Heating Qs if using part time in winter

[revitoff10]

Hello,

I've just spent hours reading through posts and my head is swimming. I have a couple of heating Qs. Little things were mentioned in other threads, but I wanted some opinions/clearer answers. We're looking at heated floors, radient tubes, forced air. Concern is being effecient/cost effective for my use (part time periodic use in MN winters), and I'm questioning if something like heated floors is over doing it considering the budget is not unlimited.

Qs
Is a heated floor or radient tubes worth it if it'll be used 10 - 15 days a month with no more than 2 days in a row (i.e. the weekend)? Garage does not need to stay warm when I'm not in it.

Is it more efficient to turn on forced heat when you need it, or keep a constant 40-50 degrees with other options?

What is the comparative 'heat up' time of each if I decide I want to work in the garage Tuesday night after work on a 10 degree day? Kick on the heater when I get home, the morning of, two days before?

No matter what type of heat, is insulating under and on the sides of the slab worth it?

Facts
We're in the process of getting quotes for building a detached 750 sq ft garage. 16ft restriction on the height. Cathedraled ceilings so figure 12 -14 ft high at the highest point. Drywalled and insulated. Garage will be used for vehicle storage and projects that will be worked on in the winter. Sanding on the body will be done as well as mechanical stuff. Lift will be used, so there won't be a lot of laying on the floor. Live in MN. Only need garage at 50 degrees to be comfortable.

We haven't gotten bids back yet, but one contractor mentioned it might add 10K to the price to build for the heated floors. Seems high if I'm not out there all time.

Thanks,

Veronica

 

[Steve in Mi]

No matter what type of heat, is insulating under and on the sides of the slab worth it?

I will say YES. Payback is pretty quick on any insulation installed and these two areas are the most difficult to retrofit (like impossible under the floor) so you either deal with it up front or learn how to forgive yourself for not doing it. I decided to insulate well and use gas forced air heat because I wasn't sure at the time I built how much time I would be spending in my shop. GFA will give you the most rapid air temp warm-up with the floor lagging behind, exact opposite of the in floor radiant heat. Turns out that I heat 24/7 all heating season and stay cool all summer w/o air conditioning. Temp in the shop ranges between 63-65 in the winter and 72-73 the warmest temp in the summer. Very comfortable. I estimate about $140. for heating last year - that's a 28' X 48' two story structure.

 

[HoosierBuddy]

I do think the insulated slab is a good idea. I might even go ahead and install pex tubing in case you someday decide to heat it 24X7. HOWEVER...I for sure wouldn't use radiant in an on/off situation as you are contemplating.

Heat up time is very slow compared to forced air gas.

The cheapest way to have heat is exactly as you are proposing. Turn it on when you want to use it. Turn it off when you don't.

Some would suggest keeping the heat on at some minimum level to control humidity...and that might be a great idea...but it will cost marginally more in fuel costs then turning the heat completly off. I'd suggest a vented forced air gas unit heater OR a gas furnace with limited ductwork for your building.

I love the hydronic heat in my garage...but I keep it at 60 all the time...and pay dearly to do so.

Phil

 

[BowtieNut]

Good advice so far. At my last house I had a 700 sq ft detached with a forced air gas furnace. At first I would just leave the heat off when I wasn't working out there, and then just crank it up when I needed it. When I rurned it on it only took an hour or so to get the air up to 50* or so, but if it's 10* out it takes quite a while before all those metal tools and cars are comfortable to the touch. Eventually I just started leaving the heat set about 40* all the time, and when I went out there to work I'd crank it up to 55* or so. That way it only took 20 minutes or so to get the air up to temp, but the tools and everything were not so uncomfortable to handle for the first couple hours. And it didn't cost that much to keep it at 40* 24/7.

At my new house I built a 1350 sq ft detached with hydronic heat in the floor. This one takes overnight to raise the temp 10* or so, so I just leave it set on 50* most of the time. For some reason 50* in here seems more comfortable than 50* in the old one. If I know I'm not going to be out in the garage for a couple weeks, I might turn it down to 45*.

I would insulate the floor either way. I went thru one winter in the new garage before I got the hydronic finished. I just used electric space heaters that first winter, and I think having the insulation under the slab made a noticeable difference. The floor is not so much of a big heat-sucking ice block.

 

[RAYJAY]

I can heat mine with forced hot water or gas forced air I my self would not let the temp get down below 40 deg. i keep mine at 50 to 55 at all times, you do not want your tools or the lift to got thru the sweating cycle every time you turn up the heat quick,

Jeff

 

[SteveU]

Not to mention in the spring when the first warm moist air comes in you will have less problem with everything getting wet & rusting from condensation if it has been kept warmer than ambient. That is a problem I have just running a salamander when I am out there working on something.

 

[revitoff10]

Thanks for the advice. I didn't really think about mosture issues with the heat up and down. A constant 40 or 45 degrees shoulds like the best way to go. Then we can heat it up a little more when using it.

 

[DaveL.]

I also have GFA. I keep it set @ 50-55 during the winter and turn it up to 60-65 when I am going to be spending some time out there. It only takes about 15 minutes to raise the temp in very cold weather.
p.s. 1200 sq ft attached garage,75000 btu Modine heater,fully insulated R32/R19