Copper pipe burst open

[HRN]

This is an inlet to a solar water heater panel sitting exposed to the elements for about 20 years. This pipeline was drained for a while because the old solar heater tank failed and I took my own time to plumb it back up. After enabling the lines, I noticed that the copper pipe going into the panel had burst open. Temperatures here never hit freezing (50F in the last few days).

I would appreciate any opinion on if the crack was just metal fatigue, or some reason I'm driving too much pressure, or did it somehow freeze and expand (during the earlier failure of the older heater).

 

[Terry]

It does look like a frozen pipe burst. I haven't seen that happen otherwise.

 

[Sponsor]

 

[Reach4]

Check your T+P relief valve. Could that have failed closed? Then maybe your pressure expansion tank failed. When the water expanded, it produced high pressure. Normally the T+P relief should limit the water pressure to 150 PSI.

 

[HRN]

I see your point. The only catch here is we never hit close to freezing temperatures in my region. No one does any winterization around here. That is why I'm wondering if I have got something else wrong here.

 

[WorthFlorida]

If I'm correct it appears to transition from a connection (brass?) on the panel to a copper pipe. If this is the output from the panel to a storage tank it is at its hottest point in the system. This seems to me, as stated by Reach that high pressure helped it failed, and in addition extreme expansion and contraction of the pipe with nowhere for the pipe to expand to, thus metal fatigue as you suggested.

 

[Jadnashua]

If the system is over pumped, it can erode the pipe from the inside, literally making points paper thin. In the scheme of things, even 150psi is way below the point that should blow out a copper pipe or fitting unless something like that happened first. To hydroform copper generally takes lots more pressure than that. Ice only expands about 9% or so, and that appears to be much more than that, too.

 

[HRN]

Thanks for the inputs. To clarify, it is actually the ingress point (cold water in) to the set of solar panels. I'm wondering if it could be thermal expansion here instead of freezing. Its a simple closed loop system with a circulator pump.

System setup here:
https://www.hotwater.com/lit/brochures/aosve01000.pdf

My solar panels are from a long time ago, I just replaced the storage tank with the latest model. It does have a TP valve on the inlet line to the solar panels. The brochure actually indicates usage of a TE tank. The older setup didn't have that one, so I didn't think it is something that I will need. Maybe that is something I missed? Can I put that anywhere in the loop (pump in/out)? Would that also help for freezing temperatures (volume expansion)?

As for freezing, all other copper pipes are either in the attic or crawl space with no special efforts to keep them from freezing for this house. I'm not sure why this alone would suffer from the freezing.

 

[Reach4]

Ahh.. so the water circulating is not connected directly to the water heater water, and instead there is a heat exchanger. It is not clear to me how that system is supposed to deal with expansion.

 

[HRN]

https://www.supplyhouse.com/sh/control/product/~product_id=SUN-80

I have the direct booster model which does not have a heat exchanger.

 

[HRN]

"Freeze Protection for Solar Water Heaters. The greatest danger to a solar water heating system is freezing. Even when the air temperature at night is well above 32°F, idle fluid in the collector can freeze, because it radiates heat up to a cold, dark sky."

I guess this is what hit me probably... I had stopped the circulator through the night because I was having a little leak, and left water in the solar panel loop idle. Temps dipped close to 40s.

 

[WorthFlorida]

20 year life span is pretty good for any system and I would just chalk it up as normal wear and tear. All the rage now is solar panels. Virtually no maintenance without battery storage. Companies are guaranteeing solars panel to produce 80% of its rated output after twenty years. About 1% degration each year.

 

[hj]

Copper would not "bulge" from excessive pressure. It froze.

 

[HRN]

Thanks again everyone for the thoughts.

As a learning from this incident, would it be that I just can't have the circulator for the solar loop non operational when the temperatures hover around 40F?

I'm trying to rule out anything that would repeat this issue because of my system design.

 

[Reach4]

As a learning from this incident, would it be that I just can't have the circulator for the solar loop non operational when the temperatures hover around 40F?

If that pipe froze, the temperature got below 32F.

Places more inland and more elevated will get colder lows. There are some cheap freeze alarms that could be useful for you.