Turning heat down when on vacation

Anyone can chime in, but for those of you in the northern states, if you leave for a week in the winter, what do you set the thermostat on?

I had mine set at 55 but by time everything (air and objects) get warmed up, I wonder if that extended run time when I returned was any more efficient then letting it sit at a higher temp.

To get it back up, the heat pump and strip heat had to run but had I left it higher, only the heat pump would have been needed to resume normal temps.

Heat pumps are not efficient enough to do what you have done. I know that it takes about 12 hours to warm our home if I left the thermostat at 55 during the winter for any length of time. Last week when it was warm, I let the pellet stove go out and didn't relight it for a few days. When it turned cold, the stove warmed the house, but it did use about an extra 10 pounds of pellets before the walls were warm again.

My geo unit is basically a heat pump. I learned not to turn down the thermostat early after building the house and moving in . My unit originally supplied 2 floors or "zones" with one thermostat for each zone. The basement received the residual heat and I just opened/closed vents as needed. Automated dampers control the heat dispersment to the 2 zones. The unit has three stages of heating, the third being emergency heat.

You'd figure that a guy that makes his living understanding control logic
would have read his manual........... But what happened was I was only using 1 thermostat for control and leaving the other one off. My thought was the basement was taken care of and the upstairs, being open design, would be taken care of by the "heat rises theory". Well winter comes around, the house is comfortable BUT the unit stays in 2nd stage (2nd highest power useage). Bills a little higher. Winter really sets in and power goes into 3rd stage sporatically and bill goes up significantly. I have a cow and call my HVAC man. He comes out and sees my setup and shakes his head.

"Greg, if theres more than a 2 degree difference (setting vs. actual temperature) on the thermostats the unit goes into 2nd stage heating. As soon as the priority setting drops it goes into emergency heat. You have to have the other thermostat on for the unit to work correctly". Jeez, I felt the lead hit my head! Well now I have a three zone setup, added the basement with it's own dampers. He told me it's better to set the temperature and leave it alone (I use all three thermostats now... ). 2nd stage uses around 60% (12 amps) more power than stage one (7.5 amps) and 3rd stage uses 130% (17 amps) more power than 1st stage. Needless to say, my unit has worked great since!

Leave it alone or just lower it to a level you can deal with when you come home. It will use the same amount of power to maintain 55F as 72F and the temperature will drop to 55F much faster than recovery to 72F not to mention the power (double) you use for the restoration!

bczoom said:

Anyone can chime in, but for those of you in the northern states, if you leave for a week in the winter, what do you set the thermostat on?

I had mine set at 55 but by time everything (air and objects) get warmed up, I wonder if that extended run time when I returned was any more efficient then letting it sit at a higher temp.

To get it back up, the heat pump and strip heat had to run but had I left it higher, only the heat pump would have been needed to resume normal temps.

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Brian,

If you were gone for a week you are a head of the game. Yes it takes quite a while to bring everything back up but you did save a lot by keeping the temp down while you were gone. Now if you were only gone for a day or so I would say don't. Remember anytime you can lower the temperature difference from inside to outside you are saving. Now anyone with a higher efficicient gas furnace in the 92% range I would not set it lower than 60 degrees and the absolute lowest would be 55.



murph

thcri said:

Brian,

If you were gone for a week you are a head of the game. Yes it takes quite a while to bring everything back up but you did save a lot by keeping the temp down while you were gone. Now if you were only gone for a day or so I would say don't. Remember anytime you can lower the temperature difference from inside to outside you are saving. Now anyone with a higher efficicient gas furnace in the 92% range I would not set it lower than 60 degrees and the absolute lowest would be 55.

murph

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Would cost be worth the being uncomfortable during recovery? If Brian uses his 1000 cord of wood during recovery probably so............

Big Dog said:

If Brian uses his 1000 cord of wood during recovery probably so............

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Hey, I resemble that!!! I started the wood burner as soon as I got in the house but it too took time to get hot...

I'd set it at 62 degrees and forget about it. That is a good temperature to keep the house nobody home cozy.

Murph summed it up pretty well for the conditions I'm presuming you have.

Our house has pretty lousy insulation and forced air propane heat. Roughly judging from the time the furnace has to run, I've found gains in dropping to 50 for less than 24 hours. Perhaps an oxymoron, but for several days if it's Dec or Jan, I won't go lower than 55F: around here it doesn't take much for pipes to freeze.

Spend the money on insulation, not propane..... it will pay off over the life of the house...

Junkman said:

Spend the money on insulation, not propane..... it will pay off over the life of the house...

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No doubt about that. When we finished the garage, we put 6" in the walls and 4" on the ceiling. We fed the furnace out there from the same tank as the house, and we can barely tell the difference in usage [as opposed to the house alone], but we don't keep that over 40F unless doing some wrenching.

The house on the other hand...there's only so much you can do with 3" walls; it came with the garage & land, so we're not out too much filling the propane tank until we build something here or move.

4" in the ceilings is way under sized. Most heat loss is through the roof/ceiling. Heat rises.

OhioTC18 said:

4" in the ceilings is way under sized. Most heat loss is through the roof/ceiling. Heat rises.

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Dang! I can't argue logic.
Actually, like half the stupid things I do [the other half are just stupid ], there was a bit of method to the madness. The walls took 6" perfectly; the stuff rated out to the Rvalue (R18? or something like that) for a house around here at that.
R38 in the ceiling would have been nice, but we noticed some Menard's discounted stuff marked as 2X4 walls but an R value of like 18 or something [didn't make sense but we didn't care ]. Satisfied my logic with a mental estimate that 30F cooler than the house would be like 1/3 the heating degree days....and for the price, figured we could get 2 layers if we didn't like it and still be cheaper than 8". Got it installed, it poofed up well beyond the the 2Xs, but not so much I couldn't see what to walk on [actually , seldom up there except to check the roof vents - it's only rated for the ceiling not additional loads]: "Perfect!" Four winters later, that building is still so stingy on heat, we don't even think about the ceiling insulation anymore.

Spiffy1 said:

around here it doesn't take much for pipes to freeze.

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Yeah, at 32 degrees I bet.

Gatorboy said:

Yeah, at 32 degrees I bet.

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Come now Gatorboy, an observation that astute should also have noted that 32 degrees F. will neither thaw ice nor freeze water.

That said, it takes somewhere around -10F outside temp and the right wind, before I'm too worried about the temp around my pipes getting below 32F. But when -20F isn't uncommon and -40 insn't impossible...I think twice before dropping the thermostat too much for extended times.

The pipe to our bathroom toilet freezes once or twice every winter and has never broken, but it has stayed frozen for more than a week. One of these years, I am going to need to fix that pipe.......