Radiant Floor Heating, Where to Start?

[matouse3]

Very nice! Who came up with your tubing layout? Also, is it ok to just attach the tubing to the insulation like that? That really seems like the easiest way to go and then just use fibermesh concrete. Or did you lay the steel mesh on top of the tubing?

I designed the layout myself from research that I had done. I wanted a single zone for the floor, with the outer lines 6" from the wall, then continuing inward with 12" spacing. I also wanted the warmest water water going outside perimeter first, then working its way inside, then back to base. Blueridge will do a design for you, but they won't do something that complicated, so I was left to my own graph paper.

You will find several threads debating the "on the foam" vs. "in the middle of slab" with the pex question. I did my research and decided that for my application, stapling right to foam was the best bet. Its easy, it holds well, and (my greatest concern) it keeps the pex away from the control cuts when the slab is finished. Once the concrete starts pouring, the pex rises a little and your get concrete all the way around the pipe (from my experience) as long as you don't over staple.

I had the steel on top of the pex, on tables to keep a consistent height with the steel mesh and to also eliminate the risk of the concrete guys hitting my pex when they were trying to pull up the mesh.

 

[danski0224]

PEX is pretty durable.

Short of purposely driving a shovel into it, it will be fine.

 

[jack stand]

Remember to "daiseychain" all of your lines together, plug one end and put in a guage and schrader (tire) valve on the other end and presurize it before you pour and monitor it during the pour. Having the proper PEX splice (or 2) on hand during the pour is a good idea.

 

[rburke65]

The kits from BlueRidge have an air pressure test kit that came with the package. Quick, easy. The manifold assembly was a little light on instructions but you should be able to figure it out. My concrete is in, cut, sealed, pressure held, no cracks after 30 hours...pretty happy.

 

[maxpower_454]

The kits from BlueRidge have an air pressure test kit that came with the package. Quick, easy. The manifold assembly was a little light on instructions but you should be able to figure it out. My concrete is in, cut, sealed, pressure held, no cracks after 30 hours...pretty happy.

Did you staple your tubing to the foam or put it on top of the mesh and pull it up?

 

[BadgerBoilerMN]

When installing radiant floor heating in a 4" slab, it is always compacted class 5, 6 mil. vapor barrier, then tube and wire on top of tube if you must. This is true no matter where you live in the lower 48.

When deciding which boiler to use for your radiant floor you go to the heat load - always the first step in any heating system - then the fuel to be used. Ask the local suppliers how much the fuel they provide costs per therm. They will know. Ask them what the trend has been over the last 5 to 10 years and choose your new boiler accordingly.

 

[matouse3]

Where's the load calculation?

Electric boilers **** a lot of juice. Got enough power?

How can you know how many loops and what size tubing without knowing how many BTU's have to be delivered?

Then you have to decide if you want a glycol solution, and how much of a mix because that changes the GPM compared to water only... which may change loop diameter and length to keep the pump sized right.

<holds thumb in air>
Yeah, throwing 4 300' loops in the concrete will do it.
</holds thumb in air>

Good luck.

This doesn't seem very helpful.

 

[BadgerBoilerMN]

I had the steel on top of the pex, on tables to keep a consistent height with the steel mesh and to also eliminate the risk of the concrete guys hitting my pex when they were trying to pull up the mesh.

...and the only way to get structural enforcement from any wire or re-bar.

Well done!

 

[unknown_element]

Do you really need plastic under the foam if you tape the seams?

 

[BadgerBoilerMN]

There is some debate over this placing a vapor barrier below an insulated radiant slab, but we find the vapor barrier, cheap, fast and effective. When you use 6mil. vapor barrier, the labor intensive taping is unnecessary.

 

[joes169]

6 mil poly costs about 4-5 cents per square foot........................

 

[jvitez]

Do you need to use red sheathing tape to tape the seams of the 6 mil vapour barrier before adding the foam board, or do you just overlap the poly by a certain amount and leave it like that?

 

[matouse3]

Do you need to use red sheathing tape to tape the seams of the 6 mil vapour barrier before adding the foam board, or do you just overlap the poly by a certain amount and leave it like that?

I was told by the vapor barrier company, that if I overlapped by 18 inches, then I didn't need to tape. I taped anyway.

 

[BadgerBoilerMN]

18", that's a new one. A foot is plenty.

 

[matouse3]

18", that's a new one. A foot is plenty.

They must have been trying to rip me off for an extra 6 inches of material.

 

[BadgerBoilerMN]

heheheee