Shared ventilation gizmo

[Inspector Gadget]

One of my inspectors found something in the field that I'd never encountered before: an HRV kit that runs the intake/exhaust through the same pipe.

I've ruled that this isn't acceptable, the logic being 9.32.2.3(4) states "A non-heating-season mechanical ventilation system shall be designed and installed in conformance with good practice such as that described in the ASHRAE Handbooks and Standards, the HRAI Digest, the Hydronics Institute Manuals and the SMACNA manuals."

HRAI says (as best as I can verify) that vents/intake must be separated by 1.8m (6ft); ASHRAE states 3m. I don't have access to the other resources, so at the moment, I've ruled that the shared intake/outlet is not permitted, and spacing must be 1.8m.

Thoughts? Differing opinions?

 

[classicT]

This could be classified as a new and innovative technology, although my understanding is similar technology has been popular in Europe for some time. As such, you should not get tied up in finding a code section that would preclude a specific technology. The code lags behind innovation. See IBC Section 104.11 or IMC 105.2.

2021 IMC [A] 105.2 Alternative Materials, Design and Methods of Construction and Equipment​

The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the code official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, not less than the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety. Where the alternative material, design or method of construction is not approved, the code official shall respond in writing, stating the reasons why the alternative was not approved.​

I've encountered similar options that were listed and certified. I have no objection to those. The ones I saw had a MERV 14 filter, plus option for an activated carbon filter.

Basic premise is that the direction of flow oscillates back and forth, typically via two of these units installed on opposite sides of the space or home. The run-time is short, allowing the transfer of energy from a ceramic heat sink to the ventilation air. Flow direction changes as energy stored in the heat sink is depleted. Efficiency ratings are fairly decent (70+%).

 

[classicT]

Check out this explanation of this system type.

LUNOS HRV - linked

 

[Inspector Gadget]

See IBC Section 104.11 or IMC 105.2.

2021 IMC [A] 105.2 Alternative Materials, Design and Methods of Construction and Equipment​

The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. ​

Canadian Codes in use up here. We have similar provisions for alternatives not in Code, but they're onerous for something like this. And this is for use with one HRV....

 

[classicT]

Canadian Codes in use up here. We have similar provisions for alternatives not in Code, but they're onerous for something like this. And this is for use with one HRV....

Sorry, missed that this was in the Canadian section.

That said, new and innovative approaches deserve consideration.

 

[Inspector Gadget]

Check out this explanation of this system type.

LUNOS HRV - linked

That appears to be intending to have multiple mini units working in cohesion: I remember looking at those concepts when specifying air-exchange units for my own house.

The split vent gizmo I pictured is for one HRV, exhausting stale air right beside the intake.

I mean, I'm open to new ideas, but this doesn't seem to be a good one.

 

[tmurray]

I've seen them and don't like them. As you mention, intake and exhaust must be separated to ensure the air stream doesn't short circuit and re-enter the building ventilation system.

I have called out vents too close together on builds occasionally. I can't imagine accepting this.

 

[Plumb-bob]

Whereas codes do lag behind innovation, we must be very conservative in our acceptance of every/any new product. That is not our job.

 

[Mac Moonfire]

Check out this explanation of this system type.

LUNOS HRV - linked

We've accepted our first alternative solution for a small 2 level house that utilizes lunos. Reach out for more info.
Also, we chose not to charge for alternative solutions in residential.

One of my inspectors found something in the field that I'd never encountered before: an HRV kit that runs the intake/exhaust through the same pipe.

I've ruled that this isn't acceptable, the logic being 9.32.2.3(4) states "A non-heating-season mechanical ventilation system shall be designed and installed in conformance with good practice such as that described in the ASHRAE Handbooks and Standards, the HRAI Digest, the Hydronics Institute Manuals and the SMACNA manuals."

HRAI says (as best as I can verify) that vents/intake must be separated by 1.8m (6ft); ASHRAE states 3m. I don't have access to the other resources, so at the moment, I've ruled that the shared intake/outlet is not permitted, and spacing must be 1.8m.
View attachment 10806
Thoughts? Differing opinions?

Can you request an alternative solution? where a registered professional would rationalize how this solution meets the intent of the code? and ultimately sign off on the performance of the product.
otherwise, it seems like you have enough to reject this questionable piece of technology.

 

[classicT]

 

[Inspector Gadget]

Can you request an alternative solution? where a registered professional would rationalize how this solution meets the intent of the code? and ultimately sign off on the performance of the product.
otherwise, it seems like you have enough to reject this questionable piece of technology.

Well, meaningful update: the contractor has pitched the idea of creating a gizmo that will take one of the "splits" and feed it into an exterior-mounted PVC pipe that leads six feet away, which will automagically give it the spacing requirement.
I've recommended we accept, since that's now gone and done what ought to have been gone and done in the first place.

 

[klarenbeek]

I know it may not apply in Canada, but the 2021 IMC has an added a statement to 501.3.1 #3 that allows for these:
......."Separation is not required between intake air openings and living space exhaust air openings of an individual dwelling unit or sleeping unit where an approved factory-built intake/exhaust combination termination fitting is used to separate the air streams in accordance with the manufacturer's instructions."

Frankly, if it helps incentivize the use of HRV's for whole house ventilation over some of the other hokey setups I see that will get turned off and never used as soon as I'm out the door, I'm all for it.

 

[Inspector Gadget]

I know it may not apply in Canada, but the 2021 IMC has an added a statement to 501.3.1 #3 that allows for these:
......."Separation is not required between intake air openings and living space exhaust air openings of an individual dwelling unit or sleeping unit where an approved factory-built intake/exhaust combination termination fitting is used to separate the air streams in accordance with the manufacturer's instructions."

Frankly, if it helps incentivize the use of HRV's for whole house ventilation over some of the other hokey setups I see that will get turned off and never used as soon as I'm out the door, I'm all for it.

I am thinking this explains the situation... we have a number of products/practices that come into Canada that are Code-compliant in the Excited States but not acceptable here. Deck construction products/techniques are a prime example.

 

[steveray]

where an approved factory-built intake/exhaust combination termination fitting is used to separate the air streams in accordance with the manufacturer's instructions."

There is that pesky word approved......

 

[Paul Sweet]

I hope that "living space exhaust air openings" does not include bathroom exhaust.

I'm wondering how well the unit in the OP will keep the air streams separated if the wind is blowing directly at it.

The Lunos unit appears to switch between intake and exhaust. It would probably be OK for habitable space (not toilets or kitchens) ventilation as long as the fan shuts down for several seconds between exhaust and intake to allow the exhaust air to dissipate.

 

[Sifu]

The single unit costs over 1100.00 (not including installation) and requires an 8" wall at a minimum per one quick google search. Would be interested in an honest cost/benefit analysis. How long before it is required, instead of allowed?