Garage Heaters, what's best?

I want our garage to be heated this winter. Aside from the benefit of my not freezing my ass off, I'd really like to keep the temp at least above freezing to melt snow and be able to wash the daily drivers all winter. 

The "main" garage shares one entire wall with the house as does the garage addition but none of the other walls are insulated. In total, it's a 3 car garage with the third spot perpendicular to the "main" two car. 

I'm leaning towards a wall/ceiling mount 240 electric unit mounted in the two car section, mostly because I can do the install myself and don't have to have a gas line run. 

Any suggestions from the group?

If you plan on heating it perpetually, your best bet that isn't running ducting from the house HVAC is to use infrared heat.  It heats the contents of the garage, not the air.  I do not know if you can do this purely electrically but it is by far the most efficient way to do it.

I worked for years in a shop heated by devices that heat the air.  I work now in a shop with IR heat.  My word the difference is dramatic.

Connecting the garage to ductwork from the house is against code, so don't do that.

First thing is to make sure the garage walls and ceiling are well insulated, including the doors and windows.  Pay particular attention to air gaps, especially around the overhead doors.

You need to run a heat loss calculation to determine how many BTUs you need to heat the garage.  There are a number of online calculators available where you enter the size of the space, R values of insulation, etc. and it pops out a number.  It's best to use several of them to get a consensus on the answer.

Do you plan on heating it continuously, or only occasionally?  Electric unit heaters are generally the least expensive to install and are fast to heat up, but most expensive to operate.  However, the operating cost is less of an issue if you're only running heat for a few hours now and then.  You can figure out the monthly cost of operation using the kilowatt-hour price from your electric bill (kilowatt-hour cost in cents X kilowatt rating of heater X how many hours operated per month).  The alternates would be either a gas unit heater or a gas radiant heater.  One popular source for those kinds of heaters is https://www.mrheater.com/product/heaters.html

If you're heating it all winter I'd hate to see you use resistive electric heat. That would probably have the most expensive operating costs. If electric is the easiest maybe a mini split heat pump? Bonus is you would also add ac. Modern air source heat pumps are good down to negative temps. They can have a resistive element in them as backup so 99% of the time they heat with only the heat pump and the resistive element kicks in when the heat pump is too cold. Diy is possible. It will cost more to buy but I think your utility cost will be like 1/3 or less. 

^ I didn't think of heat pumps, that's a viable option depending on how cold it gets in your area.  As mentioned the models available today will work at much lower temps than they used to, plus you get the benefit of air conditioning in the summer.

Doing anything to control temps in an uninsulated space is extremely wasteful and ineffective for any significant amount of time. If you're not starting with proper insulation, you're throwing money away and you're also very likely to be disappointed and uncomfortable. Not only will proper insulation lower your operating costs, but it will mean you can size your HVAC for a smaller space which should mean cheaper purchase price too.

I too would suggest a ductless mini split. Efficient heat, and the benefit of cooling in warmer times.

Thanks for the responses. My intention would be to keep the garage at, say, 50ish degrees all winter so that seems to knock electric out of the reasonable discussion. I've considered the IR heat stuff and have heard the same comments, Pete, from another friend but the good ones seem to be gas so I had written them off. Another issue with IR is that I'd need multiple units - likely two in the main garage and then a third in the addition since the heat wouldn't really transfer. 

As for the insulation situation. The wall between the main garage and the house is bare cinder block. The wall that the addition shares with the house does have some insulation that I can see but I don't know whether it's just up high or is within the whole wall. The ceiling above the main garage is uninsulated and I'm fairly certain the exterior wall has nothing in it. I'm not terribly interested in ripping all that sheet rock off but point taken that it would be a massive help. Maybe someone could blow them full. The roof of the garage addition is flat with a slight pitch so that would just mean filling the rafters with insulation.

Mini split is a very good idea but we got a quote for a 12,000 BTU single zone unit and it was $6,500 installed for an old addition on the house. I don't want heat in the garage that bad, I don't think. If memory serves, the unit would likely freeze up in the single digits. We spend usually 3 weeks of Feb in the single digits or low teens so it would definitely be tested at points.

I know you said you don't want to run gas lines, but I have one of the IR long black tube heaters that runs the length of the shop and it is awesome.

I keep the shop just above freezing (5C or so) and 10 minutes after I turn it up the work area is warm enough to be comfortable.

I do run it on a thermostat, and that is kind of pointless because of how it warms the solid objects and not the air; the thermostat senses air temp and lags way behind my body as a temperature sensor. So I end up doing manual heat control cause otherwise it gets toasty under the tube.

This would probably be your best bet if you are determined to not insulate, only I would not bother running it at all between work sessions. The difference in time to warm from sub freezing to work temp would not be much different.

insulate, insulate, insulate.  

With an adjoining wall to the house, in Michigan, I found the garage often was able to maintain enough residual heat off the cars itself pulling in (engine/radiator), as well as heat loss from the house leaking into the garage, to keep most of the garage typically above freezing enough to melt off snow from the cars all by itself. 

Once you're at that point, heating is much simpler.  I don't know much about the mini-splits people seem to like, but running a gas line is well worth it over the expense of electric consumption unless you plan to move in a year or something.  I've been very happy with a Modine "Hot Dawg" nat. gas 45K BTU heaters.  It did great in my well insulated attached 3-stall, and I took it with me when I moved, converted to propane, and now use it to heat my 24x32 garage which I insulated and had attic blown in as well.

Add a simple wifi thermostat and you can crank the heat up from your couch or before leaving work to take one more excuse away not to get out there.  :)  

You say it's a 3 car garage, so it's maybe 700 - 800sf? I think you can get one of those for less than $1000 these days and *from my understanding* it's a pretty simple DIY installation if you get one with precharged lines. Keep in mind I have never installed one, but plan to at some point so have done a fair amount of reading. Book larnin' not street smarts, I'm saying.

The current generation of mini split is good down to -25C or -13F. I don't think you guys spend much time below those temps.

I bought mine from Costco for less than $1k. I diy'ed the install, worst case you have to pay an electrician. Mine is 18k btu. 

Thread:

https://grassrootsmotorsports.com/forum/off-topic-discussion/garage-mini-split/182808/page1/

BTW, being in Florida I only tested the heat once for a few minutes to see if it worked. Not sure how good it is at heating a garage. 

Mini-splits are the way I would go. If you can read, see lightning and hear thunder, they are stupidly easy to install. A 22 SEER 12k DIY unit from Mr. Cool is less than $1700. 

I would be tempted to fasten some 2"-3" foam to the uninsulated wall. 

I agree with insulating, and making sure the garage doors seal up - after that it comes down to budget. On the low end, I bought a window A/C with a heat strip in it for my 600 sq ft garage - $500 or so on Amazon - it does require a 240V service, so if you can't DIY that there will be a cost - but that's true of a mini split or just about any heater you use except a big gas heater. I did the electrical myself and I built the A/C unit  into the window....

My house is a split level, with the garage under the bedrooms so it had to be insulated and drywalled, and even in really cold below zero winters it doesn't go below 39* or so. In that case running the heater for an hour or two gets it plenty comfy to work in there.

In the summer where we get 100+ days with high humidity it's fantastic. Getting the humidity out helps the most, but having it get down to the low 70's on a muggy hot summer day is just wonderful.

It's also nice to be able to get into a nice cool car - and the A/C recovers quickly when a garage door is opened. That's an important thing to consider - how often will the doors be opened?

I don't use it everyday, but in hot months it adds about $20 to the electric bill, and in winter it's about the same - in summer you don't care cause you have to have the A/C on in the house no matter what, and in winter the electric bill is really low so it doesn't add that much either....all in all the absolute cheapest way to go.....

I'll have to do some more research into minisplits. The company that quoted for the house does have a reputation of being expensive. I also put a call into our plumber  this morning to see about getting a gas line run for the IR heaters. 

The only thing about the minisplit for me is that I really don't feel like I need A/C in the garage. This is primarily to keep the garage warm enough in the winter to where I feel I can safely wash the cars without freezing water lines (happened at some point in this garage) and melt the ice. I'm not as concerned about being comfortable although working in 40-50ish degrees is better than the 30s. 

There are three windows in the garage but the only one that opens is in the small addition and that's the space I'm least concerned about so I don't think the window unit would work.

As for how often the garage doors will open. 4-ish times per day in the winter. My wife leaves for work, I drop the kids off a bit later, come back and work from home (most days) and then she's back after her work. Of course that varies. 

This is what I use and I love it. Using a 220v outlet I ran myself. Warms everyone garage up (2 car poorly insulated attached) in about 30 minutes to toasty temps. 

Personally, I'd run the gas piping.  Keeping a 3 car garage at 50 deg F all winter with electricity will make your meter spin like a top.

In reply to Scotty Con Queso :

Where do you live/what climate? 

What model is that?

In reply to vwcorvette (Forum Supporter) :

In Pittsburgh. It gets cold here. 5000w.