Hydro Radiant Heat Controller Question

Wed Apr 6 17:08:04 EDT 2016

You’d think if we could put a man on the moon we could come up with concrete that doesn’t crack. (Seems to me I heard once long ago about somebody mixing glass fibers into the concrete. Or have I just reinvented gunnite?) 

When my barn slab was being poured, I asked the guy “So this is guaranteed not to crack, right?” He said “It’s guaranteed against fire and theft.” 
I was very diligent about keeping it wet while it cured, and it still cracked. 

(Off-topic, but since I’m ranting about concrete: I spent a fair bit of money on some special epoxy paint and a special etchant to pre-treat the slab before applying it. I followed the directions exactly. The white paint has turned yellowish and is flaking off like crazy. I feel ripped off.) 

> On Apr 6, 2016, at 12:38 , George Handley <ghandley at kc.rr.com> wrote:
> 
> Chuck,
> 
> I was afraid of all that, and have texted my friend immediately to stop everything so he can read and understand your experience and wisdom.
> 
> Thirty some years ago or so I was about to build a period Williamsburg two story earth home on some acreage I bought that included a due South facing steep hill overlooking a lake. I learned a lot about this subject*, and feared they were doing it wrong, so your latest email is exactly what they need to know and plan for NOW.
> 
> Thanks again,
> 
> George
> 
> PS * Then came the divorce. :-(
> 
> 
>> On Apr 6, 2016, at 2:27 PM, Chuck <xtension4osx at mac.com <mailto:xtension4osx at mac.com>> wrote:
>> 
>> Every slab should have footings. It does several things. It keeps the slab from shifting as the soil settles and most importantly it holds the weight of the outside of the building. Without adequate footings the slab will crack even with significant rebar and thickness. I have poured a lot of slabs and learned a lot over the years.
>> 
>> A cracking slab with a hydronic heating system in it is the worse nightmare I can think of. I would get good footings at least 10 inches wide and 18 inches deep.
>> 
>> Being that the slab will be in contact with the Earth and the slab is being heated I would insulate it very well. The Earth is a very good heat sink and without the insulation he would be heating the Earth.
>> 
>> He should be using XPS insulation rather than EPS. XPS retains insulating properties when wet a lot better than EPS. Of course it is more expensive but well worth the money. Make sure that on top of the insulation there is a layer of highly reflective material to reflect the radiant heat back into the slab. Some folks say this is a waste of money for the reflective material but it is relatively cheap and while there isn’t any science to back it up I do know that it does work wood stud walls very well.
>> 
>> Chuck
>> 
>>> On Apr 6, 2016, at 11:06 AM, George Handley <ghandley at kc.rr.com <mailto:ghandley at kc.rr.com>> wrote:
>>> 
>>> Again Chuck, thank you for going another extra 100 miles in explaining your worthy experiences with in-floor hydro radiant heat. So many good points and things to think about. I’ve already given my friend all the printouts from different useful sites I found + your two emails, and they are most appreciative.
>>> 
>>> One big red flag that came up to me is their planned parameter insulation. From all the sites I visited, 2” of rigid foam insulation is to be put on the inside of the footings all the way down to frost line, but the DIY videos my friend and the owner of this new garage have watched indicate all the horizontally placed insulation, vapor barrier and reflective barrier that I read about, but only 2” x 4” frame on the sides of the slab. It truly is a slab on grade installation with NO footings, because it is of a pole barn design.
>>> 
>>> To further compound what I think will be a problem for them, and because it is a pole barn design, they think, and presently plan, on erecting a 2”x4" perimeter frame to pour the concrete. Then they planned on adding the 2”x4” rigid outside of that 2”x4” frame which they plan on leaving in place. I maintain from my reading that is a big mistake. The 2”x4” border frame will act as a thermal break of sorts, but will not do the job, IMHO, of doing much insulating or isolating of the concrete thermal mass.
>>> 
>>> I am of the opinion that in their pole barn design, they need to remove that 2”x4” frame and presumably with a DitchWitch or some other trenching machine, they install a 2” thick by 42” deep rigid insulation.
>>> 
>>> Please tell me what you think on this subject, so I can share it with therm. 
>>> 
>>> Again, thank you for going well beyond the call of duty! :-
>>> 
>>> George
>>> 
> 
> _______________________________________________
> XTensionList mailing list
> XTensionList at machomeautomation.com
> http://mail.machomeautomation.com/mailman/listinfo/xtensionlist

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.machomeautomation.com/pipermail/xtensionlist/attachments/20160406/efdbbdca/attachment.html>