keeping the temp consistant could be a problem. i would think you would need a larger heater and/or chiller to battle the greater delta in outside temp. of course this is from someone who has never lived up in the PNW. i know here in the south it would be a weather battle. anywhere from the 100's during the summer to the teens in the winter. most of us do not have climate controlled garages.
You got major problem with your family over this. Maybe you should scale down and make things neater. Mess up the garage is not going to be OK with her.
Anyway, temperature will be a problem. Cold in the winter and hot in the summer. It will cost a bunch more to heat and cool the tank.
Cough Cough, you think Fragman can FIT a car in his garage?
I've run many tanks out in my garage (never bothered parking a car inside) 300 watt heater will keep a 55 gallon and sump warm and fine. Garage tanks are nicer too, as the wife doesn't whine as much about slopping water and buckets around.
My next big goal, is to plumb the main house 135 tank out to a sump out in the garage with under-house plumbing........anyone else done this? I know Doug in Mill Creek did this, so what size plumbing? 1.5-2" PVC tank drains and a 1" pvc return line?
Also out in a un-heated garage is a great way to run a Cold Water reef during the winter months......our average PNW winter temps are 45-50 degrees, and so is the Puget Sound water temp. I've gone crabbing and brought back Dungeness Crab to keep 'em alive a couple weeks as we eat 'em up!
Ya I have had tanks out in the garage for 12 years now counting the current and previous homes. In my house two years ago i had the 100 gal cube plumbed under the houw and out into the garage for maintenance reasons. That was great. So what are the issues:
Cold doesn't seem to ever be much of a problem. I run two 250 W heaters in the main 200 gallon system without a problem.
Heat is another issue. Until this summer I didn't even have a chiller. Here in the Seattle area we had our nicest summer ever (mostly in the 80's) and the only problem that I had was keeping the garage cool. The tanks and their equipment kept heating it up. I installed and Attick Fan a year ago that comes on at about 75 degrees and it clears a lot of the warm air and humidity with it. Even in the dead of winter my two car garage will be between 70 and 80. I owned a $250 dehumidifier when we moved in; so I didn't hesitate to use it last winter. The garage would have been unbarably damp without it. Yes all of those rust issues would come into play as well. So yes if you are going to have a bunch of tanks in the garage the dehumidifier is a must. Just get one with the drain option so you don't have to remember to dump the 2.5 gallon tank like I have to.
You guys in warmer climates will have completly different issues in the summer with trying to keep the ambient garage temps at a resonable level. It could get real expensive to air condition the garage! I would try closing off a section of the garage and air conditioning that only! I did the same thing in my last house to retain the heat in the winter and it worked too well. I ended up having to ventilate it.
Anytime you run tanks outside the climate controlled living area, I really recommend closing that area in and setting up backup heat and cooling fans, fans will help with the humidity as well. Right now one of the wifes big complaints other than the noise is that the woodstove close by(unused) is rusting all the he** , so in the wetter climate of the greater Puget Sound area I would say its a problem that needs addressing, good luck
Ya the rust problem subsided. Another even bigger concern to me was black mildew. That stuff can be really toxic and loves the damp environment. I had it start years ago in the tiny enclosed fish room in the garage of my other house.
Didn't tell the buyer just painted over it! he probably didn't want a "fish room" anyway.