For the last two entries I've blogged about HRVs. In part one, I coveredÂ what HRVs are for and how they operate. For part two, I coveredÂ HRV maintenance and operation. Today I'll discuss installation defects.
The most common defect I find with HRVs is that they wereÂ never balanced. When HRVs are installed, a technician needs to balance the system to make sure the air getting exhausted is equal to the airÂ 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 aÂ balancing stickerÂ and I check to make sure that theÂ balancing damper controlsÂ have beenÂ 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.
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 getsÂ 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, theÂ intake and exhaustÂ locations at the exterior of the home should be located at leastÂ six feetaway 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.
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 theÂ furnace's blower fan must turn on with the HRVÂ 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.
Every HRV needs to be plugged in to an outlet. If the HRV is running off anÂ 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.