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Lennox gas forced air 2.5 yrs old and already clogged with sludge

rheller1
rheller1 Member Posts: 1
Can someone please give me some info? We had a new Lennox EL296UHE gas converted to propane, forced hot air furnace installed in 9/2018. 1/25/21 it failed to ignite and there was an E200 Hard Lockout error msg. We have had many hvac contractors over to diagnose and it was determined the Flame Rollout switch on the right side was tripping any time it tried to ignite. Upon investigation there is a tarry soot/sludge throughout our system in the condensation lines and exhaust. It was discovered the propane regulator was supplying wat below minimum pressure. My question is, during the gas to propane conversion was there a setting for a low pressure lockout that was supposed to be adjusted for propane setup? The propane company washed their hands of any involvement and the hvac company says it just happens and it's not covered under warranty. Has anyone ever seen or experienced this? 2.5 yrs old and secondary heat exchanger is clogged and needs to be replaced? Help????

Comments

  • Zman
    Zman Member Posts: 7,561
    The installing contractor should have checked gas pressure and performed a combustion analysis when they did the conversion. If they did, there will be a small hole in the exhaust vent. They probably did not and this is causing the problem. Can they provide a copy of the report?

    Was the boiler running and pulling dusty air during construction?
    Where is the boiler getting it's combustion air?
    A picture of the system and vent termination would be helpful.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    mattmia2
  • SlamDunk
    SlamDunk Member Posts: 1,571
    edited February 2021
    I ran into this on the industrial side of business in Chile. Customer burned propane with 10% butane. My company sent process burners and I set them up for propane but my engineers didn't catch the butane so the result was chunks of tar. Added external blowers for more combustion air. Problem went away.

    Sounds like you don't have enough combustion air for the gas being used. Are you sure he converted it over to propane? Propane burns 2 to three times hotter than natural gas. The orifice needs to match the BTU rating for the furnace. It may sound like comparing apples to oranges but it is more like comparing honey crisp apples to Gala apples.

    It think the responsible party is whoever sold you the furnace.