Heating the new shop

[Paul Downes]

Bobby, My brother-in -law built a 36 X 80 pole barn for his logging truck. Mind you this is in western upper Michigan where they typically have 3 seasons of good hockey weather and 1 of rough sledding. It's Usual to have 300+ inches of snow per year. He uses an out-door wood fired stove (central boiler) and has radiant heat in the barn including the pit that runs down the middle. I've worked in my t-shirt in that barn when it was -10 to -20 outside. It stays around 75 in there.

I'm thinking about adding to my pole barn to expand the wood shop, and am also thinking about putting radiant heat in the new 12 x 32 section before I pour the floor. I know it is important to put enough insulation down under the slab. I would think the amount would depend on your local average temperatures. More insulation is always better. Incidentally, I'm looking into reject foam insulated panels for the addition walls. I have been told that they go for $1 per sq. ft. @ 4" or 6" thick & they have a high R-value. I figure that if the addition's radiant heat isn't enough to heat the whole shop, I will look around for an old radiator or two to supplement. Heck, maybe I'll turn it into a hill billy shop and just hook up a bunch of old auto radiators and run a fan over them

[Ken Fitzgerald]

Bobby, I am in the process of designing a woodworking shop. There are a number of companies that have web sites that sell their products and will help you design your system for free. After a lot of research the best designs I've seen recommend 2" of insulation around the outer 4' perimeter of your slab, then 1" of insulation under the next 4' feet of your slab; leaving the middle uninsulated. In short the outer 8 feet around the perimeter of your slab is insulated and the center portion is uninsulated. Most heat is lost around the outer edges of the building. Insulating there will decrease heat loss and provide a quicker response to a change in thermostat setting. Leaving the center portion of the slab uninsulated will utilize the effect of thermal mass. In other words the building won't cool down as quickly because of the thermal mass. If you insulated the entire area, you wouldn't have any thermal mass effect except for the mass of the concrete. If you didn't insulate at all, it would use the thermal mass effect of about the top 2' of the earth under the floor and would take sometime to cool down. Like wise it would take longer to warm up. I hope to use radiant floor heating in my new shop, budget allowing.

[Bobby Hatfield]

Bobby, I am in the process of designing a woodworking shop. There are a number of companies that have web sites that sell their products and will help you design your system for free. After a lot of research the best designs I've seen recommend 2" of insulation around the outer 4' perimeter of your slab, then 1" of insulation under the next 4' feet of your slab; leaving the middle uninsulated. In short the outer 8 feet around the perimeter of your slab is insulated and the center portion is uninsulated. Most heat is lost around the outer edges of the building. Insulating there will decrease heat loss and provide a quicker response to a change in thermostat setting. Leaving the center portion of the slab uninsulated will utilize the effect of thermal mass. In other words the building won't cool down as quickly because of the thermal mass. If you insulated the entire area, you wouldn't have any thermal mass effect except for the mass of the concrete. If you didn't insulate at all, it would use the thermal mass effect of about the top 2' of the earth under the floor and would take sometime to cool down. Like wise it would take longer to warm up. I hope to use radiant floor heating in my new shop, budget allowing.

Wow, Ken thanks, I have been searching on the net with google and info like this just isn't on there so far. I have to build up the spot where I am planning to put the shop, its a little low and water stands for a while after a rain, I thought I would build it up with 6" rip-rap crushed rock and cover that with SB2, but probably should dig down and remove all topsoil and backfill it to 12" above grade, and pack it before spreading the SB2 crushed rock on it, or maybe not even use the crushed rock. Since I plan to build up the rest of the lot before building a house there I want the shop high enough that the backfill will not create a water problem when it rains.

[Bobby Hatfield]

Bobby, My brother-in -law built a 36 X 80 pole barn for his logging truck. Mind you this is in western upper Michigan where they typically have 3 seasons of good hockey weather and 1 of rough sledding. It's Usual to have 300+ inches of snow per year. He uses an out-door wood fired stove (central boiler) and has radiant heat in the barn including the pit that runs down the middle. I've worked in my t-shirt in that barn when it was -10 to -20 outside. It stays around 75 in there.

I'm thinking about adding to my pole barn to expand the wood shop, and am also thinking about putting radiant heat in the new 12 x 32 section before I pour the floor. I know it is important to put enough insulation down under the slab. I would think the amount would depend on your local average temperatures. More insulation is always better. Incidentally, I'm looking into reject foam insulated panels for the addition walls. I have been told that they go for $1 per sq. ft. @ 4" or 6" thick & they have a high R-value. I figure that if the addition's radiant heat isn't enough to heat the whole shop, I will look around for an old radiator or two to supplement. Heck, maybe I'll turn it into a hill billy shop and just hook up a bunch of old auto radiators and run a fan over them

Yeah Paul, I want a pit in the center isle of the shop to use for working under the trucks and Bluebird, if and when, I will check on the price of the pit when I get my estimate for the concrete work but will not heat the pit, it being close to the center on one end it should not get too cold. Our low temps are not severe enough to ever need 4" or 6" foam, but three would be nice.

[Ken Fitzgerald]

Bobby, try some of these websites:

www.radiantdirect.com
www.radiantec.com
www.radiantcompany.com
In the design sections they explain how to design and why. I'm not recommending any of them. It's just where I was able to glean some information about radiant floor heating systems.

also try going to taunton books....finehomebuilding they have an article on radiant foor heating.

Good Luck!
Ken

[Arvin Brown]

The insulation is not fiberglass insulation mixed in with the concrete. The insulation that has been mentioned is insulating styrofoam board (nice to have it 2" thick) that is placed on the ground prior to pouring the concrete. This acts as an insulating barrier to the heat going to the ground - thus forcing it up into the room. There is concrete that you can purchase that has small poly fibers in it. It is suppose to increase the tensile strength of the concrete, and it does - but not as much as re-bar. I would be very cautious with putting styrofoam up the edge of the concrete between the ground and the top of the slab. Check with your local termite company - termites like to eat their way up through the insulation into the walls. This was done on my home in Atlanta to insulate the concrete slab of the house and I had to remove it to sell because I could not get a termite bond!

[Robert Ducharme]

I installed in floor tube radiant heating in my house when I built it. There are 7 zones to support 6000 square feet. Below the slab are 4' x 8' x 2" slabs of foam (real exciting one day when it was blowing). Above that is the steel mesh the tubes are tied to. Near the boundrys of the room the tubes are spaced on 6" intervals with 12" in the remainder of the rooms. This system uses a 275,000 BTU boiler which also handles heating the hot water maker. House is at 7000' in the mountains of Colorado.

Advantages:

• Radiant tubes do not blow dust around.
• Temperature is very stable because of the large heat sink and very comfortable.
• The system is very efficient and less costly to run.
• If the heat is left on, the floor and equipment is heated which becomes a large heat sink. This allows any cold air coming in due to DC exhausting outside to be heated quickly. This helps keep the temperature very stable and comfortable.
• Minimal moving parts.
• Extensible to use solar heating to heat the water supply.
• Do not need to have pipes in the overhead so works well with short ceilings
• Heat closer to floor instead of ceiling
• Moisture levels in building easier to control since air not being dried by heater.
• Easy to split into zones to heat areas at different temperatures.

Disadvantages:

• When bolting equipment to the floor, need to make certain you do not drill through one of the tubes. These are sometimes hard to locate even if you take pictures.
• The lag time between time turned on and until everything is up to temperature can be significant. Especially if a large area.
• More costly to install than other systems.
• The zone values sometimes need to be lubricated.
• The floor is hotter than the room so if washing the floor, it can sometimes dry too quickly (wife's complaint)
• More Complex to engineer because the water is re-circulated without being heated. This requires fiddling around with the mixing values until it is working optimally.
• Need to leave system on - would not trust using glycol to avoid freezing.
• May be hard to tell when on or off if not located where you are working.
• Insulation below concrete stongly recommended.
• Hard to retrofit into existing structures. Although it is possible to place it on top of exising flooring and then pouring 1.5" of gypcrete on top.

I think it all depends on your expected amount of time in the workshop and your climate.

To eliminate some of these problems in my workshop, I installed infra-red radiant heating tubes overhead. These systems are about 16' above the floor and have the following advantages and disadvantages:

Advantages:

• This does not blow dust around.
• The building starts feeling warm within 15 minutes. This is because the individual is heated (as well as the equipment). Therefore, lag time is eliminated.
• If the heat is left on, the floor and equipment is heated which becomes a large heat sink. This allows any cold air coming in due to DC exhausting outside to be heated quickly.
• Cheap and easy to install (compared to floor radiant heat).
• Easier to install than forced air.
• If liquids are heated in separate area, do not need to leave the system on. This is key for intermittent use of the workshop.
• Easy to tell when on or off.
• If bolting equipment to the floor, no need to make certain you do not drill through one of the tubes.
• Very simple mechanically.
• Not necessary to place insulation below the concrete - although it would not hurt (except the wallet).
• Keeps you heated even if the door is open and cold air is blowing in.

Disadvantages:

• The level of temperature from one end of the system to the other (depending on the length) can be felt.
• Slightly more inefficient and therefore more expensive to run than other systems.
• Not extensible to use solar heating of the water running through the tubes.
• Need to be careful not to have burnable things too close to it. Once over 20 feet from the burner, can be no closer than 1 foot.

I attached a picture showing one of the two sytems I put in my workshop. These can either be straight or have bends.

[Robert Ducharme]

Forgot to mention that the overhead radiant system is a 75000 BTU heater with 75' of tube providing the radiant surface.

[Bobby Hatfield]

Anybody have experience with radiant floor heating in a new concrete floor ? Thinking of using it for heat in new shop, with 16' ceiling with the open attic, to heat the shop with stoves will cost more than the shop. Curious about zone heating, like heating the area with machines only on days when milling parts, then assembly when needed.

Thanks all, for the info and web sites for radiant in floor heating. I am convinced its the way to go, hopefully here in Arkansas it will be a reasonable cost to heat the shop, I understand the initial installation cost is more but the savings over time should make up for that.
I have yet to find anyone in this local area with experience installing this type of heating, small town where everyone knows who is kin to who, we are down to one woodworking/cabinet shop now, mine, going tomorrow to the auction of equipment of the other shop who's owner was allegedly stabbed to death by step son. May have another Grizzly, Davis-wells, Foley-Belsaw, Powermatic and Rockwell-Delta, tomorrow night if my bids are highest.