Goodman GMP100-3 problems

[silver226]

There is a Goodman GMP100-3 Rev B installed in my parent’s house up north. The furnace is having problems with the first burner (the one with the flame sensor) not igniting and/or igniting and "flickering". The rest of the burners operate properly. It seems to me that there is not gas flowing into the burners.

Here are the specs for the furnace (as found on the interior label):
Goodman Model GMP100-3 Rev B
Made in 1993
Input 100k BTU
Output 80K BTU
Temp Rise 45-75
Max Pressure 7
Min Pressure 5

This furnace seems to be much larger than they need in this house and I think they dealt with the wrong person when they had this installed. The house itself is approximately 850 - 900 sq ft single level on a slab foundation, 7.5 - 8ft ceilings, and 1/2" gas pipe running to the furnace. (From everything I’ve read and research I’ve done I think a 50-60k would have been sufficient for the house) Unfortunately I didn’t get a chance to take pictures of the setup last time I was up there.

It seems to me that there isn't enough pressure getting to the regulator and burners for this size of furnace, but I’m not sure… could it be a blocked burner or malfunctioning regulator?

Any advice would be much appreciated.

Thanks,
~Arek


[Edited by silver226 on 10-23-2005 at 09:34 PM]

[t527ed]

pick up the phone and call a pro. improper ignition can be very dangerous.

[Mr Bill]

silver226, I know all of us would like to help you but man your dealing with "gas" even a play by play could get someone hurt please call a Pro.
Thanks Mr. Bill

[tinknocker service tech]

shut it down and get some portable heaters for them and call for service. dont play with it someone can get hurt

[RoBoTeq]

Could be gas pressure, improper draft, cold chimney problems, burner issues etc. You need a pro to be inspecting that furnace, especially since it is oversized.

[joker dan]

Call a pro as noted by others iwoudnt be surprised if the heat exchanger is cracked. have the tech pull the blower and look up and also for any rings laying in the blower houseing ,these held the exchanger together when stamped together. as noted also shut it down!

[Jultzya]

Welcome to HVAC TALK. However this site has rules against giving out technical advice to DIY'ers. I have attached a link below for your convenience.

Here's something to think about though...

When was the last time you had that unit cleaned and inspected?

Now you have a problem with the unit. Fuel costs are skyrocketing.

So why not call in a professional to repair the unit? While they are there they can clean and inspect your unit to insure a safe living environment for you and your loved ones. Not to mention, having an efficient running system could save you more than the cost of the service.

What's your safety worth? I'm guessing more than the repair bill.

Thanks for your understanding.

(we can't help DIY, due to site rules )

[MadeinUSA]

Originally posted by silver226
There is a Goodman GMP100-3 Rev B installed in my parent’s house up north.
This furnace seems to be much larger than they need in this house and I think they dealt with the wrong person when they had this installed. The house itself is approximately 850 - 900 sq ft single level on a slab foundation, 7.5 - 8ft ceilings, and 1/2" gas pipe running to the furnace. (From everything I’ve read and research I’ve done I think a 50-60k would have been sufficient for the house)

Yes, I agree.

“Hundreds of thousands of Goodman furnaces are installed by some not so great installers everyday” ---- Goodman Rep.

[troyorr]

A 12 year old furnace has worked fine and now it doesn't? When was it last serviced/cleaned?

[silver226]

Sorry, I only posted this as a question as to what could be wrong. I may be completely wrong on my assumptions.

The furnace was originally installed around 5 yrs ago (and yes the sticker says it was manufactured in 93) and checked out by different Heating/Cooling pro last year from what my father told me. But all he said was that he could replace the furnace because the original installer did a... bad job of it. So all I was looking for was what the problem could be and if it could be fixed. Not step by step instructions. I wouldn't be doing the repair myself anyway unless it was a simple operation (dirty flame sensor, corroded igniter, blown circuit board... etc.)

The furnace does operate fine once it finally fires up, but it takes 2 or 3 tries before the burners stay lit. It does shut off when the sensor notices that a flame is intermittent and runs the exhaust for about 2 minutes before trying to fire again. So it's functioning properly, other than the flame issue.

My father has not noticed any gas smell in the house when he goes up there so I don't think there is too much of a safety hazard.

But again I’m not looking to fix it myself, just doing some research for my dad, and to have a guide as to if it can be fixed without having to replace the whole unit. That way when he calls to have a technician come out and fix it he can be weary of "shady" dealings.

If you still feel this is more of a DIY question feel free to remove it from the board.

[troyorr]

Cleaning the flame sensor is a homeowner maintenance task. Pull it and clean with steel wool. Put it back in and try the furnace. If that doesn't take care of it, call another company. Could be a number of things. Good luck. Keep us informed.

[silver226]

The sensor has been cleaned. It's not that it doesn't read properly, it's that the flame keeps going out on the burner where the flame sensor is (farthest burner from the regulator)

[Jultzya]

Originally posted by silver226
I wouldn't be doing the repair myself anyway unless it was a simple operation (dirty flame sensor, corroded igniter, blown circuit board... etc.)

This qualifies as a DIYer asking for technical assistance.

Which is against the rules.

Please read them and respect the site's wishes.

Thanks for your understanding.

(we can't help DIY, due to site rules )

[RoBoTeq]

You've now narrowed it down to gas pressure, cold/partially blocked chimney or burner issues.