keeps tripping limit on combustion blower
work alright while i there
something over heating but what
any help?
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.
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.
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!!!!!
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.
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....
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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Originally Posted by iowa tech
