Hello,

Having an intermittent lockout (single flashing light) problem on a Goodman GMS90703BXA. Will occasionally wake up to a cold house. Cycling the system usually restores heat. Can make the problem happen at will by having a fire in fireplace.

Per the troubleshooting guide in my manual I have cleaned the flame sensor. Have not figured out how to check the grounding (section is missing from downloaded manual) and don't feel capable of checking the pressure switch. Hoping that the fire info helps someone diagnose this.

So essentially I send signal to heat from t-stat, blower, glow light, ignition. All seems well. But periodically the burner will shut off, blower continues and it locks-out.

Pflor's comment in this thread:

http://www.doityourself.com/forum/ga...no-heat.html#b

Seems to be a good place to start but not sure how to check ground on my unit and not sure how this all ties in with the fireplace situation. Any help is appreciated. Happy to provide any additional info needed...

 

Welcome to the forums.

Do you have propane or natural gas ?
Is it a gas fireplace ?
Is your model # GSM instead of GMS ?

One blink would indicate a flame deficiency like from a burner that needed cleaning or low gas pressure.

 

If the fireplace is gas, I'm leaning to a low gas pressure issue. This is usually resolved by increasing the pipe size.

 

Having the gas pressure checked would probably be a good idea.

I have seen underground piping partially fill with water and cause similar problems.

I had a similar problem last night on a call with 1.8" W.C. entering gas pressure.
I shut off the gas to the furnace.
I saw the gas company replacing the meter today when I drove by.

 

Pretty sure that model # is correct. The fireplace is woodburning, not even a gas starter. Nat. gas furnace. Only connection between fire and furnace I can figure is it'd be a lot of hot air getting sucked down the cold air return in that room.

Thing I'm wondering about the gas pressure is why it'd be so intermittent, linked to the fireplace, and only happen at the end of a cycle. Not tied to water heater or stove use that I can tell. Most common time besides fire is middle of the night. One thing I have noticed is it can't run long without it happening. We go up a degree at a time and let it cycle down. Overheating/poor exhaust?

Can someone help me check the gas pressure myself? No one I'd be willing to pay the service call around here, even to do something specific with me watching over their shoulder.

Thanks everyone for your feedback.

 

Did you clean the flame sensor with steel wool?

Is the furnace properly grounded?

The next step is to check the flame sensor current. Do you have a meter which reads DC microamps?

You can't check the gas pressure yourself, but you can clock the meter (google how) to see if it's burning roughly the correct amount of gas. I very much doubt that this is being caused by a gas pressure issue.

 

If the fireplace doesn't use gas it is unlikely that this is a low gas pressure problem.

How many flashes are you getting at the furnace LED when lockout occurs?

http://www.acdirect.com/xcart/images...cts/IO-244.pdf

 

Houston204:
Whenever I see it flashing it is only doing so once indicating the lockout. Does it flash a separate error code before going into lockout? I've never actually been able to be standing there when it fails.

Thanks for the installation manual, hadn't found that one.

Muggle:
I cleaned the flame sensor with #0000 steel wool. There was a little buildup. It has locked out since cleaning it.

The grounding is something I am interested in checking. Not sure exactly how. I seem to have followed a wire outside, wrapped to a rod in the ground. Would need a meter to actually check it I'm guessing?

I don't have a meter but could probably borrow/buy one and learn to use it. I'm always up for an excuse to buy a tool. Recommendations for what to get/ways to learn to use it?


Anybody have a theory on how the fireplace could be linked to it? It's too reliable (every fire for the three years we've lived here representing probably 80% of total lockouts) to be a fluke. Is there some sensor that indicates the incoming air is too warm and shuts off the flame?

Thanks for everyone's feedback. Woke up to a warm house today. Happy Thanksgiving!

 

If you were to try this with an open window or door will the furnace lock out ?

Are both the exhaust and intake air for the furnace vented to the outside ?

 

A fireplace draws lots of combustion air from the house out up the chimney. If the furnace is having an issue when the fireplace is on, I would think it's a combustion airflow issue. Where is the source of combustion air coming from for the furnace? Outside source or from inside the house?

 

canuk:

Have never tried that, can do that during the next fire.

On the top of the furnace there are two ports. The right one is pvc that vents out the side of the house. The other is open to the basement. That answer your question?

tomf63:

If the intake port is the one I described above, sitting on top of the furnace next to the vented port, it's just open and drawing from the basement. Is that allright?

I do have weird pressure issues in the house. In the summer the house sucks air down the chimney (crappy old damper I try to close and then stuff with a pillow) and in the winter the damper has to sit open for the occasional fire (difficult to open and close) but I don't get a sooty smell in the house in the winter so not sure how it's all flowing then.

 

With the fireplace being wood burning, I agree gas pressure wouldn't be an issue & a shortness of combustion air would be a strong suspect.

 

Yep -- I'll bet you dollars to doughnuts that's your problem.

The one *port* that's open to the basement is the furnace combustion air intake and it really should run outside. That's the point --- to avoid issues like this.


You have a negative pressure inside the house that is *choking* the furnace since it's relying on house air to fire. The furnace has to compete for air with the fireplace , clothes dryer , bath and kitchen exhaust fans , etc..

That's why opening a window will help with make up air to offset the negative pressure.


The best fix would be to run that combustion air inlet to draw from outside.

 

Sounds like ya'll are on to something. So to test I'll crack a basement window next time I have a fire and if it doesn't lockout that ought to settle it. Then it's on to piping. Any advice? Just read the section about in the installation manual. My flue termination looks like their recommended intake termination (90* downward, no vertical section, no tee) Do I need to redo mine? Any tips on drilling through the foundation?

Only other concern was they kept mentioning not to use commercially available rubber boots on the flue because of material incompatibilities. Well that's just what I'm doing because the flue had a poorly glued pvc fitting when I bought it and it was leaking. Any concern about the boot I bought and/or where I can get one they approve of?

So many specs for the flue I'm thinking about just redoing it all. Most of the joints dripped when I bought it. Redid those but now I'm wondering what else he/she screwed up. Anything else you'd check since I know a jagoff installed it?

Thanks again for everyone's advice. We'll all be happy to have it fixed. Might be able to turn the furnace up more than 1 degree at a time now too.

This is a great forum. Just realized all the other topics covered. Headed to plumbing next. Hope everyone got a nice meal today.

 

I particularly like a concentric termination instead of two separate pipes exiting the house. Here's a You Tube video showing a concentric vent: Concentric Vent Kits - YouTube

Regarding the rubber boots; I've never had a problem in using ordinary "Fernco" couplings available at any plumbing supply house.

 

So I gave it a shot tonight. Lit a big fire and left the furnace on. Cracked the basement window and let it cycle on. Ran for what seemed like a long time. Finally felt the vents, cool air. Ran down stairs and caught it trying to cycle. Flame was out and the the glow bar was trying to light it. Let it try and it locked out.

Wasn't going to give up. Propped the 30" window open a good 5" in case it needed more. Air was flowing in hard and fast. Tried to cycle the furnace, same story, kicked on, ran awhile, locked out. Should I try it again with the burner compartment door off? Is this even a valid test? Hate to start drilling holes if this isn't it...

Don't know how my 90 year-old house could even be tight enough for it to matter but it's the only idea I've heard that made any sense with the fireplace thing.

 

Did it blink any code before it locked out? How many times did it try to light before locking out? I thought sure we had an answer, doggone it.

 

No code but (1) for lockout. I watched it try twice but imagine there must have been at least 1 more before I got down there.

By the way that concentric vent looks nice. Wonder if i could figure out how to enlarge my hole.

 

If the hole is not thru brick or block & you are somewhat skilled with a reciprocating saw, you can use that. The hole doesn't have to be perfectly round. Caulk is wonderful stuff.

You said air was comming in the window "hard & fast". I'm really grasping at straws here but, is the window on the same side of the house as the furnace exhaust and is the wind blowing from that direction?

 

No it's brick. Window was opposite side from exhaust maybe 15' from the furnace. Low ceiling basement about 1000sq ft. Worth trying again? It just made so much sense...

 

It is certainly worth trying again. This time open the window before getting a roaring fire going in the fireplace.

 

Hello everyone,

Not sure if there's any more help out there but I'm still getting lockouts (code 1) from my furnace. Thought I was getting better performance with the open window so I've left it that way. Cold basement but I didn't have a lockout for a few weeks, no fires though. Finally decided to try again and had a fire yesterday. Furnace actually made it through the whole fire, got me all excited, and then locked out a few hours after it burnt out. Then it did it to me again early this morning. Only thing left on the Goodman manual troubleshooting is to check the ground connection. Thinking about calling Goodman.

Thanks for any ideas you've got.

 

Checking the ground is certainly worth a try. Make sure the ground goes all the way back to an earth ground. Another thing to check is voltage between neutral & ground. There should be virtually zero.