# Furnace shuts off after a few minutes



## jkcountry (Feb 5, 2007)

Ok here is the deal. We are working with an older furnace probably before 1977 now it works but don't know if it is the furnace or thermostat. The Thermostat is set for 72 degrees in the house and it is 65 it only runs for like 5 minutes or so and then shuts off. If I manually go to the thermostat and turn it off and then turn it back on it kicks the heat back on. for just a little while. Now this Whole past week it has been in the single digits here, but i know if my desired temp is not met it will keep running I thought until it reached it.

I have one of those Thermostats that can be programmed to turn on at certain times of the day.  I was thinking it was the Thermostat but also after reading some of the threads here it sounds like a flame sensor but I have an older furnace and it may not have one. Any help is greatly appriciated.

Jonny
St. Louis, MO


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## Hube (Feb 5, 2007)

jkcountry said:


> Ok here is the deal. We are working with an older furnace probably before 1977 now it works but don't know if it is the furnace or thermostat. The Thermostat is set for 72 degrees in the house and it is 65 it only runs for like 5 minutes or so and then shuts off. If I manually go to the thermostat and turn it off and then turn it back on it kicks the heat back on. for just a little while.
> Jonny
> St. Louis, MO


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 very confusing statements...      "now it works"   what the heck does that mean?
And how long is a little while?..5 minutes,  10 minutes, or...?
Is this furnace gas or oil or electric?
 did this problem suddenly one day occur or has it been doing this for some time.?
Have you checked the air filter , it may need cleaning 
Post back some detailed informtion and you will receive some proper advice.


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## glennjanie (Feb 5, 2007)

Welcome to the Fourm, Jonny:
A down and dirty test would be to remove the thermostat and tie the wires together; if it continues to run, its the thermostat. I'm not too fond of electronic thermostats anyway, maybe I'm just too old but they can fail any time without notice. 
Glenn


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## Hube (Feb 5, 2007)

glennjanie said:


> Welcome to the Fourm, Jonny:
> A down and dirty test would be to remove the thermostat and tie the wires together; if it continues to run, its the thermostat. I'm not too fond of electronic thermostats anyway, maybe I'm just too old but they can fail any time without notice.
> Glenn


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wow!!! (it would be 'down and dirty' alright.  To tell someone who is not at all  familiar with  Tstat wiring to  tie the wires together is very foolish. unless a person knows what wires are what model of stat, equipment it serves, etc, ,a T stat can be destroyed simply by "tieing" wires together. 
 Jonny; most T stats, if maintained (batterys)wil usually outlast the normal life of a furnace (18-24 years or so) Some Honeywell T 87's, and many, many other makes are still ok after 20 years or more of work. Most homeowners(not all) will always blame the T stat because of their limited knowledge in the workings of a heating unit.
As I suggested in my earlier post, give us some more info on your problem.
Note; some Tstats use a red wire for incoming low voltage juice.Generally a white wire is your burner,green is to activate the fan.By jumping the red to the white normally will activate the burner, but you have to be certain of what your actually working with, especially if none of the wires are color coded.
 It's best to let us   know what your make,
, model # is,etc. ok?


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## jkcountry (Feb 5, 2007)

What I ment by it working is the furance when on is heating but it does not run for long but when I manually turn the therm. switch to off and wait a couple of seconds and then turn it to on it clicks the furnace on. then only runs for a while turning it off. The Thermostat is set at 73 degrees and it is 66 in the house now it is 20 outside and this morning it was 9. Now the thermostat is a Hunter Model 44100 I put new batts. in this morning thinking it need to be changed but they did nothing in solving the problem.  The wires coming out of the wall are red, Blue, white, and Yellow. now on the wires the red wire has a label sticker y on it, the Blue has a W label on it, white has and R label on it and yellow has a G lable sticker on it. Hope that was spelled out better for you.


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## asbestos (Feb 5, 2007)

Man 1977 ain't old I have a t-stat from round about 1949 and it works fairly well.
 It runs and old oil fired American Standard boiler from around the same time, with a newer intermatic burner.
 the t-stat uses line voltage, metal spring and relay. Were talkin' bomb-proof


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## dj43 (Feb 11, 2007)

i purchased a new home 1 month ago it. it lppks to have a new furnace beckett honeywell model it was working great until last night then it ran for a minute and shut down. it is an fuel oil unit i checked the obvious tank has fuel i thought it may have lost its prime so i bled the system. pushed the reset button the unit came on for about 30 seconds and shut down now i have aflashing green light that says im locked out  help what do i do?


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## Daryl (Feb 11, 2007)

Have you checked the flue pipe for obstructions or have I missed something about it being an electric model? Could have a partially blocked flue which could shut the furnace down early.(safety feature)


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## Hube (Feb 11, 2007)

Dj43; you just "hi-jacked " jkcountry's post .You should have started your own post. 
But as to your problem, unless your familiar with oil burners,etc, it's best to call in a pro.
it may well be that the CAD cell is dirty(sooted)and cannot detect the flame so it shuts the burner down.....Or, it may be faulty or dirty electrodes, or just a cloggedup nozzle.
oil furnaces need yearly tune-ups to keep operating well.


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