Thermoststat setback and slab coil heat?

[JJ]

My house has a 15x15 addition with southern exposure, vaulted ceiling. The addition sits on a concrete slab that has coils running through it for heat. They are connected to a propane gas boiler which also heats the hot water. The rest of the house is gas-forced air. The addition can be closed off at night and is the way I am currently running things. My question: Am I saving any energy by setting back the thermostat for that room at night and then reheating the slab in the morning? Round numbers, lets say the room is kept at 62 from 11pm until 9am. At that point, it is brought up in two steps, reaching 70 degrees by noon. 11pm back to 62.

I'm afraid I might have slept through the courses on thems, mass, btu etc..

Thanks,

[Goedjn]

Yes. Possibly not very much, but 0 savings is the lower limit.

[SQLit]

Your using your hot water heater for heating the slab? Sounds like a cheesy method,IMO.

Not knowing the ambient outside air, the insulation and a bunch of other factors it seems to me that anything here is a wild assed guess.

Guessing you might try waiting another hour or two in the morning for the sun to help out since this is a southern facing exposure. Of course if your having a blizzard that day, the sun will not help much. Heating a slab is slow business. Let alone the room. Keeping the door closed at night certainly will help a bit.

[Goedjn]

Last time we had this sort of discussion, this was the consensus. (It was water-heaters, that time)

You don't have to guess. The amount of heat the slab and the room pump into the rest of the universe is proportional to how warm they are. If they are cooler, they will pump less heat into the universe. It will *NEVER* take more energy to heat the slab back up than it would have taken to keep it warm in the same environment in which it cooled.

So unless you're using a more expensive heat-source to re-heat than you were to keep it warm*, it is always cheaper to set-back.

--Goedjn

*(this is the gotcha for electric heating, if your electric co has variable prices by time-of-day)

[JJ]

Your using your hot water heater for heating the slab? Sounds like a cheesy

Why can't people read and comprehend simple facts?

"....propane gas boiler which also heats the hot water"

[Edwin Pawlowski]

No, he said he has a 15' furnace that forces air into the slab when it get up to 62 degrees at noon time. He saves energy by sleeping from 11 PM to 9 AM. I no I red it write.

[JJ]