Comfortmaker RPJ II Enviro Plus 90 Flame stops with main blower starts
I have a 16 year old Comfortmaker RPJ II Enviro Plus 90 that is give me cause for concern.
When heat is called for the induction blow start and runs for roughly 30 seconds and ignites the burners, good so far. The burners warms the exchanger for roughly 20 to 30 seconds and then the main blower starts, this is where things go down hill. As soon as the main blower starts the flame and induction blow immediate stop. Within a second the induction blower starts again, but it also start to flash 3 times (open pressure switch) all the while the main blower is still running (I'm guessing to take the load off the exchanger).
Eventually the burners ignite and the unit runs until the temp is meet and the system shuts down.
The troubleshooter in me says I'm getting positive pressure feedback into the pressure switch that is killing the flame and induction blower as soon as the main blower starts. I'm also guessing this may be caused by a leak in the exchanger.
Any alternate or reinforcing thoughts?
There has been problems with those heat exchangers but usually if they are cracked it forces the flames off the burners out the front and trips the flame rollout switch. Could not create enough pressure to affect the pressure switch (in theory) and I have seen LOTS of those units. You may have a weak pressure switch and the vibration of the fan starting is tripping it. I would replace it first. May want to get a Comfortmaker tech check the heat exchanger etc.
"Cut it twice and it is still too short".