Lennox furnace has strange koncking sound

[ottawausite]

It's less than three years old.
I changed the filter (previous one is cheap, this one is expensive). And furnace has the knocking sound when it starts to push the air into house.
Also the air smells like something burned.

I called someone and he told me: maybe the motor pushing the air has problem...


Very happy with the furnace's quality. :mad:

[rogerrabbit168]

It's less than three years old.
I changed the filter (previous one is cheap, this one is expensive). And furnace has the knocking sound when it starts to push the air into house.
Also the air smells like something burned.

I called someone and he told me: maybe the motor pushing the air has problem...


Very happy with the furnace's quality. :mad:

we have a lennox also, and when we first moved in (new house), it had that knocking problem also whenever the furnace starts, what i discover is that one of those plastic pipes that connect to the furnace was lose, so i tighten the mounting bracket, problem solved, but we didn't have the burned smell like your describe

[Whitedart]

It's less than three years old.
I changed the filter (previous one is cheap, this one is expensive). And furnace has the knocking sound when it starts to push the air into house.
Also the air smells like something burned.

I called someone and he told me: maybe the motor pushing the air has problem...

Take that new air filter out temporarily and see if the problem goes away.

If may be too restrictive on air flow, and causing the fan motor to overheat.