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Stewzallu 03-03-2012 07:48 AM

Do I need an hrv or exhaust fan in my garage?
My issue is stale damp air in my garage because I just installed In floor heat last fall and I don't have any air movement in there unless I keep opening the door. But with cold winters here in Manitoba, the heat loss can be co$tly! Does anyone have any suggestions as to what kind of ventilation system to put in?

yuri 03-03-2012 07:56 AM

Garage? Is it a car/automotive repair commercial garage? How large in sq.ft. Most people just use a ceiling blade fan to move the air and bring the heat down to floor level if you have the height. Why is humidity an issue in a garage? do you keep artwork or something in there that needs a lower humidity?

Stewzallu 03-04-2012 08:15 AM

Haha no artwork. It's a 24x24x10 foot ceiling attached garage mostly for parking the cars in. The issue is that I have a couple windows in there that were completely frosted up this winter until I threw a dehumidifier in there to keep the humidity down. A ceiling fan would be a cheap starting point (for air movement). Will this be enough to target the issue of high humidity? How long do I have before I have to replace all my mouldy drywall?

yuri 03-04-2012 08:24 AM

As you C I live in MB too. We don't have that high of humidity here so I doubt the drywall will get moldy. I would put in a small exhaust fan into a wall and have it wired to a Paragon industrial time clock that they use in refrigeration and run it every few hours. A hrv won't work in your garage as it needs a full set of dedicated ductwork to work against and they start around $3000 installed. Acklands and Princess Auto may have a fan or go to Recon Controls and talk to John and he may be able to figure something out 4 U. Installer I would not know.

Hardway 03-04-2012 10:29 AM

take a look at this site, just watched it on FYH:yes:

Stewzallu 03-04-2012 09:39 PM

Thanks for the help on where to look for a fan and controls. However, I don't think that location is the determining factor for humidity. No matter where you are if you pull a freezing cold vehicle into a warm building, you can't tell me there is no humidity present. Ice/snow melts into water hitting the heated floor, then while draining to the pit evaporates a bit, BUT where does all the moisture go? I've got a humidity meter in the garage and unless I have a dehumidifier running, it's at 80%...between 30-50% when its running. As for the HRV, why would I need "dedicated" duct work in a single room building?! That eliminates the huge cost you're talking about, but I'm still looking at about $700 for the unit and the insulated flex intake/ exhaust lines.

yuri 03-05-2012 06:48 AM

you can buy a cheap generic hrv for that but unless you have some decent ductwork for it to work against it will be unbalanced and freezeup. needs to have balanced airflow in and out. I have never tried this in a garage as I have never had any complaints and have heated garages with some of my wealthy customers. mostly gas unit heaters and I guess they draw enough air in for combustion to get rid of humidity so you are the only guy with infloor heat and that problem. to me it seems like a lack of ventilation and a hrv won't dry the air out any better than an exhaust fan. you can try an hrv and let us know if it works.

Stewzallu 03-05-2012 07:15 AM

I'm not quite sure what you mean by needing ductwork to work against it? Sorry, I just thought that I could put in cold air intake and exhaust vents through the wall and only have the interior vents directed away from each other with a couple lengths of ductwork on each one. Could this not be done? What are your customers doing for exhaust systems? I'd like to put in an exhaust fan hooked up to the garage door opener, or if I needed to switch it on for any reason I could do that as well. Also, would it be okay to vent it Out the wall or do I need to go through the attic.?

yuri 03-05-2012 07:35 AM

HRVs are VERY finicky about the amount of air/heat going thru them across the heat ex cores. If not VERY close then the core freezes up and the unit won't work. The defrost is not enough to compensate for that. I only use high quality Lifebreath units and the manufacturer has very specific instructions on the amount of ductwork and ways to install them. I have seen and worked on them for over 30 yrs and they need to be balanced with a magnehelic pressure gauge to work properly. My customers don't have exhaust systems and don't seem to be as particular about humidity as you. Their garages may not be as air tight as yours and they don't seem to be worried about the costs either. One owns a farm implement co and has a drain pit with water in it like yours and is not complaining about humidity but I suspect he goes in and out more often and perhaps that helps. The infloor heating is probably creating a sauna effect with the water in the pit so only a decent amount of ventilation is going to solve the problem. Not sure what else to say other than you will be the test case. I would get a 100 cfm exhaust fan and timer and not get hung up on the cost of the ventilation. You can also get a industrial speed control (not a chandelier dimmer switch) to slow it down if necessary. Don't go too slow or the motor will overheat.

Stewzallu 03-05-2012 05:57 PM

Thanks for all the help! One more thing...should I be installing an intake vent as well?

yuri 03-05-2012 06:18 PM

Try it w/o it. Doubt the garage is that airtight to go into a vacuum. If you put one in the wind and snow may blow thru it.

Clapodie 04-23-2014 06:05 PM

Stewzallu, did you ever install an HRV into your garage?

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