Furnace combustion air

[Hgye]

Can ABS be used for the combustion air pipe on a furnace?

[Admin]

Yes, you can install or re-use ABS for an intake.

A vent conveys flue gas and an intake is not considered to be a vent.

For certain minor repairs you can add 636 to an existing ABS vent or termination.  Only when the appliance is replaced, or when the existing ABS vent cracks does it need to be replaced with 636, but the intake can stay ABS. 

Download Advisory FS-101-07-R1 - Here

[Trainerguy]

The B149.1-10 Clause 8.9.6 states that vents constructed using plastic piping shall be certified to ULC S636.

However the install manual for ICP products states that the combustion air system is not required to be S636 certified.

Before doing the install, I would check the install manual of the product you are installing and if it says it is ok to use ABS on the combustion air side I would check with the local inspector to make they would accept the manufacturers instructions.

Trainerguy.

[walker]

what about for cutting into the abs when doing a A-Coil replacement, am I able to reconnect it with a 636 coupling and have it still meet code.  I was taught before that if you have to alter the ABS then it must be replaced.

[Admin]

There has never been a requirement to replace the ABS vent because it was altered.  Only if the vent became deformed, seperated or cracked, or when the appliance was replaced, would the vent require replacement.

Prior to April 7, 2014, if you did cut the ABS you would have had to use an ABS coupling.  Now you can use a 636 coupling, as long as the approved transition cement is used, as per Advisory FS-101-07-R1.

2. Minor venting alterations
It is permissible to alter existing ABS venting systems with S636 approved PVC or CPVC venting components using appropriate S636 transition cements. Examples of such situations are as follows:
a. Raising of appliances, necessitated by floors being elevated during renovations.
b. Shifting of appliances required to obtain service clearances (e.g. turning of water heater because a wall was built up against a relief valve).
c. Minor venting adjustments necessitated by service work completion. (e.g. ventor changes)

The TSSA released a document in 2007 addressing the new 636 requirements - Q's and A's Plastic Venting Certification

16. I am a gas fitter – If I replace the venter motor assembly – Do I replace the whole venting system?
If the vent is in good condition – No. Simply replace the motor and attach it with type of vent that is currently used on that appliance. Replacing a part of the appliance does not necessitate the whole vent be replaced.

19. Does the combustion air piping need to be certified to ULC S636?
No – the combustion air pipe is not exposed to flue gases and does not need to be certified.

[Hgye]

Something in writing!  Thanks very much!!

[DroningVarlot]

Sorry for resurrecting an old topic and please pardon my ignorance. My ABS furnace vent snapped off just above the elbow on the outside of my house while trying to fish out mud and Hotwheels at -15. Can I simply cut it down and use a 636 coupling to reconnect the ABS? Just to clarify, the mud and Hotwheels belong to my son.

[Admin]

You should be okay doing that as per TSSA Advisory FS-101-07-R1 Section 2(c).

Existing vent alterations

1. Corrections made to existing vent termination

It is permissible to alter existing ABS venting system terminations with S636 approved PVC or CPVC venting components using appropriate S636 transition cements. Examples of such situations are as follows:
a. Addition of snorkels to accommodate grade changes, to overcome vent termination/air supply pipe freeze-offs and to correct customer complaints (e.g. blowing on bushes, window fogging).
b. Vent extensions to avoid building/air supply openings.
c. Alterations required due to deck installations.

2. Minor venting alterations

It is permissible to alter existing ABS venting systems with S636 approved PVC or CPVC venting components using appropriate S636 transition cements. Examples of such situations are as follows:
a. Raising of appliances, necessitated by floors being elevated during renovations.
b. Shifting of appliances required to obtain service clearances (e.g. turning of water heater because a wall was built up against a relief valve).
c. Minor venting adjustments necessitated by service work completion. (e.g. ventor changes)