Comfortmaker furnace problem

Big Red

I have a 10 year old Comfortmaker Enviro90+ furnace. Problem is this, the exhaust motor comes on when starting furnace, then it calls for heat and the gas kicks on and ignites. As soon as the main blower starts the pressure switch(new part) starts clicking several times and the gas kicks off and tries to restart. This happens over and over again. Unit will not stay on and heat house. Need help cold weather is coming.

mdshunk

You say that the pressure switch is new. What caused you to replace it originally? In any event, I'm thinking that your unit is acting suspiciously like it might have a popped heat exchanger.

Big Red

When I was first trying to diagnose problem, I talked to a tech and he said it seemed like my problem was a bad pressure switch, and I thought the clicking sound confirmed switch was bad, until I spent 30 bucks on a new one only to find it clicks too. I know I'm an idiot!!!!!!!!!!!!!

#CARRIERMAN

Hi Big Red

I am betting mdshunk is right. The only way to truly tell is to test the heat exchanger. I would have say to get a pro out and have your furnace checked. Its not worth your health by taking chances.

Good luck
Rusty

ChrisMc

I also have a comfortmaker, but model c9mpvo75.....I had a tech in to do its annual service and now it is leaking water. A friend said that it might be a condenser return hose, but I can't see where the problem is. Does one of the hoses have to be primed?

Wet feet drying,

mdshunk

Those drains don't need primed. Either your condensate pump (if so equipped) has failed in some manner, or the condensate drain is clogged (common). They snot up with a goo that can only be described as "snot". Put your shop vac on the end of the hose and suck the stuff out, and you'll be good as new.

There's an outside possibility that, since your furnace was just serviced, that a hose got accidentally knocked off inside the unit. Might want to slide the front cover(s) off to double check that.

acefurnacefixer

Is the condensate backing up in the furnace or in the flue pipe? This would cause the switch to chatter.

notsogoodwrench

We recently had a comfortmaker (fsm2x2400a) installed by a mom and pop shop that has serviced us regularly for the past many years. After returning from a 3 week vacation, we found the upstairs mechanical room (where the unit is) and everything around it all the way through to the downstairs, water damaged (wood floors, expensive rugs and hardcote on walls and ceilings)...very costly. When the a/c guy came to fix it, he said the drain pipe was semi-clogged (although we had checked and found it to be dripping outside). he installed a $140 gadget that will shut off the system if it backs up again.

My question is could this have been a fault of the system (pipes loose inside when they serviced or installed it)? If so, would there be anything I could do about it at this point.

He also said that our other unit, located next to it which is the original 12 year old Trane could have a gadget installed on it too, if we wanted (he didn't have another one at the time and said that no one uses these because they're a nuissance for the a/c people who have to keep coming back to reset them and usually when the a/c cooling part doesn't work and causes this malfunction, people are around to stop the leak before this kind of damage).

I hate to mistrust people we count on but would not like to be taken advantage of either. I'd like an opinion of someone who is very familiar with these units and circumstances.

bigMikeB

If there is dust or a spider web contacting the flame sensing rod the burner will keep kicking back and forth like you mention, take it out an clean it with emory cloth and chances are it will fix the issue. This is a pretty common issue.

DanDD

I have the same problem. I disconnect the drain hose inside the furnace and the water runs out. The installers have the humidifirer draining into the same pipe as the blower drain and it suck the water in to the blower ( I've correct that problem). If too much water builds up in the blower housing, the exchange blower shuts down then tries again ect... After I manualy drain it its good for another 4 weeks. The palstic drain valve assembly is glued the the side of the furnace I have no Idea how to replace that.

tholling

I would check the gas pressure entering the house and leaving the gas valve. For instance, let say that it is cold outside and the regulator has froze up or the regulator is bad. I have see this situation. What happens is that the gas pressure to the gas valve is high enough to allow the pressure switch operate and the gas valve initially operate. Once the gas valve opens and tries to ignite the pressure from the outside regulator drops and the pressure switch on the furnace shuts the gas valve off. What I have done to test this is to (not suggesting you do this) jump the pressure switch and see if the furnace will burn. YOU WOULD NOT WANT TO RUN THE FURNACE THIS WAY - THIS IS ONLY A TEST. The only other thing you can do is have someone to check the pressure coming in and leaving the gas valve. If you are talking about the GAS Pressure switch it responds to gas pressure leaving the gas valve.

MechanicalDVR

The gas pressure has nothing to do with the pressure switch in the furnace. The inducer fan operates the pressure switch in the furnace. The gas valve will open by a completed safety circuit if there is gas in the line or not. Burners in excess of 400,000 btu's have gas train pressure switches not residential equipment.

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