Oxygen dissociation

Chancey P. · Post by **Chancey P.** » Mon. Dec. 28, 2020 5:22 pm

Can anyone tell me where I can find literature that explains oxygen dissociation. And or why I can't or shouldn't run my boiler below 140 or 152 degrees Fahrenheit.
I've heard about this multiple times yet I can't find anything about it.

Post by **coaledsweat** » Mon. Dec. 28, 2020 5:39 pm

O2 disassociates from water at 153° as I recall. It doesn't recover it rapidly just below that so operating at a low of 140° isn't going to be a problem as long as you routinely go well above 153°. Water temperature is critical to its ability to absorb gas. If you are making your own soda, you want to chill the water to about 35° so it can absorb the most CO2 gas possible. When water freezes, it gives up all its entrained gases just before turning to ice. I hope all this nonsense helps!

Post by **Lightning** » Mon. Dec. 28, 2020 5:42 pm

Ok.. so what about during the off season when the boiler is at room temperature? Is there reason to worry about this issue?

Post by **coaledsweat** » Mon. Dec. 28, 2020 6:13 pm

Drain it if you want, that should solve the problem.

Post by **Lightning** » Mon. Dec. 28, 2020 6:28 pm

coaledsweat wrote: ↑
Mon. Dec. 28, 2020 6:13 pm
Drain it if you want, that should solve the problem.

I would rather not though.. cuz then I'm refilling with oxygen rich fresh water.

Post by **coaledsweat** » Mon. Dec. 28, 2020 9:14 pm

Lightning wrote: ↑
Mon. Dec. 28, 2020 6:28 pm
I would rather not though.. cuz then I'm refilling with oxygen rich fresh water.

The water left in all summer will be oxygen rich if it isn't up to operating temperature. As soon as it cools down after you shut it down it will draw oxygen into the water. There is no way to keep it out. Your system may be sealed so it doesn't leak water but you can't keep oxygen out of it.

Post by **Lightning** » Mon. Dec. 28, 2020 9:15 pm

Isn't that the purpose for using oxygen barrier pex? I'm confused..

hotblast1357 · Post by **hotblast1357** » Tue. Dec. 29, 2020 5:06 am

Lightning wrote: ↑
Mon. Dec. 28, 2020 9:15 pm
Isn't that the purpose for using oxygen barrier pex? I'm confused..

You and me both! There ain’t one person on here that drains there water for the summer! And I’ve never heard anyone complain about boiler rotting out or some other issue because of oxygen getting in there boiler when it’s below 135 degrees..

I think it relates to changing your summer air out of your tires in the fall and putting winter air in them... or making sure your ashing knife is installed properly!

Post by **coaledsweat** » Tue. Dec. 29, 2020 6:30 am

I don't remember saying your boiler rots away, not do I drain mine. The OP was worried about O2 in his water. Draining the water solves that worry.

McGiever · Post by **McGiever** » Tue. Dec. 29, 2020 11:04 am

*hotblast* be advised member *DaveBrode* unwittedly had a boiler destroyed by running below condensing temperatures for extended times.

If I were to operate a system such as the OP I'd look into some additive chemicals to protect the oxygen/water/metal interactions.

hotblast1357 · Post by **hotblast1357** » Tue. Dec. 29, 2020 11:34 am

So we all should drain our boilers in the summer?

McGiever · Post by **McGiever** » Tue. Dec. 29, 2020 11:41 am

hotblast1357 wrote: ↑
Tue. Dec. 29, 2020 11:34 am
So we all should drain our boilers in the summer?

You're missing the point.
The point is you are unaware of member whom destroyed his boiler unknowingly by running boiler temp sub 140* long term...that is all...you need not make it any more than that...

hotblast1357 · Post by **hotblast1357** » Tue. Dec. 29, 2020 2:21 pm

Is there a thread on here to read about that?

McGiever · Post by **McGiever** » Tue. Dec. 29, 2020 5:25 pm

hotblast1357 wrote: ↑
Tue. Dec. 29, 2020 2:21 pm
Is there a thread on here to read about that?

Certainty!

Post by dave brode - Can You Get Condensation Inside A Solid Fuel Boiler?

snuffy · Post by **snuffy** » Tue. Dec. 29, 2020 7:23 pm

Ahh this thread helps me understand a problem we have with a renovation project in our basement. The contractor replaced about 15' of 1/2" copper pipe with PEX (red and blue) to connect to a utility sink. Prior to the reno the water was always clean. Post reno the the water after two seconds turns charcoal color for about 8 seconds which would corelate to the amount of water in the PEX pipe and then turns clear. I wonder if this oxygen dissociation is causing the discoloration in the PEX.

Any ideas if this is the possible cause?