Comfortmaker RPJ II Ignites then shuts off?

SELLC

Hello, I am a mechanic who is normally surfing the internet on car forums.

Anyway, I have a Comfortmaker RJ II that has been having some problems. When I first turn on the heat it will work fine for about an hour and heat up the house.

After that it will kick on the smaller fan, heat up the element, and then ignite the gas. I see blue flames shooting in three cylinders, almost immedialy after that the furnace will shut off the gas, the flame goes out, but the little fan keeps running. I can turn the big blower fan on with the thermostat so I figure the blower is not smoked.

I see a small sensor that runs down thru the flame path on the 1st left "Flame Hole" (My laymans term). I am wondering if this sensor could be the problem?

I recently replaced the filter as I always do before turning it on for the season. It will turn on and off freequently. Usually no more than a 1 minute break between fire off's and shut downs.

I am hoping someone can help me here, I am mechaniclly inclined and enjoy this sort of thing. I am going to take some photos of the unit as I dont see many photos out there.

Thanks.

Edit - When I went to take the photo the darn thing stayed lit! LOL
It just figures, the furnace must know! Anyway I know its not fixed, but something is on the fritz.

Attached Images

    

SELLC

Okay. Its back to doing the same thing.

On a side note, I noticed that I had cranked the thermostat to 80's while messing with it. I turned it back down to 75 and its now doing the same thing, little fan kicks on, element heats up, gas ignites and then right away the flame goes out. I even tried to raise it back up to 80 again, but the same thing.

Not sure what to look for, but Im having fun.

SELLC

I am wondering possibly if the thermostat is the problem.

I guess everyone here is sleeping, and why not, its only 4am! LOL

I have a Honeywell 9324 old school style thermostat with the mercury switch.

Attached Images

  

SELLC

Well I am thinking about heading to the home depot here in a few hours.

I am going to buy one of them newer Honeywell Digital thermostats. I been wanting to make the upgrade for awhile now, and at less than $20 for the thermostat Ill take it on the chin should it not be the problem.

Here is the link for the thermostat
http://www.homedepot.com/Electrical-...atalogId=10053

Honeywell Model number - RTH221B Digital read out.

yuri

Remove and clean the flame sensor (rod with porcelain on the left) with fine emory paper and the face of the burner it sits in front of. That furnace is notorious for having cracked heat exchangers and popped compression rivets that hold the heat ex together. After running for awhile the heat exchanger expands and the crack opens up and that may be your real problem. I would get a Comfortmaker tech to carefully check it or just start budgeting for a new one as that one is on its last legs. The circuit board may be failing and now it becomes a money pit. I have seen dozens of them fail/heat exchangers, in the last few yrs. With the tax rebates now may be a good time for a new one.

biggles

the one thing you are saying with out realizing it is....the small fan stays on when the burner cycles off.the stats first acytion when it calls is to start the INDUCED DRAFT motor to pressurize the burner chamber.that air being delivered is monitored by a pressure switch with a tube into the small fans discharge duct...that has to remain closed thru the heating/burner running if for any reason it "bounces"the burner goes off and the pilot recycles to start...check the switch.put the gas valve to PILOT position and use the furnace toggle to power up and down with the stat calling...see if the switch closes on fan stat put an OHM meter on the 2 wires connection to check the action.clean the squirrel rounds on that small fan also might be rounded with dirt?

SELLC

Well I purchased that $19.98 thermostat today and installed it. I was impressed with it and all the features for the money.

It did NOT seem to fix the problem, however I was interested in getting a digital temp read out unit anyway. Installation was pretty simple.

I am realizing that it is doing the same thing, exhaust fan turns on, hot surface ignitor glowing, gas valve opening, flame ignites and then within a few seconds it shuts off. I then pulled the lower panel of the furnace and found the contol module and checked the switch for the lower door. Door switch is fine, however I noticed that when the system shuts down, just after the furnace lights, the diagnostic light blinks 6 times.

I have a "The General 90" style control panel. Dont know what six blinks means, but I would be interested in knowing.

I see some folks think this unit is on its last legs, so if you could also tell me what I am looking at in terms of cost if I just went ahead and purchased an entire brand new furnace. I would likley install it myself. I looked on HomeDepot online and also Lowes but I didnt see any furnaces!?

I would really like to fix this one, even if I installed a new one, I would take this unit out to the gargae and attempt to repair it for use out there, where it wont be used as much. Regardless, I appreciate the help thus far.

Attached Images

    

sgthvac

Did you clean the flame sensor as Yuri suggested. Thats more than likely the problem. The other things that Yuri talked about are accurate as well. As if I need to confirm Yuri's comments. He's been in the business longer than I have. If you don't have a CO detector I'd go buy one because your furnace is on it's last leg.

yuri

There is a list of red blink codes stamped on the control and or the back of the lower furnace door.

SELLC

Just to be sure I have added another photo of what I think the flame sensor is.

Also can anyone give me information about what 6 blinks on the module means?

Thanks

Attached Images

 

SELLC

Ok. I didnt see that before I responded. Ill check it out and clean the flame sensor right now and report back.

yuri

That is the flame sensor.

sgthvac

Yes thats the flame sensor. As far as 6 blinks, have no clue. each manufacturer has there own codes. Would need the manuel for the unit.

SELLC

Ok, just as Yuri said the flash code is on the back of the panel.

It reads-

1 Flash = System Lockout
2 Flash = Pressure Switch stuck Closed
3 Flash = Pressure Switch stuck Open
4 Flash = Open high limit switch
5 Flash = Open roll out switch

Dont see anything about six flashes, however I know it's six blinks because I have counted it 4 times now. I know I am not going crazy!

Attached Images

  

SELLC

I wonder if they consider anything more than 5 flashes a contenuous flash? Seems odd because after it flashes 6 times there is a brief pause and it will flash 6 times again, and again.

It also says

Continuous Flashing = Flame Sensed with no call for heat.

I also wonder if maybe the guy did not wire the thermostat to the module proper. Seems to be some strange things going on there. Ill post more about that after I clean up the flame sensor.

This will be my second winter in this house, and I recall this thing not working the greatest last year. Early this spring we had to call our gas company because out meter was leaking and you could smell natural gas outside the house. The tech whom came out said that our regulator was bad, but also said that he would replace our meter. I took photos of the entire ordeal and requested them to check the accuracy of the meter since there was moisture, bugs, sticks and other debris inside the guage. I figured I would put that out there as well. I was told by the State of Michigan that our gas provider has an obligation to replace any meter that has not been in service for more than a year. I bought my house as a foreclosure and it sat empty for several years. Still no word from the gas company on the accuracy of that meter. What really honks me off is that these utility companies expect us to tow the line, yet when it comes to them towing the line... HA!

Attached Images