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furnace running constantly

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  • furnace running constantly

    We have a Trane XL80 furnace with a Honeywell thermostat, and live in northern Ohio. We've only lived in this home a few months, and don't really have a reference. We have a 2400 sf 2-story home.

    My question is, our furnace seems to run... A LOT ! It turns on for 8-10 minutes at a time, every 5 minutes. So it's running an average of 40 minutes an hour? Our other home's furnace turned on every 15 minutes or so for 5-10 minutes at a time. This one seems to do nothing but run! Does this seem normal? Thermostat is in a good location of the home, so we've ruled out drafts or wrong location.

  • #2
    Re: furnace running constantly

    Is it the furnace or the fan that is running, some times the fans thermostat is set so it runs more to retrieve the heat that in the system and pushes it out into the room, and the heat or burners are not on all the time the fan is running.

    the heat deferential on the thermostat may be less if this is a new thermostat, (the difference of where it shuts off and turns on),
    Last edited by BHD; 12-26-2007, 10:00 AM.
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    • #3
      Re: furnace running constantly

      I think we may need more information than what is described here.....

      How many BTU's is the furnace? Is it a high efficiency unit or a mid efficiency unit? Is the thermostat at it's set point and the furnace keeps running? ?As mentioned is it still blowing hot the entire time?

      Does it's tendancy to run all the time reduce as the outside temperature climbs? Does it stop running if you turn the thermostat below the current temperature?


      • #4
        Re: furnace running constantly

        Looking at Trane's website, I learned that this is a two stage furnace.
        I've received similar complaints from customers where we've installed Amana's two stage furnnace. (AMH95 series) If the furnace is maintaining the temperature that the thermostat asks for, there isn't a problem. It's likely that your furnace never runs long enough to go into second stage or high fire mode. When the weather turns colder, and the furnace experiences longer run times, then it will start to go into high fire mode a little sooner. I've always been told (and explained to customers) that a properly sized furnace just matches the heat loss of the house on a design day. A design day is based on the coldest temperature that you can expect to see in your region. Here in Western New York, we use 0 degrees. If the contractor picked a furnace that exactly matched the heat loss of your house, then on a zero degree day, the furnace would run 24 hours just to maintain 70 degrees in the house. Every other day of the year, the furnace is over-sized. The logic behind and the advantage of a two stage furnace is that it can provide a lower amount of heat (usually 60% 0f it's rated output) in low fire mode most of the time. This not only, prevents overheating and large temperature swings, but also improves fuel efficiency.


        • #5
          Re: furnace running constantly

          Originally posted by Kneescar View Post
          I've always been told (and explained to customers) that a properly sized furnace just matches the heat loss of the house on a design day. [/FONT]
          Ok, this does make a lot of sense. But then, if the house is to grow (addition/s) then you'll have the wrong size furnace. Of course no one really knows when an addition will be put on (unless planned). So then this furnace maybe a 3 yr old furnace and it would need to be replaced, because they did put up an addition. Some people may plan on doing an addition, thus buying a bigger furnace, then never actually building the addition. This is just added thoughts. So I do tend to lean towards the thought that if there is to be an addition to be built, within 5 yrs, plan for it now if replacing or upgrading to a more efficiency furnace. I know I went off the topic here, thats why its just an added thought.
          Great Link for a Construction Owner/Tradesmen, and just say Garager sent you....

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          • #6
            Re: furnace running constantly

            Not a big furnace tech...Im in Florida ...but check the simple things first.

            1. Furnace runs alot....ok what temp are u setting t-stat at? What is outside tempature. We get customers who say ac runs alot...well t-stat is set at 70F and its 90F outside...soo of course its running kind of the reverse ?? for u. IS fan switch on t-stat set on auto or will run all the time in ON position...not just when furnace fires up. Also try setting a thermomter near the t-stat..even digital ones can be off...see if t-stat is reading for example 72F when the actual temp is 75F....some t-stat have a softwear adjustment.

            2. Along thouse is your homes inuslation??? Also what kind of shape is your duct work in?? a leaking duct heating your attic and not the house will cause problems.

            3. are your flters clean?? A dirty filter keeps the unit from getting air...soo runs but not getting enough air to meet running with a pillow over your face..hard to breath.

            4. Check you A coil....again not a big furnace tech....down here we have cooling coils generaly above the heater air handler....sooo hot air has to pass through the ac's coil....if Coil is dirty..cloged...not have good air flow can keep unit for properly heating your home.

            5. like some have said...high effecncy furnaces and ac unit...will run after heat/cooling turns off to get last few BTU's out of it...we uslay set it for 90 seconds...sooo when u say running all the it also running when the flames are off?? U may also have flames but not proper a car needing a tune up...system is working but needs my spelling

            Check the simple things..especialy the air flow...once u rule out the obvious as not beig the problem...then u may want to call a local company to do a tune up...or diagnostic....

            Hope this helps..