Roof Penetration Best Practices for CSST on Sloped, Asphalt Shingled Roof

[Stringpark]

Hello,

I'm trying to understand how best to run corrugated stainless steel tubing (insulated with EPDM) through my sloped (27°), asphalt shingled roof. The folks at Northern Lights were kind enough to sent me a picture of an installation where the tubing and insulation was run through PVC pipe with rubber flashing.
IMG_0013.jpg

I also saw the same technique mentioned in this guide http://www.solarpanelsplus.com/pdfs/...n-manual-2.pdf. However, I'm uncertain of how the PVC is secured in the attic in this first scenario.

Alternatively, I saw in this video https://www.youtube.com/watch?v=BKC_qQH97r0 (12:50 or so) where the insulation was cut in order for the CSST to be run by itself through an Oatey flashing (with small opening), then covered with a flexible aluminum flashing with butyl backing (couldn't find the product in the video, but looks like Onduline makes an equivalent https://www.homedepot.com/p/ONDULINE...P696/301764729). In this scenario, I'm concerned about the Oatey flashing being in direct contact with the CSST, as the temperature rating for the product is 180° and most sources I've read on the internet have indicated that insulation should be rated much higher than that for solar thermal (not sure if the same applies for flashing or not).

The last scenario I'm kicking around is simply running the CSST (EPDM insulation and all) directly through an Oatey flashing (with larger opening to accommodate the insulation) and then wrap with the Onduline flashing.

I'm really inexperienced with roof work, so if you have any insight to provide, I would greatly appreciate it.

Lastly, on a somewhat related note, I'm a bit confused as to whether or not it would be the end of the world if I were to create the roof penetrations slightly higher on the roof (12" or so) from where I plan the top of the collectors to be. Reason I'm asking is that it will be a closed loop system with an air vent mounted only a few inches above the collectors, and I've read that the air vent should be at the highest point in the system. Just wondering if the CSST penetrating the roof a few inches above the air vent is a big deal or not.

Thanks in advance!

[peakbagger]

The approach I used with my SHW system years ago was to cover my copper tubing with closed cell pipe insulation insulation and then sliding it up into a PVC pipe that matched the OD of the insulation. It was a snug fit.I then used a standard Oatey roof boot. I also weaved in shingles to cover the exposed surfaces. I am a fan of the pictured photo with all the rubber exposed. My SHW system is about 20 years old and no leak issues.

The air vent really is optional if you purge the system with a charge pump and circulate the liquid until there are no air bubbles coming out the return hose.. Many air vents fail eventually and cause a loss of glycol and they usually get replaced with a plug.

[Stringpark]

Thx for the info @peakbagger! So how did you secure the pvc pipe? Do they make a specific product for this scenario, or did you just fabricate something?

[J.P.M.]

Hello,

I'm trying to understand how best to run corrugated stainless steel tubing (insulated with EPDM) through my sloped (27°), asphalt shingled roof. The folks at Northern Lights were kind enough to sent me a picture of an installation where the tubing and insulation was run through PVC pipe with rubber flashing.
IMG_0013.jpg

I also saw the same technique mentioned in this guide http://www.solarpanelsplus.com/pdfs/...n-manual-2.pdf. However, I'm uncertain of how the PVC is secured in the attic in this first scenario.

Alternatively, I saw in this video https://www.youtube.com/watch?v=BKC_qQH97r0 (12:50 or so) where the insulation was cut in order for the CSST to be run by itself through an Oatey flashing (with small opening), then covered with a flexible aluminum flashing with butyl backing (couldn't find the product in the video, but looks like Onduline makes an equivalent https://www.homedepot.com/p/ONDULINE...P696/301764729). In this scenario, I'm concerned about the Oatey flashing being in direct contact with the CSST, as the temperature rating for the product is 180° and most sources I've read on the internet have indicated that insulation should be rated much higher than that for solar thermal (not sure if the same applies for flashing or not).

The last scenario I'm kicking around is simply running the CSST (EPDM insulation and all) directly through an Oatey flashing (with larger opening to accommodate the insulation) and then wrap with the Onduline flashing.

I'm really inexperienced with roof work, so if you have any insight to provide, I would greatly appreciate it.

Lastly, on a somewhat related note, I'm a bit confused as to whether or not it would be the end of the world if I were to create the roof penetrations slightly higher on the roof (12" or so) from where I plan the top of the collectors to be. Reason I'm asking is that it will be a closed loop system with an air vent mounted only a few inches above the collectors, and I've read that the air vent should be at the highest point in the system. Just wondering if the CSST penetrating the roof a few inches above the air vent is a big deal or not.

Thanks in advance!

I bet the piping shown in the photo will get an air lock between/at the 2 elbows sooner than later that will either greatly reduce or stop the flow altogether, particularly if the system flow rate is as low as most are.

Unfortunately, unless you spend a boatload of $$ on them, air bleed valves do have a propensity to get stuck either closed or slightly open. Just the nature of the beast. Still, what you read is good advice and std. practice for good system design.

That means a high point air bleed at the highest system point, as well as at any other intermediate, isolated, local high points in the piping that can't be worked around by good piping layout. Air will collect at such (local) points and slow down or block flow just like the high point in the system.

I only have/need one air bleed on my SDHW system and I inspect it ~ 2X/yr. or more often and change it out sooner if I see drips. Make provision to inspect them and also provision to spot leaks.I

[Stringpark]

Interesting, thx for that @J.P.M.! Regardless of which roof penetration method I choose, I was previously thinking of incorporating a “drip loop” of sorts in the tubing, but it sounds like it would be better to plan on a layout that keeps the tubing on a continuously upward path (as much as possible).

For securing the PVC, I suppose I could just bridge the rafters with a 2x4 and attach the PVC to that with a u-bolt. For some reason I was just drawing a blank on how to secure it, but that should work I reckon.

[J.P.M.]

Interesting, thx for that @J.P.M.! Regardless of which roof penetration method I choose, I was previously thinking of incorporating a “drip loop” of sorts in the tubing, but it sounds like it would be better to plan on a layout that keeps the tubing on a continuously upward path (as much as possible).

For securing the PVC, I suppose I could just bridge the rafters with a 2x4 and attach the PVC to that with a u-bolt. For some reason I was just drawing a blank on how to secure it, but that should work I reckon.

You're welcome.

There are supports/strapping products made for such purposes. Among other requirements, and probably not a huge problem for most reasonably well designed domestic SHW systems, be mindful of piping/tubing stresses induced from thermal dimensional changes.

[peakbagger]

I just used regular old PVC pipe. I think I drilled the hole through the roof so it just missed the roof joist and then screwed it to the joist with standard electrical PVC clamp.

[Stringpark]

Thanks once again peakbagger and J.P.M.! Incidentally, both of you guys helped me tremendously on this forum a couple years ago when I was building my ground mount PV system, which turned out great BTW. Solar thermal is whole different beast I'm finding out, but will hopefully be as rewarding as the PV project was.

[J.P.M.]

Interesting, thx for that J.P.M.! Regardless of which roof penetration method I choose, I was previously thinking of incorporating a “drip loop” of sorts in the tubing, but it sounds like it would be better to plan on a layout that keeps the tubing on a continuously upward path (as much as possible).

For securing the PVC, I suppose I could just bridge the rafters with a 2x4 and attach the PVC to that with a u-bolt. For some reason I was just drawing a blank on how to secure it, but that should work I reckon.

You're welcome.

There are supports/strapping products made for such purposes. Among other requirements, and probably not a huge problem for most reasonably well designed domestic SHW systems, be mindful of piping/tubing stresses induced from thermal dimensional changes.

[J.P.M.]

Thanks once again peakbagger and J.P.M.! Incidentally, both of you guys helped me tremendously on this forum a couple years ago when I was building my ground mount PV system, which turned out great BTW. Solar thermal is whole different beast I'm finding out, but will hopefully be as rewarding as the PV project was.

Yea, different sort of analogous to the same way speed boats are different from race cars. Having designed (among other things) power boilers for a living, I'd suggest solar thermal is a lot closer to boiler design than PV.

[peakbagger]

Gad I could help, Its learn by doing and reading what other folks have done. No doubt the PVC trick came off a forum somewhere