Carrier gas heater sputters with access door open

mgmtrnr

I have a Carrier 48GS/48GX Combination Gas Heating/Electric Cooling unit.

It has direct spark ignition.

I replaced the blower fan a couple weeks ago and that is fine.

I have not had to use heat until last week. Once I finally turned unit on for heat, one burner would fire up but the other would not. The gas from the unlit burner was being blown into the house so it didn't smell too good to say the least.

I cleaned the flame sensors and both burners fired up!! All was great except when I closed the access door, I could hear the burners sputter and almost go out. I have left about an inch gap in the access door and the unit is heating the house and keeping a constant temp with no gas odor but I don't want to leave the access door like that.

Anyone know why the burners would sputter when the access door is closed?

Don't know if this matters but the burners do have some rust on them. The unit is about 6-7 years old.

Thanks in advance for any of your advice.

UBoiler

I am not a tech.

If the door is closed the burners sputter as if to go out. I f the door is left open the burners burn fine. And when the burner used to work fine the door was kept closed? OK Where's your source of combustion air? Do you have an air source from outside that has become blocked? Nest or something?

I was surprised to see you say that one burner orifice continued to release gas while the other burned. That scenario very much disrupts my calm.
Gas in search of an ignition source is not a good thing.

I just re-read what you typed. Those burners can get scale or/and rusty. Some of this forum's archives talks about how to vacuum and clean the burners properly.

Be sure to let us know how this plays out. Don't be hesitant to call a professional. View it as a tutorial, ask a lot of questions, and get your money's worth. Be careful and good luck. Cliff

mgmtrnr

I also am not a tech so please explain what you mean by "your source of combustion air".

A certified tech has already been out but that was when only one of the burners was lighting. He recommended cleaning the orifices and (if I dared) clean the flame sensors. The cleaning of the sensors worked and then the thing with the access door started happening.

His visit only cost me $69 and he left me his personal cell phone so I may give him a call back to see if he wants to do a "visit on the side".

The two burners are quite rusty so I may look into just buying a couple new ones. The whole "burner area" has been vacuumed but I will search the archives to see if I can easily clean the burners or just get a couple new ones.

Thanks for the reply and I will post my results.

UBoiler

Modern combustion boilers and furnaces will have an air line connected to the outside to bring in fresh air for the appliances combustion. Older systems used the air from inside the house. Old house's weren't very air tight. In the 70's energy conservation got people to seal the drafts under doors and around windows and such. So all that fresh air that was leaking into houses really wasn't pouring in anymore. For waste gases to properly vent out a chimney other gas has to replace it or the chimney doesn't work well or safely. Today's furnaces will have some tube or vent to provide outside air for combustion.

It seemed to me that you leaving your combustion door open was bypassing your combustion air source because for some reason wherever your burners were gettting combustion air was now blocked. Any chance your unit has a tube or metal vent that terminates on one end at your units combustion chamber and on the other end outside that is now blocked off under snow or new landscaping or has a door that someone closed to keep critters or drafts from entering the house? This fresh air source I am referring to is not your combustion gas vent (chimney).

Good luck. Cliff

mgmtrnr

Thanks for the response.

I will look to see if anything is blocked. No snow here so maybe it could be something else.

When you say, "tube"...how big of tube should I be looking for 1", 2", or bigger?

I know the exhaust vent is open and fine but will look for blockage elsewhere.

bigMikeB

Usually combustion air comes through a vent stamped into the door of the burner section with a small hood on the outside.