HRV realities?

[richyrich]

I'm still getting to know the heating system in my new house. I never had an HRV before and although I basically understand it and like the idea of more fresh air, I'm still a little suspicious as to how good a job it does and overall if it's worth it. Wondering about other peoples' opinions.

For a start, if I go outside, the outlet from it is blasting out really quite warm air while the intake pulls in freezing air. In theory there's some heat exchange going on in the unit but it doesn't "feel" like very much - it feels more like I'm throwing out tons of air I just spent money heating in exchange for freezing cold air I then have to pay to heat up! Feeling the duct coming out of the HRV and back into my return, the air it's introducing is freezing cold.

I realize this is all pretty anecdotal but how do others see their HRV operate - is the "freshened" air coming out of it and back into your system super-cold at this time of year or does it feel there is some decent heat exchange going on?

I've taken to turning it off at night and back on in the morning - seems a good balance between getting fresh air in the house, keeping it cosy at night and not throwing my money away! Would be nice if I could do this automatically or even have it on intermittent but it seems my control options are limited.

HRV is a Constructo 1.5ES by the way. To be honest taking a look inside it I'm not blown away by the sophistication! Wouldn't surprise me if it's way on the low end of builder units and this could be a big factor....

[good2know]

There is a control box on the side of the unit. You can use that to set it to run at a continuous very slow speed. This gives you enough fresh air and increases the time for heat exchange.

[Halton Home Inspector]

You are right that the HRV is not 100% efficient. Most HRV's will transfer heat from the outgoing "stale" air to the incoming cold fresh air, but it will not transfer all of the heat.

The key is to not use your HRV more than you need to.

How much and HRV should be used is not the same for each family. If you have a large family, pets, and do a lot of cooking then you would want to use your HRV more than a couple who eat in restaurants half the time.

Personally, I'm not a fan of HRV installations that also vent bathrooms so hopefully you have normal exhaust fans in those rooms.

IMO, you should not be using your HRV in the summer on hot humid days. After all, it's a HEAT Recovery Ventilator.

[lex_rx]

A good system should actually be simple and effective rather than "sophisticated".

House needs fresh air supply and exhaust stale air. I guess the simplest in the good old days is open windows on the "air intake" side and open another on the "exhaust" side of the house.

With houses built tighter these days, a mechanical process is introduced. Anything that captures some heat/cool air is better than turning the bathroom fans that used to exhaust directly outside (again, zero recovery of hot or cool air).

[richyrich]

Originally Posted by good2know

There is a control box on the side of the unit. You can use that to set it to run at a continuous very slow speed. This gives you enough fresh air and increases the time for heat exchange.

Thanks, I do know about that. I actually read the manual and keep that control in the off position so I can use the wall control upstairs.

[foxborough]

Here's an article written by a home inspector from Winnipeg. It may be helpful.

http://homes.winnipegfreepress.com/w...-woes/id-3050/

I've always been confused about HRVs in Ottawa. You wouldn't use a HRV in the summer if you have the a/c going, as it is counter productive. Ottawa has extremely dry winters, with most home owners complaining about cracking and shrinking hardwood due to the relative humidity in their homes being too low. You wouldn't run a HRV then either as the intent of a HRV is to control the humidity in your home by replacing the humid air in your home with the drier air from outside. So it would seem that you would only run a HRV for a little while in the Spring and early Fall, where quite frankly, I am okay to just open a window for fresh air.

[gerapau]

Get an ERV instead of an HRV.

[Trepex]

Originally Posted by foxborough

Here's an article written by a home inspector from Winnipeg. It may be helpful.

http://homes.winnipegfreepress.com/w...-woes/id-3050/

I've always been confused about HRVs in Ottawa. You wouldn't use a HRV in the summer if you have the a/c going, as it is counter productive. Ottawa has extremely dry winters, with most home owners complaining about cracking and shrinking hardwood due to the relative humidity in their homes being too low. You wouldn't run a HRV then either as the intent of a HRV is to control the humidity in your home by replacing the humid air in your home with the drier air from outside. So it would seem that you would only run a HRV for a little while in the Spring and early Fall, where quite frankly, I am okay to just open a window for fresh air.

You still need to cycle te air in the house though to bring in fresh air. My ERV is a good compromise. It does a much better job at maintaining humidity, and you can just supplement with a humidifier in the winter if necessary. My AC is more than capable of dehumidifying as necessary in the summer. Our ERV runs year round - normally in its "smart" mode where it monitors indoor/outdoor conditions and optimizes its runtime in order to get the necessary number of daily air changes.

[Halton Home Inspector]

Originally Posted by foxborough

I've always been confused about HRVs in Ottawa. You wouldn't use a HRV in the summer if you have the a/c going, as it is counter productive.

You are correct. The last thing you would want to do is to run an HRV on hot humid days in the summer. An ERV is much better suited for that.

But,,, it's no wonder why many people are confused about HRV's vs ERV's and it seems some manufacturers are also confused and some are changing their opinions as well about where in North America HRV's and ERV's should be used. Where HRV's were at one time the number one choice it would appear that the ERV is actually the better alternative in many areas.

The good news is that some of the VanEE HRV's can be converted to ERV's by changing the exchanger core. I'm not sure if that provides a full conversion it may be an option.

Check out this link at - http://www.dpoint.ca/blog/item/181

[jebise101]

I'm in the same boat I understand its for fresh air, but every time I turn it on its always throwing cold air and makes the house feel really cold, not only that but it also keeps the furnace blower running 24/7. Only time we turn it on is while cooking to keep the smell out of the house. I also hate the fact that its very limited in terms on functionally. I would have preferred to turn it on for 15 minutes per hour or something to just keep the air fresh and not have it on for hours.

Still understanding it but I believe if the control unit on the HRV is set to intermittent and a percentage is set on the humidstat, the HRV will stop once it reaches the desired "humidity", this is where I get confused. The house humidity is around 30% humidity but the hudistat for the HRV needs to be around 55% if set any lower it runs 24/7.

I don't really get why this is backwards or what the correct % should be set to keep the house comfortable.