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I recently found this site and have discovered a lot of good info on home construction, so figured it was my turn to jump into the fray. Here goes,
I have been in the process of building a new home over the last two years and am to the point of insulating around the stapled up radiant floor heat in my crawl space. The Heatway tubing is attached between TJI’s that are 16 oc. My question is how much airspace do I need between the insulation and tubing, if any? Also, do I need paper back insulation or would non-backed insulation work if I put plastic up after insulating? I live in Montana and winters can be rather cold, what R value is recommended. I have been told R19. Your thoughts and recommendations are appreciated.
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Mike,
If you look at your design (Heatway's proprietary Heat Loss and Design) you will find the minimum R-value for the insulation below each room. If floor coverings or other components have changed since that design, the figures need to be updated to reflect (as constructed).
Heatway specifies a slightly different approach to it's staple-up procedure than other tubing companies. They want full contact with the subfloor. I am not positive(I am only familiar, I don't design or commission rubber tube)but I think I remember a need for staples every 6 inches(?).
They also specify that you use a foil faced insulation. The foil surface should face the tubing but not be in direct contact. I think they want a two inch airspace.
Give John Sweaney a call at Heatway (1-800-255-1996). He would be able to give you definitive recommendations for your project. Although there is currently a huge legal battle going on between Heatway, Goodyear and some homeowners concerning failures directly and solely related to Goodyear supplied Entran II, I would document all phases of your radiant project with video. I would recommend the same with any mechanical product that is buried behind finish materials.
Jeff
*Jeff,Thanks for the advice. I was hoping you would see this message. It appears you are the pro on this subject.Mike
*Good luck Mike. I wouldn't characterize myself as "the pro" in the field but I also wouldn't deny that I bring a non-partisan view and a "professional approach" to the field of RFH, however unconventional I may appear at times. Of course, this is the internet, who really knows, eh?Tell John Sweaney I referred you(please), he is an adversary(might I qualify that as a very knowledgable and capable adversary).Jeff
*Contact Heatway as Jeff recommended. Once you find your insulation/airspace requirements, plod on.The easiest way I've found is to use rigid half-inch foil-faced board insulation. You can cut is slightly wide and friction fit it between the TJI webs, tucking it up against the flange for a 1.5" airspace. Hold it off the flange for a larger airspace. I then use R-19 FG batts under the foil-faced board. If you fail to get a tight friction fit, tack a few nails into the TJI web to hold to foam board in place.That's about the minimum for your first floor (cold basement ceiling). For the second floor, depending on calcs, you could use the foil-faced with R-11. I prefer R-19 everywhere. None of these FG batts need to be faced.Run the numbers, see where they lead. The rigid foam will give you a consistent airspace with a more even heat distribution. If not properly installed the FG can "fall" in the joist bay, creating too large of an airspace, severely reducing the efficiency of your heat delivery system.Has the heating been run yet? If not, consider lining the holes in the joists that the PEX runs through with a cardboard tube or a bit of FG. Nothing spectacular, just a small strip of cardboard wrapped around the PEX where it passes through the joist. If the PEX was run too tightly or with too much slack, as the tube goes through it's heat/cool cycle, it can make a few creaks and groans as the PEX rubs against the sides of the hole in the web of the joist. The cardboard or FG reduces chaffing/friction, helping to eliminate the noise. If the tubing was laid out properly the noise may not be an issue, but it's much easier to do it now...just in case.Congradulations on your radiant floor heat. You and your bride have made a very wise choice.
*MongoThanks for the reply. A lot of good info. Didn't think about using foil back ridged insulation. Will explore the possibilities. As you can see, has taken me some time to get back to my post. I have many things that take up my time. Don't get time for the computer much. Again, thanks.
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I recently found this site and have discovered a lot of good info on home construction, so figured it was my turn to jump into the fray. Here goes,
I have been in the process of building a new home over the last two years and am to the point of insulating around the stapled up radiant floor heat in my crawl space. The Heatway tubing is attached between TJI's that are 16 oc. My question is how much airspace do I need between the insulation and tubing, if any? Also, do I need paper back insulation or would non-backed insulation work if I put plastic up after insulating? I live in Montana and winters can be rather cold, what R value is recommended. I have been told R19. Your thoughts and recommendations are appreciated.