Winter Vacation Temp

We are going on vacation the first week of February & live in the northeast. Considering the price of natutal gas this year, I am wondering what is the lowest safe temp to leave the thermostat on to keep pipes from freezing, etc?

 

There is no simple answer to your question. It depends on how well insulated the house is, how much air infiltration there is, where the pipes run in relation to outside walls, what type of piping (type 'M' or 'L' copper, CPVC, PEX, etc.), etc. How much thermal mass in the house, such as lots of masonry or tile work, will affect temp. swings.
Is the heating system forced air or hydronic?
All it takes is one drafty spot to blow onto a copper pipe for a hydronic system, and that one frozen spot can stop the heat from getting to the rest of the house. In a reasonably insulated house with no drafty spots near piping, 45°F might be a safe setting. In an older, draftier house, 55°F could be a safe setting.
Whatever setting you use, shut the water off coming into the house and open every faucet. Flush the toilets. If the forecast for the next 10 days might be for temps in the single digits, you might want to consider adding some RV antifreeze (NOT automobile antifreeze) to each toilet and sink trap.
I have seen several freezeups from the boiler or furnace not starting due to a failed part (and then there are those that just ran out of fuel).

 

It's forced warm air by natural gas

 

If I turn the water off & drain the system, won't that adversly effect my hot water heater? (It's a tank type)

 

How long are you gonig to be gone?

if it's a week, have a neighbor/family check on the house daily.. I'd set the heat down to 50. Have them turn the heat up the day before you get home.

If it's a few weeks or more.. Id' suggest turn of the water main in the house. And if you don't want or no need for someone to walk the house, I suggest you to get a "Winter Watchman" control made by Honeywell. THey are sold at Home Centers. (We have them at Home Depot), and plug a lamp in there. You can set this at a temp to turn on the lamp if your furnace fails, and temp falls at this set point.. Put it in a window that a neighbor can see.

 

Good suggestion on the Winter Watchman. I found a $9 red rotating "partylight" at Walmart that I have used with the Watchman. It is a red rotating beacon. There are also self-contained battery operated units out there that will strobe yellow and/or red.
Don't worry about the hot water. I did not suggest draining the hot water tank. I suggested opening all faucets. That will relieve pressure in the water pipes, minimizing the chance of a burst pipe if it does freeze.

 

Thanks for your replies....we'll be gone for about 1.5 weeks and the house is pretty well insulated. It's about 30 years old & no drafts. I hate the thought of paying the major oil companys more profit....I normaly heat the house entirely with a nice Harman coal stove in the family room basement. I'll have to run the central forced warm air by gas furnace while we're away. Does 45F sound warm enough to keep the pipes from freezing?

 

45 is pushing it. Stay at 50.