flue pipe on 90+ furnace

Landen · 02-09-2011, 01:20 AM

Is my flue pipe too close together on my new 90+ rheem furnace? They put the w/heater through old flue vent then merged 2 pipes into 1 concentric vent kit through the roof for new furnace. Our co detector went off tonight after wife was cooking(gas stove) and w/heater running. The 2 pipes are about 1.5-2 feet apart....I think the old flue is sucking in fumes from new furnace? I checked all pvc connections and it all looked fine. After airing house out I cut the water heat off until furnace guy gets here in the morning. Reset detector too. Any thoughts?

unicursalhex · 02-09-2011, 01:35 AM

Too close in my jurisdiction. Here we need 3' minimum. I doubt that would make your detector go off as its a closed combustion system (meaning the air thats pulled in through the concentric kit does not come out of the heat registers)

**beenthere** · 02-09-2011, 04:36 AM

Was your range hood exhaust fan running at the same time? If so, it may have caused a negative pressure in the house.

Could also be that the old chimney is too large for the water heater now.

Landen · 02-09-2011, 10:09 AM

Quote:

Originally Posted by unicursalhex

Too close in my jurisdiction. Here we need 3' minimum. I doubt that would make your detector go off as its a closed combustion system (meaning the air thats pulled in through the concentric kit does not come out of the heat registers)

unicursalhex,
I'm in Illinois near STL. I'm not sure what the code is but I know an inspector is suppost to come out and check thier work soon. Would this be in the instruction booklet for the pipe placement? Also just turned the water heater back on while the furnace was running and went out back ,it looks like some of the fumes that is forced downwards out of the old flue cap may be pulled into the new concentric cap. I thought this would shut the new furnaces down?? Anyway I'm not taking a chance with my family so after the w/heater heated up I shut it down until the installer gets back out here today.Thanks

Landen · 02-09-2011, 10:27 AM

Quote:

Originally Posted by beenthere

Was your range hood exhaust fan running at the same time? If so, it may have caused a negative pressure in the house.

Could also be that the old chimney is too large for the water heater now.

beenthere,
No the exhaust fan was not running but my wife had the stove on for about 1.5 hours fixing dinner...When the co detector went off she turned it on so I told her that not good so she turned off and we quickley opened the windows.
He thinks the pipe is too big on the old flue so he wants to make it smaller. thanks

Landen · 02-09-2011, 04:09 PM

update ..now our smoke alarm went off and I thought our house was on fire because quite a bit of smoke gathered in our hallway. I cut all the power to the furnace and the smoke cleared. I called the installer back out so he thinks our blower or board has went out. the blower was very hot to the touch.. now he went after a blower and new board ...stay tuned

I just wonder if this is why the co detector went off too...can't believe we had all thi trouble with a brand new furnace already........

**beenthere** · 02-09-2011, 07:49 PM

Not something that happens often.

Landen · 02-10-2011, 12:11 AM

Ya our furnace repairman said its probably been close to 20 years since he had this much trouble with a new furnace. It would be mine

! He put a new motor in the fan housing tonight and now its making a humming noise and can even hear it through the vents. Its been smelling like oil too which I know is nomal on new parts but it doesn't seem to let up much. He's coming back tomorrow and try and quiet the blower down...Im ready to scrap it and start all over

unicursalhex · 02-10-2011, 02:18 AM

Bummer, sorry you're having such problems. What furnace do you have? I had a pain in the ass furnace a few months ago that came from the factory with the ground wire missing, line voltage and neutral crossed, and vacuum hoses disconnected. I corrected all the visible problems and It fired up once and ran for a few seconds, shut itself off. Next cycle a large flash came from the furnace and it never ran again. My point is that it does happen and as long as your installers are making the effort it will all get taken care of. The manual will have venting specifications, whip it out and I bet it will tell you it needs to be 3' away from any other vent or intake.

**beenthere** · 02-10-2011, 06:00 AM

Quote:

Originally Posted by Landen

Ya our furnace repairman said its probably been close to 20 years since he had this much trouble with a new furnace. It would be mine

! He put a new motor in the fan housing tonight and now its making a humming noise and can even hear it through the vents. Its been smelling like oil too which I know is nomal on new parts but it doesn't seem to let up much. He's coming back tomorrow and try and quiet the blower down...Im ready to scrap it and start all over

Usually don't really get a oil smell from a new motor.

Landen · 02-10-2011, 09:30 AM

Quote:

Originally Posted by beenthere

Usually don't really get a oil smell from a new motor.

Ya thats what i was thinking too. He is suppost to come back today and take a look at it.

UPDATE: HE JUST CALLED AND SAID HE IS REPLACING THE WHOLE FURNACE! Thank God! I was afraid we should have kept our crappy 1992 goodman..LOL

I hope this is the last of our problem and thank you beenthere,and unicursalhex for you help.

hvaclover · 02-10-2011, 05:03 PM

If the water heater was orphaned by the removal of the old furnace the chimney now becomes too large to draft properly with only the water heater
flue gases to keep warm enough to draft well.

The furnace blower can pull the indoor press low enough to cause an already badly drafting chimney to back flow into the home and trip the monoxide detector.
Or if the detector is over five years the sensor could be worn out and alarm to any steady stream of cooking smells.
But to me the whole scenario smells fishy.

hvaclover · 02-10-2011, 05:08 PM

In all my thirty plus years I have replaced many furnace blower motors and none of them filled the home with smoke. There is nothing in the motor to sustain combustion to make smoke. The windings overheat and melt causing an open in the windings.

There ain't no smoke!

hvaclover · 02-10-2011, 05:11 PM

Quote:

Originally Posted by beenthere

Usually don't really get a oil smell from a new motor.

You are letting the OP get away with murder Been. Motors never smell of oil they can't because the bearings are sealed.

**beenthere** · 02-10-2011, 05:40 PM

Quote:

Originally Posted by hvaclover

You are letting the OP get away with murder Been. Motors never smell of oil they can't because the bearings are sealed.

He said what he thought the smell may be from. I answered you don't really get an odor like that from a motor. A simple exchange of thought. No murder, no foul.