OT, Insulating copper pipes on my shop heating solar collector

laminar-flow · Jan 26, 2018

I have a solar collector on my roof for heating water which is pumped into the slab. There is .750 copper pipes that feed the collector that I insulated with the cheap black foam wrap around insulation glued together with RTV. I painted it with black latex to keep the UV off of it and it has worked OK for a few years but now the paint is peeling and the birds have scratched off some of the paint.

What I am thinking is to wrap it with something like a 2" wide cloth, (cotton?), lagging and coating (saturating) the cloth with some kind of protecting hardening paint. This paint, or similar, has to be UV reflective, flexible, and able to soak into the cloth somewhat.

I'm looking for some lagging product ideas or other ideas for protecting the insulation which is on these pipes already.

Scottl · Jan 26, 2018

How about gaffer's tape over the insulation? It is waterproof and the cloth backing should hold paint well.

Black would be McMaster # 7612A94. Also available in other colors.

A good exterior latex should be flexible and white would reflect maximum solar. I find Crylicote Gold to be a very good exterior latex.

bloomautomatic · Jan 26, 2018

silver roof tar, like you'd use for mobile homes. probably solvent based, so you'd need to check it on the foam to make sure it doesn't dissolve it.

should be able to take the UV, water, sun, etc.

v

Monarchist · Jan 26, 2018

Scottl said:
How about gaffer's tape over the insulation? It is waterproof and the cloth backing should hold paint well.

Does NOT last long. Nor even the top grade of Nashua's metal-foil duct tape. Sun gets at the adhesives if nothing else.

Best to put new and better primary insulation in place, then cover with light-metal shielding - similar gage to Aluminium or steel siding or better. Guttering turned downside-up for a minimum.

Not to forget that hailstones exist, too. Copper wont care, insulation may, and if guttering gets dented? So what? Dead easy to ignore.

Cheap enough, faster than tapes or paints, not hard to cut new runs of it.

laminar-flow · Jan 26, 2018

That silver roof tar sounds good but messy. Sheet metal, while being the way the pro's do it, would take me days. It is not just a straight run but a manifold. Is there a source for cotton 2" wide tape and what is it called?

DDoug · Jan 26, 2018

FWIW, the "can foam" is now available in black.

How it holds up unpainted, to UV (the regular stuff needs covered) I don't know.

EDIT: Looks like this one will hold up without painting:
Landscape Black Foam Outdoor Adhesive | Touch 'n Foam

steve45 · Jan 26, 2018

You have UV in the Pacific Northwest?

I don't know if this stuff holds up to UV, but it holds up to battery acid: RANDOLPH ACID PROOF BATTERY BOX BLACK PAINT #345 from Aircraft Spruce

Kinda smelly & sticky, like tar, but it eventually dries OK. You might put it on your insulation.

They also make UV resistant PVC pipe. You might split it and put it over the insulation.

laminar-flow · Jan 26, 2018

If it is black, it should have enough carbon black in it to block most of the UV. Yes, we have UV here in the PNW. UV gets absorbed by the atmosphere a lot. That is why when the sun is overhead one has to be careful and observe sunscreen and hats. As the sun sets though, the UV transmission through the atmosphere is nil. A good thing to remember is that when the sun is below 45 degrees, there is almost no UV getting to you.

I need to wrap it up as the RTV that I glued the seam with is not sticking in all places. The insulation most certainly had mold release on it and prevented good adhesion with the RTV.

DDoug · Jan 26, 2018

Please don't tell me you used RTV to glue to the copper.....

Maybe the newer RTV doesn't have it, but it always had acetic acid in it,
and it caused problems with copper.

Miguels244 · Jan 26, 2018

digger doug said:
Please don't tell me you used RTV to glue to the copper.....

Maybe the newer RTV doesn't have it, but it always had acetic acid in it,
and it caused problems with copper.

Standard rtv has ascetic acid.
The version rated save for electrical does not.

DDoug · Jan 26, 2018

Miguels244 said:
Standard rtv has ascetic acid.
The version rated save for electrical does not.

And just exactly which one did the OP use ?

Miguels244 · Jan 26, 2018

digger doug said:
And just exactly which one did the OP use ?

Good question.
I had a 'bad thing' happen before I learned the difference.

Just spreading the lesson.

Chip Chester · Jan 26, 2018

Hate to say it, but the As Seen on TV Flex Seal is spray or brush on, UV stable, black, white, clear, gray, and seems to work OK in multiple lighter coats. Not sure if it's bird-resistant, but it'll be harder and less attractive to them. Easy to apply, and will definitely last longer than even good gaffer's tape. Won't be as long-lasting as pipe, gutter, or aluminum siding/trim bent up with a break, but even if you need to re-fresh it every couple of years, it's easy, fast, and cheap-ish (but not dirt cheap.)

Plus, if your screen door boat leaks, you're all set.

Fair warning: if you lived a few states farther south, it would give you cancer. But you should be fine up there.

Chip

DDoug · Jan 26, 2018

Dumb question, by why not plumb it with PEX ?

It's insulated (at least partially) as it stands, easy to use.

Miguels244 · Jan 26, 2018

digger doug said:
Dumb question, by why not plumb it with PEX ?

It's insulated (at least partially) as it stands, easy to use.

Or purpose made material.
stainless steel solar piping | solar line sets

dcsipo · Jan 26, 2018

mini split systems solve this by using these

Rectorseal Fortress Line Set Cover - Fortress Line Set Cover - Rectorseal Line Set Cover - SupplyHouse.com

dee
;-D

Monarchist · Jan 26, 2018

dcsipo said:
mini split systems solve this by using these

Rectorseal Fortress Line Set Cover - Fortress Line Set Cover - Rectorseal Line Set Cover - SupplyHouse.com

dee
;-D

Sheesh! Go over to your local Big Box and compare that with ignorant guttering prices.

Chip Chester · Jan 26, 2018

To add to the plethora of choices... Electric utility companies use a flanged, U-shaped screw-down molding to protect wires coming down a pole and routed to underground (residential) conduit. UV and critter-safe, big enough for two 3/4" insulated pipes if you stack 'em, and it's stout enough to miter joints and glue up with PVC cement. Not dirt cheap either, but may be available on the surplus market. Paintable in your choice of decorator colors -- there are rattle-cans of plastic-friendly paint at your local hardware store.

MattiJ · Jan 26, 2018

laminar-flow said:
That silver roof tar sounds good but messy. Sheet metal, while being the way the pro's do it, would take me days. It is not just a straight run but a manifold. Is there a source for cotton 2" wide tape and what is it called?

Going along with your cloth idea:2" or 3" wide glass fiber rowing impregnated with 2 component (urethane) paint.
Old boilerhouse pipes were covered with something like that... asbestos cloth with some binder.

surplusjohn · Jan 27, 2018

i have protected ntlon air lines running across a roof buy covering with two layers of split corrugated tube. staggering the seams. held up for at least 10 years

OT, Insulating copper pipes on my shop heating solar collector

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