In floor heating vs. radiant vs. forced air in shop??

[jgrreed]

Hi All,

I'm looking to pour a slab, insulate, and finish my 35x40 shop this summer. It's wooden framed, and metal cladded, with 10' ceiling, and a sliding door. I think I'm going to change the sliding to an overhead door.

I've heard many different opinions on how to heat it, and I'm looking for some experienced opinions to sway me.

I'd love to hear your opinions on cost of install, cost to run, comfort, and any things you'd change with yours.

Thanks!

-Jer.

[mjncad]

In floor heat is radiant; just as the gas fired tubes hung from the ceiling are.

In floor takes longer to respond to changes in thermostat setting due to the thermal mass of the concrete. Essentially from what I've read, you need to keep the temperature set 24/7 for it to be effective. Also, should you have a leak in the in-floor tubes, repairs are more difficult and expensive. Some say the concrete will act as secondary containment, and it very well may if the tubes are completely encased in concrete as they should be. I would use rebar set on dobies/chairs with the PEX tied to the rebar instead of welded-wire-fabric (WWF) with the PEX tied to the mesh. If you go the in-floor route, accurately document where the tubes are in case you need to drill holes in the concrete to mount a piece of top heavy machinery (e.g. drill press).

Radiant tubes on the other hand are lighter, and since there isn't the thermal mass of the concrete to deal with as in-floor heat, they respond faster to changes in thermostat settings. They will be easier and cheaper to install and maintain too. This is the type of heat I plan to use in my shop. However, your 10' ceiling will probably prevent the use of this type of heater.

As for forced air in a shop, I think it's evil. Shop buildings tend to be leaky regarding air infiltration. Why pay good money to try and heat the world so to speak. Also all your hot air is going to be at the ceiling where it does the least amount of good unless you use some sort of fan to circulate it lower like a ceiling fan running in reverse (winter mode) does.

Whatever you choose to do...insulate it as that is the cheapest form of heat you can get so to speak.

Good luck, and please let us know what you choose to do.

[cmhyland]

I think part of the problem with heating these spaces is that the slab provides radiant cooling
even when your heating the space. You have to overcome the fact that you have many tons of thermal mass radiating cold into your space.

I think you should look into radiant in the floor and solar pannels on the roof to
heat the floor.. I've seen this done before and it works very nicely...

Alberta may be on the cold side for this so research will be the key...

Regards,
Chris

[Spudland_Dave]

I've spent the last 2 years researching this for my upcoming (hopefully) shop....
mjncad is right in that Radiant is the way to go when it comes to 24/7 heating...set it and forget it or else you wont like it and more then that it probably wont work. What I plan on doing is using BOTH Hot air and the Radiant slab.
a) This is a "hobby" shop for me, I have a full time job so other then nights & weekends, there is no need for me to keep it hot all the time.
b) Radiant is nothing short of spectacular, the heat is even & real nice when your working on the floor, melts off the vehicles, tractor, etc.. and puddles dry quickly.
c) Hot air furnaces can be had relatively cheap, my dad paid 150.00 for a gently used Miller out of a mobile home headed to the scrap heap and it works excellent.

All that being said, What I plan on doing is setting the radiant heat to 40 degrees and keeping it there. so the shop & contents wont be freezing, etc...and when I want to work in the shop I'll manually turn up the T-Stat on the hot air and use that to take the chill out of the air...best of both worlds.

[polo1665]

My garage/workshop is very similar to yours, 32'x40', metal clad, 12'ceilings and a 10' garage door. Mine is insulated and drywalled with a concrete floor. I have a natural gas radiant direct vent wall heater. http://www.cozyheaters.com/pdfs/prod...DirectVent.pdf
I have to say that this heater was not properly sized for this shop space. The high ceilings seem to play a big factor. With the outside temperature at or near zero the inside temperature holds about 44 to 46 deg F. At 20 deg outside temperature it holds pretty well near 60 deg inside. If I use a fan above this heater it helps somewhat, but it is still too small. Unfortunately I was not in on the design phase of this building. I probably would of opted for some kind of a forced air heater, I am lucky enough to have free natural gas, so fuel consumption is not a limiting factor.
A good friend of mine put in an outside woodburner and in floor radiant heat. He did this after the fact and merely insulated over the concrete, laid his hose and built a wood floor over that. I have to say that the warm floors are nice and keep your feet warm all the time. He does have the same trouble with maintaining temperature in the extreme cold weather (probably due to the wood burning aspect, and the fact that the building is probably not insulated as well as it could be). I guess my point is, whatever you decide to use, make sure it is sized correctly for your space and make sure that your building is well insulated as mjncad pointed out. If I was building new I would probably look at in floor radiant heat very closely.

Mark

[Egon]

It's cold in Hinton.

Do some local investigating with heating firms to get their opinion and find out how the costing goes. You may have to look a little farther away than the local town to get a wider range of opinions and design options.

High efficiency Gas fired water heaters and circulating pumps should be relatively inexpensive as compared to hot air furnaces. Heating Zones may be easier to establish. Slab insulation may prove expensive. The warm floor may be of benefit when working on equipment. Things like air exchangers may come into play if you are doing serious work in the shop.

Experienced contract help may not be readily available???

And do keep us informed. Slab heating is becoming more popular and new information always helps.

[BungeeII]

I had a radiant tube heater down the middle of my 32x40x12 shop and it worked wonderfully. When not in use, I'd leave it set around 45 degrees. When I needed the shop, crank it up to 70 and you're as snug as a bug in a rug. I probably went through less than 200 gallons of propane a year on that, and we used the building pretty regularly. Keeping a barn heated will help prevent heaving. The entire barn was insulated, of course.

This is where you'll want advise from someone a lot smarter than myself...
I ~believe~ 10' might be too close to the floor to heat the space evenly. You may need 2 runs down the length of the barn. I could be completely wrong about that, though.

Roberts Gordon is the product that I used and will undoubtedly use again.
ROBERTS GORDON ® Infrared Heaters, Forced Air Unit Heaters and Radiant Heating Systems

[actionaj]

Heated floors are really nice you just can't turn the heat off and on. Or it takes a long time to heat back up. If I ever build a new shop thats the way I would do it.

[The Baron]

I have a 30' x 30' attached garage with infloor heat. It was -25 here this morning and I have no problem keeping it warm. The advantage to the infloor heat is the comfort of having your feet warm. If you have forced air and turn up the heat you will still be standing on a slab which is the temperature you had it set to maintain. If your feet are warm you will feel warmer and if you are laying on the floor well, that is better too. Another advantage is if you open a door to get out your vehicle when you close the door the heat stored in the concrete helps replace the heat that you just let out the door. In my case with the garage attached, I did not want to hear a Hot Dawg running on and off in the garage because it seems they always vibrate just enough to hear elsewhere in the house. What is important is keeping your loop sizes under 300' and in our case we spaced our 1/2" Pex tubing about 15" apart. In my garage I have 3 - 300' or less loops. I would also stress the importance of putting 1.5" styrofoam under the slab, This helps keep the heat in the concrete and not in the ground under the slab and allows you to staple the pex right to the foam and then place your rebar on top of the tubing. There is much information out there on infloor heat. The guy who wrote the book on it is John Siegenthaler. He in fact did write a book about it and we just got it from our library to read up on this while we were designing our home. I am very impressed with the infloor heat both in our home and the garage. Hope this helps. Tim

[deputyrpa]

I installed my own hydronic radiant heat system in my 1850 sq. ft. log house, including the basement slab. When the shell was completed, I used the basement slab as the only heat in the house, and it it provided adequate heat for the main floor as I continued to build. I used a vapor barrier, 500psi High-R foam insulation, stapled the pex to the foam, isolated the slab from the walls with Tuff-R, and then poured fiber-reinforced 400psi concrete. I use a 100K BTU modulating condensing propane boiler. Upstairs, I built a sandwich system on top of the subfloor using extruded and lightweight aluminum plates, and installed second-stage ceiling loops in the bedrooms. I also ran two 3/4" copper pipes up to the south-facing roof for a future vacuum tube solar panel. That alone will provide enough hot water to heat the slab.

I plan on doing the same when I build my garage - it is clearly the most efficient type of heat distribution. One needs to insulate appropriately to direct the radiation to, and retain the heat in, the desired areas.