Plumber69
In the Trades
Slab infloor radiant floor heating. What do you you want the heat of the slab at your feet.
Infloor heating question
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hj
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Are you making a statement? Asking a question? Making a criticism? OR looking for information? IN any case it does not make much sense the way it is posted.
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Plumber69
In the Trades
New to radiant floor heat. Just ran 2000 feet of 1/2 pex in my barn floor in 1000' loops later to find out that was a bad idea. I haven't went any further as far as hooking up anything to run the system. My question is will it be so inefficient I should just scrap the idea and chalk it up as a loss?
hj
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If it is 20 degrees, any water spilled would turn to ice, or maybe you are making an indoor skating rink. 40 degrees would also be cold, and ridiculous. You want the temperature to be comfortable, and that can vary by user.
Craigpump
In the Trades
Hope you didn't pour the floor.
rjbphd
In the Trades
You would get better help from this site.. heatinghelp.com experts there will be your deciding factor.
Thanks
Craigpump
In the Trades
You're going to have too much friction loss, that will cause excessive pump pressure, poor circulation and uneven heating.
It's a 1700 square foot building foam insulated...I guess my question is will it be so inefficient that I would heating cheaper with a forced air furnace due to the energy the pump would be using?
Cacher_Chick
Test, Don't Guess!
Craigpump
In the Trades
If you have the boiler, use a Modine style heater.
rjbphd
In the Trades
Stay the hell away from forced air crap.. get some nice size cast iron radiators to achieve the comfort you seek
Jadnashua
Retired Defense Industry Engineer xxx
The hassle is, you can't move water through the pipe fast enough reliably such that it stays warm the whole way...that's why you really need smaller loops so that the water can stay warm enough throughout such that you get semi-even heating. If you can break the loops out so that they are shorter and more even (you'd still want the ability to adjust the flow through each with balancing valves), it should work.
The radiant effect typically can mean that you'll be warmer at a lower temperature than you would with forced-air systems. Given the thermal mass of the slab, it can take more than a few days upon initial startup to warm things, but from then on, it will be able to modulate and keep things comfortable. Whether it will be able to reach any specific temperature will depend on how well the place is insulated, how well it is air sealed, and how hot you run the water. There are limits on how warm you can make the water for both reliability and safety. On a green slab, you do not want to start out with the water being very warm...things need to cure a bit more and the excess water to evaporate otherwise, the heating strips will stress the thing and can cause cracking as it changes the curing rate along the heated lines.
The radiant effect typically can mean that you'll be warmer at a lower temperature than you would with forced-air systems. Given the thermal mass of the slab, it can take more than a few days upon initial startup to warm things, but from then on, it will be able to modulate and keep things comfortable. Whether it will be able to reach any specific temperature will depend on how well the place is insulated, how well it is air sealed, and how hot you run the water. There are limits on how warm you can make the water for both reliability and safety. On a green slab, you do not want to start out with the water being very warm...things need to cure a bit more and the excess water to evaporate otherwise, the heating strips will stress the thing and can cause cracking as it changes the curing rate along the heated lines.
Thanks for the info. I really can't break the loops without busting out a portion of my brand new slab. I did insulate the ground very well and the building is really tight and we'll insulated. Once the floor is brought up to temperature if I was running the water in the direction that would heat the outside portions of the floor at the beginning of the loop making the center of my building the ends of the loop be the best way to approach it?
Jadnashua
Retired Defense Industry Engineer xxx
Applying the highest heat to the coldest area is generally the way it is done that I've seen. But, trying to push any sort of flow through 1000' of (I'm assuming 1/2" pex) may mean literally no flow at all.
I may just have to chalk it up as a loss and lesson learned I'd hate to throw 3 or 4 grand into the rest of it for a poor result
Jadnashua
Retired Defense Industry Engineer xxx
As an experiment, you could hook up a pump and see what kind of flow you get. I do not expect it will be all that much, and you need x gallons/minute to enable y amount of heat transfer based also on the delta-T (the difference between the slab and the water). You can look those numbers up...I don't have them memorized. If you needed antifreeze in case the system might end up off and it could see below-freezing temperatures, the heat transfer is reduced because of it - IOW, you won't get as much heat out of the system if it uses antifreeze verses plain water.
Thanks I think I will give that a shot first
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