Question about Heat Recovery Ventilation system

[oz388]

ok i know that the HRV is to exchange the heat from the warm stale air of bathrooms, kitchen and laundry with fresh cold intake air from outside of the house. But I'm not sure how the stale air from bathrooms, kitchen and laundry is exhausted through the HRV that is located in the basement, aren't kitchen exhaust hook fan and bathroom ceiling fans all duct directly to the outside of the house either through the vent on roof or the walls?

[benyl]

My Active HRV has a dedicated set of ducts that draws air down to the basement. The ventilation fans still vent to the outside.

There are some HRVs where the vents are connected, not to the outside, but down to the basement.

http://www.buildingscience.com/documents/information-sheets/content/info-611-balanced-ventilation-systems/images/Info611_Figure_03_web.jpg

My HRV supplies the new fresh air back to the furnace for distribution. Both Furnace fans are constantly going.

[mr2mike]

All I know is they're constantly running and in the winter there's this de-icing mode that it goes into seemingly every 15min, which is loud.

[benyl]

I've never heard mine. I know it is working as I can see the water discharge from the de-icing.

[mr2mike]

Must have just been this condo complex and how it was installed?

[oz388]

Originally posted by benyl
My Active HRV has a dedicated set of ducts that draws air down to the basement. The ventilation fans still vent to the outside.

There are some HRVs where the vents are connected, not to the outside, but down to the basement.

http://www.buildingscience.com/documents/information-sheets/content/info-611-balanced-ventilation-systems/images/Info611_Figure_03_web.jpg

My HRV supplies the new fresh air back to the furnace for distribution. Both Furnace fans are constantly going.

Hi if you have dedicated set of ducts draw warm air down to basement to heat up the cold intake air, then what is the point of energy saving? You are basically losing internal temperature to heat up the intake air every time when furnace is running, right? I can only see this system works is to use the unwanted warm air from the house, such as the exhaust when cooking, taking shower or drying the cloth...

[Yuubah]

AFAIK, the main benefit of HRV is to cycle the stale air in your home for fresh air and using the heated indoor air to warm up the cold outside air. Not much benefit in the summer, but in the winter this could save you a few bucks in heating costs.

If you don't care about having fresh air cycling into your house, then HRV doesn't really benefit fit you.

[avishal26]

Originally posted by benyl
My Active HRV has a dedicated set of ducts that draws air down to the basement. The ventilation fans still vent to the outside.

There are some HRVs where the vents are connected, not to the outside, but down to the basement.

http://www.buildingscience.com/documents/information-sheets/content/info-611-balanced-ventilation-systems/images/Info611_Figure_03_web.jpg

My HRV supplies the new fresh air back to the furnace for distribution. Both Furnace fans are constantly going.

This seems to be the norm for most new builders these days. My 2012 build has an HRV just like the one in your pic.

As for bathroom exhaust - when I take a shit - I want that air out of the house as fast as possible! haha don't need the whole house to smell :rofl:

[oz388]

Originally posted by Yuubah
AFAIK, the main benefit of HRV is to cycle the stale air in your home for fresh air and using the heated indoor air to warm up the cold outside air. Not much benefit in the summer, but in the winter this could save you a few bucks in heating costs.

If you don't care about having fresh air cycling into your house, then HRV doesn't really benefit fit you.

well explained, thanks.

[benyl]

Yes, the main reason is to cycle the air inside the house with fresh air.

It also removes smells and smoke from cooking really quickly. haha.

[oz388]

Originally posted by benyl
Yes, the main reason is to cycle the air inside the house with fresh air.

It also removes smells and smoke from cooking really quickly. haha.

Ya in winter i only cycle the air inside by opening all the windows when chinook comes, unless i burned something during cooking.

Another question, so if you have the HRV in-placed does that mean the ventilation automatically starts whenever the furnace starts??

[benyl]

If you have a passive one.

If you have an active one, you can choose when to run it and it is independent of the furnace.

I have it set to run 20 minutes every hour. It can also run all the time.

[kenny]

I've been reading up on passive vs active HRV and the biggest difference is that Active HRV (actually an ERV) can maintain moisture levels in a home whereas a passive HRV does not. So, in Calgary if you're adding in a ton of moisture to the dry air, a passive HRV will dump that humid air back out and draw in dry air. An ERV would transfer that moisture in the warm stale air to the incoming fresh (dry) air.

Both passive and active systems are the same when it comes to recovering heat from stale air. Passive systems can also be set to run independently of the heating/cooling system but it would use the fan in the furnace to drive the air vs the active system which has its own fan that is far more efficient than a furnace fan.

Passive HRV is part of the building code now I think, which is why all new builds have them. It's certainly not something that builders are including on their own haha.