larry1

Hi - I have acomfortmaker RPJ II that was new in my house when I bought in 1993. I recently am having problems with the furnace lighting off. The indicator module shows "2" blinks which indicates "pressure valve contacts are closed". If I shut down the fan motor for a few seconds and then power back up the furnace will light and work normal at least until it reaches thermost temperature.
Is this a pressure valve problem in which I can just replace or is something else going?
I appreciate any help.
Larry

yuri

It reads pressure switch code. There is a red tube from the pressure switch to the ventor fan. Carefully remove it (both ends) and blow thru it, there may be water/condensation in it. If it still does it the switch may need replacing. That furnace should be carefully checked by a Pro as it has had LOTS of heat exchanger problems/failures/cracks. Safety comes B4 saving $$.

Hvac pro

There can be two sets of pressure contacts that could be closed.

1. the gas pressure?

2. the inducer/combustion pressure contacts ?

when you have a furnace that you rely on for safety and warmth and depend on it .
Among your family, it would be wise to have it checked out by a professional.
your life may depend on it.

Also, each time you power off the unit and restart it , you may be erasing the correct error fault code and resetting the furnace, and what oyu may be looking at is a code that might be something different???

Does the Furnace even ignite the or does it go to fault next time the furnace calls???

next time , after the furnace is reset, after it becomes satisfied at the thermostat, make it call for heat again at the t-stat.

then go watch the sequence of operation , see what happens.

does the induce/combustion small fan start up first, then the ignitor lights then the gas burners come on, then the blower fan motor?

or where does the furnace stop at which point? what was the last part of the sequence of operation? what came on last and then stopped prior to going into fault error code?


Thanks , wasn't sure if that was the code,,,, you posted in the middle of my posting.... good idea,,, it would be usually a good start, unless the stack has a blockage or the motor is bad??? inducer/combution...

i was uncertain with the pressure valve as the description of the error?

larry1

Yuri and HVAC Pro - thank you for you responses. The furnace does light off in the correct sequence. I know this because this is the first day I am home, I first noticed this problem the last couple of days when I get home in the evening after working all day that the furnace is not working, I would then cycle the power switch and it would be fine through out the night. This is the first morning I have been able to monitor the process and the it has lit off and kept up with the thermostat settings for the last two hours this a.m.
I will check the rubber hose as Yuri has suggested -perhaps that is why it is an intermittent problem?
I did not know that these units have a history of heat exchanger problems.
Larry

yuri

Take a paper clip/nail/small drill bit and poke it thru the hole where the tube attaches to the ventor fan as it may be partially blocked. That unit has SERIOUS problems with bad heat exchangers. Condemned 2 this winter. They crack and then have flame rollout from the burners.

Hvac pro

nobody said the sequence was wrong

trying to determine when the furnace drops out is

Let us know what you find....

larry1

ok, I had to go to work for a couple of hours and the burner was not on when I came back home - just the typical blower running. I cleaned the tube and the pressure switch (?) the diaphgram that the tube is connected, I did not find anything obvious.
How do I check for a bad heat exchanger? Is it possible that the unit heats up enough over a couple of hours that (if the exchanger is indeed cracked) the exchanger expands and that causes a pressure drop? so, in actuallity the switch is doing it's job? other than that as of yet I cannot see when it drops off, as I said it kept the stat temp for a couple of hours this morning before I left for work.

larry1

I had the fire department check for CO and there is no excessive Co. It is clear. I am guessing that with a bad heat exchanger I would have an increase in CO(?)
Larry

beenthere

Nope.

Many heat exchangers are bad, but release no CO into the air stream.
Until its too late for the owner.

The inside of the heat exchanger is under a negative pressure, and the outside of it is under a positive pressure.
So seldom does it release CO into the air stream, until the heat exchanger gets excessively bad.

yuri

An experienced tech can test them by putting a stick thermometer by the rollout switch. Normally the air sucked INTO the burners is about 70 deg F. After the fan cuts in and the heat exchanger gets HOT, 5 mins, if it is cracked then air will blow thru the crack and start forcing the flames out the front of the furnace and the temp will steadily rise to up to 300 deg F and the switch will trip. LOTS of those heat exchangers crack and lots of them were held together by copper rivets which can pop and open up the exchanger.