My house has a gas-fired boiler and hot-water radiators. I've noticed a strange problem since moving in a few months ago.

If the weather is moderately cold (in the 30F - 40F range), my house feels chilly.

But if the temperature gets very, very low (say between 10F - 20F), bizarrely, the furnace seems to do a better job. My whole house feels toasty; so much so that I'll often be caught off guard when I leave the house.

What could cause this?

  • Where is your thermostat located? – BrownRedHawk Apr 6 '16 at 11:42
  • In my dining room, on the first floor – Bill Apr 6 '16 at 11:43
  • sounds like a combination of bad insulation (so some rooms get colder faster) and poor thermostat placement. – ratchet freak Apr 6 '16 at 11:51
  • Unless you've measured the air temperature separately with reliable thermometers, I'm going to venture out on a guess and say the warm feeling is merely a contrast. Also, a 64F house will feel chilly when you're not up and moving, but can feel quite hot if you just came inside from shoveling snow. It's all relative. Next step is to measure the temperature throughout your house and compare to your thermostat. – BrownRedHawk Apr 6 '16 at 11:54
  • "feelings" are devilishly unreliable. To have a hope of troubleshooting this properly, you'll need a data-logger of some kind. You'll go mad trying to troubleshoot off feelings, and potentially waste a lot of money. – Harper Apr 7 '16 at 0:18

Just a guess, but the colder it gets the longer the boiler cycles and the hotter the delivery water temperature gets so therefore the radiators get hotter before the thermostat shuts the boiler off.

In moderate temperatures, the thermostat shuts the boiler off before it gets very warm and so your radiators are barely above room temperature.

Check to see if your boiler has any kind of temperature control on the delivery water going out into the system. You may be able to adjust that for better performance in moderate weather.

Good luck with your project!


This could also be caused if your thermostat is in the warmest room of the house. Or if the thermostat is constantly near warm objects like electronics or even people.

When it is really cold outside those heat sources are less effective at influencing the thermostat.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.