Heating a 28x26 attached garage

[Thebert41]

Hello everyone, I'll start off by saying I just stumbled across this forum yesterday and can't believe how much time I've spent on it already and it's a great resource I wish I found a long time ago.

Now for a bit of background we just bought a new build house in which we got possession a couple of days ago so my first order of business is of course getting the garage insulated and heated as I live just outside of Winnipeg in Canada. Had we found this house earlier before the garage pad was poured I would have gone in floor heat but that ship has sailed. The garage is attached to the house 28' wide by 26' deep with 11' ceilings and 2x6 walls. This week coming up I plan on insulating the garage with roxul R24 for the walls and R40 the ceiling. It has a double door that is insulated.

Now for heating it, there is no gas at the property since we have a HE electric furnace so it will have to be a 240V electric heater in the garage unless someone has other ideas. The the plan is to have the garage heated at minimum 50 degrees year round with outside temps sometimes down to -20F. Right now I'm debating between a 5000W unit and a 7500W unit and just wondering if anyone has any suggestions on a particular model and whether I should go to the 7500W one of if the 5000W will be enough? I've seen a lot of threads on this already but people tend to have garages that aren't as well insulated or if they are running electric heaters like those it's not to keep a garage heated all winter long.

Thankfully due to our abundant hydro electricity we have very cheap power at only 7.381cents / KWH the cost to keep it heated won't be excessive.

Anyway I'm open to any suggestions and I will keep an ongoing garage finishing set of pictures to throw up when I'm done.

 

[CNGsaves]

Congrats on the house & garage. Welcome to GJ.

Go ahead and Update GJ Profile with your location.

With such cheap electric, you've got it made. However, be sure to Plan Ahead and do all your ROUGH ELECTRIC before you get ramped up to insulate. Put in 240v line for air compressor, welder, etc now that you have open studs. Also can never have too many outlets so plan out where you'll have workbench, etc.

Finally, lighting needs planned out and finished before you insulate ceiling.

For heaters, I'd maybe get two. Simple oil filled heater (ie 1500 watt) that you leave on all winter for maintenance temperature and provide some heat down low where you'll be working. The big 5,000 watt ceiling mount heater would have thermostat to 50 degrees and allow warmup over 50 when you're working out there. Good luck.

 

[Thebert41]

I guess I should have added the ceiling and wall attached to the house which will have the workbench on it are already dry walled as part of the fire code here.

Lighting I'm planning on using these to keep it well lit
http://t.homedepot.com/p/Commercial-Electric-4-ft-LED-Shop-Light-54103161/205331022/

The walls also have lots of 110v plugs every roughly 8 feet apart around the garage and I plan on running the wiring for the lights in metal tubing commercial style on top of the drywall.

 

[Rickcnc]

Thankfully due to our abundant hydro electricity we have very cheap power at only 7.381cents / KWH the cost to keep it heated won't be excessive.

Here in Ontario we also have more hydro electricity then we can use.. yet our rate is closer to 20 cents / KWH when you consider all the additional charges on the bill.

We have been known to pay the US to take our over flow and subsidize nuclear operations for power never produced.

IF you are planning on staying in the new home for a while maybe you want to consider a Mini split.. have heat in the winter and AC in the summer.. Although your winters might be a little cool for a mini split.

 

[jvitez]

Hello fellow prairie Canuck. Welcome to GJ!

I heated an attached 22x24 garage, 2x4 wall with R12 fibreglass, R40 fibreglass batt ceiling, insulated 16x7 garage door, with a 4800 watt construction heater and it did fine. This works out to 9.1 watts/sq ft.

Your wall insulation is better (excellent choice with Roxul BTW, I used it for my new home's garage), but your garage is bigger. I'd go to R50 for the ceiling, and use blown in cellulose. A 5kw forced air unit heater would probably be enough, but how often do you open the door, and how quickly do you want to reheat the space? There's little downside to slightly oversizing an electric heater, except wire size and cost.

A 7.5 kW heater would be 10.3 watts/sq ft, 5 kW would be 6.9. Your choice. Me? I'd probably try the 5 kW heater first, as I'd rather have a forced air heater running for longer as it keep the air circulated, reducing heat stratification (hot air rises, so all the hot air eventually ends up at your ceiling, and your uninsulated concrete floor is cold, so you're cold down where you are, and the ceiling is hot where you're not).

But honestly, I'd rather use electric radiant heat for all the radiant benefits. Here's a couple of examples:

http://www.ouellet.com/en-ca/products/residential-products.aspx?product=ORC

http://www.ouellet.com/getattachment/948c0f5b-a9f0-4bb2-b593-9dc891838a87/OKB-(ORR).aspx

 

[Thebert41]

Ok thanks I'll have to look into those, is there any problem parking vehicles under them though ? Would it be really hard on the paint?

 

[Charles (in GA)]

Who in the H3LL builds a garage in Maintoba and doesn't insulate it? Sounds crazy that you are now having to do this.

 

[Thebert41]

Well it's a new house so it's amazing how few garages actually get insulated

 

[jvitez]

Who in the H3LL builds a garage in Maintoba and doesn't insulate it?

Yup. Cheaper, cheaper, faster, faster........and yet the going rate for new house builds here is $200-300 a square foot not including the lot. Absolutely crazy. I simply don't get why folks here value granite countertops and hardwood floors over proper building envelopes and excellent HVAC. We live in the frozen-winter prairies, plus hot summers, -30°C to +30°C. Penny wise and dollar foolish.

I was speaking with a custom sheet metal guy. He said that once he found out how little the home builders here pay the HVAC contractor, and therefore how little the actual installers get, he said the only way to make any money would be to fly through each job by cutting corners which he wouldn't do. He does insurance restorations instead.

But anyway, Thebert 41: your 11 foot tall ceiling should prevent overheating your car paint from a ceiling mounted radiant heater, but electric ones do come in low and high intensity versions, so I'd suggest contacting Ouellett directly and ask them. Post back their answer as I'm sure many of us would be very interested too.

 

[Elginz]

My 24'x24', 2x4" walls, fiberglass in the walls, OSB in and out, 3/4 foam under the floor, lots of blown in fiberglass in the attic, 10' 4" high walls, 8' x 16' overhead door. I use a 3,000w radiant tube heater. -2 deg, and windy can't quit keep up to 60 deg, 50 yes, 60 no, but that is mostly all the leakage from the overhead door in the wind. I need a new overhead door. I LOVE my Marley, in fact so much I put one in our studio. No noise, No breeze, almost instant warmth. I do heat my shop all winter.

 

[jvitez]

Elginz: thanks for posting, and the pic! I think this is the first electric radiant heater pic I've come across on GJ.

On a watts/sq ft basis, you're at 5.2. That's a great real world example especially in a cold midwest climate like WI.

 

[DEnd]

I don't have a heating suggestion (because they have already been posted), but since you have an attached garage I highly suggest that you put in a exhaust ventilation system. This is to keep garage pollutants out of your house, not to be able to run your vehicles inside. Such a system can be a low CFM bathroom exhaust fan installed in the garage, running continuously. I don't have a CFM recommendation as I have zero testing done to know for sure, but my gut feelings and some back of the envelope calculations suggest that 15-30 CFM should work. There have been a few studies that show garage pollution is of concern, with attached garages contributing significantly to indoor carbon monoxide and benzene levels.

 

[Thebert41]

Ok thanks for showing me that radiant heater I think with our temperatures here I might try 2 of those or try one of those and then whenever I'm in the garage wanting to work on something use a temporary construction heater to top it up.