Is lowering heat temp at night worth it in this cold?

We normally lower the thermostat a few degrees at night to save on energy cost - but I've heard that this isn't as efficient in extreme cold conditions.

Would love to hear some feedback on this from the community! 


Daytime range is 64-68, nighttime we let it go down to 60. We do hear it come on every night when it gets this cold. 


In this extreme cold we only drop from 68 to 66, instead of 68 to 62.  Our furnace guy said it takes a lot of energy to push the heat up more than 2 degrees when it's below freezing so its a strain on the system and expensive.


I don't follow. Wouldn't you want to make it lower in extreme cold? Seems to me with sub-zero weather, your heat will be working a lot harder to get to 66 then to get to 62.

EBennett said:

In this extreme cold we only drop from 68 to 66, instead of 68 to 62.  Our furnace guy said it takes a lot of energy to push the heat up more than 2 degrees when it's below freezing so its a strain on the system and expensive.



Here's the 2 differing opinions:

1) Don’t set back your thermostat. If you normally set back your thermostat to save energy, don’t do that during really cold weather. Your furnace is having a hard enough time keeping up to begin with and it just doesn’t have enough extra punch to warm up after being set back. Once the temperatures return to the 20s or 30s you can resume your setback strategy.

2) “When no one is home, definitely lower the temperature—58 degrees is a good target,” says Dave Moody, who has more than 25 years experience in HVAC and is vice president of marketing at Service Experts Heating and Air Conditioning. “Don’t let anyone tell you that your furnace has to work harder to bring the temperature up from a cooler temperature. That’s a myth. No matter how cool the house has gotten, it will warm up at the same rate.” According to Moody, this rule applies to all types of furnaces, and holds true even when the temperature outside is very cold. You should turn down the heat before you go to bed, too. Besides saving energy, you’ll also be more comfortable when you’re sleeping.




drummerboy said:

I don't follow. Wouldn't you want to make it lower in extreme cold? Seems to me with sub-zero weather, your heat will be working a lot harder to get to 66 then to get to 62.

EBennett said:

In this extreme cold we only drop from 68 to 66, instead of 68 to 62.  Our furnace guy said it takes a lot of energy to push the heat up more than 2 degrees when it's below freezing so its a strain on the system and expensive.

This is also where my research has led me to and I’m running an experiment the next two months see if it makes a difference in my gas bill. 


I'm not letting the heat go as low primarily to prevent the water pipes from freezing that are on exterior walls (like the kitchen & bathroom sinks). We've also opened up the vanity cabinets to let more heat get to those pipes.


Just thought I'd throw in here that the hotter something is, the faster it loses heat.  So, a 68 degree house will lose heat faster than a 58 degree house.  


And a thought from my mother -- back when she was young, the house was cold in the morning because someone had to get up and shovel coal into the boiler.  Once the fire was going, the steam heat warmed the house right up.  I would think the same would be true today, only hopefully with more efficient boilers.



jamie said:

Here's the 2 differing opinions:

1) Don’t set back your thermostat. If you normally set back your thermostat to save energy, don’t do that during really cold weather. Your furnace is having a hard enough time keeping up to begin with and it just doesn’t have enough extra punch to warm up after being set back. Once the temperatures return to the 20s or 30s you can resume your setback strategy.

2) “When no one is home, definitely lower the temperature—58 degrees is a good target,” says Dave Moody, who has more than 25 years experience in HVAC and is vice president of marketing at Service Experts Heating and Air Conditioning. “Don’t let anyone tell you that your furnace has to work harder to bring the temperature up from a cooler temperature. That’s a myth. No matter how cool the house has gotten, it will warm up at the same rate.” According to Moody, this rule applies to all types of furnaces, and holds true even when the temperature outside is very cold. You should turn down the heat before you go to bed, too. Besides saving energy, you’ll also be more comfortable when you’re sleeping.

I have to disagree that the house will warm up at the same rate. It will warm at a slower rate. A post below said its the temperature difference. It is. A 68 will lose heat faster than a 58 house, the temperature difference between inside and outside being greater in the 68 house. If it were 58 outside, the 68 house would lose heat and require heating, but not the 58 house.

Forced hot air furnaces work the same. There is no such thing as working 130% emergency when its really cold outside. They just work longer to keep the house heated. Some advanced systems have variable fan speeds but I think they are really for optimizing A/C.

At night we drop the temp by 8 degrees. Its enough to keep us warm while saving energy by reducing the temp difference.


This is part of an e-mail from Woolley's - Preventive Measures to Avoid Frozen Pipes. Keep thermostat set at same temperature day and night in all areas of home. If you normally turn back the thermostats at night discontinue that practice until temperatures moderate. It is advisable to even keep the temperature of your home warmer during extreme cold periods.


and for the many of us with steam heat - don’t setback at all.  Just doesn’t work with steam given the systems depend on keeping radiators hot to distribute heat even After each cycle is done.

With temps about to hit -2, that’s an enormous use of energy to heat the house, I suspect this is at the outside limits to which most heating systems are built to, too much lowering and probably many systems just don’t have capacity to catch up 



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