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Thermostat or Furnace issue.

festo Member, Email Confirmation Posts: 1
I am not the owner of the apartment building I live in, but there are four rents using a single oil fired forced hot water furnace,obviously each with their own thermostat, my apartment is the only one with issues.
We are unable to keep a constant room temperature. If we set it for 70 it will register 74 on the thermostat, but the room will still be cool,if I turn it up to 76 it will kick in and run pushing more heat than we need.
They have had several technicians look at the problem with no resolution. So far they have installed 3 different thermostats, and all 4 flow control valves, no change.
The current thermostat is a Honeywell T8775A Digital round non - programmable thermostat.

The thermostats they are using are a basic set up as far as I can tell, but obviously they are missing something,
I am not and don't profess to be a furnace tech,but as last resort I thought I would try a blog.

I would appreciate any and all feedback.
Fred Stone


  • SuperTech
    SuperTech Member Posts: 2,205
    How is the boiler zoned? Does it use zone valves or does each zone have it's own circulator? The zone control and the operation of the circulator or zone valves need to be checked.

    Its possible that a zone valve is stuck open. Or the problem could be related to an electrical/wiring problem. This should be easy to check and confirm if something is wrong with a multimeter.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    That's a tricky one. Is this a newer problem?
    Which wall is the thermostat on? Is there anything generating heat near the thermostat, even from inside the wall?
    That's not the best thermostat, and I've had bad ones right out of the box.
    If you put a thermometer next to the thermostat, are they reading close to the same temperature?
    I'd probably shoot a thermal imaging camera at it to see if that provided any clues.
    Is the thermostat set up properly (cycles)?
    Seems like you're getting enough flow, just wide swings.
    Maybe the transformer working the zone valves & thermostats for everyone isn't big enough.
    Had a customer with a similar problem and the thermostat was right next to an old-style television. The heat from the TV was affecting the thermostat.

    There was an error rendering this rich post.

  • Jamie Hall
    Jamie Hall Member Posts: 23,655
    It should be child's play for a competent tech. However...

    For your poking around -- if you can -- you mention zone valves. So we'll assume zone valves and one pump. You need to identify which zone valve serves your apartment, and then...

    Turn your own thermostat way down. Go and check. That zone valve should be closed. Now go up and turn your thermostat way up. Check again -- that zone valve should be open, and the circulating pump should be running (and maybe the boiler, but that's a different control). Assuming all is well at this point, go up and turn your thermostat down just far enough that it stops calling for heat. Go back down. Your zone valve should be closed.

    Thermostats are sometimes out of calibration, but the newer digital ones usually aren't that bad -- but it's worth checking it with a reliable thermometer next to it.

    Thermostat placement is important too -- no draughts, not near a window or radiator...

    And report back what you find from the above testing, please!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ChrisJ
    ChrisJ Member Posts: 15,922
    It says it's 74 but it's chilly in the room. Do you have a thermometer you can put in the room? Move it around every hour or so, see if it agrees with the 74 the thermostat is claiming.

    The thermostat is either wrong, or it's in a bad spot and something is heating it.

    Raising it to 76 overheats the room because that's what happens if you try to raise a system with some mass up 2 degrees, it generally overshoots.

    Sounds like a simple control problem to me.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Iceman1127
    Iceman1127 Member Posts: 2
    How is it zoned??? Zone valves or circulators without that info it's hard to determine the problem. Just guessing is not gonna help