What kind of results has anyone had installing pex under a conventional floor joist first floor. Thinking of stapling pex then light spray foam on bottom no transfer plates.
underfloor pex install
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Not sure about the spray foam part, but there is no problem doing it this way as it is the same setup that many home-owners use. What is your floor finish?
I would use fiber-glas with a reflective surface so pipes can be accessed if needed and leave a 1" cavity beneath the pipes. It'll work.
I would use fiber-glas with a reflective surface so pipes can be accessed if needed and leave a 1" cavity beneath the pipes. It'll work.
maple1
Minister of Fire
If you spray it, very little heat will make it to your floor. The piping will be virtually surrounded by insulation. So, no on the spray.
BadgerBoilerMN
Member
Stapling PEX to a sub-floor is hasn't been done for along time. If you are referring to a suspended tube system you might have something for floor warming in a warm climate.
For designs in all of Wisconsin we use plates or Ultra-Fin according to the heat load for the room in question. Fiberglass is the standard. Reflective surface is not worth trouble.
If you use plates foam will work fine, again, depending on the heat load.
No heat load, know nothing...
For designs in all of Wisconsin we use plates or Ultra-Fin according to the heat load for the room in question. Fiberglass is the standard. Reflective surface is not worth trouble.
If you use plates foam will work fine, again, depending on the heat load.
No heat load, know nothing...
Wook660
Member
I just finished installing Uponor joist trak in my house and am so far very pleased with the results. It's much more expensive then the cheap thiin stamped panels that go under the pex but also much more effective. I'd recommend them or at least look into them.
Please explain further how aluminum plates improve the heat transfer? As I understand it they help spread out the heat transfer and avoid hot spots but don't actually increase it as long as the design and amount of pex used is exactly the same. From my experience they more than double the cost of the installation so most people don't bother with them in the NW, staple up is still the most common method for retro-fits here with little negative feedback.
We stapled up 1/2" pex 8" o.c. in the last house we built. 3500+ sqft . Works great up here in the northern parts of NY next to Canada. roughly 1/2 house is carpet and the other 1/2 laminate floor. Even a 28x 30' section with 16 ' ceilings... We spray foamed the rim joist areas and put a foil insulation ~ 1-2" under the pipe
I did my house using Uponor plates. One advantage is you can heat with lower water temperature because of the improved transfer. This has effectively increased my storage capacity by increasing the delta T.
we did a wirsbo staple up system underneath our kitchen floor. love it. works well. just put fiberglass 2 inches below, that helped alot.
You will require much higher water temperatures and still have not much in the way of heat transfer.
Check the tables and calculations in the Uponor Complete Design Assistance Manual, available as a free PDF.
I used heavy Thermofin C plates as an under floor retrofit under hardwood and tile and could not be happier.
Check the tables and calculations in the Uponor Complete Design Assistance Manual, available as a free PDF.
I used heavy Thermofin C plates as an under floor retrofit under hardwood and tile and could not be happier.
Karl_northwind
Minister of Fire
y'know. physics.
the same way that a copper pipe delivers more heat when it has a bunch of little aluminum fins around it in baseboard radiators. Pex by itself is a poor conductor, so the aluminum contacts a large area of the pipe rather than just the little bit of sub-floor, which is also not terribly conductive.
Wook660
Member
Yes, those aluminum plates get very warm quickly and transfer heat directly to the floor. You insulate right up against them instead of leaving a space to heat the air pocket typically done with the staple up. But, I'm no expert by any means, in fact I don't have a lot of experience with radiant floor heating so I'm glad my system is working very well because besides all the homework I did before the installation, it was really a risky experiment.
Karl_northwind
Minister of Fire
that's the thing about doing it the best way possible. reduce the risk that something is going to go wrong, or not perform the way you hoped.
I am not sure where to post this question: We have a hose that permeates oxygen in a hydronic heating system. We want to know which is the best chemical inhibitor to use to remove the oxygen?
maple1
Minister of Fire
All the hydronic conditioners have O2 scavengers as part of the package. More expensive brands have better inhibitor packages.
If you have non barrier tube you will need to keep adding the O2 scavenger as it will be consumed. I have had good luck with the Rhomar brand. be sure to get a test kit also.
Any way to isolate the non barrier tube from ferrous components with a plate HX and stainless circ pump? It may be cheaper in the long run.
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