Radiant Floor Heating double bubble foil and trouble, DIY radiant floor design bubble foil,

Radiant Floor Heating double bubble foil and trouble, DIY radiant floor design bubble foil,

Radiant Floor Heating /double bubble foil and trouble

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Question

www.radiantguard.com/instructions/FLOORRadiantUnderBetweenWoodJoistsInsta

Please tell us who should we believe!

Respectful Regards.

ANSWER: I think you should always believe the saleman. Not.

I can begin to tell you how I really feel about bubble foil «insulation». Suffice it to say that radiant «barriers» of any kind are of very questionable value under any kind of radiant panel. I am not an advocate of staple-up radiant floors since they have limited output and require higher design operating temperatures than sub-floor radiant systems installed with extruded aluminum panels.

If a reflective material were to get dusty the reflective quality of the material would be greatly diminished. Having pulled down many ceilings over the years I can tell you they have all been full of dust unless nearly brand new.

If you insist on a true staple-up (not recommended) foil or will do little to improve the system. If you opt for a more conventional and accepted «suspended tube» radiant system, you will want to follow the majority of PEX manufacturers installation procedure of suspending tube the tube an inch or so below the floor and the insulation an inch or so below the tube.

You see; even if the bubble-foil guys fantastic claims for enhanced R-values were true, you would still be short of R-value. Suspended tube sub-floor heating systems work primarily by super-heating the air space below the floor to be radiated. More air, more energy and time to heat the floor above.

Since the specific application is uncommon in general construction, more room exists for exaggeration.

QUESTION: Thank you for your informative response. Then is there every a situation that would benefit from double bubble foil? I see from one of you previous answers that you did install DBF, you state «I did staple up bubble foil (one of its few useful applications) over my stapleup in order to gain the increased surface area and enhance the radiant heat factor of the tube.»en.allexperts.com/q/Radiant-Floor-Heating-3710/2008/9/Radiant-Floor-Tubin. Please clearify the proper use circumstances for DBF.

Kind Regards.

Radiant Floor Heating double bubble foil and trouble, DIY radiant floor design bubble foil,

Answer

I did, in fact, install bubble foil «insulation» below an existing staple-up radiant floor heating system in my own house that was not performing up to expectations. The installation of bubble-foil below my own radiant floor had no measurable affect. Shiny, attractive, cheap, easy and useless for radiant panel heating applications. Period.

Please do not ask me any more questions about bubble-foil, the evidence (including rare government action against fraudulent manufacturers claims) is absolutely conclusive.

Bubble foil «insulation» has an R-value of one(1); that’s it, one. It is a good reflector of radiant energy if kept clean and given an air gap. It is a good vapor barrier. Foil may have a proper place in an attic in Florida or Texas but there are likely better products for this as well. As it relates to radiant floor heating, bubble foil is most certainly worthless below any slab-in fact counter productive, and at best a waste of money below a suspended radiant floor, as its only value would be ease of installation and perhaps convective heat current isolation.

Most use fiberglass designed for the particular installation. Both craft backed fiberglass and un-faced fiberglass protected and sealed with drywall. Some use solid board products, which work exceedingly well if caulked air tight and capped at the ends of each joist space. I have use spray foam below extruded plates, but again this is with considerable knowledge of both the PEX and the foam I specified. For DIY radiant floors, I like to keep it simple.

A properly designed sub-floor radiant panel heating system designed without the obvious benefits of extruded aluminum heat transfer panels must be properly sealed. A «staple-up» (more properly a «suspended tube»), radiant system actually super-heats the air below the floor to be radiated. The «radiant heat comes from a the floor surface. In order to do this the air in the joist space must be isolated, trapped and the energy therefrom made to go to the radiated space above instead of adjacent spaces below. The percentage of radiant energy in such a system is relatively low. Without plates, the conducted energy is also a small percentage of the whole. So we are left with convection. Accepted practices of insulation are still best and the R-value dictated by accepted radiant floor design parameters. No guessing, no speculation, no wasted time or money. Science is a beautiful thing.

Please support those whom support the radiant floor heating industry and are dedicated to the comfort of their customers and the future of the industry.


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