Reuben's Home Inspection Blog


HRVs, Part 3 of 3: Installation Defects

For the last two weeks I’ve blogged about HRVs. In part one, I covered what HRVs are for and how they operate. For part two, I covered HRV maintenance and operation. Today I’ll discuss installation defects.

The most common defect I find with HRVs is that they were 
never balanced. When HRVs are installed, a technician needs to balance the system to make sure the air getting exhausted is equal to the air coming in. If more air comes in than what goes out, you’ll have a pressurized house… and vice versa. Neither of these conditions are good for the home.

To make sure an HRV is balanced, I look for a balancing sticker and I check to make sure that the balancing damper controls have been screwed in place. If they’re not screwed in place, a balancing sticker means nothing. If I don’t see a balancing sticker, I don’t make a big deal about it, but I’ll often make a note in my report that it’s missing. If there are no balancing screws, I recommend having the HRV professionally balanced.

HRV Balanced

Most HRVs are installed hanging from straps or chains and springs to minimize the transfer of any annoying vibration from the fans. If an HRV gets mounted to the wall, I check the installation manual to make sure that this is an acceptable installation, and I listen on the other side of the wall to see how loud it is. When they’re mounted incorrectly, they can be very noisy!

As a rule of thumb, the intake and exhaust locations at the exterior of the home should be located at least six feet away from each other. I’ve never seen an installation manual that allowed anything less. It’s also important to make sure the intake is at least ten feet away from any sidewall vented gas appliances, such as a powervent water heater or furnace. The intake should also be located at least ten feet away from anything smelly, such as where the garbage containers get kept.

HRV Intake & Exhaust

The ductwork that feeds the intake from the exterior and exhaust to the exterior needs to be properly insulated. If it’s not properly insulated, you’ll feel an obvious cold draft.

If the HRV ducts are only attached to the furnace’s return air, they must be at least three feet away from each other, and the furnace’s blower fan must turn on with the HRV to prevent the air getting added to the house from short-circuiting and getting pulled back out of the house. Every manufacturer recommends connecting the furnace’s blower fan to the HRV for optimal performance, but it’s not always a requirement.

HRV Connected To Return Air Plenum

Every HRV needs to be plugged in to an outlet. If the HRV is running off an extension cord, this is an improper, unacceptable installation. Repair requires the installation of an outlet.

That’s about all of the HRV installation defects that I can think of, and that concludes this mini-series on HRVs. As always, please email or post any comments or questions!

Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 4 commentsReuben Saltzman • December 29 2009 06:02AM
HRVs, Part 3 of 3: Installation Defects
For the last two weeks I’ve blogged about HRVs. In part one, I covered what HRVs are for and how they operate For part two, I covered HRV maintenance and operation Today I’ll discuss installation defects. The most common defect I find… more
HRVs, Part 2 of 3: Maintenance & Operation
Last week I blogged about why houses need HRVs This week I'll write about maintenance and operation of HRVs, and I'll try to cover the stuff you should know if you own one. The information in this blog is general - every… more
HRVs, Part 1 of 3: Why We Need Them
Many months ago I wrote a blog about how houses can often have moisture problems when old furnaces are replaced with high efficiency furnaces The fix that I mentioned at the end of the blog was to install a H eat R ecovery V entilator,… more
New Windows Are Nice, But You'll Never Get A Payback
I've heard some pretty outrageous claims from window replacement companies. The most common 'hook' for selling replacement windows is that you'll get a R eturn O n I nvestment (ROI ) because of all the money you'll save on your… more
How to Buy A Category 2 Registered Vacant Building In Saint Paul
If you're in the market to buy a fixer-upper home in Saint Paul, there's no need to be afraid of registered vacant buildings - at least not most of them. There are three categories of registered vacant… more