Presidential III Model 7900

[DrifterBigJohn]

First and Foremost ...THANK YOU FOLKS FOR A GREAT SERVICE TO THOSE OF US TRYING TO SAVE MONEY AND DO IT OURSELVES......THANK YOU...

Now on to the problem at hand.....

My elderly mothers mobile home has a Presidential III.Model 7900 Gas Furnace.....after lighting the pilot light around 2 weeks ago and starting the heater up.....It worked just fine...cycled thru and did as it should.....an hour later it would not work...found the pilot light out ...Lit it and continued on....next morning..No HEat...Pilot light out again...decided the thermocoupler may be the culprit..Replaced it...made sure it was seated well..lit the pilot light..positioned the Thermocoupler tip into the flame of the pilot light.....glowing a nice dull red...set the temp..burner came on...all worked just fine..for a couple of cycles....then the pilot light went out again....lit it again and this time watched it closely when the burner and blower came on....flame didnt seem to dance around..nice blue flame...watching the burner and pilot while the burner is on...it seems that the pilotlight goes off and the thermocuopler tip begins to cool...when the burner kicks off....so does the pilot light and all is done and finished....turn the on off pilot knob to pilot ..press it in....start it all over again......PLEASE HELP....What else am I missing...

[Robert]

Hi,

IF the pilot light is not being blown out by wind gusts, etc., then there are only two things that control it.

Thermocouple and gas valve. Since thermocouples are relatively cheap and sometimes you can get a bad new one, I would try one more.

IF it still won't work, then testing thermocouple with meter would be next. If it reads as it should, then would suspect a bad gas valve.

Due to expense, may wish to let an hvac tech check things before buying a new gas valve.



Thanks,
Robert

[DrifterBigJohn]

ROBERT..........THANK YOU ..THANK YOU..THANK YOU........

Waited on a friend of a friend to look at the heater, he told me that the heat exchanger was probably going to be the culprit because the pilot light was gettting SUCKED out when the blower came on......So we left it at that and began searching for alternative heat sources......

But, something just didnt seem right. The flame aways looked good and strong, wasn't dancing, constant blue...no yellows...and with a Carbon Monoxide Detector on the first vents on either side of the heater...and GETTING NO READINGS,.,,,,Something just didnt sound right...

So I grabbed a 24" Thermocoupler from another Hardware Store...Got comfy as I could and got to work...Pulled the burner and pilot assy out...checked them, cleaned them just in case. Added the new thermocoupler...found a metal collar with a manual push pull lever that slid back and forth over the front of the burner tube....had not paid attn to this last time....

So buttoned it all back up...fired it off.....let it cycle 3 times...wow..its working..ok ok , dont get excited its done this before...So I left moms waiting for that phone call that it had quit..

That was Thanksgiving.....Today is Sunday......AND THE DAMN THING IS STILL WORKING GREAT.....WOOOOOOOOOOOOOOOOHOOOOOOOOOOOOOOOO.....

THANK YOU ROBERT AND ALL THE REST OF YOU FOLKS WHO WORK THIS SITE ....YOUR EXPERIENCE AND KNOWLEDGE MADE MY THANKSGIVING A TRUE DAY OF THANKS...

Should you ever need assitance with a motorcycle, thats what i do for a living....parts, service etc..drop me a line would be more than happy to help you out...

[Robert]

You're very welcome, happy to help and glad all is good again with the furnace.


Take care and best wishes,
Robert