Furnace pro's...a bit of help?
#3001222
01/02/22 05:41 PM
01/02/22 05:41 PM
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Joined: Jan 2003
Posts: 2,776 St. Louis, Missouri area
Cometstorm
OP
"Beat It"
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OP
"Beat It"
Joined: Jan 2003
Posts: 2,776
St. Louis, Missouri area
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My HVAC setup is tanked propane (under 35F), and heat pump (over 35F). Trane XV90 furnace. About 12 years old. Today, the heating (its about 20F outside) started blowing cold air. When I switch off the system, wait a bit,, and turn back on...it will heat for about ten minutes, then back to blowing cold air. Of course I suspect the "flame sensor" but cannot find one behind the panel. The burners are behind a cased metal box at the top of the unit. There are several couplings going into it (the burner box). One I know is the "temp trip limit switch", the other I don''t know. But they both have two wires going to them. Flame sensor is only supposed to have one. THere are three screws to the burner box, but I have not (yet) removed them because I don't see a "single wire" going in (that would lead me to suggest there is a flame sensor inside). There are stickers around the system stated it has been "modified" for this particular propane setup, so I don't know if that makes my "system guts" different from most. I've Amazon ordered an exact "flame sensor" and "temp" limit switch. As stated tho, I have no idea where the flame existing flame sensor is. Or does the temp limit switch work as such? Any thoughts out there are much appreciated!
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Re: Furnace pro's...a bit of help?
[Re: topside]
#3001285
01/02/22 07:59 PM
01/02/22 07:59 PM
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Joined: Oct 2005
Posts: 8,906 Ontario, Canada
Stanton
Don't question me!
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Don't question me!
Joined: Oct 2005
Posts: 8,906
Ontario, Canada
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Go on YouTube and type in your furnace model and "flame sensor" and you'll find what you're looking for. Actually I think its more of a gas flow sensor than a flame sensor. Either way, you'll find what you need on YouTube.
Last edited by Stanton; 01/02/22 08:00 PM.
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Re: Furnace pro's...a bit of help?
[Re: Powerflow]
#3001343
01/02/22 11:06 PM
01/02/22 11:06 PM
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Joined: May 2019
Posts: 6,306 nowhere
Sniper
master
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master
Joined: May 2019
Posts: 6,306
nowhere
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The flame sensor in my 25 y/o gas furnace craps out roughly once a year. Each time, I remove the sensor and clean it with a Scotchbrite pad. That seems to be doing the trick. You might want to have a pro take a look at that, seems your might be generating soot and that's an issue.
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Re: Furnace pro's...a bit of help?
[Re: 360view]
#3001392
01/03/22 10:12 AM
01/03/22 10:12 AM
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Joined: Jan 2003
Posts: 10,752 North Dakota
6PakBee
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,752
North Dakota
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First comment is about the modified for propane label. The vast majority of gas appliances are set up for natural gas. Propane has about twice the energy of natural gas so the main gas valve AND the igniter both have restrictors in them to allow the use of propane. Otherwise you'd burn the appliance up. As to finding the igniter, follow the gas piping from the discharge of the gas valve. It leads to the burners and the igniter will be in the same location as the burners. Good luck.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Furnace pro's...a bit of help?
[Re: Powerflow]
#3001516
01/03/22 02:27 PM
01/03/22 02:27 PM
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Joined: Jan 2008
Posts: 2,275 ILLINOIS
volaredon
top fuel
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top fuel
Joined: Jan 2008
Posts: 2,275
ILLINOIS
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The flame sensor in my 25 y/o gas furnace craps out roughly once a year. Each time, I remove the sensor and clean it with a Scotchbrite pad. That seems to be doing the trick. Yup. Have had to do that about every other year on my Rheem house furnace
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Re: Furnace pro's...a bit of help?
[Re: Cometstorm]
#3001715
01/03/22 07:30 PM
01/03/22 07:30 PM
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Joined: Jan 2003
Posts: 2,776 St. Louis, Missouri area
Cometstorm
OP
"Beat It"
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OP
"Beat It"
Joined: Jan 2003
Posts: 2,776
St. Louis, Missouri area
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OK, it’s about 7 AM, 54 degrees in the house. I started it again, and “at the moment” it’s running a nice blue flame (hardly any yellow). While it’s running, the light code is 40 green to one red. I’ll advise how it goes. Thanks all! I fear it will just start blowing cold shortly, but we’ll see). Update: It’s now 5:30 pm, system has been holding at 72 F all day, and cycling to keep it there. Dang furnace gremlins! All I can do is keep an eye on it!
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Re: Furnace pro's...a bit of help?
[Re: 360view]
#3001896
01/04/22 10:46 AM
01/04/22 10:46 AM
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Joined: Jan 2003
Posts: 2,776 St. Louis, Missouri area
Cometstorm
OP
"Beat It"
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OP
"Beat It"
Joined: Jan 2003
Posts: 2,776
St. Louis, Missouri area
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Thanks 360! It’s now 9 AM the next day. All has been perfect for the past 24 hours (knock on wood). Actually had to back the propane heat down to 68 a few minute ago. Aside from removing the panels, the only thing I did was remove this, then re-installed it. I didn’t even disconnect the two wires. C340366P02 - American Standard OEM Furnace 3" Replacement Limit Switch https://www.amazon.com/dp/B00FEM579...K3TA6YAMKT3SBMA?_encoding=UTF8&psc=1I doubt this part is an issue. From what I’ve read, it’s failure symptoms are cold air, and 24/7 can operation. My fan is now cycling, as is the whole system. But I have a new one on order anyway. If I have another issue, and replacing it doesn’t help… then it’s service tech time. But all perfect for now, and panels back in place.
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