Burner switches on and off/fan still blows.

Eric81

I'm just going to get right to it.

I have a Coleman Evcon oil furnace that does turn on and run, fan blows barely warm air through the registers, but the burner switches on and off even when the fan is still blowing. I believe it switches off way too early while fan is still blowing and the heat exchange cant get hot enough hence the barely warm air and why my home can never get op to temp.

Here is a description of how it runs.

Oil burner fires up fine, fan kicks on and blows air after a few minutes. After about 5 minutes, burner stops(fan is still blowing) then after a couple minutes burner kicks on again(fan never stops) It will do this over and over, the air never gets hot and takes forever to get the room up to temp.

I've listened to other furnaces run and their burners do not switch off until the room is up to temp. Their burner will switch off when the room is warm and then switch off, letting the fan blow it cool, until next cycle. MY furnace burner switches on and off like 40 times during a cycle while fan is still going.

So why wont the burner keep burning until the room gets warm?

I'd appreciate any input .

Eric.

billtwocase

I would start with a new air filter. Is it over fired? Returns blocked by rug or furniture?

Jamie Hall

As Bill says -- start with a new filter, then check and make sure all duct dampers are open, all registers are clear, etc. It sounds as though it's doing exactly what it's supposed to do -- with a restricted air flow which gets the heat exchanger too hot, and the burner shuts down.

It could also be a fan problem, but if there's air flow I'd look for the filter first...

RobG

A good thorough system cleaning would be a good place to start. As stated above, it sounds like an airflow issue.

wmtandson

see if someone can discover what safety switch is turning the gas burner off
High temp? possibly

billtwocase

There is a high limit disc, and it is doing it's job. Air flow is the issue here, more than likely