Should I be concerned with overheating my PEX?

What brand of pex? The temp rating isn't really a max rating, but max rating at a certain temp. Wirsbo is rated for 180F @ 100 psi and 200F @ 80 psi.

i run mine at 200* and have noticed that it shrunk after it cooled down. it shrunk for a while the has seemed to stop.

I have blown pex apart during power failures. Be carefull what you plumb to where. I have changed all mine to hard pipe. Water everywhere is not worth it. Good luck.

Do you run 80psi in your boiler??

I am just asking because I have 10-15psi in my boiler. Boiler max temp is 180*

Perhaps their service temperature ratings stop at 200F for a reason.

What happens at 220F? Might not be hard to reach even 230F or 240F in a pressurized system during a power-out or equipment failure scenario.

Water all over the place is a nuisance but the possibility of a pipe bursting at high pressure and temperature then flashing to steam while you're standing next to it dealing with your boiler situation makes me wonder about pushing the limits of plastic.

Could be a fun experiment done on a small scale outdoors behind a window.

mine got so hot it un-sweated the pipes after a power failure.

Just for fun you could try it out and see what happens.

Load up the wood boiler and let it get ripping and then shut off the electric power. Stick around and watch what happens.

I'm not certain how much heat 30ft of 3/4" pipe can lose to the air, especially if it is indoor air that's not all that cold. If this is a glycol-filled system and the dump is outside you would have a good chance of shedding some heat in winter, I suppose.

Perhaps a good idea to look into some sort of battery backup to keep the circ pumps going? I wouldn't imagine they use all that much juice.

My dump zone is 30 ft of black iron pipe connected to 2 huge cast iron rads in my cold garage so i would say it will put off alot of heat.

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That sounds more like a real dump zone.

I missed the part about exactly where your PEX is. I thought you were running it right off the wood boiler.

I still think a test run without power would give you a great sense of confidence in it.