My sister's house has water pipes on the roof. Though this is Florida
(Gainesville), it gets cold enough that they need some protection.
We've tried every kind of pipe insulation we can find in the big box
stores, and it all falls apart quickly in the sunlight, even the
highest quality stuff. I'm looking for ideas.
The pipes carry water for a water/air heat-exchange heat pump. It's
almost always running when the outside temperature is below freezing,
and combined with the fact that an extremely cold night might get down
to, oh, 12F every 20 years or so, we're not worried about what happens
under normal conditions. The worry is what happens when electrical
power goes out, or if the unit malfunctions. The pipes are PVC and I
figure that, unprotected, they could freeze to breaking in an hour or
two. It hasn't happened yet, but the worry remains.
There are two parallel pipes, 1" diameter IIRC (or close), about 5"
apart, total length from eaves to unit about 40'. (Once they turn
under the eaves, I have little worry about freezing.) They are about
1-1/2" above the roof surface (held up by bits of 2x4). There are
three right angles. Where the pipes reach the unit, they have a short
distance that's farther above the roof, but that's another problem.
Option 1: I figure if I had some light weight 8" PVC pipe, I could rip
it into two halves, spray a little foam insulation on the inside, and
make a sort of Quonset hut over the pair of pipes. I haven't found
reasonably light weight PVC pipe, and the normal stuff in that size is
expensive and probably pretty difficult to cut.
Option 2: I could maybe do a similar thing with 3" or 4" PVC pipe --
rip it, spray foam insulation, and put it on top of one pipe before
the foam sets. This would not protect the bottom of the pipe, but
might be sufficient. Or glue some strips of foam board to the bottom
... the latter would eventually deteriorate in the sunlight, but would
be fairly easy to replace.
Option 3: I could use 8" diameter metal ducting, split, as in Option 1
above. That's expensive, hard to cut lengthwise, and probably would
Option 4: I could make a plywood box to go over the pipes, and line it
with foam insulation board. But I would have to use PT plywood, and
I've only seen that in 3/4" thickness. Heavy and expensive. I really
only need 1/4".
Option 5: I could do a similar thing to Option 4 with PT lumber. Have
not compared cost with PT plywood, but seems to have the same