Tankless Boiler Venting

look at the venting section of the installation manual for the make and model of your boiler. These are available online. BTW while PVC is acceptable for intake air, you can’t use it for the vent…. should be Polypropylenene or stainless steel (Z vent)

Hi Eman, Thank you. I read the installation manual and it doesn’t indicate anything about a 3 foot distance from the building. The manual shows the vent extend a few inches out of the wall with a 12″ clearance from any windows. I should have clarified – I am asking about NYC DOB code requirements beyond what’s in the manual. As well as safety of such a long length of plastic pipe lying exposed in the yard.

Was a permit pulled for this work?

Hi Chris! yes we have a permit.

To my knowledge, there is no DOB requirement for a 3 foot distance from building . I have installed a lot of HE boilers (lochinvar,buderus, viessman,weil mclain, baxi,noritz,navien, triangle tube) , but have never done that unless it was to meet the venting manual requirements. Occasionally had to run a length along the wall to meet a 10b foot from property line requirement. But, as I always tell my clients, I am constantly learning and may be wrong

I didn’t think there was a 3 foot requirement – my architect said that it might be the case so I wanted to make sure. Thank you so much. I suspect GC is just running the length of the wall and into the yard to do it the easiest way. It looks unsightly and could have been concealed between the studs on the inside and vented out through the wall.

This is what I got back from the DOB so thought I’d share
The horizontal termination needs to comply with the NYC Fuel Gas Code (FGC), 508.3, item 3 (see below).

3. Horizontal terminations shall only be allowed if they are in a nonhazardous location and if the appliance has a sealed combustion chamber (direct vent) or integral vent in accordance with the appliance listing and manufacturer’s instructions. In addition, horizontal terminations shall comply with the following requirements:
3.1. Where located adjacent to walkways, the termination shall be not less than 7 feet (2134 mm) above the level of the walkway.
3.2. Vents shall terminate at least 3 feet (914 mm) above any forced air inlet, other than the forced air inlet for the subject direct vent or integral vent appliance, located within 10 feet (3048 mm).
3.3. The vent system shall terminate at least 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from or 1 foot (305 mm) above any door, window or gravity air inlet into the building.
3.4. The vent termination point shall not be located closer than 3 feet (91 4 mm) to an interior corner formed by two walls perpendicular to each other.
3.5. The vent termination shall not be mounted directly above or within 3 feet (914 mm) horizontally from any gas or electric metering, regulating, venting relief equipment or other building opening.
3.6. The bottom of the vent termination shall be located at least 24 inches (610 mm) above finished grade.
3.7. The maximum heat input of an appliance served by single horizontal vent termination shall be 350,000 Btu/h (1025 kW), unless otherwise approved by the Commissioner.
3.8. The maximum heat input of all appliances served by horizontal vent terminations located within a 10 foot (3048 mm) radius shall be 350,000 Btu/h (1025 kW), unless otherwise approved by the commissioner.
3.9. The vent termination shall be located a minimum of 4 feet from the lot line or from adjacent buildings. The termination shall be installed in accordance with the gas vent manufacturer’s listing and installation instructions.

the only rationale that your contractor may be citing is 3.4 or 3.5, both of which can be resolved by the vent piping inside the building before it pops through the wall…there is zero rationale for the intake air, though some manufacturers require minimum distance between intake and vent

Thank you. 3.4 could be an issue but might be surmountable. I don’t believe I have any of the conditions mentioned in 3.5. Re: Rule 3.1, what would be considered a walkway? Is a paved backyard or steps to the yard from a deck considered a walkway?

if it is (can’t tell….discretion is always left to the inspector in the field, meaning that the guy who shows up may not agree with the last guy)you could resolve the issue by height of termination…your contractor should be working with you, not against you

DOB has been super helpful. More info for anyone interested in the topic

Please note that all combustion air intakes must have a 30 inch clearance minimum, as per NYC Fuel Gas Code FGC 304.4.3 (manufacturer’s instruction manual shows 12 inches or as required by code). Below is the code for your information regarding the combustion air intake clearance:

304.4.3 Prohibited sources.
– Openings and ducts shall not connect appliance enclosures with a space in which the operation of a fan will adversely affect the flow of the combustion, ventilation, and dilution air.
– Combustion, ventilation, and dilution air shall not be subject to ice or snow blockage. No combustion, ventilation, and dilution air inlet shall be less than 30 inches (762 mm) above grade.
– Combustion, ventilation, and dilution air shall not be obtained from a hazardous location, except where the fuel-fired appliances are located within the hazardous location and are not installed in accordance with this code.
– Combustion, ventilation, and dilution air shall not be taken from a refrigeration machi nery room, except where a refrigerant vapor detector system is installed to automatically shut off the combustion process in the event of refrigerant leakage.
-For structures in areas of special flood hazard, air shall be obtained from a location
complying with Appendix G of the New York City Building Code.
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I’ve had more than one inspector enforce the (3.9) distance-from-lot-line rule. It’s “at the discretion of the inspector”, as the DOB often says.

The GC/plumber ran boiler vents in bathroom floor and poured the slab over it. Secondly, from the boiler room to outside, the vents have about 12 turns before they terminate outside.I am planning to get a new plumber but wondering if anyone has thoughts on either of those two things.

Generally each 90 counts as 5 feet of run on HE boilers… check the installation manual or venting addendum for your specific make and model. More important is the vent material approved by nyc? That means stainless (z vent) , polypropylene, or perhaps cpvc. PVC is not allowed for the vent but okay for the intake

thanks, I did not follow the bit about 90 counts. Vent material if fine I believe but seems weird to bury a vent under concrete in my opinion especially as the install is not completed and we have no idea if the vents work. Attaching pics of the pipe information [2020-07-12 19](//muut.com/u/brownstoner/s3/:brownstoner:1D6d:2020071219.59.25.jpg.jpg) [2020-07-12 19](//muut.com/u/brownstoner/s3/:brownstoner:B9PG:2020071219.59.45.jpg.jpg)

The Navien manual says maximum 8 elbows for 3″ pipe. These are all 90degree elbows. I think we’re within the max length of 150 feet

Also we have multiple elbows in some of the 5 foot lengths

I wouldn’t bury a vent but it seems okay if the total length approved minus 5 feet for each elbow complies to the manual

We don’t have 5 feet per elbow unfortunately. There also doesn’t seem to be a pitch to the vents – it’s all horizontal.