Comfortmaker RPJ II Pressure Switch

hansolos · 02-24-2010, 07:12 PM

I have got a Comfortmaker RPJ II Enviro Plus 90 furnace that has been acting flaky. I just replaced the induction blower, it started making off balance noises. And after removing it off I found that it very off balance was and the turbine was cracked). I also have issues with the furnace not starting up on every try. The induction blower will run and eventually turn off and try later. I've found the the system flashes 3 (pressure switch open). The next time it might fire right up.
If I let the induction blow start and remove the rubber tube from the inlet of the pressure switch (the tube the runs to the combustion box) the 3 flashes stop and the furnace fires right up, stays running until the house reaches temp.
I only disconnect the tube until the 3 flashes stop and reconnect.
I'm guessing it's the pressure switch not hold position, I've checked and all the tubes are clear.
Neither the intake or exhaust for the induction blower are blocked.
Any ideas?

yuri · 02-24-2010, 07:28 PM

On the back of the old inducer there usually is a restrictor plastic orifice plate. It needs to be installed on the new one or it won't suck properly. They can crack and get damaged but apparently are available. The pressure switch is doing its job as a SAFETY device and monitoring the draft thru the heat exchanger. NEVER EVER tamper with it or you could have a flamerollout/fire/damaged furnace!

hansolos · 02-24-2010, 07:41 PM

Roger that!
I do have a small plastic ring that looks to be roughly the same diameter as the inlet on the induction blow, but I have no way of connecting it to it. There were tiny plastic... rivots the broke apart. Guess I'll have to find an alternative.
Thanks for the heads up and quick response.

yuri · 02-24-2010, 07:50 PM

Apparently you can order that orifice from ICP/Comfortmaker. Cheap, cheesy POS that orifice but thats life.