New Wall Furnace Shuts Off, Overheats Wall Cavity

Noheatnow

Hi all,

Installed a new Housewarmer wall furnace from Lowe's. 

35,000 BTU, made to fit 2x4 wall with 16" OC studs.  Perfect application for my 1953 home.  Installed it right where the old one came out.  Fits same 4" oval B-vent.  No blockages, straight shot up flue to vent cap.

Runs for 5 minutes, vent safety shut off switch trips (runs 10 minutes with roof-top vent cap removed).  Inside the 2x4 wall, gets blazing hot, seems like the 4" oval B-vent isn't doing its job properly or something.  Got plenty of clearance going through top plate of wall.

The oval goes up to a "converter" that changes it to round, and this round is what pops into the roof cap. 

Here's the rub:  New furnace is taller, had to shorten flue somewhere.  Couldn't access the attic, so cut 6 inches from bottom of oval, where it contacts header plate.

Please help if you can,

Thanks, Steve

CMadatMe

You Can't Cut

B-Vent for starters. Suggest you call a professional. Obviously the equipment is telling you something is wrong and most likely it's the venting.

Zman

Be careful

You may be wandering outside the DIY world. A 1953 vent that you cannot access or inspect makes me nervous from the get go.Cutting B vent is another issue. Is it possible that the appliance is set up for the wrong fuel?

I think some professional help is in order. You stand a serous risk of burning the house down or killing the occupants with CO.  

Noheatnow

Right.....B-Vent.

I know, the vent is what you'd suspect.

Can someone explain this design: it's got four tubular heat exchanger pipes, yet the flue exhaust at the header is a mere 1" by about 5".  It seems like an extremely tiny port to allow hot gases to escape from four large heat exchanging pipes.

To clarify, you CAN see the vent, it's just next to impossible to reach, with a super flat roof, and ceiling joists 36" on center.  The access hole in the ceiling makes it nearly impossible to put plywood up in the attic to crawl it.

We are calling a (so-called) pro...I look forward to posting the outcome here.  With the B-Vent being unblocked, and not touching any wall surfaces, I can't even imagine why this thing is getting so hot.  Unbelievably hot.  35,000 BTU's is obviously wayyyy too much for this living room/kitchen.

Thanks

CMadatMe

I Pulled The Manual

This morning and there is a big note concerning venting and flat roofs. Describes exactly what you are experiencing. Playing with venting is not an DYI job. Seriously suggest you get a pro.