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carrier furnace issues

6K views 2 replies 2 participants last post by  sbroways 
#1 ·
I have a carrier furnace with a standing pilot light.

I can get the pilot light lit - no problem, it will stay on forever as long as I don't turn the thermostat up, and get the burners to light up. At first, when I turn up the thermostat, everything works as normal; the burners fire up and the blower comes on. I've replaced the filter and thermocouple, but once the furnace starts, it only stays on for about 5 min. Then it shuts down: first all the burners go out, then about 2 seconds later the pilot light goes out. The blower stays on through all this and will continue to stay on as long as the thermostat is up. I talked to a couple of HVAC guys about the issue. I was told it was either the a bad valve (i guess the main valve that the thermocouple and pilot light are connected to) or that I have a crack in something (can't remember the name of this part) and that it may be leaking carbon monoxide into my house. I don't believe these are the problems. The furnace is so close to working, I'm really hoping for a simple solution.

Any advice would be greatly appreciated, thanks in advance.
 
#2 ·
Hi sbroways

If the furnce is older than 20 years old. It could have a cracked heat exchanger. But if its not cracked, look and see if the pilot flame has a yellow tip. If you answered yes to this, the pilot burner assy. needs to be pulled and cleaned. This should be all that is required, however you will need to completely diassemble the pilot burner. This means to remove the pilot orfice and clean it also. Take your time to do this, use a wire brush and you can use the canned air that you use on a computer to blow the debris off. Once you have it all cleaned up, reassemble it and make sure to check the pilot tube for leaks before attempting to light pilot. I don't mind giving the advise, but I don't want you getting hurt. If you don't feel comfortable with this process, please seek out professional help. Have the heat exchanger tested with a chemical called HEAT EXCHANGER ANALIZER. This is an important part of a yearly tune up. This will let you know if you have a problem, and eliminate any questions.

Good luck
Rusty
 
#3 ·
Cleaning the Valve

I removed the pilot light and thermocouple from the valve. I then removed all the screws I had tools for, from the valve. There are several screws left that require a star wrench type security key. I have the gas shut off at the furnace, but I'm wondering what precautions (shutting off gas to whole house?, release the pressure in the valve??), I need to take before disassembling the remainder of the valve.
-It is a Honeywell Valve. If you need more information about my project, I can post photos.
Also, when I removed one of the screws (allen wrench) it had grease on the bottom of it, and I wondering where I can get some of this stuff (i checked home depot, they didn't have it). I dropped the other matching screw in the dirt and lost the grease. The grease is yellow in color, and was in a ring around the bottom of the screw.

Thanks again for your help.
 
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