Need advice on garage cooling

[mikesm]

Hi. I live in Northern CA and have garage that gets very hot in the summer, especially if two cars that have been driving around in the outside heat then park inside. It's a large 3 car garage, attached to the house. The wall between the garage and the house is insulated, but there is no insulation between the ceiling of the garage and a small storage space directly above it. That storage space is also uninsulated, and though it's passively ventilated gets really hot.

I am thinking a good approach would be to add ventilation from the ceiling of the garage into the storage space that would help cool both spaces off. The garage has a number of vents at floor level (that have screens on them to keep bugs out), so there would be a plenty of return air to feed the fan.

The storage space shares an insulated wall with a kids bedroom, so the fan would need to be quiet since naps are going on next door. I was thinking of using two or three high volume Panasonic bathroom fans that are very quiet, but together might put out 400-500 CFM of ventilation.

I don't really need to worry about heating - it gets a little cold there but not really a problem.

What do you think of this idea? Is that too little airflow? Do I really have to go with a larger fan unit? Are some of those available that are relatively quiet?

Does a normal HVAC company do this kind of work? Would it also make sense to insulate the storage space?

Thanks in advance!

 

[HoosierBuddy]

If I understand you correctly, you want to exhaust your hot garage into a hotter attic space to cool both? If that's what you are thinking, I guess it would work as long as the ambiant air you are pulling in through the bugscreens is cooler than your garage AND there is some way for the air you are putting in the attic to get out.

I wouldn't do it though.

I'd just put an exhaust fan in the garage itself out a window. I bought one like this. It just fits into a partially opened window and plugs in to any recepticle. As long as I open a window on the other side of the garage to let air in, it does a decent job. It was less than $50, and I can take it out when I don't need it.

Phil

 

[mikesm]

Phil, thanks for the reply. The storage area above is vented. There are vent holes all around the edge of the storage area (it looks like an attic, but the attic is actually higher - it's hard to describe).

Your proposal won't work in my garage, as the windows don't open. They are not the type. I'd have to redo a window in order to try and fit it in, and in any case the ceiling is fairly high and that's where the heat accumulates.

thx
mike

 

[85NHALF]

Our company (described on another thread) manufactures a system that is specifically designed for cooling garages. However, it is really directed toward someone who wants to spend considerable time in the garage without spending a bundle on AC.

If you are wanting to just ventilate the ceiling of your garage, you might want to consider a 4500 CFM 24" belt drive whole house fan. Lowes and Home Depot sell them for about two hundred dollars. The belt drive fans are much quieter than the direct drive fans. You just need to make sure that your vents will handle that much air. Also, if you are planning on being in the garage, the fan will be pulling in outside air that will be the same as the outside temperature.

Good luck!

 

[ni[x]it]

I would recommend radiant barrier in the attic of the garage. It shouldn't cost more then $70.oo or $100.oo in materials. The labor is free, right? I bought mine from http://www.energyefficientsolutions.com/

Then make sure your soffits have tons of ventilation. You can get 8"x12" screens at HomeDepot or Lowes for about $1.oo a piece (space them about 2' apart). Or, you can buy 8' long extruded metal 'continuous ventilation' panels, also at Lowes or Home depot for about $6.oo per 8' section. Labor is free.

This alone should substantially decrease attic temps, which will help decrease garage temps.

Then, if needed, Install a small whole house attic fan to pull your garage air out through the attic/soffit vents. I dont think bathroom ventillation fans are NEAR enough to circulate air in a 3 car garage. Smaller fans are fairly quiet to run. Although larger attic fans can be run slower and still move a substantial amount of air.

If you're garage door faces southernly or gets substantial sun, I'd recommend adding some kind of carport cover structure. This of course gets expensive. Otherwise, when in your garage, keep the garage doors open only 1/4 to 1/2 way only... The less sun you have entering the garage the cooler it will be.

 

[nonhog]

FWIW the whole house fan thing is a good idea , however the one I bought 10-15 years ago was loud because of the metal louvers flapping in the breeze.
And that whirring fan noise was pretty loud too.
They move so much air you really have to be careful with pilot lights and such.

 

[85NHALF]

The new whole house fans have plastic louvers that are much quieter. Also, there is a big difference between the belt drive and direct drive fans. The belt drive fans make more of a rumbling sound and are not bad on low speed.

Nonhog is right about pilot lights. Also, you need to make sure any gas appliances (water heater, clothes dryer, etc.) are not effected by any back draft coming down the flue.