Radiant Heat-How did you secure the Pex?

[pamike]

Getting ready to build a shop with radiant heat in the floor. Floor will be 5" thick. There appears to be two general methods of securing the Pex tubing.

-Method 1-Staple Pex to insulation
-Method 2-Tie Pex to wire mesh

Method 1 Pros-
-Keeps pex near bottom of floor so saw cuts or floor anchors are possible.
-Less risk of damage during pour
-Pex can be secured prior to messing with all the mesh

Method 1 Cons-
-Pex isn't completely surrounded by concrete so heat transfer may not be as good

Method 2 Pros
-Best heat transfer
-No special stable tool needed

Method 2 Cons
-Pex is at unknown height. No saw cuts or anchors possible.
-More risk of damage during pours??

Lets hear your opinions. I know a lot of people that have used method 1. I talked to a guy I know that has done a lot of radiant heat. They use method 2 and shamed method 1, but then again all they use under the slab is bubble wrap...

 

[Briguy_123]

I used Method 2.
34x48 six loops
2 inch mesh chairs.
Tied mesh to chairs.
Tied tubing to mesh.
6+ inch slab, I did saw cut successfully.
approx 3500 zip ties.
I was real fussy, so the process took many hours and was a pain in the ****.
After this experience If I were doing a 4" floor I would staple down then add mesh or use the foam made to hold the tubing.

 

[Matsgarage]

Here is my method, I'll call it method 3, no staples, or tie wraps, steel goes on top of the pipe and it's safe to cut, no risk of the pipe floating. The foam also incorporates a vapour barrier on the tubing side, and its interlocking so once its set in place it cant move apart. all in all this was the best method I paid $1.50 CND per sq/ft , and 28 cents per foot for the tubing Watts radiant pex with OX Barrier, will be running an IBC modulating, condensing boiler model HC13-50 , 13k-50k BTU/h. I've done multiple radiant projects and this is by far the cleanest / easiest way to install radiant heat under slab.


https://www.dropbox.com/s/eqebx4tu93s8dmc/IMG_20151003_132954.jpg?dl=0
https://www.dropbox.com/s/xittkfje5phk27d/IMG_20151003_132959.jpg?dl=0

https://www.dropbox.com/s/s6sezixb4gm772i/IMG_20151009_135307.jpg?dl=0

 

[4cyclic]

Number 1 method.

Stapler was rented for not much and it was easy on my back.

 

[mopar440_6]

The sub-contractor my GC hired to put the floor in used method 2 the first time around. After I realized he was trying to screw me as he had put the foam-foil-foam (not)insulation under it, we ripped everything back out. When we reinstalled it over proper 2" R10 foam board, we used method 1 and put the mesh on 2" chairs over the tubing. Had zero issues during the pour. IMO, method 1 is the only way to go. We were able to sawcut the floor and I can add anchors later as I need to without fear of damaging a tube. Also, the entire slab (rather than the top half) will act as thermal mass but at the expense of responsiveness. However, I plan to use a slab sensor and keep the ambient set around 58-60*F all the time so responsiveness isn't a huge concern.

 

[goneflyin2002]

I think there's nothing wrong with any of these methods-
To me the bottom line is- as long as you have good insulation underneath the slab, it doesn't matter where the pex is.
The heat will go into your room, not the ground.

 

[purplezr2]

Used method 1

Laid roughly 1400 sqft in of foam and tubes in about 6 hours with three guys. This included unloading foam, rolling out the pex, and having lunch. Went pretty fast after the first run was laid down.

 

[Vt_k9]

I used the staple method. The con issue for me was the thickness of my concrete, 6". I was told this would cause a delay in the heat rise if I were to turn the temps up. I have radiant in my house...there is no way I would play on using a lower temp and rely only on radiant heat to increase the temps.

I like knowing that I can go 5" deep for any hole or cut in my floor with no issues (in case I need to bolt something to the floor). I did not run any radiant heat in the area where I planned for my lift or chain pots to go.

In my case the second option of tying the tubing to the wire would have raised it to only about 2-3" from the styrofoam, not a huge gain, but a lot more time to install than the staple method.

I used 3" styrofoam under my slab to help with heat retention.

Mike

 

[PWC Repair]

I think there's nothing wrong with any of these methods-
To me the bottom line is- as long as you have good insulation underneath the slab, it doesn't matter where the pex is.
The heat will go into your room, not the ground.

Agreed, heat rises.
I will be zip tying mine to the rebar.

 

[Briguy_123]

Here is my method, I'll call it method 3, no staples, or tie wraps, steel goes on top of the pipe and it's safe to cut, no risk of the pipe floating. The foam also incorporates a vapour barrier on the tubing side, and its interlocking so once its set in place it cant move apart. all in all this was the best method I paid $1.50 CND per sq/ft , and 28 cents per foot for the tubing Watts radiant pex with OX Barrier, will be running an IBC modulating, condensing boiler model HC13-50 , 13k-50k BTU/h. I've done multiple radiant projects and this is by far the cleanest / easiest way to install radiant heat under slab.

Do you have any pics of the pipe layout?
Was insulation installed on the edge after the picture was taken?
Most of the heat moves horizontally.
Installing 4" of xps 4' down to the footing is a good practice.

 

[Fishplate]

Agreed, heat rises.

Actually, warm air rises. Heat goes in all directions.

Heat is transferred by three methods, convection, conduction, and radiation. That's the warm air, the heat moving through the slab, and the Sun. Use them wisely.

 

[jonjon1]

http://www.amazon.com/dp/B0014EES7C/?tag=atomicindus08-20

thats what I use, have laid 100's of thousands of feet of tubing, we have 5 or 6 of them, that is the newest model, has the kick stand, spring, etc, I have some older ones that work good too, looks similar with out all the upgrades...

If you are doing 1 floor, I would zip tie them, why spend the money to save a bit of time? If you were closer I would let you borrow one of mine...

 

[sands35]

As long as the PEX is above the foam, heat is going to get into the concrete. I guess you can get silly and put it under 10" of concrete. That might be a problem in terms of rate of temp change, but eventually, it will get the concrete warm.

There are some areas where the practice is to bury the PEX in sand (above insulation) then put down concrete on top of that.

 

[Matsgarage]

Here is my method, I'll call it method 3, no staples, or tie wraps, steel goes on top of the pipe and it's safe to cut, no risk of the pipe floating. The foam also incorporates a vapour barrier on the tubing side, and its interlocking so once its set in place it cant move apart. all in all this was the best method I paid $1.50 CND per sq/ft , and 28 cents per foot for the tubing Watts radiant pex with OX Barrier, will be running an IBC modulating, condensing boiler model HC13-50 , 13k-50k BTU/h. I've done multiple radiant projects and this is by far the cleanest / easiest way to install radiant heat under slab.

Do you have any pics of the pipe layout?



Was insulation installed on the edge after the picture was taken?
Most of the heat moves horizontally.


Installing 4" of xps 4' down to the footing is a good practice.

I don't have one picture of the entire layout, its arranged in 4 loops, all around 230' per loop , running 2 pump zones, 2 floor sensors. just over 900' of pipe.

foundation was insulated right down to the footing, I believe heat rises no matter what type of heat. There will be some loss through the wall,

we use fiberglass door cut outs from the manufacturing of doors, they are quite cheap to buy and are tough as nails, 1 3/4 thick foam with fiberglass on either side.

 

[86turbodsl]

Method 2. With saw cuts. You're not supposed to cut more than an inch or so into the concrete. These are control joints, not separate blocks you're making.