use of pex pipe in a system

[nova]

To connect the panels thu the attic it would be a lot easier to use than copper.

Someone said that pex can't take the high temps.

[inetdog]

To connect the panels thu the attic it would be a lot easier to use than copper.

Someone said that pex can't take the high temps.

It depends on the design temperature and pressure of the system as well as the worst possible case.

Pex tubing is chemically stable well past 180F, but may not be rated to withstand its full design pressure at higher temperatures. In particular, even when the tubing itself can withstand its rated pressure at higher temperatures, the combination of thermal expansion and material flow resistance may keep fittings, particularly slip-on fittings, from withstanding that same pressure.
If your panels can produce a stagnation temperature of 212F (or even higher temperatures because of pressurization and coolant composition), you can expect PEX to fail. If you have high stagnation temperatures but an open (zero pressure) system, it might survive, but why risk it.

[nova]

Not worth the risk to have an overhead leak or burst pipe.

Just was thinking about alternatives

[russ]

I don't remember the temps off hand but PEX won't take the possible stagnation temperatures.

[LucMan]

To connect the panels thu the attic it would be a lot easier to use than copper.

Someone said that pex can't take the high temps.

On a drain back system with flat plate collectors it's OK to use if you connect at least 15 ft of copper piping to the collector inlet and outlet.
Do not use on a pressurized evacuated tube system

[russ]

On a drain back system with flat plate collectors it's OK to use if you connect at least 15 ft of copper piping to the collector inlet and outlet.
Do not use on a pressurized evacuated tube system

OK for a stagnant flat plate? No.

[josefaz]

To connect the panels thu the attic it would be a lot easier to use than copper.

Someone said that pex can't take the high temps.

Most, if not all new homes in Arizona, has pex pipes in the attic. Our 6 years old home has it and no issues so far.

[cssolar]

Most, if not all new homes in Arizona, has pex pipes in the attic. Our 6 years old home has it and no issues so far.

I have used plastic pipe too for solar installations

No problems so far to report ! and much cheaper than copper too ! ( although the fittings can be expensive )

Tony

[russ]

What are temperature limitations for PEX?
PEX tubing can be used up to 200° Fahrenheit for heating applications. For plumbing, PEX is limited to 180° F at 100 psi. Temperature limitations are always noted on the print line of the PEX tubing. PEX systems are tested to and can be used with standard T and P relief valves that operate at 210” F and 150 psi.

Even CPVC is not specified for panel stagnation temperatures.
CPVC systems conforming to ASTM D2846 are rated for continuous service at 100 psi and 180 degrees F and are marked accordingly. The model codes recognize CPVC's capability to handle short-term pressure/temperature excursions beyond these levels.

[nova]

Most, if not all new homes in Arizona, has pex pipes in the attic. Our 6 years old home has it and no issues so far.

Is that with solar or domestic water?

[josefaz]

Is that with solar or domestic water?

Sorry, I didn't realize the topic subject. The pex I'm refering to is for domestic water use.

[LucMan]

OK for a stagnant flat plate? No.

Drainback system. Collectors empty when set temp is reached, loop pressure 0 PSIG.

[russ]

Drainback system. Collectors empty when set temp is reached, loop pressure 0 PSIG.

Oh my - how cute! Look at the original post - as follows "use of pex pipe in a system

To connect the panels thu the attic it would be a lot easier to use than copper.

Someone said that pex can't take the high temps."

It is really something to realize what a drainback system is!

My post is dead on.