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WHY WOULD MY FURNACE SHUT OFF BEFORE IT REACHES REQUESTED TEMP ON THERMOSTAT
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Welcome to the forum; One reason it would shut off is because it has tripped the High Limit.Did it finally come BACK ON a few minutes later to make up the thermostats set point? OR, without coming back on ,did the thermostat,(after a few minutes) finally show it had reached the set point? Post back with this info and we will advise further. Thanks. There are a couple of reasons why some furnaces do this. Hube -
Hi Hube
It did come back on but it never reached the requested temp. The temp in the house remained at 15 degrees (C)but we had the thermostat turned all the way up to 25 deg (C). This was over the last 36 hours and the house has gotten no warmer than 15 deg. The furnace will come on for a few minutes then shut off, on for a few minutes then off again.Two weeks ago I had installed a new thermostat and thought this would take care of the problem but it would still get no warmer then 20 degrees(C)and that is when the temp outside -16. I thought this would see us through til after this season but it is now minus 40 degrees out with the wind chill and we are starting to take notice!! Hope you have some helpful hints- thanks for replying
>quote:Originally posted by Hube
Welcome to the forum; One reason it would shut off is because it has tripped the High Limit.Did it finally come BACK ON a few minutes later to make up the thermostats set point? OR, without coming back on ,did the thermostat,(after a few minutes) finally show it had reached the set point? Post back with this info and we will advise further. Thanks. There are a couple of reasons why some furnaces do this. HubeComment
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You said you put a new thermostat in. Did you set it to the proper cycle setting?.Are you sure it said was compatible with this type of heating system? What type of thermostat, setback, programmable,? make?Model? HubeComment
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Hi Hube the instructions said to take the numbers of the old unit (thermostat)and i checked them with the one on furnace also the range of numbers (0 to 9.5 A) Our furnace was 6.5A .The thermostate is a honeywell dial (2) wire Mercury switch model.I don`t know what you mean by (setback)Thanks.
quote:Originally posted by Hube
You said you put a new thermostat in. Did you set it to the proper cycle setting?.Are you sure it said was compatible with this type of heating system? What type of thermostat, setback, programmable,? make?Model? HubeComment
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The inst said to use the numbers off the old thermostat and i looked on the unit also just to confirm. the new thermostat is a honeywell two wire mercury switch dial.
quote:Originally posted by Hube
You said you put a new thermostat in. Did you set it to the proper cycle setting?.Are you sure it said was compatible with this type of heating system? What type of thermostat, setback, programmable,? make?Model? HubeComment
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Fire guy; Ok, the thermostat sounds ok to me. Tell me, when the burner kicks in and then shut off a few minutes later, does the blower (fan) come ON and run for a few minutes? Or does the blower (fan) Not ever come on? HubeComment
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Hube The blower fan does come on , and the burner continues to run . Its like the furnace has an internal thermostat and shuts itself down?.But the fan will run for A period of time after. thanks Fire Guy
quote:Originally posted by Hube
Fire guy; Ok, the thermostat sounds ok to me. Tell me, when the burner kicks in and then shut off a few minutes later, does the blower (fan) come ON and run for a few minutes? Or does the blower (fan) Not ever come on? HubeComment
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Ok, like i said in my FIRST reply to you; it could be a faulty, or incorrect setting of the "High Limit Control. This is sometimes adjustable. Look it over . There can be a fan on and off setting, and a High (safety) setting. Let me know, HubeComment
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Hube On my furnace the control unite has fan control and a guage that I belive to be high limit control control, the numbers on it are 110 - 150 where should it be. and is that the high limit control. Fire Guy. ThanksComment
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Fire Guy; The fan control usually has 2 indicators, one for fan on set at approx 95, and one for fan off set at approx 125. It would appear by your description,(gauge) your High Limit is probably a "fixed" one, but, if it is adjustable it could be set at approx 180-200.MAXIMUM. Check it out.BTW, how's the temp in the house doing.? Hope your not freezing, HubeComment
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Hube Thanks for all the info, you have been a big help.P S The temp is still not to bad around 16 (c) The good news is its only minus 18 (c) outside. Iam going to change both high limit and fan control units. Fire GuyComment
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New limit may do the same if there is a nother problem first dettermine why it goes off on limit a dirty filter will cause this evenComment
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Not enough heat.
Lukewarm heat coming from duct? The duct is barely warm?
I had the same problem with my Rheem High efficiency furnace.
we called the Gas Company. He tested the gas coming into the house and then to the furnace. He disovered that the gas pressure was not proper.
They calibrated the gas and as more gas pressure was applied to the flames got bigger in the furnace and heat was immediate.
The cause was a flexible copper pipe was installed beween the black gas pipe and the furnace. Some gunk was in this pipe. the gas pressure up to the house was ok. It was in the house that the pipe was 50% plugged with putty like substance.
i hope this helps.
Altrade
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I have to ask here is the filter clean and new. I dont think you have a AC coil there but if so is it clean . The blower wheel is it clean????? The small cup blades in it get dirt build up .That makes them flat and they dont blow the air .you can go off on high limit.
then is the anticipator set right on the tstat. Also if its LP pressure should be set 11" W/C You have lots of ifs ifs here.
ED
My mistakes dont define me they inform me.My mistakes dont define me they inform me.Comment
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