Goodman Furnace

jhvac

I installed an 90% upflow goodman furnace. The furnace will only run with the burner door off. I have checked the gas flow, pressure it has 3.75 inches of water column, 12.7 inches of water column on the inlet side.
Sometime with the door on it wont start on the first attempt. When it goes to the second attempt it creates somewhat of a explosion/roll out.
But yet if I leave the door off the furnace workes well. On the exaust side it is vented with 2" pvc pipe less than 15' plus 2 long sweeping 90's. On the inlet air is ran with less than 10' of pipe plus 2 90's. I have checked the inlet air side for obstructions and found none. Does anyone have a sugestion to how I can make it run with the door on. Model GKS90904

jhvac

I installed an 90% upflow goodman furnace. The furnace will only run with the burner door off. I have checked the gas flow, pressure it has 3.75 inches of water column, 12.7 inches of water column on the inlet side.
Sometime with the door on it wont start on the first attempt. When it goes to the second attempt it creates somewhat of a explosion/roll out.
But yet if I leave the door off the furnace workes well. On the exaust side it is vented with 2" pvc pipe less than 15' plus 2 long sweeping 90's. On the inlet air is ran with less than 10' of pipe plus 2 90's. I have checked the inlet air side for obstructions and found none. Does anyone have a sugestion to how I can make it run with the door on. Model GKS90904

genecarp

CALL TECH SUPPORT, THEY SHOULD TROUBLE SHOOT IT with you.

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BigMikeB

First of all 12.7 inches wc is high on the inlet side if it's natural gas. I second the call to their tech support, there is a venting issue, it isn't getting enough air in for proper combustion.

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hf05

is there a hose on the burner box going to a pressure switch check that..or put door back on ,cut inlet about a foot up if it fires whats that tell ya ??

Dr Heat

you need to run 3" on both int and ex the limit on 2" IS 25' EACH 90 IS 5' IF THEY ARE LONG SWEEP. You are very close we only run 3' Because we ran into this several times.

MechAcc

Need to check the draft with a magnehelic or digital manometer. You'll have to tee into the hose from the burner box to the pressure switch attached to positive side of meter and tee into the hose from the inducer/collector box depending upon where the negative side is tapped into the negative side of the meter. Most pressure switches will have a pressure range on it. If the pressure is nominal close to the range the possible causes sagging vent pipe trapping water or some other obstructions (children just love tossing rocks and other things down vent pipes wondering where they have gone), under sized vent, inducer running slow either from bearing or from low voltage to inducer, drain trap dirty, and finally heat exchanger leakage.

On the heat exchanger leakage leave only one side of the magnehelic hooked up. Turn thermostat heat off fan switch to ON. Block intake and exhaust pipe. Turn power on and watch magnehelic if meter moves the heat exchanger has a leak. Crimped rings broken off or crack in the heat exchanger.

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hvaclover

12" is excessive. our gas valve regulator is probably malfunctioning and passing excessive gas. Ain't enough air to ignit with the door on.

Call the gas supplier to check the meter. But if they are dicks like they are here you might want to close down your gas cock til you gt around 7" supply gas.

If your furnace gas control hasn't been ruined it should light. Have the HO call the gas utility and watch him measure the pressure at the meter.

Unless i miss my guess the meter is screwed.

jrobbins

Thats a 90,000 btuh furnace right? It calls for 3" PVC on both the exhaust and intake piping in the goodman installation manual. The gas pressure also needs to be turned down to around 7" WC at the gas meter. You problem will go away if you do these two things.

jwiehagen76

I agree with the others flue size too small gas pressure to high whats the pressure coming out of valve? You could add a regulator before furnace as well

Enzytebob

Dr Heat is the winner!! Only use 3" piping on the 90+ furnaces, You'll never see this issue again.

hvaclover

Heck. I assumed sine you labeled your self an HVAC guy you would know the proper venting. After all it is in the manual.

Too many guys don't read the instructions and that is just cocky over confidence.

I start my guys on a job only after I have pulled the install instruction to make sure there have been no changes since the last unit I bought.

Forget asking the counter guy. They either don't know or won't tell you.

hvacrman

are we sure this is an hvac guy and not ho, i mean it is pretty easy to sign up here. , first clue = goodman second clue = 3 posts

erheating

Good call Hvacrman.

greengenius_A_C

If you only look on the 3rd page of the manual in the product specs chart it says 2" venting diameter...but if you look near the bottom of the page in the notes it says "2 or 3 inch depending upon furnace input, number of elbows, length of run and installation (1 or 2 pipes)". Get to know your codes, or where to look them up.

acefurnacefixer

another clue is the post is in the picture forum, and not a single picture.....

CompleteW&D

It's obviously a Home Owner. Or if it is a real HVAC dude, then I would certainly question his knowlege and training.

Why in the world folks cheap out on something as important as their family's comfort (and safety), when quality name brands aren't that much more expensive is beyond me. But, I guess it happens in everything.

I mean, why hire a professional HVAC contractor who knows the proper size intake and vent piping required, the proper gas pressure needed and knows how to trouble shoot a problem instead of asking on a forum? No, it was cheaper by far to use Joey Lunchbucket with a tool belt and a pickemup truck who bought a cheap furnace and gave them a super duper price.

Since Cheap Charlie hasn't got a clue as to what's wrong, the HO needs to come on a professional contracting forum to ask.

But hey.... they got a GREAT deal, so that's all that matters I guess.

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- John Williams

Complete Window and Door

Dr Heat

wait a minute who put this furnace in Joey Lunch-bucket or cheap Charley am confused.

Also wonder why even vent the flu8e gas outside there is a lot of heat in flue gas. Think of the money you could save if you vent it inside you would never need to buy food again.

If any one has Joey lunch-box's Phone number please share it I need major surgery and I would like to get a price. Cheap Charley did my vasectomy so I have no Idea why those kids aqre calling me Daddy.

CompleteW&D

LOL... well, shouldn't have mixed my installers up and caused all that confusion. Joey Lunchbucket was the guy who installed the contraption. Cheap Charlie was the dude called in to find out what's wrong. In either case, I'm quite certain the HO got what they paid for.

It would be funny, except what they describe could potentially be very dangerous. But dang, they got a good deal.

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- John Williams

Complete Window and Door

Ken Good

Gas pressure at the meter should be no greater than 9" WC for residental applications. Call the utility in your area and they will replace the regulator. As to installers not reading the manual, this is the number one reason for rejects and additonal costs.