To b-vent or not to b-vent? That is the question.

[Daddy-0-]

Final mechanical inspection today on an addition with a new gas furnace (not a 90+). Contractor installed hard pipe dryer duct (not b-vent) for the vent and ran it horizontally out of the side wall. He said, "I know I need to put a cap on it but I can't find the right one." Excessive defects was only the beginning. Should have taken a picture. There isn't a way to run a b-vent through the roof on this one either without a real ugly chase. The addition is mostly open with vaulted ceilings. I told him maybe a heat pump or upgrade to a 90+. Any ideas?

 

[peach]

not an easy fix, Daddy. Of course, I don't have a fuel gas code handy.. (which is kind of odd). I believe there is more than one issue with the installation; let me do a little digging and get back with you.

 

[Jobsaver]

You can use b-vent a horizontal application with a draft inducing fan kit. The kits run about $250 - $500. It will include a geometric damper installed close to the appliance, and a draft inducing fan motor installed at the terminating (exterior) wall. The fan will require 110V at the wall, and a thermostat wire run back to the appliance.

 

[SCBO1]

"I know I need to put a cap on it"

Do they still make a wall thimble so the pipe can have clearance thru the wall?

pc1

 

[klarenbeek]

Remember a draft inducer needs to be installed in accordance with both it's listing AND the appliance's listing (IFGC 503.3.3). Unless the furnace manufacturer allows it, a draft inducer can't be used. They could build an insulated exterior chase on the outside of the house around the b vent.

 

[Daddy-0-]

Contractor has contacted me and he wants to take the power vent method like jobsaver described. He said that the manuf. installation instructions list that as an add on kit. I think this is the easiest way out. I have seen lots of power vented water heaters but never a furnace. Thanks for the responses and I will let you know if the install passes.

 

[Jobsaver]

Daddy-O: The most common problem I find inspecting furnaces with horizontal "b" vent and a draft induction fan is that the geometric damper is not always installed close enough to the appliance. Most I have inspected call for the damper to be installed within 3-4' of the appliance. But, I have heard that others call it to be installed near the induction fan. It is my understanding that it is important to install the damper level, and in the proper location, to keep the flue gases from backdrafting during periods of low atmospheric pressure. Be sure and check the installation specs on your particular situation.

Good luck.