Heating & Air Conditioning Building a Home

Keeping fresh air intake fresh ?

5 years ago

In our current house we've had a few instances of bad smells coming in our fresh air intake. A couple of times it was dead rodents. HVAC folks like to put fresh air intakes (HRV & MUA, not combustion which we don't care about the smell) near outside mechanical equipment since that is often the shortest route and groups all of the less appealing stuff together. Animals also like to hang out and sometimes die near mechanical equipment, particularly in the winter when this is a slightly warmer spot.

Have others had problems with this?

We're debating moving our fresh air intakes to a place that may provide fresher air but will also be much more visible. Trying to decide if it's worth it.

Thanks,

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Comments (4)

User
5 years ago
Not worth it. You just need better vent covers.
just_janni
5 years ago
I think the short answer is "it depends". Our fresh air on the existing house was specifically put somewhere where it was NOT near any kind of electromechanical requirement, AND not near car exhaust AND not near lawn to try to find the best place that would have the least amount of chemicals and potential pollutants being brought back into the house ostensibly to provide "fresh" air.

Having this done in a thoughtful manner is more and more important when the rest of the house is tighter and less leaky.

From Building Science:

Ventilation System Intake

A supply-only or balanced ventilation system offers control over the source of dilution ventilation air. This is a considerable advantage if the outdoor intakes are located where they will not likely entrain contaminants, dust, debris, odors or other substances that would degrade indoor air quality. The following rules are offered to govern location of outdoor air intakes.
- Intake must draw through an intake grille or register located on an outside wall or soffit and not the roof.
- Wall intakes must be located at least 10 feet from any appliance vent or any vent opening from a plumbing drainage system. Wall intakes must also be 10 feet from any exhaust fan discharge outlet unless that outlet is 3 feet or more above the intake location. (IRC 2006, Section M1602.2).
- Intakes should not be located directly above any wall exhaust or vent.
- Intakes must be protected against rain and pest entry with durable rust- and rodent-proof materials.
- Intakes must not be located within 10 feet above any paved surface or roof.
- Intakes must not be located in proximity to an area where vehicles or motorized equipment is likely to idle for any length of time.
- Intakes must not be located where they might be obstructed by drifting snow (consult local experience as to the height of snow drifts against buildings).
- Intakes must not be located within a zone of significant ground-level dust and debris generation (e.g. mowing, leaf blower use). At a minimum, intakes should be 2 feet above grade.
- Intakes must not be allowed to be obscured or hidden by vegetation. Vegetation must not be allowed to grow within 3 feet of a ventilation system intake.
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opaone
Original Author
5 years ago
last modified: 5 years ago
Thanks all.

This question is regarding new construction as we are building a new house and they've just begun doing HVAC stuff. I should have made that more clear.

The mechanical equip (2 large units, 1 small mini-split) will be located along the north wall in the orange area. Current plan is for fresh air (1 14" & 1 12" MUA + 1 14" HRV) intakes to be located along the same wall. We are thinking about moving them to the wall where the green box is shown which would be much more visible as it's in the front entry courtyard area. The Mechanical room is the space between the orange & green boxes.

The planned location on the north side of the house may well be OK. Fresh air is important to us so we just want to make sure that we're pulling in fresh air and not air that is tainted in some way.

BTW, vent covers will not keep out smells.

Thanks,
just_janni
5 years ago
If that green area is landscaped - I'd be concerned about smells and chemicals there for weeds or bugs or fertilizers. What about on the back garage wall, well away from the outdoor units? And less likely to be in an area where chemicals will be used?

Keeping fresh air intake fresh ?

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Keeping fresh air intake fresh ?

Comments (4)

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just_janni

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just_janni

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opaone
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