Gas and Oil Home Heating Furnaces - Day and Night Furnace -- gas won't stay on

I've contacted the LL and have talked to her, but she is giving me the runaround. Bottom line, the gas doesn't stay on for more than 3 minutes before shutting off.

Beginning Temp = 62
9:08 Furnace clicks "on"
9:08 30 seconds later, the gas turns on
9:09 30 seconds later, the blower turns on, house is now being heated
9:13 Gas turns off, only blower running
9:17 Blower turns off
Ending Temp = 62.5

1 second later, cycle starts all over again.

I've replaced the thermostat with no change in the problem.

Yesterday the LL had a repairman replace the control board...claimed it is working properly, but this morning still had the same issue.

I think it's insane to say that it's "normal" for it to take 4 hours to heat an 800 duplex from 62 to 69 degrees. In every other place I've lived that had a gas furnace, the warm air continues to blow until the target temperature is reached.

Help?

Hi Deb
No, thats not right. Sorta sounds to me like the upper limit is being reached. I'm sure one of the experts will way in soon. But... are you going to mess with it yourself? I wouldn't think so, since you are renting.

Definitely should stay on until its getting close to set temp, then burner should shut off, and fan will continue for a few min to remove residual heat from furnace, hopefully stopping right at or near setpoint.
Good Luck

Best in 2008

Heck no I'm not going to try to repair it! LL will be sending repairman out again. I have a feeling she's getting ripped off, or (more likely) is calling the cheapest place around. You get what you pay for!

I KNOW that it's not right. I do have heat, but it takes forever to warm up in the morning -- it's around noon before it reaches 68!

It's a very small place (about 800 sq ft), I could probably heat it faster by leaving the oven door open.

Your furnace sounds like it is behaving properly, actually.

It is just that it is shutting off before your set point.

Because the blower is also shutting off, it seems like the stat is shutting off. Perhaps the stat gets too quickly warmed up in that location, and because of that, temporarily shuts off. But then after no more hot air is blowing, the temp at the stat quickly falls again, due to house belongings and air still emitting only 62 degree temp, and then the furnace starts up again. (I have come across this type of situation in houses)

What kind of stat did you install? If a digital, did you happen to notice if it had a programable swing temp? Also, are all the switches inside set right (i.e., to gas if you have a gas furnace, instead of to electric?). Do you still have the instruction sheet that came with it? If it is a mechanical type, maybe the heat anticipator setting is too low.

Actually, the blower is shutting off about 4 minutes after the main burners go off, just about what it would take to come down from a high-limit situation. ;)

I do not think it is the thermostat because eclecticdeb would have stated that it works fine with the thermostat set higher, also ruling out an 'anticipator missadjustment' on the thermostat. Everything in that play by play snapshot points to the high limit. My money is on gunguy45's diagnosis. :thumbup: Let's keep it simple.

Good luck,

Charlie:coffee:

How old is the furnace? Trying to determine which type of ignition system we are talking about.

Said that the filters my BF had installed were "too good" and were not allowing enough air to get to the furnace, in effect making it overheat.

So, he suggested that we remove the filters and run it like that until we can get "cheaper" filters installed. Why he didn't suggest this before he had the LL pay $500 for a new control board.....???

So....it seems to be running okay now. However, every now and then it reverts back to the same problem. We can "fix" it by resetting the furnace when we actually power it down (turn off the switch), then turn it back on.

So, right now I don't know WHAT to think. I haven't had a chance to get new filters...it will be interesting to see if "cheap" filters make it overheat.

Don't know how old the furnace is. (sorry)

THANK for all your help...It's really been beneficial to be able to talk somewhat intelligently to the repairman.

The fact that the furnace continues to overheat occasionally even with the filter removed suggests that the airflow through the furnace and ductwork is impaired. That could be a return air duct covered up or multiple warm air registers closed.

Also, a dirty fan wheel plugged up with dust could be a problem.

A collapsed duct espcially the return air duct, or something plugging it up is a possibility.

An overfired furnace with too much gas going into it is a possible though unlikely soiurce of the problem, as would be a fan set at too low a speed.


Frankly, it doesn't sound like your repairman did a very thorough job of diagnosing the problem. He should have measured the heat rise across the furnace to see if the furnace was still getting too hot after removing the filter, and determined what additional problem was contributing to the problem.