Thermostat set-back

OFF - max minimization

Some of mine have an "off" position that could let the pipes freeze.

I'd creep them down until the building begins to take too long to heat back up in the morning.

On the other hand..the next morning...max maxification. It is an interesting question when one thinks about it actually.

Are they programmable? Mine are and if I program them for 68 degrees at

If not, a major consideration is how long it will take to bring the heat up in the morning. If they are strictly manual, you might not be able to set them back much without having a lot of discomfort in the morning. As Jim said, try creeping it down & see.

There is a middle-ground thermostat which doesn't anticipate, but just switches to the higher setting at the programmed time. With this kind, the set back can be as low as it goes, but you have to set the return early enough for recovery.

I wouldn't go the "off" route - I envision your factory building as not-too-modern, poorly insulated, and likely to freeze up if the heat is off.

Bob

Richard is correct. The amount of fuel used overnight plus what it takes to warm it up in the morning will be minimized by turning it off overnight.

I'm worried about water and sprinkler pipes freezing. I guess I should have mentioned that.

Yes, there are 6 overhead gas heaters, each with it's own programmable thermostat. The building is old block with a tongue-and-groove wood roof with modified bitumen membrane on top...no insulation to speak of. So, I must maintain above freezing.

What I was thinking is is it cheaper to keep the building a bit warmer that run full bore for a long time in the morning?

Tom Gardner fired this volley in news:OKSdnQ_AZ5Z14BzPnZ2dnUVZ snipped-for-privacy@giganews.com:

No. Heat loss is a function of the differential temperature between inside and outside. The warmer it is inside, the more loss.

Although it's a little counter-intuitive, a heavy burst of fuel consumption to bring it up from too-cool to comfortable will cost you less than running it warm all night. It always runs "full bore" when it's on, anyway.

The heat mass inside the building requires the _same_ amount of energy to raise from cool to warm, as it does to keep it warm. It's only the losses through the walls and ceiling (and windows and doors) that make the difference.

Remember, the warmer it is (on average) the higher the losses. So, shutting down at night lowers the average temperature, thus lowering the cost.

But to be honest, the difference is so small you probably wouldn't care, even if you noticed.

Lloyd

Lloyd

Well Yeah!

So maybe Off is a bit extreme?

Might be a good thing to consider other issues. If the temperature gets below the dew point, stuff happens long before your pipes freeze. Rust Mildew

Then set it barely above freezing, taking into account how much insulation there is between the pipes and your shop vs. the pipes and the outside.

Really, this depends on your weather and how your shop is constructed.

In that case, you now have a minimum temperature to keep - "above freezing." What the thermostat has to be set to, in order to keep that, is a variable that only you can be sure of. Once upon a time, my brother worked the midnight shift at a gas station in Minnesota. During "the coldest winter in fourteen years." Sitting there all bundled up to keep from freezing when he went outside to pump gas, he would turn the heat down to keep from roasting. Until the first of the bottle pop in the stacks by the window would break from freezing. "Ah, the sound of time to warm up the place." You may want to find another means of determining if you've set the thermostat too low than waiting to see if the pipes freeze. Not knowing where you are, I can but pontificate. It also depends on "how cold is cold" and How long does it stay that cold?" I.e it is one thing if it dips to the mid twenties at night, but warms into the mid forties during the day, quite another if it stays below freezing till spring.

It will also depend upon the level of heat retention in the place. That is, how much insulation you have, and how fast does the heat inside leak out. Might want to consider insulating the pipes, or using the wrap around pipe heaters to keep them from freezing. I dunno about your specific situation.

Warming it in the morning is another question. Again, how fast do the heaters warm it up, and to what temp? And how fast it exeunt the building.. You probably know this already, but also "dress warm". Save on heating costs if you don't have to heat the place "as much."

Ideally, you could program the thermostats to keep the place above the freezing point at all times, and set to warm it up so that is it is "comfortable" when you get there in the morning.

-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."

And, as someone else mentioned, condensation. One of the better approaches to that (but I'm fairly sure Tom doesn't want to redo his heating system) is to run some radiant floor heat, which couples to cast-iron machines, keeping them warm - or actually run heat loops into machines. It's not a responsive system (turns up/down poorly due to the large coupled mass) but it can be used in concert with an air-heating system for more rapid changes, and greatly reduces the odds of rusting the ways.

The general generic assumption for most construction (may not apply to Toms old factory, depending on location of heat, thermostat, insulation or lack of it, and water/sprinkler pipes) is that 45 (or more conservatively 55) is generally "safe" with respect to freezing pipes in buildings that were not build insanely (which can freeze pipes when the inside is 70F, due to terrible pipe location and lack of insulation.)

Or if you have an unusually cold winter -- in the Willamette Valley it rarely gets below 20F, and then only briefly; I remember one year where we had a cold spell that stayed down in the single-digits or low teens for a week. The water district lost several meters (the standard depth here is just a couple of feet) and we lost a pipe in the wall behind the washer.

At least, you're not paying for a lot of BTU through the roof all night.

I remember someone posting about a building where they did the setback, and ended up splitting a bunch of pipes. The repair cost more than the saving.

The heat lost, is the heat you paid for. So, any temp reduction is less heat lost.

Please consider calling in some estimates, for insulation. That may pay for itself in a few years.

If you can read your gas meter you could compare consumption both ways over similar cold nights. You might first find the lowest practical setback temperature on an overcast night or weekend that won't drop below freezing.

I just Alt+PrtScrn'd the clock at 08:09:10 on 11/12/13 jsw

That would probably be worth correcting. Roof insulation? Is it possible?