Floor radiant heating

[TDJD]

Does anyone have experience with the water radiant heat in a pole barn? Ive got a 40x30 that Id like to heat. Half the barn already has a cement floor. When I pour the other side I was thinking to lay the pex tubing in. Also I was thinking about adding a heat exchanger with a fan, since it would only have tubing under half the building. Ive got an outdoor wood furnace for the house. Its over sized for the house, and it has another set of water outlets available, so it wouldnt be hard to run the lines out there. The barn isnt currently insulated, but Im thinking to have it spray foamed. Thoughts?
Thanks

 

[muleman51]

Under floor is the best you can get. I had friends that built three shops over the years. Overhead forced air heat first, way better than outside. Then it was radiant tube in the next shop thought that was great, except that it burned the paint off the top if you were too close and froze underneath what you were working on. Last shop under floor pex, much more efficient everything warm, could bring in frozen equipment by morning would thawed, and all at a lower temp setting. However it needs to stay on, you can't walk in and just turn it up. If I ever build that shop that's what I will put in.

 

[Jaden]

My shop building is radiant floor heat in the insulated, finished portion. I heat 1200 square feet with a 50 gallon water heater. It's great heat; slow to respond, which can be good or bad. For any job where you are moving around, 60 degrees F is as warm as you want it. You can only practically emit about 20 BTU's per square foot of concrete, so a heat loss calculation and insulation are necessary. You should include insulation below the floor and around the edges. A company SlantFin has a heat loss calculator online to get approx. heat requirements.

 

[jhwis]

I am in a similar situation with an outdoor boiler. I built a 30 x 48 garage with 12' walls. I didn't put tubes in the floor. I simply ran lines to the garage and run a modine heater that I can turn the fan on whenever I want. The hot water circulates constantly, so even with the fan off it stays 35 degrees if it is 0 outside. when it is 30 degrees outside it's a balmy 45 degrees in there. I feel like I can control the heat better and use far less wood than heating the floor continually. Put the tubes in and you can always decide either way.

 

[Tony in SD]

Floor heat is the way to go. I dont know anyone who has floor heat that wish they had done something different. But almost everybody, that I know, that has other types of heat in their shop, wish they had put in floor heat.

 

[wore out]

Your plan should work well. You will need some sort of "tempering valve" setup to supply lower temperature water to the underfloor heat vs. the heat exchanger.

Be sure to use the correct "oxygen barrier" PEX or Pex-Al-Pex.

 

[rustred]

i have worked in shops with floor heat and cant stand floor heat. feels like i am on stove. my feet sweat as it is, without heating them up more. i like the radiant overhead heat the best. as a working shop its not what i would ever want.

 

[FBH44]

I had radiant floor heat once and hated it. My feet got hot, and I couldn't get away from it. No matter where I went, hot feet. Hated it. Did I mention I hated it?

 

[Eric in IL]

Radiant floor heat is the gift that just keeps giving to the fuel supplier. It will be more sensible if you are feeding it wood and cutting for yourself.

The problem with it in a shop (for me anyway) is you can't turn it down when you leave for the night.

You have to be honest with YOURSELF in making this decision. Will you be in the shop working everyday? Will you be physically able to cut wood for the boiler in the future?

Don't get me wrong, it is nice in my 2 car garage that is set for 45 degrees. I went with suspended radiant tube in my shop. So far I'm satisfied it was the right choice for ME.

 

[redforlife]

A guy I know was talking about his new shop. He didn't put in floor heat. His reasoning made sense. And kind of relates to what your saying.
He said the people he got to do his cement, were reasonable. But didn't do floor heat. He questioned thier ability to do it right, and opted to not spend extra money to get somebody else. Ok. His choice. He also said somebody else put in floor heat. And insulation was not put down under the cement. So thier floor heat now goes into the ground, and not up through the cement.
Must be more to it, than what a guy realizes.

 

[Jerrycpp]

I put floor heat in my insulated 40x70 shop. I put 2 of rigid Styrofoam under the concrete, and use a 55 gallon electric hot water tank with a Taco pump. The PEX is spaced about 18 between loops, and was held in place with 6x6 mesh for pouring. I have the pump on a timer, and control the temperature by how often the pump comes on, 15 to 30 minutes at a time. I don't let the floor get too warm because that makes my feet hot. I keep the shop above 55 degrees, so it is never super warm but also never cold. This setup works very well for me. This is the third floor I've done, and I would do it again.

 

[db4600]

There are a lot of good opinions here. Ive been around it since its inception and seen a lot of dont do installs and heard mixed reviews pertaining to comfort and efficiency. More recently I hear contractors with shops moving away from in floor to forced air or radiant.

 

[Mike M]

I did not go with floor heat or spray foam do to the costs. I must say this is the first topic on this I have read here and there have been a lot of them where some did not like the floor heat ?
You already using an outdoor wood burner would be a plus as it sounds like you have extra unused capacity.

 

[cjunrau]

floor heat is the only way to go. as far as the half without floor heat I would just have a fan at the ceiling of the half with, blowing gently to the unheated area.
Most heat pumps get turned on and run all the time. reason for this is it takes time to bring temp up in floor. Around here most people have the room temp set at +10C the temp rises a bit when the sun shines in though a south window and the floor actually gets hotter without the boiler even having to come on. the wood burning guys have the heat pump set at a certain speed so as to not over heat the shop. some have hooked the thermostat to the pump but it makes the temp rise and lower a lot more. 30X60 shop on Gas boiler in Manitoba cost about $45 a month in winter to heat. I have heard guys say less but hard to believe.

 

[Super H Mike]

It is nice how fast the floor will dry up in the winter.

 

[Ken Macfarlane]

If you don't have much for building insulation, when its cold out your slab temps are way too high for comfort.

In super well insulated building the slab temp is so low it feels cold on the feet.

I haven't turned on our shop in floor heat yet, tubes have been there for years but I didn't finish insulating the roof yet.

 

[RBnWA]

I would have floor heat over anything else a 1000 time's over. When it's zero outside and bring in a tractor trailer it get's very cold laying on a creeper under a cold truck. If a truck has to come in for the next day and has ice and snow hanging on it. Give it a few hours and it will be clean and dried off. Floor might have some wet spots but a sgeegie will take care of that quickly. Nice for farm equip. to or anything else. RB

 

[stevieb49829]

I'm on my second slab with PEX in it. I built a water-jacket outdoor wood boiler, with a circulating pump, and never looked back. I like to keep the floor around 60 degrees, which is warm and toasty on my feet. So far, I used about 1.5 cords of very dry maple, and our N. Idaho winter has been colder than normal. Probably use about 2.5 cords before summer. 20x36 heated side of the shop is 11' ceilings, and R-19 fiberglass. Pex is about 2' on center, two zones. I and my BIL laid the 2 EPS with the Pex stuck to concrete screen with zip-ties. Took about 4 hours to lay it before the concrete guys showed up. If you need advice on DIY all you'll need to do is ask - there's a bunch of knowledge on here. Note the replies! steve

 

[Jaden]

The less insulation a building has, the hotter the floor has to be to maintain room temperature. Mine runs 70 - 75 degrees floor temp when room temp is about 60. Very comfortable.

 

[Pete in Holland MI]

We have hot water radiant heat in the floor of the log home we bought last spring. First experience, and loving it. Floor surface stays 80-85F & comfortable on your feet. Slow to recover. About a degree per hour, so no setting back at night. Articles I've read, it's the most efficient way to heat a house. Radiant heat doesn't raise like other heats. Open loft (no radiant heat up there) is 3-5 degrees cooler that the main floor.

 

[Jim in N.M.]

Strange, Nobody ever mentioned radiant under floor in a house, just shops! I built my home 22 yrs. ago put under floor in with a thermostat in almost every room, I can control any part of the house. I have never had any issues with it PERIOD. In my shop I put an infra-red tube down the center of the shop wouldn't have it any other way, It heats items and the floor. Jim in N.M.

 

[2SteveWI]

I have a 40x30 shop with 12 foot walls in North Central Wisconsin. The floor has about 850 ft of 5/8 pex in the floor in 3 loops. Love it. The heat comes from an outside wood furnace, and also heats the hot water for bathroom in shop. Shop is insulated in walls and ceiling. Keep thermostat at 50 degrees at night. Turn up to 55 if working but as others have said it doesn't heat up fast. If its -10 outside 50 degrees is hot.

 

[pcsaw]

You can run an overhead heater with the water from your outside wood burner it's easier to control the heat especially since you would only have the floor heat on one side

 

[504]

I have Pex in the floor it's not hooked up but it is about time(retirement is coming)I bought the pex online and talked to the guy quite a while. He told me you have to insulate the floor or the heat goes down he told me twice you have to break the heat transfer to the ground. He suggested double bubble foil backed. I bought the pex from him and the insulation from a local company. I will use a water heater and pump. I have six zones in each half of the shop(12 total). I just have not had the need for the heat,the 10 to 12 hour days are going to slow down(at least I am)

 

[hje2]

We have PEX radiant floor heat in our home and in our soon to be finished shop/garage. We used Crete-Heat panels in the garage which has an R-15 value and the PEX runs between the "hockey pucks" and holds the PEX in place. Spacing for the PEX is 1 foot.

 

[caterpillar guy]

I have mixed feelings about in floor heat. My brother bought a house with it in and every time he came home from some trip he would hear a leak of water where the copper tubing broke in the floor. So chop out the floor fix then redo the hole in the floor. This was in a house on a slab built in the 60's or so. Probably before pex the reason for copper tubing. He finally junked the furnace and we put in forced air and ran duct work down the walls from above and made a duct to go through the ceiling joist to connect it. He now has pex in his new shop floor with heat from an outside wood furnace. He has not had it running yet so don't know how it is going to work out. Can't remember if they insulated from the ground. I think they did. Will be a nice shop when he is done. So nice I probably don't dare to work in it. The dirt will be scared to fall off on the floor.

 

[johnlobb]

Dan Holohan on the website heatinghelp.com has a book about radiant heat for non contractors. Make sure you put in enough edge and under insulation. I used to be a rep for Slantfin, they have excellent boilers and equipment...

 

[Blackhole49]

If you have natural gas or propane, you should really check out radiant tube heat. It is easy, efficient and cheaper. Very good at reflecting the heat down and warming the floor. I've had it in both my barns since 2002. The big barn (30x48x12) is uninsulated and will still get to 55 in 10* weather. The little barn is insulated and I keep at 45*. It will heat to 60* in about an hour.

 

[BarnyardEngineering]

You "my feet got hot" types do realize that you can turn the temperature DOWN, right? You don't need to have it set at 120 degrees F.

If you couldn't turn the temperature down the problem was with your installer/installation not the concept of radiant floor heating.

Man don't ever mention anything techno-ma-logic-mical on this site! They want their crank windows, paper menus and open fires in old oil barrels for heat.

 

[coonie minnie]

I have a heated shop, 54 by 120, and we did not put in infloor heat. I do not regret it in the least. We DO have in floor in the milking parlor... it is way more fussy as it seems there are always boiler issues.

When we did the shop, the in floor heat was an extra 17k just for the tubes. We bring in a lot of really heavy stuff, so potential for cracking and shearing a tube was a concern.

As far as a cold floor, we insulated around the edge of the shed, and have no issues. Being we keep the shop 50-60 degrees all winter, the concrete pad never really cools off.

I've heard some complaints that in floor is slow to recover after having the door open, and then others refute that.

Being you have a boiler, go for it. Be sure to insulate the pad, and use enough rebar that settling isn't a problem. If you didn't have the boiler, though, I wouldn't do it.

 

[VAC400]

When I built my shop over 10 years ago I installed floor heat, the shop is 60x60 from floor to ceiling is 27 feet. The heat is set at 60 degrees or higher depends on what is going on. You can go in there with a cold tractor covered with snow or ice it will warm it up and the floor will be dry before morning. The little propane boiler is on the wall and no noise from fans coming on. There is 2 feet of stone for the base, a plastic layer to stop water from coming up, 2 inches of blue board with the pex stapled to it then there is 10 inches of cement with 5/8 rebar every foot. I am happy with this system and I stay warm.

 

[mrslesq]

I am building a shop on an old 24' x 48'chicken house wall foundation. I put 2 foam with knobs on it for in-floor heat with 2 zones. One zone will be 24' x 16' work area with a loft overhead and the other zone the rest of the building. I have not gotten the building built. The tubing was relatively low cost and I would have put 2 of foam board under it anyhow so I'll find out if I like it or not. After the concrete is pour it is hard to go back.

 

[ss55]

Are you working with a heating contractor to size up the system, or is this a Do-It-Yourself design by eyeball? Will the shed stay heated all winter (steady state heating) or only heated on the days you will work in it (lots of cold start-ups)?

Insulation under and around the heated concrete slab will save a lot of heat, more than insulating the rest of the building. If starting from a cold floor, allow two days or more to warm up a frozen slab. At start-up the cold slab will quickly suck the heat out of the hot water within the first few feet and you will just be circulating cold water through the remainder of that loop. You can actually trace the loops by watching which parts of the floor warm up first and then follow the loop as the rest of the floor slowly warms up. Multiple short loops tied into common headers will give you faster warm-up times as more concrete is exposed to the hottest water.

Check the capacity of your boiler against the new heat load from your shed. An un-insulated shed could draw 2 to 8 times or more heat as much heat as the same square footage in the insulated house. On the coldest days you may have to shut down part of the shed to maintain enough heat for the house.

There is always that trade-off of how much usable shop time do you loose preparing extra wood while the weather and the shop are comfortable, so you can work in the shop when the weather is miserable.