IMPROPER EXHAUST VENTS AND DRAIN PIPE

**CHARLIE VAN FLEET** · 03-22-2011, 03:47 PM

HEY ALL

1998 international comfort furnace. is this a proper exhaust duct connector. rubber elbow was hot and soft at inspection--should it not be all pvc duct. and next picture is condensate tray drain pipe--should it not also be soild pvc. never saw it this way before

thanks

cvf

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**CHARLIE VAN FLEET** · 03-23-2011, 12:24 PM

hey all

any help on this

cvf

**Markus Keller** · 03-23-2011, 02:05 PM

The coupling looks like a standard Home Bebop neoprene plumbing hub. I can't imagine it is rated for that use. The furnace manufacturer probably has specific requirements for the exhaust pipe that don't include a plumbing coupling. My guess is they lost the original adapter fitting at some point.
The drain has no trap, air gap and is reduced in size, so No.
On stuff like this I write it up as non-standard installation and not conforming to Manufacturer specifications; install properly per Manuf. Specs. I don't usually bother to look up the info.
The few times I have been challenged on it, I look up the info, email it out and it shuts them up. When the Seller makes 'claims' its Ok, I have the client ask the to provide Manuf docs proving its Ok. Of course they never can. The majority of the time, Seller has an HVAC guy come out, he tells them its wrong anyway and its just faster and easier to repair than fight about it.

**Eric Barker** · 03-23-2011, 08:33 PM

The problem I have with the drain line hose is that it tends to kink - kinda like it is in your photo. Then crud gets stuck where the I.D. is reduced and things begin to back up. Hmmm! Are those water stains from the coil cabinet?

**Bob Harper** · 03-25-2011, 05:30 AM

I agree w/ Eric on the condensate tubing issue. Yes, I see staining at both the Aux. tapping and down the right side so you know they've had drainage issues in the past. If the returns are not sealed nor the filter slot covered in a dusty environment, you can get gobs of crud on the A coil that wash down clogging the drain. That's one reason for the Aux tapping.

As for the use of a Fernco fitting Charlie, you'd have to refer to the listed instructions. Some allow it and some don't. You should use a small mirror to inspect for cracks in the neoprene on the back side and around each drawband. What you cannot see but should be tested is if this makes a proper seal under pressure. If you note the primer stains it would appear this pipe has been cut and patched with the Fernco instead of a PVC coupling. That raises the question why cut it? Most mfrs. recommend attaching the starter section of PVC to the appliances collar with RTV silicone caulk so you can remove it for inspection, testing or to replace the blower. Look to see if the blower appears to have been replaced.

If you have a clogged A-coil and a replaced combustion blower, what else is bad? I would want a thorough inspection inside and out of this furnace along with combustion analysis and performance testing.
Bob

**Bob Knauff** · 03-25-2011, 02:05 PM

Pretty common to see the plastic condensate drain nipple cracked or broken by too rough handling when pushing the drain line in place. Gently lift on it to see if it's broken. Also, its possible to have had the nut over tightened to the point of it being stripped and loose the seal. If left unattended, the condensate may well run down into the furnace cabinet and damage a circuit board or metal components of the firebox or blower. There is evidence of lots of moisture running across the cabinet top already.

I have never seen a Fernco fitting used on the exhaust side of a HE furnace like that but often find them on the air intake side. I agree with Bob. The owners manual or mfg. should be consulted. Perhaps the installer thought they couldn't seal ABS to PVC. Perhaps the ABS is not rated for high temps either?

An excerpt from a Carrier brand 4- Way Multi-Purpose Direct Vent Variable Capacity Condensing Gas Furnace Mdl.58 MVP Install Manual regarding "Combustion-Air and Vent Pipe Attachment"

NOTE: All pipe joints must be cemented except attachment of
combustion-air pipe to inlet housing connection since it may be
necessary to remove pipe for servicing.