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Radiant in floor heat cost.


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First off what does it cost to do? Cost of 2" foam board and pex? A basic setup for 400 sq ft. I am basically adding on to my shop. Currently I have a 30x40 pole barn with 16' lean too on both sides. It is 16' side walls also.  One side is my work shop.  20 its 16x40. I need more space. The way my current barn is (bought it this way) is a standard horse barn. Drive through isle with hay lofts on both sides. So the cheapest thing I can do is use the space i already have that I dont utilize. So I'm thinking tear out some stalls and pour a floor. Voila add 10×40 with the only limiting factor being 10' ceiling height. I'm good with that because my other side is still tall enough I can work around that part. Yah it will suck having posts in the middle but I'll deal with it. 

So my question finally comes back. I have a wood boiler sitting 10' away. I've been wanting to run a loop for air heat exchanger but havent yet. If I'm pouring a floor in basically the other half of what my shop WILL be and I go ahead and put radiant in. What's your thoughts? My theory is that radiant will circulate enough heat to keep my whole shop above freezing (say 50*)  while I'm away. Keep in mind I work fulltime so no need to heat it to 70. Now weekend rolls around I can kick on my heat exchanger and bring it up to 65-70 in no time.  Worth the extra cost or not? 

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Basic plan is to put in 1 linear foot of 1/2 PEX for every square foot.  Use 1/2 inch PEX with an oxygen barrier. I recommend you only use type A PEX, normally sold in a plumbing supply house. It costs 43 cents a foot here at Ferguson (national plumbing chain) but is available from supply house.  I use Uponor or Rahua.  They do sell type B and C PEX at the box stores and lots of people use it, but it’s hard to replace it in a slab.
 

I would lay three loops, one loop around the perimeter and back staying about 8 inches from the edge of the slab, and the return only about 9 inches in.  Then two small loops on about 1 foot centers.  The idea is to lay it in a spiral and come back out the spiral, not back and forth.  This is intended to make the heat even. 

from your boiler three loops on a simple manifold, 3/4 copper is enough size for three loops.  I would use a 3/4 mixing valve a small circular like a Taco 007.  It’s all you need. Set your floor heat to about 85 and see how it reacts. 
how you get the hot water from your boiler to the building might need another pipe  

taco pumps are $100

mixing valve is $100

and then you need a bit for a manifold 

 

for controls you can do a few things, easiest is buy a line voltage thermostat and hook it to the pump, otherwise you can get creative

 

 

this was a quick overview, let me know if you want more information

 

 

 

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Pictures are for reference to give you an idea of what I've got. Dont mind my 1086 this was when it was ugly. 

Now I have a room built above the loft as an office/ spare room against my shop. So removing the loft is out. I have a desk up there and keep my manuals and farm stuff there where its quiet. No kids. Lol

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Don’t worry about poles in the middle of your shop unless you’re planning on being able to unfold your 16 row corn planter inside. 
I wired a smaller factory once. It was probably 80x150. Clear span. The owner hated it because it was expensive and there was no place for outlets for electric and air. When they added on, more than doubled, a few years later there were poles about every 25x25 in a grid. 
It all depends on what you are doing inside. 

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I use 5/8s pex laid out in a square ft  Try to buy the longest loop you can so to not have a splice in the concrete. I used the blue board on a couple floors i did but it was a pain so i used a foil bubble bubble roll to insulate. Roll it down lay out your reinforcing mesh and attack your pec with rebar wire tys.  big areas you will need a manifolfd. Got to Farm Tek. They have everything you need. I have done a 40x 80 .40 x40 36 x 40 . A 20 X60  buildings .i used a LP hot water heater. i also did my basement and tap into my hot water boiler. Farm tek can help you

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Look at Crete heat on YouTube. I tried to get a link but it didn't work for me. Something like this makes it easier to run the tubing. Or the other way I have seen it done is 5x10 sheets of reinforcement wire blocked up 2" above the insulation and zip tie the hoses to that. Have to chute or pump the concrete. Mennonite crew who did our shop used a simple pump usually used for silo shotcreet 

 

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Floor heat is efficient but it’s downfall is the ability to rapidly change the temperature. If you plan on working in there on weekends you would have to turn up the heat on Friday night. When I first built my shop I turned the heat down when we left for three days and it took the better part of a day to warm it back up when we got home. Now I set it on 65 and leave it there  

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7 minutes ago, from H to 80 said:

Floor heat is efficient but it’s downfall is the ability to rapidly change the temperature. If you plan on working in there on weekends you would have to turn up the heat on Friday night. When I first built my shop I turned the heat down when we left for three days and it took the better part of a day to warm it back up when we got home. Now I set it on 65 and leave it there  

maybe exchanger is too small...?

unless you are away for long periods or just cant afford it  should be set +- 55-60* all season

in our car washs with no walls only run 30 days year, when ice is expected,within an hour it is melted and will keep that way down to 18 then  just close to the runs

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Just now, mmi said:

maybe exchanger is too small...?

unless you are away for long periods or just cant afford it  should be set +- 55-60* all season

in our car washs with no walls only run 30 days year, when ice is expected,within an hour it is melted and will keep that way down to 18 then  just close to the runs

Not sure how many runs or what temperature water a car wash has. I do know I have 6 circuits on one foot centers and my regulator is set to deliver 130 degree water to the manifold. If I turn the heat down to say 45 it takes a long time to bring 250000 pounds of concrete back up to 65. It is a comfortable and efficient heat but not designed to be rapidly adjusted. 

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car wash is 4.5k s', 8" concrete  with   7 runs of avg 500'  

at <33* no freeze fresh water runs 60-100% in open air, just slip walls

keeps ice away in 1 hour and down to 22* set on 45*

<20* runs full out ,if below 16*  turn on super,  purge water with meth and shut off power

when 1 site got auto air doors to keep out the wind it was tropical at 45*

 

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 Ak has it pretty darn close.

when I bid them When in business I planned  for $2/sq ft for materials.

if you got your wood stove already the other materials (what He had listed) will be right in line

use a good pex, not junk. Spend it for uponor 

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2 hours ago, from H to 80 said:

Floor heat is efficient but it’s downfall is the ability to rapidly change the temperature. If you plan on working in there on weekends you would have to turn up the heat on Friday night. When I first built my shop I turned the heat down when we left for three days and it took the better part of a day to warm it back up when we got home. Now I set it on 65 and leave it there  

I currently have a wood burner in there forced air. Plan was to actually install a water to air heat exchanger blowing in there as well. What I was saying if having half the shop heated floor would keep the whole shop say 50* all winter then kick on heat exchanger and bring it up to 70 fast. Or leave my forced air burner in there. Either one. I wish I had the ability to do my whole floor radiant. But that's what I get for buying a shop instead of building. 

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4 hours ago, 12_Guy said:

Don’t worry about poles in the middle of your shop unless you’re planning on being able to unfold your 16 row corn planter inside. 
I wired a smaller factory once. It was probably 80x150. Clear span. The owner hated it because it was expensive and there was no place for outlets for electric and air. When they added on, more than doubled, a few years later there were poles about every 25x25 in a grid. 
It all depends on what you are doing inside. 

Thats true. My plan is to cut another rollup door to the right of my existing one which will be the new part. Might only get a 8 or 9' tall door in there but it would work for skidsteer and small stuff. Pickups etc. 

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2 hours ago, zleinenbach said:

 Ak has it pretty darn close.

when I bid them When in business I planned  for $2/sq ft for materials.

if you got your wood stove already the other materials (what He had listed) will be right in line

use a good pex, not junk. Spend it for uponor 

At $2 that was just pex. Or does that include foam board 

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16 minutes ago, Missouri Mule said:

At $2 that was just pex. Or does that include foam board 

When working a bid for a system the rule of thumb is is 1 ft of PEX per square foot of slabe and insulation underneath. We use 2 inches of blue foam under the slab. So for me $2 would be both, Foam and PEX., PEX is not expensive, but some places mark it up a LOT

 

Ferguson

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And then Supply House

image.thumb.png.ed4d04d974e7be5de67b1a52a6685efe.png

 

 

and you can stop there for now, put the PEX and Foam in and you can add the heat later. IF you want.. very hard to go back 

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2 hours ago, Missouri Mule said:

I currently have a wood burner in there forced air. Plan was to actually install a water to air heat exchanger blowing in there as well. What I was saying if having half the shop heated floor would keep the whole shop say 50* all winter then kick on heat exchanger and bring it up to 70 fast. Or leave my forced air burner in there. Either one. I wish I had the ability to do my whole floor radiant. But that's what I get for buying a shop instead of building. 

This is very standard here, install floor heat and add a water to air unit heater for quick make up.  In fact if I ever get if completed this is what was put in my own shop.

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Truth with floor heat that you can't have quick temperature swings but this applies both ways. Today we had a 14'x22' garage door open numerous times and 5 minutes after any of those times you couldn't even tell. The concrete slab retains the heat for a while

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43 minutes ago, bitty said:

Truth with floor heat that you can't have quick temperature swings but this applies both ways. Today we had a 14'x22' garage door open numerous times and 5 minutes after any of those times you couldn't even tell. The concrete slab retains the heat for a while

My buddies shop is that way also. Amazing how the cold just vanishes. My thing is though half my shop would not be floor heat. Wish I had the money to tear it out but that would be a waste. 

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Had this argument a few times. Air weighs .0807 pounds per cubic foot. Doesn't take much to heat or cool it. The shop I used to work in weighed something like 300 tons, with contents. You aren't going cool that off very fast. Most times, even when very cold, the Modine wouldn't even come on when you opened the door. 

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I'll only add I have had great experience with supply house and also uphonor pex.  We used supply house to remodel 5 different places.  I could order everything from my chair at the end of the day and the stuff would be on my door step 2 days later.  To an amateur the uphonor seems much more flexible and easy to work with then the chain store junk also.

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When I built my shop I wanted radiant heat to they talked me out of it. When I built my house I wanted radiant heat and they talked me out of it.

I won't be talked out of it again.

Thx-Ace 

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34 minutes ago, acem said:

When I built my shop I wanted radiant heat to they talked me out of it. When I built my house I wanted radiant heat and they talked me out of it.

I won't be talked out of it again.

Thx-Ace 

I am doing more side jobs. Hope to go out on my own in a few years. I go the other way. I try to talk people into floor heat. Normally the general contractor is the one against radiant heat. 

 

2 hours ago, Missouri Mule said:

My buddies shop is that way also. Amazing how the cold just vanishes. My thing is though half my shop would not be floor heat. Wish I had the money to tear it out but that would be a waste. 

With your wood boiler I would still go with unit heaters and radiant where you can. Always things you would have done differently. Such is life

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ive seen a couple setups around here that use hot water heater for the exchanger and a small lil pump with a shutoff valve to regulate to flow - both guys said it worked wonderful - key is dont move teh water fast, move it VERY VERY SLOW

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when we added the paint room way back in early 90's floor heat was the way to go,safe even heat, down fall was no one wanted to leave the room. 12 years ago the main shop was increased nearly 100% . All floor heat,very nice with warm feet your whole body is happy. Bad part is when on a creeper after lunch and all is quiet ......well zzzzzzz. Next phase is to cut out the center of the original floor and add the loops. The manifold was built for this next step. 2 years ago we built a new market barn and floor heat in that as well.

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