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Why Wouldn't My Gfa Furnace Fire Up?



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NILLINOIS

Ok, not really Corolla..or even car related..but an interesting DIY-kinda project. My 12yo Carrier Furnace wouldn't fire up.

The symptoms: Turn on furnace...Blower motor starts and runs for 3 mins. Then draft induction motor starts. After about 1 min the Hot surface ignitor SHOULD start glowing..but didn't..Hmmmm...

My casual observations made me think that I just needed a new HSI..but after getting a new one and installing it, still the same problem.

Now to start hunting what else could be the problem.

NOTE: GFA furnaces are definetly DANGEROUS and should be approached & diagnosed with extreme care!

I figured, If i couldn't figure it out, I'd just call a serviceman and bite the bullet. But I wanted to be sure it wasn't a $5 part that I'd have to end up paying $150..so off I went.

Going to all references I could find on operations & parts on GFA, I found most modern furnaces have something called a Pressure switch, which reads the pressure on the flue. If there is sufficient negative pressure, the switch will close, indicating there is exhaust for the burner gases ( CO! ). It reads the pressure in the flue via a 1/4 tube. Sometimes, these tubes get blocked or develop a kink..but not in my case.

References said to just remove the switch ( pic below ) and test for continuity with a multimeter. Just suck on the tube and test. If the switch is still good, the contact will close when there's pressure. Mine worked fine.

https://s74.photobucket.com/albums/i265/NIl...t=P1010008s.jpg

Next, It is indicated that one should test the pressure while the draft induction motor is running. To test,

you need a magnehelic gauge, which I bought on eBay for $12. After about 10 days, I tested the pressure

and it was ok too! Hmmm..now what?

After scouring various forums and websites, I found a great DIY site which sells appliance parts. There was

mention of a couple of 'limitor switches' that must be functioning properly to send voltage to the circuit board before the controller will fire up the HSI. It was BRIEFLY mentioned that one of the limiter sensors/switches has a 'reset' button in the middle. I found the sensor, and found the button. Pressed the reset button...and tried it..VOILA..it fired up perfectly.

I emailed the webmaster of the site thanking him, and asked what that limitor switch is for? He said it's a temperature switch. If the temp in the flue goes above a certain temp, the switch will disengage and prevent the furnace from starting ( presumably, another safetly precaution if the flue becomes overheated ).

He suggested I look down the chimmney for any obstructions ( Bird or Wasp nest ). I did so, took my most powerfult flashlight but found nothing. A clear shot all the way down to the furnace.

Well, that's my story. I still don't know what caused the temp limitor to pop, but the furnace has been going for about 3 weeks now no problems.

Come to think of it, I vaguely remember the day the furnace stopped firing up...back in April, during a VERY windy day. I suppose its possible a huge gust of wind blew down the chimmney and back-pressured the exhaust gas enough to cause the breaker to trip. FYI.

BTW, here's the website for diagnosing and repairing. Arnold is a nice guy:

http://arnoldservice.com/Troubleshooting_H...ng_Problems.htm

Good DIY steps in troubleshooting. This probably would have helped by folks with their system (same problem on a 1987 Carrier unit) - but in the end they ending up getting a new one anyways since the existing furnace was already pretty old.

tashirosgt

I have a Carrier gas furnace, a "Weathermaker" or something like that. It worked when it was first installed (in warm weather) but when winter came, it had the same symptoms as yours. The installer fixed it. He said the city gas pressure changes between the warm and cold season so he had to adjust it. I've had the problem once or twice since then and have fixed it by turning an adjusting screw to regulate how much gas goes to the burner in its sealed combustion chamber. Not being near the furnace at the moment, I can't describe the location of this screw, but as I recall, it's fairly obvious. The symtoms were caused by the burning failing to sustain a flame. A safety arrangement shuts off the gas and tries to exhaust any built-up gas.

One summer the city tore up the whole street and replaced the sidewalks and gas lines and gas meters. That winter the furnace would not start. I called the city (on a Sunday) and a worker, who was somewhat angry, showed me there was adequate pressure at the meter by opening the outlet full blast. The furnace installer came and examined the plumbing. Just inside the plumbing to the house he found the pipe was partially blocked by a small pastic cap, the kind that is put on the end of pipes to protect the threads before the pipe is sold. I suspect the new city plumbing had something to do with this.

Larry Roll

OK, I'll bite. What is a "GFA furnace?" This is a terminology I haven't seen before. How does it differ from a normal gas or oil-fired furnace?

Bikeman982

I don't know too much about furnaces, but I suspect if it is gas, that there is not a good pilot light, or the gas is not working correctly. Might be a clogged jet.

NILLINOIS

GFA-Gas Forced Air

Bikeman982

Ok, not really Corolla..or even car related..but an interesting DIY-kinda project. My 12yo Carrier Furnace wouldn't fire up.

The symptoms: Turn on furnace...Blower motor starts and runs for 3 mins. Then draft induction motor starts. After about 1 min the Hot surface ignitor SHOULD start glowing..but didn't..Hmmmm...

My casual observations made me think that I just needed a new HSI..but after getting a new one and installing it, still the same problem.

Now to start hunting what else could be the problem.

NOTE: GFA furnaces are definetly DANGEROUS and should be approached & diagnosed with extreme care!

I figured, If i couldn't figure it out, I'd just call a serviceman and bite the bullet. But I wanted to be sure it wasn't a $5 part that I'd have to end up paying $150..so off I went.

Going to all references I could find on operations & parts on GFA, I found most modern furnaces have something called a Pressure switch, which reads the pressure on the flue. If there is sufficient negative pressure, the switch will close, indicating there is exhaust for the burner gases ( CO! ). It reads the pressure in the flue via a 1/4 tube. Sometimes, these tubes get blocked or develop a kink..but not in my case.

References said to just remove the switch ( pic below ) and test for continuity with a multimeter. Just suck on the tube and test. If the switch is still good, the contact will close when there's pressure. Mine worked fine.

https://s74.photobucket.com/albums/i265/NIl...t=P1010008s.jpg

Next, It is indicated that one should test the pressure while the draft induction motor is running. To test,

you need a magnehelic gauge, which I bought on eBay for $12. After about 10 days, I tested the pressure

and it was ok too! Hmmm..now what?

After scouring various forums and websites, I found a great DIY site which sells appliance parts. There was

mention of a couple of 'limitor switches' that must be functioning properly to send voltage to the circuit board before the controller will fire up the HSI. It was BRIEFLY mentioned that one of the limiter sensors/switches has a 'reset' button in the middle. I found the sensor, and found the button. Pressed the reset button...and tried it..VOILA..it fired up perfectly.

I emailed the webmaster of the site thanking him, and asked what that limitor switch is for? He said it's a temperature switch. If the temp in the flue goes above a certain temp, the switch will disengage and prevent the furnace from starting ( presumably, another safetly precaution if the flue becomes overheated ).

He suggested I look down the chimmney for any obstructions ( Bird or Wasp nest ). I did so, took my most powerfult flashlight but found nothing. A clear shot all the way down to the furnace.

Well, that's my story. I still don't know what caused the temp limitor to pop, but the furnace has been going for about 3 weeks now no problems.

Come to think of it, I vaguely remember the day the furnace stopped firing up...back in April, during a VERY windy day. I suppose its possible a huge gust of wind blew down the chimmney and back-pressured the exhaust gas enough to cause the breaker to trip. FYI.

BTW, here's the website for diagnosing and repairing. Arnold is a nice guy:

http://arnoldservice.com/Troubleshooting_H...ng_Problems.htm

So, the bottom line is that it is fixed now and working fine. That's good news!