New Office Space, Two Furnaces with one thermostat (I think)

Discussion in 'HVAC Heating & Cooling' started by dankoos, Jan 2, 2019.

  1. dankoos

    dankoos Member

    Joined:
    Jul 14, 2009
    Location:
    Columbus, Ohio
    My small company purchased new office space that has two furnaces...one in the middle of the space and one on one side of the space. The space is around 5,000 square feet and is basically rectangular with the elevator/stairs in the middle (2nd floor space). The one thermostat we know exists shows the current temp at 76 but is set for 69. Even when it is set lower than 69, the actual temp always seems to be in the mid 70's. Is it possible there is a hidden thermostat somewhere for the second furnace? The thermostat we know of is your standard Honeywell programmable...I have the same version in my house. If it makes sense there is just one thermostat, what might cause it to be so much over the set temp? New thermostat needed maybe?

    I have been through the set schedules and at no time is it set to be higher than 69.
     
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Occupation:
    Retired Systems engineer for defense industry.
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    New England
    Some fancier thermostats have remote sensing, but it's not that common.

    What sort of equipment is in the space? Is is possible that the combination of lights, equipment, people are providing enough heat to keep it that warm?

    Is the upstairs where it is always hot? Without proper return ducts, and the natural tendency of hot air to rise, the second floor could easily end up warmer.

    As an experiment, turn the thermostat off, or set it to some way low temperature and see what happens to the room temperature.

    Also, keep in mind that sometimes, the placement of the thermostat may need to be changed if it gets breezy, or is isolated from the main space, or sees direct sunlight.
     
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  4. dankoos

    dankoos Member

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    Thanks for the reply. We haven't actually moved into the space yet, this high actual temp has been the case every time we are in there. We bought the space w/o and inspection, so we have to deal with it. It is a 2nd floor unit (office condo) and was built in the late 90's I believe. One of the times we were in there, the thermostat was set at 55 and it was still hotter than hell in there. If we have to call someone out to come look, so be it, just wondered if there was something easy we could look at first. One of the furnace closets is extremely warm vs. the other, making me guess one unit is running most if not all the time to get it to the current temp. Although, it is not like they keep running after it hits mid 70's.
     
  5. Dana

    Dana In the trades

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    It's a bit hard to diagnose the system with the minimal information at hand. 999 wild guesses could all end up being wrong.

    Replacing the thermostats with wireless (not to be confused with Wi-Fi) thermostats makes it easy to move the thermostats where they seem to work the best, and may take less time than actually tracing out where the control wiring & ducting all goes.
     
  6. WorthFlorida

    WorthFlorida ?

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    Are the furnaces gas, oil, or electric, forced air? Is one of the furnaces always running? The one that you feel is always warm, if you know how, disconnect the thermostat wire at the furnace and it should shut down. Then turn up the thermostat that you know of and check if the other furnace fires up. With forced air systems, FAN setting at the thermostat can be set to AUTO or ON. ON will run the fan continuous, AUTO only runs when heat or cooling is called for.

    Most programmable thermostats uses two or three AA batteries for power. They will always show a display even with the thermostat wires disconnected.

    Most office space has dropped or suspended ceilings. You can lift the panel away at the ceiling by the known thermostat and look for the thermostat wire. It generally will go to the direction of the furnace. It is possible that one thermostat handles both furnaces if someone knows how to do it.

    If you are really lost, then you’ll need to call an HVAC company.
     
    Last edited: Jan 4, 2019
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    For one thermostat to work two furnaces, the most reliable way to do that is with an isolation relay for one of them, and be powered by the other.

    As said, with the info you've given, everything is a guess.
     
  8. dankoos

    dankoos Member

    Joined:
    Jul 14, 2009
    Location:
    Columbus, Ohio
    Some additional info: The thermostat is a Honeywell FocusPro 6000. I turned the thermostat OFF yesterday and the office stayed at 74 degrees (I am in Ohio) all night and it was in the 40's last night. I tried pulling thermostat off of the wall and the wiring looks correct, green wire going to G, White wire to W, Blue to C, Yellow to Y, red to R, and the jumper pin is still in. One other note, inside one of the furnace rooms is a wall switch (right next to the furnace) that is in the "on" position, but someone wrote on the drywall, "leave off". Not sure if that has anything to do with anything. The switch is not labeled in any way and since it is a drywall wall, i cannot follow the wires. One last thing, I lied, there are three furnances.
     
  9. dankoos

    dankoos Member

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    Columbus, Ohio
    All THREE furnaces (I missed one before) are gas, forced air. All wiring is in the floor I believe because the ceilings are cathedral or whatever you call it, the ductwork is visible and hangs from the ceiling.
     
  10. WorthFlorida

    WorthFlorida ?

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    Retired
    Location:
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    That wall switch could be a cutoff for the gas furnace. Of the three furnances, are any of the chimney flutes hot or are they direct vent? If the room is staying warm then you should hear a blower running at one of the furnaces.
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    IF the switch says leave off, it wouldn't be an emergency shutoff...it would need to be one for the furnace to function, and you could turn it off to disable the furnace.

    WHat it might be is a manual ON to force the furnace to run continuously. If you didn't, shut it off and see what happens. After shutting the thermostat off, was the furnace still running (at least one of them)? If so, that could be that manual on switch, a miswiring, or a short somewhere.
     
  12. dankoos

    dankoos Member

    Joined:
    Jul 14, 2009
    Location:
    Columbus, Ohio
    Thanks all for attempting to help. Had tech come out and turns out I am an idiot. There were 3 stats after all. One was the programmable, another was this little tiny thing I thought was something else, and the last one was downstairs in the common area (building is two floor two unit condo). Turns out the third furnace services the common areas on both floors, including restrooms. So one of the two on our floor was set higher and causing the whole unit to stay warm. Plus the one downstairs gets cold due to the front door, so I lowered it a couple degrees more than the two upstairs. Real strange design in my opinion.
     
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