[jmyers63]

I'm sure this has been addressed in the past, but I've not had any luck searching for my answer.

We have a weekend/lake house in southern Iowa that I installed an air to air heat pump last spring. We don't winterize the house, so it's it's important we keep enough heat to keep the pipes from freezing, and I think it's probably betting to the new hardwood floors we installed. (We have a humidifier on the hp.)

My question is how should I run the temperature for the unit. Currently, I've been setting the thermostat to 50° when we leave and raising it when we arrive on the weekends. And at this time of the year, we may only use the house 1-2 weekends per month.

Knowing the hp will call for the backup electrical heat when I raise the t-stat more than 2°, am I kidding myself by keeping the heat low when we are not there? The installation company said we would be okay doing this, but another professional told me it would be cheaper overall just to set the t-stat at 65° and leave it. I don't remember the exact ratings on the system but I know the AC side is 16 seer and rated at 4 tons, and the resistance heat packs total 20kw. They told me the hp should function to around 10°.

In the depth of winter, we may see a few days of sub zero temps, but normally the lows are 10-20° and the highs are 20-30°.

So, let it run at 65 or keep setting it back to 50 when we aren't there?

 

[beenthere]

I would set it to 60. 50 is too low for most, if not all heat pumps. I would also get the aux heat staged, and controlled by outdoor temp. So that it doesn't come on unless really needed, and no more comes on then is needed.

If your only there 1 or 2 weekends a month. You are probably saving a little with your set back. But not as much as you thought.

 

[user_12345a]

You could lock out the aux heat with a switch and raise the temperature over 24-48 hours before getting there, but if the heatpump conks out unattended, you're screwed. or do what beenthere has suggested.


Got internet there? Get a wifi t-stat and turn up the heat before coming.

For fast warmups you'll be stuck using aux heat to recover.

 

[DOUG1111]

Do you snow, north people use alarm if HVAC malfunction???? http://www.fox2detroit.com/news/170540-story

 

[jmyers63]

I do have a Wi-Fi t-stat, but the local internet company and I are feuding. They advertise $39 for life, but offered $79 for the first year and $99 afterwards. No Wi-Fi for me.

Spoke with my local REC rep this morning they he suggested setting it at 60° if we were coming down every weekend. If it'll be more than 2 weeks, he said to go to 55°.

The aux heat is controlled just be demand. If the temp is more than 2° lower than the t-stat setting, the aux will kick on. The HP is set to run at all times and not shut off when the aux kicks in, so the installer said they felt no need to put an outside sensor on the system and make it more complex. I understand this is a philosophical question more than a hard and fast rule. The HP I have at my full time residence is the opposite. That installer said they felt it was better to rest the HP when the aux kicks in or the temp goes below 10°.

 

[user_12345a]

On demand aux heat is fine if you maintain a constant temperature.

If you need to bring the temp up every weekend, it's really bad because the aux heat comes on and offsets the savings.

If you can keep the aux heat off above a certain low outdoor temp or lock it out somehow above 60f indoor, you can program a 7 day t-stat to bring on the heat ahead of time, have it gradually warm up the house over a day and skip the aux heat.

The heatpump can't do the fast warmup alone.

 

[beenthere]

I do have a Wi-Fi t-stat, but the local internet company and I are feuding. They advertise $39 for life, but offered $79 for the first year and $99 afterwards. No Wi-Fi for me.

Spoke with my local REC rep this morning they he suggested setting it at 60° if we were coming down every weekend. If it'll be more than 2 weeks, he said to go to 55°.

The aux heat is controlled just be demand. If the temp is more than 2° lower than the t-stat setting, the aux will kick on. The HP is set to run at all times and not shut off when the aux kicks in, so the installer said they felt no need to put an outside sensor on the system and make it more complex. I understand this is a philosophical question more than a hard and fast rule. The HP I have at my full time residence is the opposite. That installer said they felt it was better to rest the HP when the aux kicks in or the temp goes below 10°.

Your brand may be different. But I know of no heat pump that recommends or rates their heat pump to operate at an indoor temp of less then 60°F.

A thermostat that locks out the aux heat when the heat pump can handle the recovery. Would save you a lot of money.

 

[zootjeff]

I Recommend the Vision Pro 8000 thermostat. It gives you full control of your aux heat and you use an outdoor wired thermostat (15 bucks plus some doorbell wire) and then you can have the AUX cut off at 35 degrees.. As for if it will work below 60, do you have the make/model of it?

 

[Malcolm Willis]

I would add a controller for the mini split, so that you could remotely turn the unit on/off and adjust temperature. Since you don't have a WiFi connection at the lake house, then it should be a GSM based controller that you communicate with using SMS messages.

 

[jmyers63]

I believe it has the Vision Pro 8000 t-stat on the system, but no outside temp monitor. I'll double check that this weekend. Same with the model number of the unit. I think it's a Rheem, but I could be wrong on that - out of sight, out of mind. Locking out the Aux function above 35° sounds like a great way to save some money. And we've already decided to set the temp at 60° when we're not there and 65° when we are.

 

[beenthere]

Set the aux lock out to 20°F. If you get up to the place when its 25 outside, and its only holding 55, then you know you need to raise the lock out to 25. If its holding 60, you can lower it to 15. Unless ti can't raise the temp to 65 while your there.