HRV hook up

**michael Rodney** · 07-14-2014, 07:22 AM

This was not an actual inspection, but I noticed this in a home a few days ago (see pictures).

It appears to me that this configuration was incorrect: the two un-insulated connectors are connected to the same return plenum, while the insulated ones are terminated outdoors.

What do think?20140713_144109.jpg 20140713_144136.jpg

**Jerry Peck** · 07-14-2014, 08:06 AM

Originally Posted by michael Rodney

It appears to me that this configuration was incorrect: the two un-insulated connectors are connected to the same return plenum, ...

I believe the uninsulated ones are air connectors, air connectors have stricter limitations of use than air ducts have.

**michael Rodney** · 07-14-2014, 08:32 AM

Yes but are they supposed to be connected to the same return plenum...about 10 feet apart?

**Jim Luttrall** · 07-14-2014, 05:48 PM

Here is a diagram that might be useful. Of course with this setup, the HRV fan would have to overcome the static pressure of the furnace fan during furnace operation.
Your setup basically appears to short cycle the air without doing much good.hrvImage.jpg

**John Kogel** · 07-14-2014, 06:09 PM

The installer thought he would pull some stale air from the furnace return and replace it with fresh, maybe? So somebody ended up paying out a buch of money for something that does a little bit of good maybe on a good day. When the furnace is shut down, it will be a useless waste of electricity. Maybe with a constant flow it will work a bit.

HRV works best with returns and intakes completely separate from the furnace ducts, IMO, AFAIK.

**Raymond Wand** · 07-14-2014, 07:03 PM

That is one of three recommended installation methods recommended by manufacturers.
Simplified Volume Ventilation
http://www.venmar.ca/DATA/DOCUMENT/1...ES_HRV_ERV.pdf

**Raymond Wand** · 07-14-2014, 07:45 PM

BTW how old is this furnace installation? If its newer the air intake and exhaust for the furnace is now required to be PVC piping and not ABS. But this is why I am asking as to the age of the home/furnace.

**michael Rodney** · 07-15-2014, 05:29 AM

Originally Posted by Raymond Wand

BTW how old is this furnace installation? If its newer the air intake and exhaust for the furnace is now required to be PVC piping and not ABS. But this is why I am asking as to the age of the home/furnace.

Its just a rough guess but the house maybe about 10 years old. I really do not know for sure.
It was not an inspection, I just happen to be there and looked up at the HRV.

**Raymond Wand** · 07-15-2014, 05:36 AM

Okay if thats the age then ABS was the standard. If memory serves me correctly ABS was discontinued for use on furnace 3-4 years ago and new installations or upgrades must now be PVC.

**Bryce Jeffrey** · 07-16-2014, 06:07 AM

636 required on all new installations starting August 1, 2007

**John Kogel** · 07-16-2014, 09:31 AM

Thanks, Raymond. I've never seen it done that way.

Simplified Volume Ventilation
(For homes with forced air heating. See illustration at right.)Fresh air and exhaust air flow through the furnace ducts, which simplifies the
installation.
The use of bathroom fans and a range hood is suggested to exhaust stale air.
NOTE: For this type of installation, the
furnace blower must be running
when the unit is in operation.

If using Method 2, make sure the furnace blower operation is synchronized with the unit operation!
See Section 5