Heating my garage with a boiler

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paco_06

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Looking for advice using my hardy heater to heat my new detached garage. I've had the heater five years or so and it works great heating our house and water. I've found a self contained coil with fan on eBay for a couple hundred bucks and it seems the way to go.

https://www.ebay.com/itm/50-000-BTU...ng-Unit-Heater-Single-Speed-Fan-/191874531414

Has anyone else found anything better? I'd like to have it on a thermostat just like my house.

Also, my garage is 30x56 with 10' ceilings, is 50k btu large enough? All the calculators I've used shows I need anywhere from 40-60k....



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Lot of thinks to consider. Do you have the insulated pipes from the OWB ran to the garage? Is the floor in the garage already poured? How much insulation do you have in the garage? How warm do you like to be? If the floor isn't poured I would put tubes in the floor. I love my infloor heat. I also have a coil in a propane furnace that I can turn on if I want a little more heat than the floor is set at.
 
Sounds small. I think your biggest heat loss is the floor. I’d double check your floor calculations
 
Yes, it's a concrete floor, sealed up fairly tight with good insulated doors. I'm in Alabama, so it won't get terribly cold and I figure I'll leave the thermostat on 50 unless I'll be out there for an extended time.

And I wanted so bad to just run pipes in the slab, but really didn't know how much to do and not to mention with my luck I'd end up with a leak and wouldn't be able to use it anyways!

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Is it insulated under the slab?

How would you use the heat? Would you keep it a main minimum temperature all winter, or would you heat it up before using it then not use the heat again until you use the garage?

50k btu/hr is a fair sized heat load, actually - do you have the capacity and extra wood?
 
I just bought 2 Dragons Breath heaters from Alternative Heating & Supplies yesterday. 70,000 BTU each. I'm using one in my work shop 24x56x 10' ceilings and one in my garage 24x24x 11' ceiling. 50,000 will work but will take longer to reheat after opening doors. I bought both units the same just to make parts easier. That is a fairly small looking exchanger.
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I just bought 2 Dragons Breath heaters from Alternative Heating & Supplies yesterday. 70,000 BTU each. I'm using one in my work shop 24x56x 10' ceilings and one in my garage 24x24x 11' ceiling. 50,000 will work but will take longer to reheat after opening doors. I bought both units the same just to make parts easier. That is a fairly small looking exchanger.
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Let me know how you like those! I'm thinking if those will work for you up north, then the 50k should be fine for me. I was really thinking a 75k would be best for my garage, but can't find one reasonably priced. They also sell a 100k for maybe 100 bucks more, but I think that'll be I over kill.

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@paco_06 my dad has a 40x70 insulated shop with 14 foot ceilings and in floor set at 50, we also installed a 100,000BTU unit like you are looking at as a recovery for when we open the doors, I can tell you that after you close the door and turn that air unit on within about thirty 30 minutes you need to shut it off or you are sweating and getting rid of of clothes. We are in Central Iowa and that is the case even on the coldest days, without it you will want a jacket on for a couple hours after the door is opened, the floor takes a long time to warm the air back up. If that 100,00 can drive that big of a building up from around 40 to 72 in a matter of 30 minutes to an hour here I don't think you will have any issue with a 50k and the size you have.
 
I went in floor in my barn and couldn't be happier. I also work in there for 8+ hours a day with lots of tig welding, so a forced air unit would constantly be blowing my shielding gas away.

Water going into the floor is currently at 98F going in, about 80F coming out. Outside temp is 15-20F last few days. Walls are r19, ceiling is r30. Building dimensions are 35x50, but it's 32' tall to the 3rd floor ceiling from concrete floor. Inside the barn its 64-65F in first floor, and only 1-2° cooler on third floor. As for recovery times, I had the 12x14 door open for a solid 45 mins yesterday spraying fluid film on the underside of my truck. When the haze cleared, I shut the door and within 10 mins I could take my jacket off.

As for my experience with forced air units, my neighbor has a 50kbtu forced air unit in his 40x60 with 10ft ceilings. It will warm the place up to 65f within 20-30 mins from 35F. Downside is the floor obviously stays chilly unless you keep it above 50F in there.
 
I also wanted quick recovery time as we open the door quite abit and it gets windy where I live. I already heat it with a wood furnace but it cooks us out of the place at least with this we hope to keep it a consistent temp and can give it a quick blast of heat to get the temps back up after opening the door.
 
To the OP I have a 30x60x16 shop pretty well insulated I have infloor heat and also installed a coil in my propane furnace and run it when I open the door a lot to get a faster recover. I think a 50,000 BTU unit will more than do the job in your area. I run a Garn for my boilers.

Cantoo looking at your pictures I see you run a buzz saw, cordwood saw. What is powering that one? I have one with a stand alone engine I cut a lot of hedge with mind.
 
@paco_06 my dad has a 40x70 insulated shop with 14 foot ceilings and in floor set at 50, we also installed a 100,000BTU unit like you are looking at as a recovery for when we open the doors, I can tell you that after you close the door and turn that air unit on within about thirty 30 minutes you need to shut it off or you are sweating and getting rid of of clothes. We are in Central Iowa and that is the case even on the coldest days, without it you will want a jacket on for a couple hours after the door is opened, the floor takes a long time to warm the air back up. If that 100,00 can drive that big of a building up from around 40 to 72 in a matter of 30 minutes to an hour here I don't think you will have any issue with a 50k and the size you have.
I went in floor in my barn and couldn't be happier. I also work in there for 8+ hours a day with lots of tig welding, so a forced air unit would constantly be blowing my shielding gas away.

Water going into the floor is currently at 98F going in, about 80F coming out. Outside temp is 15-20F last few days. Walls are r19, ceiling is r30. Building dimensions are 35x50, but it's 32' tall to the 3rd floor ceiling from concrete floor. Inside the barn its 64-65F in first floor, and only 1-2° cooler on third floor. As for recovery times, I had the 12x14 door open for a solid 45 mins yesterday spraying fluid film on the underside of my truck. When the haze cleared, I shut the door and within 10 mins I could take my jacket off.

As for my experience with forced air units, my neighbor has a 50kbtu forced air unit in his 40x60 with 10ft ceilings. It will warm the place up to 65f within 20-30 mins from 35F. Downside is the floor obviously stays chilly unless you keep it above 50F in there.
Exactly the info I was looking for! Thanks guys.

Yeah, I hope to just leave the thermostat on 50-55. I won't be in there much, but it will be nice to know I can crank it up to 70 if need be. I just didn't want to be way undersized, because I still feel the 100,000k will just be way too much.

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rancher2, I do have 2 buzz saws that are PTO driven but that one on the tractor is a Japa wood processor. I bought it a couple of years ago and finally decided to do something with it. I made a PTO shaft for it and just bought a new hydraulic pump for it. I need to rebuilt the slide for the pusher too but it looks like it's going to sit for awhile again. Too many projects on the go. Just got the auto cycle valve installed on my splitter tonight. Hopefully test it out this weekend and then stick it out back in the field until spring. Converting one of my electric conveyors to a gas engine is next on the list, have all the parts just need the time. The darn list keeps growing.
 
Well I finally got the heater installed this weekend. My garage is somewhat finished. (Siding, doors, windows and such) but not sealed up tight yet. The 50k heater does a fairly good job, but I will have to admit, I wish the fan was a little stronger. I'm convinced that after interior walls and ceiling are finished, this little heater won't have a problem in my garage.

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paco_06, sorry I meant to respond to this thread after I had my 70,000 btu unit installed. I have it installed and like it but recovery is not as quick as I was hoping even with this bigger unit. It's been really cold here and it just doesn't have enough size to get the heat out of the water. There is enough air flow just not enough surface area. I keep the wood furnace running with just a few pieces in it on days when we know we will be opening the door a lot. My son is a mechanic so stuff going in and out fairly often. Having the shop heated to 55 or 60 all the time is nice but it takes awhile to get warm enough especially if stuff is covered with snow. We don't use near as much wood in the shop furnace now which is nicer.
 
Thanks for the info, yeah I almost think a wood burning heater inside would be all around better, but I just don't want to take up the extra space and have another place to pile wood.... Hind sight is 20/20 and I should've bought the 100k btu heater as the fan on it is 2 1/2 times stronger. I've been emailing with the seller, I'm hoping they'll let me exchange it or possibly get me a part number for the larger fan. If I completely insulate and finish the interior of my garage, no question it'll heat it for my needs, but no more heat than it puts off the pump has to run constantly which in return is burning a ton of wood! Looks like 45 degrees is where I'll leave the thermostat and bump it up to 50 when I'll be in there a lot. I told the seller it's just weird that this 50k unit is a good bit larger than the coil I have for my 2000' house and it just doesn't heat as well because of the smaller fan...

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If you could find a couple (or even more than that) of used big old cast iron radiators, and a couple places to put them, you could maybe add those into the loop, after it goes through the HX. They put out good heat, with lower temp water, but it's more of a steadier maybe lower high output kind.

Only thing is they might start corroding some inside on an open system without some water treatment.
 
I recently got heat going in my shop and went thru alot of the questions and concern you are going thru. As a rough rule of thumb with insulation in modern 2x6 construction 25BTU/h per sq ft gets you in the ball part with an outside temp of 10 degrees and inside temp of 70 degrees. I ran several more complex heat load calcs and had serveral conctractor quote heating systems for my shop. In the end I came out with 19 BTU per sq ft in my shop (4200 sq ft, 2x8 constructions, 17.5' ceilings, r30 walls, r38 ceiling, 2" foam on foundation walls and slab) which was the same that Viega came up with when doing my radiant layout. Other companies came up with much larger heat loss values, but by monitoring my inlet and outlet temperatures I feel Viega and I were spot on. I had considered air handler units and radiant and am very happy I went with radiant. I have a single air handler like your I got from a friend and installed in my 864 sq ft garage. It heats the garage but I'm hot at the work bench where it blows and cold near the opposite end of the garage.

When I was quoting systems everyone recommended multiple air handler units to help keep the temperature even all around the building. On company recommended 2 150KBTU/h units and another recommended 3 100KBTU/h units (they also wanted quote me a 4th unit).

You may just want to contemplate keeping the unit you have and adding another on the opposite side of the building.

What is the inlet and outlet water temperature on air handler? What size pipe and how long is the run to your garage? That will tell you if the fan or pump is to small.
 
When I ordered mine they screwed up and sent the order twice so I paid for and have 2 units so I'm just going to install the other one at the far end of the shop. I have the wood furnace set up so it blows right into the working bay so it melts vehicles off quickly and that is real handy. I would like the room back too but melting the snow is worth the space.
 
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