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Old 12-16-2010, 12:09 PM   #1
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Whats Up DIY..
long time DIY'er and avid cheapskate..

last night we came home and it was pretty cold in here..
fiddled with the Tstat, heat came oon.. sweet..

10 minutes later.. still cold. heaters off.. hmm.. fiddle Tstat.. comes on..
sure enough.. right back off in 3-4 minutes..
http://2.0delaware.com/heat/2.jpg <--pic of model #
http://2.0delaware.com/heat/4.jpg <--pic of model #

http://2.0delaware.com/heat/1.AVI <-video of good spark, flame and ventilation..

I have had the flu damper get stuck before.. so I went.. and played with it.. didnt 'seem' to be stuck..

but.. I took it off, WIRED THE FLU OPEN, and jumped the wires to make it think that the damper was there..

still.. same.... problem.....

so, thought it would be worth a try to clean te flame sensor..
well. its a PITA to reach, but I could squeeze a screw driver in there to
rough it up a bit..
http://2.0delaware.com/heat/3.jpg <--heat sensor in flame
still.. same.... problem.....

however, when I was sitting there watching and listening.. I noticed that
the flame sensor sparks right before it shuts down..
I took a video
http://2.0delaware.com/heat/2.AVI <-spark at shutdown

never noticed that before... is that a Red Flag for anybody???

it is in the flame nicely.. do you think it could be just a bad sensor or
maybe the control box?


oh, by the way... IT WAS FREAKIN COLD LAST NIGHT.....

Thank you for your time and please let me know what you think?





edit to add:
http://2.0delaware.com/heat/1.jpg <--control box attached to flame sensor

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Old 12-16-2010, 01:22 PM   #2
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Try shorting the T-Stat heat leads. If the furnace fires up on a call for heat and continues for a few minutes -not seconds- (+you have eliminated a possible blocked vent condition) it sounds like a dirty or defective stat trying to "short cycle" the furnace.

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Old 12-16-2010, 02:09 PM   #3
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


not the Tstat..

I didnt even think about that... I wish it was the problem though..
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Old 12-16-2010, 03:14 PM   #4
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Check the high limit switch when it shuts down. Furnace may be going into a lockout due to an overheat. Have seen those lockout/spark modules lock out erroneously also.
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Old 12-16-2010, 03:40 PM   #5
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Im digging around to find where it is...
quick question though..
if it were overheating, would it turn back on by itself when it cools?
also, after it shuts off, I can flip the breaker and it turns back on for 'about' the same amount of time..
(without giving the blower time to cool the firebox)

would you think overheat or the lockout control?
anyway to bypass the lockout box?
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Old 12-17-2010, 07:42 AM   #6
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


I cant find where it is?????

have looked at every diagram and schematic I can find...
where the heck is the 'high limit switch'?
is it in the lockout box?

this is only the second time I have worked on a heater..
the first time I only hadto change the blower motor.. and that was a cake walk..
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Old 12-18-2010, 10:12 PM   #7
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


found a friend of a friend that came over to look at it..
and he agrees its probably the ignition/shutout control box..

found one for $130 online..

lets hope its the problem..
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Old 12-19-2010, 07:42 AM   #8
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Could still be a flame sense issue . I'd remove the rod and burners then clean them up good before buying parts. Doesn't take hardly any rust or oxidation on the rod and burner face to make a normal 5 microamp into a very weak .4 microamps. If you have a meter that reads DC microamps put it in series between the rod and the wire and see what the reading is.
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Old 12-19-2010, 09:44 AM   #9
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


A big thanks to Marty S. I have shot trouble on boilers, scorched air furnaces, and water heaters, all with that flame sensor rod in them and I was told by a manufacturer's rep one time about the virtues of cleaning the rod, burner, and ground points around the "brainbox" and fire box, but no one ever explained to me about needing a DC meter with a microamp meter scale or the values that pertain to good versus bad circuits. Now I are more dangerous!! Grampa Bud
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Old 12-19-2010, 09:47 AM   #10
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


yea.. we took out the sensor and sandpapered it..

and it still did the exact same thing..

Im a little worried that im going to drop the 130 on on the box and I only needed the
75 flame sensor.. but Im really leaning towards that box..

plus when it shuts down, the box does cut the voltage to the sensor...
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Old 12-19-2010, 09:55 AM   #11
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Grampa Bud every brand has a different microamp scale so it is brand and burner specific. Lennox can be as low as 1.1 and a healthy Carrier can produce up to 5-7. Need to know the flame failure setting the board has. The higher ones are easier and more fun to work with.
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Old 12-19-2010, 02:25 PM   #12
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


I'll grant you that Yuri, but at least knowing roughly what Hi/low readings to look for is a big heads up that seems to be a trade secret.
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Old 12-19-2010, 02:32 PM   #13
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


delaware it is good that the brainbox shuts of the current to the sensor at the end of call for heat, but like the other guys have said it is the current that is detected during operation that can make or break your day. Tighten and loosen and retighten the mounting screws for the brainbox and the burner assembly and any ground screws on the furnace sheet metal. A good ground will help improve your sensor's current flow.
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Old 12-19-2010, 02:58 PM   #14
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


Quote:
Originally Posted by Grampa Bud View Post
I'll grant you that Yuri, but at least knowing roughly what Hi/low readings to look for is a big heads up that seems to be a trade secret.
Some Yorks use as low as .3

there is no range that fits all brands.
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Old 12-19-2010, 03:01 PM   #15
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Carrier Heater cutting off after a few minutes (pictures and video) HELP.. -cooold-


And I thought Lennox was a pain with their 1.1 on the whisperheats. Correct use of allygator clips is necessary.

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