CPVC Vent for Condensing Water Heater

[Robert Field]

This is a commercial/multi-family installation of a replacement building water heating system that now has to comply with the latest Air Quality requirements. The vent has changed from a Class B to a IV. The problem is the boiler room is in the middle of the building and the roof is four stories away, and to get there the original 10" installation required two 90 degree turns and access to the old flue is very limited. The better route is through the parking garage to the outside, which includes coring a 7" hole in a reinforced concrete wall. The garage is classed as "open". The question is, is there any code that prevents the pipe run across the parking garage from being 5" CPVC? There are no interferences that can't be avoided and the elevation would be above other drain lines.

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[Jerry Peck]

The first question becomes this: what materials do the manufacturer's installation instructions (MII) allow/require for use as the vent?

With the second question being: what is the maximum horizontal run, and at what minimum slope, is allowed/required by the MII?

The next question (your question) will need to be looked up in the California mechanical code, and possibly cross-checked with the California building code (the mechanical code may answer the question), I am not familiar with the California codes.

[Robert Field]

The first question becomes this: what materials do the manufacturer's installation instructions (MII) allow/require for use as the vent?

With the second question being: what is the maximum horizontal run, and at what minimum slope, is allowed/required by the MII?

The next question (your question) will need to be looked up in the California mechanical code, and possibly cross-checked with the California building code (the mechanical code may answer the question), I am not familiar with the California codes.

Thanks Jerry,
We're ok on material & distance. The question is the type of material, CPVC, traversing the garage is the only issue. I'll keep looking.
Thanks again.
Best, Bob Field

[Jerry Peck]

2021 ICC IFGC
- 501.14 Category II, III, and IV appliance venting systems.
- - The design, sizing and installation of vents for Category II, III and IV appliances shall be in accordance with the appliance manufacturer's installation instructions.

The above is a start, check the Fuel Gas Code that California uses:
- https://up.codes/viewer/california/c...nd-vents#802.0

TABLE 802.4
TYPE OF VENTING SYSTEM TO BE USED [NFPA 54: TABLE 12.5.1]
- Category II appliance
- Category III appliance
- Category IV appliance
- - (all of above) As specified or furnished by manufacturers of listed appliance (Section 802.4.1 and Section 802.4.3)

- 802.4.1 Plastic Piping
- - Plastic piping used for venting appliances listed for use with such venting materials shall be approved. [NFPA 54:12.5.2]


- 802.4.3 Special Gas Vent
- - Special gas vents shall be listed and installed in accordance with the special gas vent manufacturer's installation instructions. [NFPA 54:12.5.4]



- 802.3.3.2 Leakage
- - Forced draft systems and portions of induced draft systems under positive pressure during operation shall be designed and installed so as to prevent leakage of flue or vent gases into a building. [NFPA 54:12.4.3.3]

Without further research, my first thoughts are the 802.3.3.2. Leakage could be the challenge to meet - what happens if there is a car fire in the open parking garage (it happens)?

The vent may reasonably be required to be encased in a shaft enclosure rated for (X) hours (X = 1, 2, 3, or 4 hours, depending on the rating required of the structure, and may require a pressure test for leakage prior to being enclosed in the shaft (and/or be tested after being enclosed, but testing before could potentially save a lot of work if a leak were found).

You would want to verify that there was sufficient slope so as to allow for/provide for positive condensation drainage back to the point of condensation collection and discharge piping (no 'dips'/'bellys', revers slopes, etc).

Just doing some thinking out loud (as I type).

[Robert Field]

2021 ICC IFGC
- 501.14 Category II, III, and IV appliance venting systems.
- - The design, sizing and installation of vents for Category II, III and IV appliances shall be in accordance with the appliance manufacturer's installation instructions.

The above is a start, check the Fuel Gas Code that California uses:
- https://up.codes/viewer/california/c...nd-vents#802.0

TABLE 802.4
TYPE OF VENTING SYSTEM TO BE USED [NFPA 54: TABLE 12.5.1]
- Category II appliance
- Category III appliance
- Category IV appliance
- - (all of above) As specified or furnished by manufacturers of listed appliance (Section 802.4.1 and Section 802.4.3)

- 802.4.1 Plastic Piping
- - Plastic piping used for venting appliances listed for use with such venting materials shall be approved. [NFPA 54:12.5.2]


- 802.4.3 Special Gas Vent
- - Special gas vents shall be listed and installed in accordance with the special gas vent manufacturer's installation instructions. [NFPA 54:12.5.4]



- 802.3.3.2 Leakage
- - Forced draft systems and portions of induced draft systems under positive pressure during operation shall be designed and installed so as to prevent leakage of flue or vent gases into a building. [NFPA 54:12.4.3.3]

Without further research, my first thoughts are the 802.3.3.2. Leakage could be the challenge to meet - what happens if there is a car fire in the open parking garage (it happens)?

The vent may reasonably be required to be encased in a shaft enclosure rated for (X) hours (X = 1, 2, 3, or 4 hours, depending on the rating required of the structure, and may require a pressure test for leakage prior to being enclosed in the shaft (and/or be tested after being enclosed, but testing before could potentially save a lot of work if a leak were found).

You would want to verify that there was sufficient slope so as to allow for/provide for positive condensation drainage back to the point of condensation collection and discharge piping (no 'dips'/'bellys', revers slopes, etc).

Just doing some thinking out loud (as I type).

Hi Jerry,
Thank you for your great thoughtful response. It sent me scurrying for the code books. For this service I didn't find any restriction of running the 6" CPVC direct vent through the garage. There is one code provision that suggests the vent could be terminated in the open garage. The board approved the garage route and the next task is to have a structural engineer sign-off on the 8" hole in the reinforced concrete wall separating the boiler room from the garage.
Thanks again for your professional input.
Best regards,
Bob Field

[ROBERT YOUNG]

Hi Jerry,
Thank you for your great thoughtful response. It sent me scurrying for the code books. For this service I didn't find any restriction of running the 6" CPVC direct vent through the garage. There is one code provision that suggests the vent could be terminated in the open garage. The board approved the garage route and the next task is to have a structural engineer sign-off on the 8" hole in the reinforced concrete wall separating the boiler room from the garage.
Thanks again for your professional input.
Best regards,
Bob Field

Are you referring to concentric vent? See it many times.

"the vent could be terminated in the open garage." Could you post that code article please. There are likely clearance restrictions.