Replyis this a 90%?
Professional Member
model m3rl080a
ser m3a050301139
keeps tripping limit on combustion blower
work alright while i there
something over heating but what
any help?
Professional Member*
is this a 90%?
Global Moderator
I would first pull the inducer motor off and check to see if the restrictor plate (inducer orifice as they call it) is damaged, eaten away, or has fallen out.Originally Posted by iowa tech
If the inducer is pulling too much flue gas through the orifice, the gas is not having enough time to cool off by staying in the HX long enough.
You can also put a temp probe in to see if the flue temp is above 145ºf to eliminate the possibility of a bad switch.
The part number for the orifice on the 80,000 btu unit is #155315R.
Instead of learning the tricks of the trade, learn the trade.
Professional Member
Temp is about 135 in flue
New c blower install by first tech
Yes 90%
Global Moderator
135ºf flue temp is tripping a 145º limit.
How far away from the inducer did you measure the temp?
Assuming you are confident of your temp reading, and the 135ºf flue temp is stable, I would be installing a new limit.
A combustion analysis would help in determining if the readings are stable.
Instead of learning the tricks of the trade, learn the trade.
Professional Member
i remember my first time with a problem similar....the disc was so rotten that it wasnt there. i was pulling my hair outa head untill some other guy said that the opening should be 1.5 inches.....i said its about 3.... disc wasnt even there or any signs of it...hahahaha
couple months later i go to similar call....new apprentice was like omg u so smart...lol i told him the long version....he laughed....
Please, Please Please......keep the Factory Smoke in the Wires!!!!!
Is it Rum'Oclock yet???
Professional Member*
135* flue temp.
combustion analysis would help determine whats going on. 135* is max you want on a 90% furn
check air supply blower wheel and secondary heat exchanger. Make sure your moving enough return air. usually low airflow or overfired causes flue temp to be that high.
you need 150cfm per 10,000 input btu with 90% furnace.
Professional Member*
I find a lot of these m3 furnaces with inducer limit tripped. To date, every one was due to corroded or missing orifice.
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Invaluable information, thanks, hear of this one time only but the other tech never found the issue that I know of.
Professional Member
Orifice.. one for the memory banks...
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Professional Member*
The older Lennox ghr 26 had them also.
Professional Member*
Yes. Did you ever see one of those corroded? They obviously used better material.
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No but I have seen the condensate box come apart and not close ps switch. Inside of it i mean. The old discs always seem fine in the inducer!
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you do mean valuable?
Global Moderator
"invaluable
in·val·u·a·ble
adjective beyond calculable or appraisable value; of inestimable worth; priceless"
Valuable/invaluable - the same
Flammable/inflammable - the same
English is weird.
Last edited by kdean1; 11-09-2012 at 09:52 PM. Reason: clarifying
Professional Member*
Lol I guess what I meant was invaluable as in so useful you can't put a price on it, seems like I heard that expression somewhere but maybe I got it wrong. So yes unmeasurable value.
Professional Member*
thank you kdean and joe.
the English language is pretty jacked up.
to, too, two, there, their, they're.....etc
Professional Member*
Never would have crossed my mind. How many furnaces have this "restrictor plate"?
This site is unvaluably inmeasurable.
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Lol
Professional Member
Every nordyne furnace has one since they all use the same inducer (within a model series). A 60k btu will have a restrictor with a small hole, while a 120k will have one with a big hole.
The faulty restrictors seem to be on models made in the early to mid 2000s. They were made from an opaque plastic that flakes away. The problem is most pronounced on units where the filter was not changed often enough.
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