in floor heat question

glennster

Well-known Member
looking to get concrete poured in part of my morton building. shed is 60x120, has a 30x60 area for a shop that is insulated. planning on in floor heat and adding an 85k hanging shop heater, propane fueled. i see several types of heating units used for the in floor, i plan on an antifreeze for the system. some are using just a regular water heater, some using a boiler type furnace and some use a tankless type heater. what are the advantages/disadvantages to each system? also, i would like to keep the tubing 5 feet away from the edges of the slab on three sides, and 10 feet away on the back wall in case i need to bolt something to the floor. ( air compressor, hydraulic press, lathe, radial drill ect). any problems with that plan?
 

Being a draftsman, once the floor tubing is in position, I would draw up a map of the tubing and any other obstacle.
Then the tubing could be laid in without a bunch of void areas.
And still be confident of not drilling anchor holes into the tubing.
 
As Double07 stated, document well where the lines are placed..photos, drawings etc.. A five foot vacant area will be noticeable for lack of heat in those areas. I have a wall mounted propane boiler. Very very efficient and takes up very little space. Add glycol for protection of the system. You lose a little efficiency but well worth it.
 
Someplace I read that unless you heat the concrete 24/7 it may take too much time for the heat to recover..

2 pounds of concrete is equivalent to 1 pound of water.

In other words, it will take 1 BTU to change 2 pounds of concrete 1 degree F.
A 6 inch floor has a lot of weight.

Back in the 60's people in my hood put radiant heat in the ceiling. Then covered wires with plaster. Guess what? Cracks in the plaster. No way to prevent cracks.

I wonder with a floor your size how likely will you develop cracks in the concrete?

I think turning heat off when not in use makes more sense unless you have an outside boiler and heat with wood.

Then having an oversized furnace may be better.

I think if you are in an extremely cold climate, insulating under concrete will be a good idea.

I need to add fill in my garage. I used pea gravel. The air spaces between the gravel acts like insulation too.

It's your money. Let us know how well it works..
 
Neighbor insulted and put tubing in the slab in his 32x40, he put up a 85k btu reznor and that keeps it toasty warm all winter. He hasnt found a reason to hook up the floor heat.
 
i have a contractor that will do the pour, it will be 30 by 60 ft for the shop. they will install the compacted substrate, then a vapor barrier, then insulation panels, reinforcing wire that will also hold the heat tube. over that 6 inches of concrete, and they are pouring piers at the doors. my plan is to keep the floor at about 45 degrees or so at all times over the winter and raise the temp if i get a big project going. the hanging heater is to kick the temp up if using the big doors. i would like to keep the machine tools at a stable temp to avoid condensation. expansion joints will be saw cut and then sl1 added to the cuts. i am thinking of adding a thermostat i can control from my cell phone, or possible one of those nest type systems.
 
I ran my first leg of PEX along the perimeter, about 6-8 inches in. That's the hottest water, and where the most heat is lost - at the edge of the slab. You could easily map that run if you keep it parallel to the wall, and then bring the next leg out to be clear of any holes you might drill. Mine is a wood-fired boiler, with propylene glycol antifreeze. Heated slab is 32x20. I use about 2-3 cords per year in N. Idaho. Takes 2-3 days to get the slab to about 50 degrees, and somewhat of a fire each day to keep it there. steve
 
Some are saying to map the tubing before pouring. Just so everyone knows. A couple years ago I was working in a garage with radiant tubing in the floor. We borrowed a thermal detector from a plumber that plugged into a smart phone. Turned up the heat for a while and were able to see on the phone screen where the tubing was quite clearly. Drilled our holes with no problems.
 
Also a good idea for radiant slabs is a thermal break near the outside walls so heat is not conducted to the outside. Can be an expansion joint or foam. I have seen foam cut on an angle so very small break in the surface. I don't know how heavy vehicles you may work on besides cars but I am a firm believer in rebar, not just wire.
 
if i need to split a big tractor i want a strong floor. my radial drill weighs around 7 k pounds, and i have a 150 ton hydraulic press.
 
Radiant in-floor heat is the way to go!

We had an in-floor system installed (approx. 4000 ft of 3/4 copper) back in 1969. ...The system had one design flaw. ...The supply manifold was imbedded IN the concrete. ...The return manifold was above the floor and had a balancing valve on each loop.

We were fortunate we never had a loop leak or get damaged because with the manifold buried in the concrete, there was no way to isolate a damaged loop.

Whenever we had to drill a hole, we would wet the floor and turn the heat on. ....The loops would appear first since they were the hottest part of the floor.

We were told water entering the floor should not exceed 140*. ...Since there will be a temperature drop in each loop, flow needs to be adequate to try to stabilize temps in all parts of the floor.

Efforts should be made to make the various loops the same length. ...Try to avoid ANY splices/couplings/fittings in the slab. ...Don't let anyone tell you only one continuous loop is needed.
 
Only 2 kinds of concrete that that is cracked and that that will be cracked. I'm not sure I would go with in floor heat. Nor would I cut it. I've cut floors and they still crack where they want also if it cracks which it is going to sometime you may get a leak with the crack. My brother had a house with it in the slab and seemed every time he came home from being gone for a weekend or not he was coming home to a leaking floor. This house was built before he bought it and was probably 10-30 years old when he bought it.
 
I'm with you. Pay a little more for a 6 inch floor and it's not going anywhere. I even have a 6 inch drive. It has been there for 20 years and hasn't cracked even at the expansion joints.

I guess if you keep the floor at a constant temp that may be the best thing to do..
 
You should at least investigate Radiant Tube Heaters. They heat from the floor up. I've had them in 2 barns since 2002 and absolutely love them. They are very efficient also.
 
If you want to raise the temp at will,when you want it,radiant is NOT the way to go.Radiant is set it and forget it.I've run thousands of feet of the stuff,and the guy I worked with always says it takes 3 days to normalize.The new fire station in town raised some worries about recovery,but they turned out to be baseless.If you open all the doors,then close them,that mass of hot concrete warms it up again almost instantly.Dries wet trucks and equipment fast too.20 + years now with zero problems.I was in a big lumberyard/millwork building and saw some radiant tubing going into the floor.That building is 140 X hundreds of feet.It had at least a dozen of those bundles of pipe going down into the floor.Built in 04,and the manager said it has been zero problem. You do not turn it up and down though.It has it's place,and if you want to change the temp to fit your needs then it is not for you.
 
(quoted from post at 10:34:16 05/26/22) ...... planning on in floor heat and adding an 85k hanging shop heater, propane fueled
I use an oil fired boiler for my shop radiant heat. Originally planned on, and plumbed for Modine heaters .....


my plan is to keep the floor at about 45 degrees or so at all times over the winter and raise the temp if i get a big project going. the hanging heater is to kick the temp up if using the big doors.
I set my shop radiant at 60 degrees and forget it. Once heated, doesn't use that much more to stay at that temp, than a lower temp.
Never found the need to hook up Modines. Open a 12 foot door for 10 or 15 minutes, feels cold till doors are shut. Then pretty much back to warm from the radiant. Everything stays warm but the air, that recovers pretty fast.


Efforts should be made to make the various loops the same length
Very Important. Water takes the path of least resistance. If one loop is mch shorter than others, most if not all the water will flow through that one loop, leaving the others cold.


Try to avoid ANY splices/couplings/fittings in the slab. ...Don't let anyone tell you only one continuous loop is needed
Spot On Advice
No more than 300' per loop.



36 x 40 Shop

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Apartment Above Shop

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Edge insulation and if you have a high water table, under system insulation is a must, if you don't put it in, you're heating the world! Dan Holohan of Heatinghelp.com sells a book for the layman on how to install radiant heat. An excellent investment to keep one from making mistakes on the install...
 
The hvac who did mine told me about a job where they failed to fill the tubes with water before the pour and the tubes tried to float. He said the concrete guys were stomping the tubes back down. I wasn't there so I can't verify. We filled mine. Easy step to take.
 
The hvac who did mine told me about a job where they failed to fill the tubes with water before the pour and the tubes tried to float. He said the concrete guys were stomping the tubes back down. I wasn't there so I can't verify. We filled mine. Easy step to take.
Probably wasn’t stapled down like they are suppose to be
 

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