Building new shop need some info

I'm just circulating water thru 1000' of pipe. I want the mass of 50* ground under the floor.
The guys I've talked to up here tell me the larger mass is more efficient, evens out highs and lows. And as I said before wet sand would do a much better job of transferring heat. If a guy could figure out a way to keep a consistent moisture content under a slab, you'd be on to somethin

I would never put pipe in the concrete. Concrete moves, ive been in plenty of shops that the joints have opened up. A meat head sawing joints or a joint opening up a lil to far rupture a line and then u have a real problem on your hands. I know there's lots of studies out there but I'll take common sense over studies any day.

Well, do it your way, but common sense says you put the heat where you want it, not in sand a foot away from the space you're trying to heat, UNLESS you don't want the heat there right away, like I said for solar or other unique heat storage. I disagree that it's obsolete, but it's not what you typically want to do if you're heating with conventional fuels, or wood fire that's maintained constant. "larger mass is more efficient" is like saying larger engines are more efficient, basically irrelevant.

With all the talk of getting heat into a shop, how about A/C that doesn't cost an arm and a leg for us who battle the heat?

Geothermal heat pump. Ground loop, pond loop or well water. Thermal mass is NOT your friend.

Yeah, unless you have access to a year around running spring for cool water, vertical drilled ground loop would probably be the best, a large installation.

Thermal mass is a great tool if you are accessing a natural sourse of it. It is a costly endeavor if you are paying real energy dollars to heat (or cool) it.

With a proper under slab bed along with properly placed and cured concrete, heat tube breaking should not be a problem. Todays heating tubes are very forgiving to concrete cracking. Heated slabs should not frost heave if kept heated. Cutting them if cutting the floor is a completely different issue. No different than cutting in floor electrical conduit. If plans include future floor cutting it probably is best to stay away from in floor heat.

lantraxco said:

Yeah, unless you have access to a year around running spring for cool water, vertical drilled ground loop would probably be the best, a large installation.

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I won't argue best, but a well with a relatively shallow water table is a whole different league of cost. If you have the room (and know a guy) a conventional horizontal ground loop will be much cheaper than drilling (and more efficient as the bores are usually undersized due to the cost vs excavation).

Joeyslushr said:

I'm just circulating water thru 1000' of pipe. I want the mass of 50* ground under the floor.
The guys I've talked to up here tell me the larger mass is more efficient, evens out highs and lows. And as I said before wet sand would do a much better job of transferring heat. If a guy could figure out a way to keep a consistent moisture content under a slab, you'd be on to somethin

I would never put pipe in the concrete. Concrete moves, ive been in plenty of shops that the joints have opened up. A meat head sawing joints or a joint opening up a lil to far rupture a line and then u have a real problem on your hands. I know there's lots of studies out there but I'll take common sense over studies any day.

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Please do your self a favour and read up little on radiant floor heating and cooling. you do not want bury the tube below the slab. you want to insulate the below the concrete with a "minimum" of R12 high density Styrofoam insulation. depending on the thickness of the slab your tubes should be at least 2" to 3" below the top. heat travel to cool, hot air rises, with out insulation you are loosing heat below your slab that when the heating season is done will continue to radiate up for weeks and sometimes months causing you to have the hottest shop in the summer.

Joeyslushr…….ditto on the pex in the concrete - I'm in the process of putting radiant heat in a shop I'm building for myself with 10" floors and 35 ton overhead crane - I'm pouring the floor in smallish, well reinforced sections and leaving a full construction joint between sections with an independent radiant loop in each section - if any movement occurs the tubing will not be effected as it would be at a control joint cracking, which seems to be your concern - requires sealant at the joints for a watertight floor……no big deal - anyway, good luck with it

I used 1/2 inch pex in the concrete, to do it over again, I'd go with larger pex and shorter runs, mine are 300-330 foot runs, I'd go with at least 5/8ths pex in the concrete and keep my runs shorter, in bone cold weather that lasts weeks on end, like last winter, we were having issues keeping the floor temps up.

I'd never consider putting pex under the concrete ever, anyone that does must not have rats, moles, mice or any other burrowing critters anywhere near you, a nice warm insulation pad under the concrete makes for a very appealing place for critters to burrow into under the concrete and live, and eat whatever is down there to chew on, mainly a pex waterline.

I love my zones when I put mine in, there are no lines that cross cracks in the concrete, each zone has its own manifold and we pipe the hot water to each manifold via under concrete pvc pipes.

I'd also go with larger feed lines to the manifolds than I did, mine are only inch pex, we may very well end up putting two inch pex to feed the shop with hot water.

As for wet sand to use as a base material, I'd never consider that unless you had Styrofoam over it and a vapor barrier on top of that, I also put drainage lines under the base material to wick off excess moisture, not allow it to stay there, all the studies I've ever read, say moisture on any insulation lowers its R value not increases it.

I also left a gap between the wall and the floor, as a buffer space, so if I were to ever have problems or needed to put in a waterline from outside, I'd never have to touch my floor portion with the infloor heat in it, its also a temper zone space to keep the hot water from the cold walls, there are two spacer boards, expansion joints, one between the outside wall and spacer floor and the next between the spacer floor and the shop floor, that space is about a foot wide and I'd do it again the next time.

I also left a gap between the wall and the floor, as a buffer space, so if I were to ever have problems or needed to put in a waterline from outside, I'd never have to touch my floor portion with the infloor heat in it, its also a temper zone space to keep the hot water from the cold walls, there are two spacer boards, expansion joints, one between the outside wall and spacer floor and the next between the spacer floor and the shop floor, that space is about a foot wide and I'd do it again the next time.[/QUOTE]

Would u have a picture of how u did that. Really good idea. Gonna have ta do something like that.

Daro, I'm not sure if I have pictures of doing that while we were remodeling or not, I'll have to go back and look.

Mine was completely different than most, we did a remodel of an existing building, not something I'd do again or recommend unless you really love what you have on hand, it just adds so many challenges and costs I'm not sure its worth it, one being concrete removal of the old and to reinstall new. In order to achieve that, we needed to be able to use a striker board to level the concrete as we poured, there are a couple ways to do it, one being set up the forms a foot from the old wall, and do the pour, pull the forms and then go back and fill in the gap, which is what we did.

The other issue we had was an existing concrete block wall to deal with, both as a construction standpoint and the strengthen it, and then insulate it, so we ended up with foot thick walls to do both at once, the foot gap is under the now enclosed walls. But we ran two years before we got it all done, and those two years we decided to do it again or over the next time, we'd still leave the gap next to all outside walls, but we didn't in front of any of the doors.

We hashed over the water issue more than anything else. I wanted to be able to put antifreeze in the floor piping and shut down the shop for a winter at a time if need be in the future, and in order to do that we'd need frost free hydrants, which could easily be able to be hooked up, there is a buried water line now just outside the north wall, water came into this building in the past anyhow, pipe it under the wall and hook up frost free hydrants in the wall cavity and cut an opening to get at them, pretty cheap and simple. In the end we ran water into the office, hooked a manifold there to pipe water into the shop, all lines are set on a slope with a drain on one end and shut off in the office, all I'd have to do is heat the office and shut down the shop for a winter.

My concrete guys have poured a lot of shops, but never one as big as ours. They plan on doing at least three pours, and using a belt truck. My question is, the heat guys want to run all the heat tubes at one time. How do you form a separate area with the heat piping in place? We are going to have propane boiler, and shop will have three zones. I know you can run pipes to each zone. I suppose you bring them up so they can connect to the manifold?

Yup. You turn the ends of the lines up to go to a manifold. I might be tempted to run some PVC sleeve or conduit so the lines to the two remote zones were serviceable, maybe with a box in the floor at the end of the conduit so if you ever needed to you could cut the line and replace the feeders at least? Maybe overthinking it.

Around here they call them sweeps or electrical conduit that curves into a 90 degree bend, we run the waterlines in them while in the concrete layer and they stick up above the floor, this somewhat protects the water lines from accidental shearing off or mice chewing on them at the floor level.

A telebelt is a great machine to use to move concrete, we used one to pour my service pit walls since a pumper truck couldn't get inside the building.

If you bring the zones up into a common manifold and a line springs a leak, there is no way to jack hammer out one loop without damaging the rest of them. I ran two loops per manifold and used five manifolds in all for my shop, that way if a loop leaks, I only have to jack hammer out two loops worth of concrete, not a third or half the building or live without that portion of the shop floor being heated.

I also know of a couple guys who laid pvc pipes under the base material beforehand and as a backup heat source, the use forced air heat piped into the pvc and it comes up at floor level and works great, wish I'd have done this for a backup heat option as well, but saw it after my shop was done.

well Guys I am getting some time to send some pics of the new shop , we frame it last fall and now if I can get the time to finsh it but work keeps getting in the way. It turn out reall nice and it only took three day to frame it , but when you call in some framer freinds that do this ever day it don't take long. wiring is all past now so the inslulation can begin. Took me and my wife three days to install the door ,its 18' wide and 16' high. I have 19' 2" to the ceiling.

here is pics of the construction of it the JCB was A life saver

driveshed said:

I have used 2" insluation under the concrete and also 6 mil poly for a moisture barrier. I went with a 32" ICF wall also..

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I told a friend to put the insulation below the floor but I was over ruled by the guy doing the cement floor says the weight of the truck would crack the floor using it under. I would like to know the order in which you prepped the floor for the cement .

cat320 said:

I told a friend to put the insulation below the floor but I was over ruled by the guy doing the cement floor says the weight of the truck would crack the floor using it under. I would like to know the order in which you prepped the floor for the cement .

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Structural foam. About twice the cost of normal insulation. Now required by code on floating slab buildings in Minnesota heated or not. We have even put it under a loading dock unheated slabs and have had no issue with frost heave or cracking at all. If going with floor radient heat current recommendations are to keep the heating tubes in the top 1/3 of the slab.