Is a HRV the way to go?-installed/update

[cale262]

Another Yes here, HRV + 700 fish gal in the house, everthing is good, although I do notice the HRV runs 24/7 in the winter...

[toxic111]

What I was getting at is they are not required by the National Building Code, which is the model code for Canada. I do not know the eastern codes, but in SK, AB & BC they are not required. They are a very good idea as modern homes are sealed too well.

[bkelly]

thanks guys this really tells me id be doing the right thing, Kelowna is dry in the winter, summers not that humid either. Ill keep you posted on the changes with it and how the install goes.

[e46er]

Originally Posted by toxic111

What I was getting at is they are not required by the National Building Code, which is the model code for Canada. I do not know the eastern codes, but in SK, AB & BC they are not required. They are a very good idea as modern homes are sealed too well.

Depends where u are as well
They are mandatory in Vancouver Bc but not the surrounding cities

[sphelps]

My house is new and it has a simple exhaust fan plumbed in from the cold air return to outside. Does the same thing as an HRV but without the heat exchange. I thought about upgrading but I figured I'd leave it for at least a year before I bothered. I have it connected to a central thermostat that controls humidity levels as well with the exhaust fan and the humidifier. I believe most of the time HRVs are controlled either by simple timers, local humidistats or even just a light switch. Anyways I watched the heat bills last winter when I first connected up the exhaust fan and control and I didn't notice any difference in consumption. I have 100 gallons open top upstairs and about the same worth of open sumps downstairs but there is a lot more exposed water surface than a typical 200 gallon system. The thermostat I use also has some other features it uses to limit window frost, not sure exactly but it works and it's a different setting than the set humidity which is still maintained.

So I guess for me I wouldn't bother with the HRV, I doubt the extra cost and install would ever pay off. But it will likely depend on the demand for it but there are other options for humidity control. You should also check your furnace, it should draw in some fresh air when it operates and many times moisture and mold problems are a result from poor air circulation, not always directly a result from high humidity from lack of ventilation exchange.

[mike31154]

Originally Posted by sphelps

My house is new and it has a simple exhaust fan plumbed in from the cold air return to outside. Does the same thing as an HRV but without the heat exchange. I thought about upgrading but I figured I'd leave it for at least a year before I bothered. I have it connected to a central thermostat that controls humidity levels as well with the exhaust fan and the humidifier. I believe most of the time HRVs are controlled either by simple timers, local humidistats or even just a light switch. Anyways I watched the heat bills last winter when I first connected up the exhaust fan and control and I didn't notice any difference in consumption. I have 100 gallons open top upstairs and about the same worth of open sumps downstairs but there is a lot more exposed water surface than a typical 200 gallon system. The thermostat I use also has some other features it uses to limit window frost, not sure exactly but it works and it's a different setting than the set humidity which is still maintained.

So I guess for me I wouldn't bother with the HRV, I doubt the extra cost and install would ever pay off. But it will likely depend on the demand for it but there are other options for humidity control. You should also check your furnace, it should draw in some fresh air when it operates and many times moisture and mold problems are a result from poor air circulation, not always directly a result from high humidity from lack of ventilation exchange.

After reading through some of the info provided in the links from Delphinus, I'm not convinced an HRV is necessarily useful or cost effective for everyone. There are a lot of factors to consider before forking out the dough for one of these, even if the government is providing some incentives. It really seems to be very dependent on age of home, how well it's sealed & more importantly the climatic conditions where you live in the winter. Seems to me having a code requiring HRV in a place like Vancouver makes no sense. It never gets cold enough long enough for the heat exchange portion of the system to provide any payback, nor is an HRV effective for humidity control in the summer. Well designed exhaust system similar to what sphelps has should work quite well to keep humidity under control.

Not sure I follow how exactly your system works though. The exhaust fan pulls air directly from your furnace cold air return? Is there another fan or at least opening to the outside to allow fresh air in to replace the exhausted air? My house was built in the late '50s and there are plenty of places for fresh air to get in. I have a fireplace in the basement as well as one in the living room, so I need to figure out if exhausting air without providing incoming would cause backdraft thru my chimneys. I also remember when I replaced the furnace in the condo I lived in in Ottawa, new code required the installer to run a simple duct from outside to the furnace to provide fresh air.

EDIT: Just found another link worth checking out. Good discussion on HRV, ERV and some of the pitfalls that may be encountered when considering any kind of ventilation system.

http://www.greenbuildingadvisor.com/...ngs/hrv-or-erv

[rayjay]

For me, I went with the HRV rather than the ERV because the Lifebreath engineer I dealt with (factory here in London) said the ERV can freeze up in winter and they never advise ERV when temperatures routinely hit below -5° C in winter. If you don't have that situation, an ERV could be considered, again, depending on just what you are looking to accomplish.
He also did calculations using winter house temperatures and square foot of all open water surfaces and temperature of the water in the tanks to figure out what size HRV would be needed for the volume of my home.
Lastly, he advised me NOT to use the humidistat as when the HRV is not actively running, the air exchange is not occurring and air exchange was important to me to keep pH from dropping too much in the tanks.
In our location, surrounded by the Great Lakes, humidity is extremely high in summer and I certainly don't want an ERV that is going to reintroduce some of that moisture back into the incoming air.

[sphelps]

Originally Posted by mike31154

Not sure I follow how exactly your system works though. The exhaust fan pulls air directly from your furnace cold air return? Is there another fan or at least opening to the outside to allow fresh air in to replace the exhausted air? My house was built in the late '50s and there are plenty of places for fresh air to get in. I have a fireplace in the basement as well as one in the living room, so I need to figure out if exhausting air without providing incoming would cause backdraft thru my chimneys. I also remember when I replaced the furnace in the condo I lived in in Ottawa, new code required the installer to run a simple duct from outside to the furnace to provide fresh air.

The exhaust fan only works when the furnace is on, just like the humidifier. So if the exhaust fan is active it creates a negative pressure and the furnace will draw in make up air from outside. And yes the exhaust fan draws air directly from the cold air return.

[MarkoD]

In my house we have a switch by the thermostat that turns on all 4 bathroom exhaust fans and turns on the furnace. Moisture gone in no time.

[sphelps]

Another thing to check is your humidifier, make sure it's not the source for the moisture problem. Ask yourself how it's controlled and if it makes sense. Often they use a local humidistat that isn't accurate to begin with and it's location isn't effective. Disconnected the humidifier for a while and running the furnace fan more often and observing the change in humidity should tell you if there's an issue.