Concentric exhaust/intake caps for HRV's and the 2012 IRC

[klarenbeek]

How many of you see a concentric termination designed for both exhaust and fresh air from an air exchanger? Prior to the 2012 IRC there were no distance restrictions between environmental air exhaust and mechanical air inlets, so I always went off manufacturer's instructions, typically 6', but some also approved a concentric termination.

M1506.2 is a new addition to the 2012 IRC, which puts restrictions on mechanical air intakes for residential, including 10' of separation between any exhaust and mechanical air intake. Since the termination violates the new code section, I'm no longer approving their use.

Anyone have issues with this yet? The manufacturer of the concentric cap left me a message today wanting to discuss.

 

[markw]

Environmental air is considered air that is not part of the HVAC system,so if you have E.R.V equipment,I would consider it part of the HVAC system therfore the no enviromental (exhaust) air to worry with. Now if you have a basic exchanger there......

 

[klarenbeek]

I would argue that it IS exhaust air. Once pulled out of the furnace duct system, it is no longer part of the heating or air conditioning system. The IMC commentary includes building ventilation air as one of the types of environmental air. This is air that is required for building ventilation by IRC 1507. It is the exact same air as would be exhausted out from an exhaust fan mounted in a hallway.

Also 1506.2 requires the separation from an any air exhaust opening. It doesn't specify what type of exhaust. If it is air being discharged from the building, it is exhaust air. See the definition of exhaust system (there is no definition of exhaust air).

 

[markw]

So if you have an exterior/ground level ERV (typical on a larger commercial installation,pack unit) with factory made intake/exhaust config. on the side, you would not approve if under 10'?

 

[klarenbeek]

So if you have an exterior/ground level ERV (typical on a larger commercial installation,pack unit) with factory made intake/exhaust config. on the side, you would not approve if under 10'?

A factory intake/exhaust integral to the unit itself is covered by the listing of the unit, whether its a commercial ERV or a package gas heating unit with a built in economizer, and as such would be acceptable. What I'm talking about is a typical residential style ERV with field installed ducts going from the unit to the exterior of the building. The concentric termination is not an integral part of the unit or required to be used by the manufacturer. It is similar to a furnace manufacturer requiring 24" service clearance, but the code requires 30". The stricter requirement is enforced

 

[markw]

Ok I follow- I thought the termination cap was included/supplied by the manuf. and approved for use. I dont think I have seen a aftermarket type cap, been out of the trade for a year. New materials out everyday- Thanks for the info.