We're nearing the completion of our build and we've just found out that the air intake for our HRV is at ground level beside our house. They assure us this is where the air intake always goes, but for us it's terrible: the neighbours smoke out back, have barbecues, etc. and it's all going to get blown into the house (my wife has asthma triggered by smoke). To my mind, the logical place for the intake (in pretty much all cases, not just ours) would be just below the roof at the center back of the house. Does anyone know if there's a standard practice for HRV air intake positioning? Is there a maximum run, or anything like that? Thanks, Colin.

If the HRV is located in the basement/crawlspace of your home, then the logical place for the intake would be near ground level, because this would provide the shortest, most direct routing of the duct work. However, there is no rule that I am aware of that requires this location. I suspect your location was the easiest for the installers. I'm sure it will add to your costs, but it should be possible to move the intake to a location you are more comfortable with.

As a general rule I don't like to see intakes below about 8' about grade. In addition to the things you've mentioned they take to pick up blown dust, mold from leaves in the fall plus they get covered with snow (not sure where you are) and careless lawn mowers can blow grass cutting into them. Unfortunately your options may be limited if your almost completed. Perhaps runn a duct up the outside wall with some sort of "boxout" that becomes an architectural feature? Maybe add a couple dummy boxouts to make the active one make visual sense? Not sure what else to suggest......

Thanks for those thoughts. I can't fault them for finding the easiest solution for installation but just always assumed there would be a reg that would demand it be somewhere sensible (e.g., specifying a particular height off the ground, at least).

Yes, we've already told the builder that one way or another it's getting moved. We have some pretty good options as far as relocation goes. Fortunately the current location is *near* the back of the house so it's not all that visible. There's a recess at its location and it could follow that up through the soffits, and then just elbow straight to the back of the house.

Hopefully there aren't restrictions on the length of the line.

The diameter of the added ducting may have to be increased.  We suggest 8" diameter duct for our 200 cfm units when (each) duct is over 10 feet, and for 130 cfm units when length is over 25 feet.  This is for units with a strong fan curve.  Every inch of duct must be insulated from the unit to the outside (intake and exhaust).   The wall cap should have screen sized between 1/8" and 1/4" diameter.  Your air exchanger will have to be re-balanced, otherwise it will contribute to negative pressure. 

I think we'd be looking at a 40' run to get up to to the roof and to the back of the house. We have 8" conduits right now.

Just curious: what's the purpose of insulating the intake line? To prevent condensation? I guess we probably need to clean those air lines regularly, right (once per year)?

Here in MA we do have some regulations that dictate locations of intakes for heating systems. They were brought about as a result of heating intakes beiing located to close to the ground, and as a result snow would sometimes cover them up. The change was made only a few years ago and only after a couple of people died from carbon monoxide poisoning as a result of snow buildup. Actually a good friend of mine, who lost not only his daughter but his unborn chald as a result. They do not regulate the intake of HRV's systems other than to tell you that the intake cannot be located within 10' of the exhaust or plumbing vent. I always install the intakes at least 8' off the ground and sometimes need to consider loaction of the unit to keep the runs short, otherwise as Duane stated the CFM rate drops significantly.
Funny but most of the HVAC guys here in MA don't really understand HRV units, they are not typical in this area. Only when specified for a tight house are they even thought of and then without experience they can sometimes be installed incorrectly.

Tom Pittsley
[email protected]
www.eebt.org

My ERV manufacturer specifies that the intakes be away from plumbing vents, auto exhaust and chimneys. Also specs that the intake and exhaust be at least 4 feet from any outside corner and the exhaust and intake be 10 lineal feet apart. I recommend you go through the manufacturer's installation requirements and get your builder to adhere to them, at least. I am building near Durango, CO, at 7,300' MSL and no way I could have intake or exhaust near ground level!

I should check on the install requirements as they were situated about 5' apart.

Fortunately we've found a route through the house taking the inlet from the middle of the south wall to the North edge of the West wall. Where it comes out, it will be easy to extend it straight up as high as we want. Our mechanical guy had said that one has to be careful about bringing it out where the wind would blow directly across it, as the negative wind pressure could pull the air back through it. (Presumably the addition of some sort of cap would make this a non issue.)