For radiant under floor heating how close should the plastic pipe be to the
underside of the subfloor? Is the reflective bubble insulation better or
fiberglass bating? My plumber installed the piping 5"-8" below the subfloor
and I have open web joists. It will be very difficult to insulate with the
foil-bubble insulation now. Should I insist that he re-attach it closer to
the subfloor? Thanks for any opinions.
Im no Hvac pro but the ones I have seen the pipe is touching the
underneath of the floor above. Again I dont know what is commonly done
but foil bubbe wrap insulates little. Go by proven-tested R value
raings, those bubble wraps are expensive per R value and I have never
seen a true rating , only the BS they print saying ' it is like R5 " for
ex. Fiberglass has a commonly known and proven R per inch, apx 3.5 R "
. Bubble wrap doesn`t.
Does the air space come into play. If the plastic pipe is 1" under the
subfloor and then insulation or if the pipe is 8" under and then insulation
will they heat the floor the same? My joists are 16" deep.
What I have seen is stapled to the floors ceiling and covered by a
sheet of aluminum or steel with a round recess that fully covers the
pipe and is stapled to the ceiling, then fiberglass is used if called
for, by design. Did he use Pex, as Bob said Photograph everything and
call the manufacturer and follow their guidlines.
If he screwed this up there is no telling what else he totaly
botched-hacked in. Was a load calculation done? , Proper fittings?
proper spaced staples or brackets, valving, boiler size, pump, manifold,
air bleeding, etc etc etc. It is not a job for someone to learn on or
My recommendatrion is that if this is how your plumber left a completed job,
take lots of pictures, have them examined by the manufacturer of the
tubing. Wait for their reply. I would then ask the plumber to remove all
of his work and return all of your money. If he will not, sue his ass in
small claims court. THIS IS NOT A PROPER WAY TO INSTALL PEX TUBING FOR
UNDER SUBFLOOR APPLICATION. You do not want him to return to your home and
reinstall it. You don't want this plumber to use your house as his on the
If your plumber installed the PEX 5-8 inches below the floor without any
insulation, I suspect that you're not getting any heat at all from the
installation. Does the floor even get warm?
Here's a picture of what a good installation should look like, using the
heat transfer plates that HeatMan mentioned:
Read the bulletin as well as looking at the sample; it can give you an
idea of what to look for. Your current system sounds like it's working on
convection heat transfer rather than conduction as it should be. Fix this
before you even consider trying to insulate.
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