Hvac

fabricator · 10-24-2008, 05:49 PM

Who is the heat and air guru
I have a rheem classic 90 about 4 years old
started in the spring thought it was low on propane
but is still doing it this fall
will cycle and heat like it should then cycle off
next time it will cycle blower will kick on
cycle back off b/4 it should, kinda like it runs out o propane ?
will cycle on off on off on off several times
without lighting, will go in shutdown mode... I guess is what it would be called
10- 15 minutes later will go thru the same ****
sometimes it will light and run sometimes it wont

thermostat cause this?
HELP..

wilson1010 · 10-24-2008, 06:21 PM

thermocouple

JeffK5 · 10-24-2008, 06:25 PM

Quote:

Originally Posted by wilson1010

thermocouple

Bingo!

Had my NG furnace do the same thing ....

fabricator · 10-24-2008, 08:04 PM

thremowho?
these hard to replace ?
where to buy?
guess i need model # and name of furnace
cost much?

itbrokeagain · 10-24-2008, 11:34 PM

616 5750 Mike sawyer.

carwash · 10-24-2008, 11:50 PM

same thing happened to ours this past spring to end the season. replaced the whole thing... not sure if the thermocouple is hard or expensive, we just needed a new furnace and didnt want to dump any money into the old one.

JeffK5 · 10-25-2008, 09:25 AM

A thermocouple is nothing more than temp. probe that sends info to the "brain" in your furnace.

When it acts up it gives the units controller bogus information , the problem my furnace had was it thought the fire on the burner failed to light so it shut the gas off ...even though the fire was burning as it should.

Turns out the thermocouple had shorted internally and was not sensing any heat ... no signal from the TC to tell it "successful ignition" so it shuts down.

Cheap and easy!

nick · 10-25-2008, 02:19 PM

your furnace should have a flashing light on the control board count the number of blink through the door do not take blower door off it will reset the board and you will have to wait for it to do it again on the door somewhere there should be a list of numbers that will give you the definition of what the blinks mean.. a 90% furnace does not have a thermo couple it has a flame sensor my guess is the furnace is getting to hot check your filters

RuffedUpXJ · 10-26-2008, 01:37 PM

Mine actually started acting up and it was due to the pressure switch which tells the control board the exhaust fan for the fumes is working. I did read my basically CEL on the board and thats what came up and I jumped it for now so the control board believes the switch is sensing the exhaust fan is working but Monday I am getting the switch so I don't need to jump it every time I want to heat my house it.

Basically the way your furnace will work is the exhaust fan will turn on first and it hopefully works and then the pressure switch tells the board everything is good. Then the hot surface igniter kicks on and glows. Then the gas control valve kicks on and starts the gas flow which goes through your plenums. The gas is ignited and the flame sensor send a voltage to the control board saying there is a flame. Sometimes the FS goes bad and you need to replace it ($30). So mine would cycle and start and reach a flame but after about 5 seconds of igniting the gas it would kick of because the exhaust weren't be sensed as leaving the chamber. But there should be a little plastic lens so you can see your control board with the lower cover on. Once it messes up and doesn't continue to run watch to see if the LED blinks. If it does take the cover off and read the panel which should tell you what might be wrong.

Hopefully that helps a little.

itbrokeagain · 10-26-2008, 03:56 PM

Little trick. Take some fine grit sand paper to the flame sensing rod. These get all carboned up and dont sense the heat properly. On a 90% Rheem Im guessing its a spark ignition and if its like the waterheaters, the spark ignitor is also the flame sensor.

fabricator · 10-26-2008, 11:14 PM

took the covers off
kinda dusty, 1 filter wasnt put in correctly
since i cleaned them last...what a dumb ass
anyway vacuumed the area
found what appears to be a round springy switch thing
about the size of a quarter
cleaned it real good wiped it off with finger
wiped something else down... inch or two long
about 1/4 inch round
anyway ducked the safety switch down
like anyone would and fired it up
went thru a cycle just fine
12 hours later
is still working fine
hopefully it is fixed
thanks guys

pete · 10-28-2008, 02:35 PM

did anyone fess up that they were a hvac guy. I need a furnace installed.have the furnace just dont have duct work yet. let me know if anybody does this cheap lol thanks pete

itbrokeagain · 10-29-2008, 12:56 PM

Quote:

Originally Posted by pete

did anyone fess up that they were a hvac guy. I need a furnace installed.have the furnace just dont have duct work yet. let me know if anybody does this cheap lol thanks pete

Quote:

Originally Posted by itbrokeagain

616 5750 Mike sawyer.

:)

fabricator · 10-29-2008, 02:45 PM

yep, seems to still be still working
the way it should

fabricator · 11-08-2008, 11:35 PM

furnace isn't fixed, it is just messin with my head
well at least it's not periodic, doesn't work at all now
took what appears to be the flame sensor out
sanded, put it back in.
has LED's... flashes 4 times then starts what i think is a new cycle
doesn't even get to the ignition stage at all
pressure switch maybe.
looks like the yellow pages on this
not sure what else to do here
Called the # above but hate 2 keep aggrivating to guy
is a far drive for him

itbrokeagain · 11-09-2008, 11:19 AM

Hmmmm I thought he lived around here.

fabricator · 11-09-2008, 04:41 PM

said he lived in harrison
jacked with the pressure switch
seems to be working, getting correct volts anyway
started jacking with thermostat and it started working again

yellowjacket · 11-10-2008, 03:46 PM

hvac dude here. back of your furnace doooor should have a chart what those codes mean. if it is your pressure switch not making, check 2 things. when your furnace is tying to light but failing, take your front combustion air (burner) door off. if it lights now, that means youve got a restiction in the intake pipe. leave, birds nest, ect. dosent light? try to clean your trap. if your furnace is a 90% or more, youll have tubes going down from below the inducer motor to a cannister(trap) before out to the drain. take it off and flush it in the sink. make sure you have it primed with water upon reinstall. hope it helps, rob. ive got to pm you about some other stuff, anyway. rob

cincygman · 11-13-2008, 10:21 PM

Is the furnace fixed yet? You can't leave a guy hanging....................

fabricator · 11-14-2008, 11:18 AM

lol...
yep is/was the POS thermostat

cincygman · 11-14-2008, 11:15 PM

OK, just had to know. By the way I'm also a tech if Yellowjacket isn't around.

fabricator · 11-15-2008, 12:39 AM

I appreciate the help
lord knows i need it

10-24-2008, 05:49 PM	#1
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	Hvac Who is the heat and air guru I have a rheem classic 90 about 4 years old started in the spring thought it was low on propane but is still doing it this fall will cycle and heat like it should then cycle off next time it will cycle blower will kick on cycle back off b/4 it should, kinda like it runs out o propane ? will cycle on off on off on off several times without lighting, will go in shutdown mode... I guess is what it would be called 10- 15 minutes later will go thru the same **** sometimes it will light and run sometimes it wont thermostat cause this? HELP.. __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

10-24-2008, 06:21 PM	#2
wilson1010 Join Date: Feb 2007 Posts: 147	thermocouple __________________ Unimog 406 XJ with a bunch of stuff put on by somebody else

10-24-2008, 08:04 PM	#4
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	thremowho? these hard to replace ? where to buy? guess i need model # and name of furnace cost much? __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

10-24-2008, 11:34 PM	#5
itbrokeagain Just Empty Every Pocket - CORE Member - Join Date: Feb 2007 Location: Amelia Posts: 1,435	616 5750 Mike sawyer. __________________ 91 fj 80 on 37 Nitto Muds with a 10k winch. Cage and sliders coming soon.

10-24-2008, 11:50 PM	#6
carwash pimpin' IS easy Join Date: Jan 2007 Location: Union, KY Posts: 3,344 Images: 605	same thing happened to ours this past spring to end the season. replaced the whole thing... not sure if the thermocouple is hard or expensive, we just needed a new furnace and didnt want to dump any money into the old one. __________________

10-25-2008, 09:25 AM	#7
JeffK5 Tiny Member Join Date: Jan 2007 Location: Colerain Posts: 798	A thermocouple is nothing more than temp. probe that sends info to the "brain" in your furnace. When it acts up it gives the units controller bogus information , the problem my furnace had was it thought the fire on the burner failed to light so it shut the gas off ...even though the fire was burning as it should. Turns out the thermocouple had shorted internally and was not sensing any heat ... no signal from the TC to tell it "successful ignition" so it shuts down. Cheap and easy!

10-25-2008, 02:19 PM	#8
nick wheeler Join Date: Jun 2008 Location: owingsville ky Posts: 25	your furnace should have a flashing light on the control board count the number of blink through the door do not take blower door off it will reset the board and you will have to wait for it to do it again on the door somewhere there should be a list of numbers that will give you the definition of what the blinks mean.. a 90% furnace does not have a thermo couple it has a flame sensor my guess is the furnace is getting to hot check your filters

10-26-2008, 01:37 PM	#9
RuffedUpXJ On XJ 2 Now Join Date: Feb 2007 Location: Fairfield Twp. Posts: 314	Mine actually started acting up and it was due to the pressure switch which tells the control board the exhaust fan for the fumes is working. I did read my basically CEL on the board and thats what came up and I jumped it for now so the control board believes the switch is sensing the exhaust fan is working but Monday I am getting the switch so I don't need to jump it every time I want to heat my house it. Basically the way your furnace will work is the exhaust fan will turn on first and it hopefully works and then the pressure switch tells the board everything is good. Then the hot surface igniter kicks on and glows. Then the gas control valve kicks on and starts the gas flow which goes through your plenums. The gas is ignited and the flame sensor send a voltage to the control board saying there is a flame. Sometimes the FS goes bad and you need to replace it ($30). So mine would cycle and start and reach a flame but after about 5 seconds of igniting the gas it would kick of because the exhaust weren't be sensed as leaving the chamber. But there should be a little plastic lens so you can see your control board with the lower cover on. Once it messes up and doesn't continue to run watch to see if the LED blinks. If it does take the cover off and read the panel which should tell you what might be wrong. Hopefully that helps a little. __________________ 88 XJ - 5" lift - 35" BFG's - Bumpers - Rock Rails - Homebrewed OBA - Roof Rack - Tube Doors - Trimmed - Dented 87 XJ - D44 - Disco D30 - 235's - 231TC - Stock for now

10-26-2008, 03:56 PM	#10
itbrokeagain Just Empty Every Pocket - CORE Member - Join Date: Feb 2007 Location: Amelia Posts: 1,435	Little trick. Take some fine grit sand paper to the flame sensing rod. These get all carboned up and dont sense the heat properly. On a 90% Rheem Im guessing its a spark ignition and if its like the waterheaters, the spark ignitor is also the flame sensor. __________________ 91 fj 80 on 37 Nitto Muds with a 10k winch. Cage and sliders coming soon.

10-26-2008, 11:14 PM	#11
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	took the covers off kinda dusty, 1 filter wasnt put in correctly since i cleaned them last...what a dumb ass anyway vacuumed the area found what appears to be a round springy switch thing about the size of a quarter cleaned it real good wiped it off with finger wiped something else down... inch or two long about 1/4 inch round anyway ducked the safety switch down like anyone would and fired it up went thru a cycle just fine 12 hours later is still working fine hopefully it is fixed thanks guys __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

10-28-2008, 02:35 PM	#12
pete Join Date: Mar 2008 Location: sharonville Posts: 26	did anyone fess up that they were a hvac guy. I need a furnace installed.have the furnace just dont have duct work yet. let me know if anybody does this cheap lol thanks pete

10-29-2008, 02:45 PM	#14
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	yep, seems to still be still working the way it should __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

11-08-2008, 11:35 PM	#15
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	furnace isn't fixed, it is just messin with my head well at least it's not periodic, doesn't work at all now took what appears to be the flame sensor out sanded, put it back in. has LED's... flashes 4 times then starts what i think is a new cycle doesn't even get to the ignition stage at all pressure switch maybe. looks like the yellow pages on this not sure what else to do here Called the # above but hate 2 keep aggrivating to guy is a far drive for him __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

11-09-2008, 11:19 AM	#16
itbrokeagain Just Empty Every Pocket - CORE Member - Join Date: Feb 2007 Location: Amelia Posts: 1,435	Hmmmm I thought he lived around here. __________________ 91 fj 80 on 37 Nitto Muds with a 10k winch. Cage and sliders coming soon.

11-09-2008, 04:41 PM	#17
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	said he lived in harrison jacked with the pressure switch seems to be working, getting correct volts anyway started jacking with thermostat and it started working again __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

11-10-2008, 03:46 PM	#18
yellowjacket barely breathing Join Date: Mar 2008 Location: alexandria, ky Posts: 889	hvac dude here. back of your furnace doooor should have a chart what those codes mean. if it is your pressure switch not making, check 2 things. when your furnace is tying to light but failing, take your front combustion air (burner) door off. if it lights now, that means youve got a restiction in the intake pipe. leave, birds nest, ect. dosent light? try to clean your trap. if your furnace is a 90% or more, youll have tubes going down from below the inducer motor to a cannister(trap) before out to the drain. take it off and flush it in the sink. make sure you have it primed with water upon reinstall. hope it helps, rob. ive got to pm you about some other stuff, anyway. rob

11-13-2008, 10:21 PM	#19
cincygman Join Date: Nov 2008 Location: Pleasant Run Farms (near Fairfield) Posts: 378	Is the furnace fixed yet? You can't leave a guy hanging.................... __________________ Romans 7-8

11-14-2008, 11:18 AM	#20
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	lol... yep is/was the POS thermostat __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....

11-14-2008, 11:15 PM	#21
cincygman Join Date: Nov 2008 Location: Pleasant Run Farms (near Fairfield) Posts: 378	OK, just had to know. By the way I'm also a tech if Yellowjacket isn't around. __________________ Romans 7-8

11-15-2008, 12:39 AM	#22
fabricator Join Date: Jan 2007 Location: Cincy, Oh Posts: 947	I appreciate the help lord knows i need it __________________ For you guys who can't drive, I have owned a frame rack for several years. Prices are based on your skill and ability to wreck it....