Beacon-Morris heater and insulation in MN

[mness4]

Hello,

I'm new to the forum and I'd like to insulate and heat my garage. It's a 3+ (extended third stall)...I can measure when I get home if needed. The house is 4 years old. The garage doors have an insulated core and the seal at the bottom seems ok. However, I do notice some ice in the garage during the winter. I might need to seal that better.

As for the insulation, the walls and ceiling are drywalled but not insulated. I have access to most of the attic space, and I can cut an access to the rest of it. I was planning to blow cellulose into the walls and in the attic after I convince myself the HomeDepot Green Fiber (??) brand is suitably fire-retardant. Any lessons learned that I should consider? My biggest issue is understanding how effective 3 1/2 inches of cellulose in the walls will be when MN winters reach extremes of -20F (generally close to 0F most of the time). The literature on the heater I'm looking at (see below) estimates a deltaT of 45F for whatever R value they assume. I would like to keep the garage heated all the time. I have a woodshop that I would like to use in the winter...maybe not on extremely cold days. This degree of heating makes me wonder how warm I can keep it. I would assume -20F outside means ~0F in the garage (unheated) or 45F (heated.) Does this sound about right?

As for the heater, I'm looking at a Beacon Morris 75,000 btu unit at Menards for $448 until 11/14. Would the 75 be adequate to heat 3+ stalls with room to spare, given my effective R value? The 90 is a step up at $922, so I would rather not go that route. I priced a simlar Lennox unit for $900 (may have been a 100,000 btu though.) I called the local HVAC company, and they want $3000-3500 for a heater, installed!!! They said ~$500 if I only want them to run the gas line. Wow!

Anyway, any advice on the insulation or heater would be appreciated. Sorry if I missed a thread. Please point me in its direction.
Thanks,
Mike

 

[padronanniversary]

Mike, I'm not too far from you in the twin cities, just about 30 miles due north.

I have a 3+ garage too, but my garage door was not insulated. I put the menards door kits in, as well as insulated the attic space, and did not do the walls. The back wall is insulated, but the three sides for the most part are not.

I have a menards 75k heater in it, and ran it last winter no issues. I ran it to about 70F when ever I was in there, and it had no issues keeping up with the temperature.

My attic is around R30 or so, with the garage door with the foamy stuff at R7.

Hope that helps

 

[FThera]

I'm in the Twin Cities and have a 24x34x11 3 car with R30 ceiling, and R19 walls. The doors are insulated but only with B-board cores so maybe R3. Half the garage walls are common with the house so no heat loss there. I have a 45,000 btu heater and have no problem keeping it at 70. A lot of the time I only keep the stat set at 40 and the heated almost doesn't run unless it gets close to 0 outside.

You really should do a heat loss to determine what size heater you need. To large a heater and it will short cycle, and be less efficient.

 

[jklingel]

It may be advisable to Google one of the online heat loss calculators, just for kicks. All you do is enter your data, and it cranks out the heat loss. Either that, or use Q= UA(delta T) and run the numbers yourself. Your delta T (design temp, I suspect about -20) is also available online, or a local engineer will have it. Cellulose in the walls will work far better than fiberglass, but I would be concerned about your AIR barrier, and perhaps a vapor barrier (if recommended for your area. buildingscience.com has a map for such determination). I realize the time and money, but if you don't want issues down the road, I would consider nuking the drywall and doing it properly; air sealing, wet-packing cellulose or cellulose or cotton batts), and a VB, if required. If you use the Ho De Po cellulose, make sure it has been treated w/ borates; those are the fire and bug/animal retardants.