Finstall_manual_t925.pdf
Pretty easy manual to read.
Thanks for the replies.
Yeah. I have a similar Lux with the same capabilities, just no touch screen.
Since I installed it and am now paying a lot more attention to Aux Mode, one thing I am accepting is the fact that you can't just tell it to not use Aux heat. You'll freeze if it gets below 30. If you want a livable interior temp you just have to live with Aux Mode heating.
I have just asked Lux for some info about the Logic the stat uses. Should get that shortly, but I think it kicks in the Aux heating if after 30 minutes or so it doesn't sense an increase in temperature towards the Set Temp. This makes sense to me.
In my case, because I have three timing zones to work with in the mornings, I just have to have it step up gradually till it reaches the Daytime Set Temp around 10am.
I'll have to play around with it for a few days but I think it will be a matter of simply gradually increasing the Set temp over a 3-4 hour period, while fine tuning the range in which Aux heat is used or not used. I know it's got to be used or the house just won't get warm.
In the meantime I'll wait to hear from Lux and sit down with a pad and work with the timing of the 3 zones I have to work with.
I really just want to get this layed out now so I don't have to think about it all winter. It's 17 outside now and it's just running and running :-).
Beats being cold though. At least I heard the other day this winter is projected to be warmer than last year thanks to La Nina.