Theremostat settings for baseboard heat

Discussion in 'HVAC Heating & Cooling' started by TWM, Nov 28, 2010.

  1. TWM

    TWM New Member

    Messages:
    2
    Location:
    Michigan
    I've recently bought an older house with a gas boiler for baseboard heat. System runs fine, I've bled the air out of it.

    My question is about what to set the thermostat at. I've been told that it is better to keep it set to a constant temperature day and night since it must run for a long time in the morning to heat the house back up, as opposed to short bursts to keep it at a constant temperature. I've also been told the opposite. Which is true?

    It's a single zone system.

    Currently I keep it set to 65 during the day, and 60 at night.
    Last edited: Nov 28, 2010
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,824
    Location:
    New England
    You can save about 8-10% by setting back 10-degrees for 8-hours or so. But, if it doesn't have enough reserve to heat the house back up again rapidly, you might need to turn it back up so early, it wouldn't be off very long.
  3. Dana

    Dana In the trades

    Messages:
    2,790
    Location:
    01609
    Setbacks work in two ways: Longer burns are more efficient than short, and there is less heat lost from a cooler house than a warmer one.

    Only if the boiler is VERY small, wit output perfectly sized for the 2% coldest hours of the year would overnight setback savings be so minimal as to not be "worth it".

    A burn shorter than 10 minutes has measurable cycling losses, an a duty cycle less than 25% has substantial standby losses. Overnight the duty cycle drops to zero, and the longer it's off, the lower the standby loss. A worst-case scenerio would be running 5 burns an hour of 3 minutes or less each, since it would suffer both maximal standby loss + losses incurred during ignition and flue purges. Time your temperature-maintence burns on a day when it's 30-40F outside- if they're shorter than 5 minutes, a Beckett Heat Manager or Intellicon 3250 HW+ economizer retrofit would yield double-digit savings.
  4. TWM

    TWM New Member

    Messages:
    2
    Location:
    Michigan
    Thanks for the info about the Intellicon unit. I have been looking at the time the furnace is burning each morning and find that it is indeed performing very short burns(sometimes less than 5 minutes). After reading through these forums, I think I will be making a purchase of the 3250 HW+.
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