None bladder expansion tank.

[jdboy9]

I have a quick question regarding expansion tanks. I realize the bladder style that you purchase is more expensive than say a propane tank with x amount of air pressure in it that you made yourself. I also realize why one might want to go the lesser cost of the two.

My question is what about air transfer to your water supply from a none bladder type expansion tank?? Isn't this going to cause problems in your system?

 

[RobC]

I have a non bladder set up. I'm using a 100 gallon propane tank. This has been in service for about 1 year and I have not added or let air out since original set up. This topic had been talked about and I think the consensus was nobody had to adjust the tank air or water volume since any had been put in service, which would lead you to believe that there wasn't a lot of transfer going on.
I believe it's the O2 or oxygen that is really what will cause the problem and that is even a smaller amount that the total "air" capacity in the expansion tank.
Some had suggested to fill tanks with an inert gas and although ideal was probably not necessary due to the low percentage of actual O2 present. Air is more nitrogen than oxygen and traces of other gases.
http://mistupid.com/chemistry/aircomp.htm

 

[North of 60]

If you mount that non-bladder tank in the right spot it can be a good air collector.
Non-bladder tanks used to be the only thing.
As long as they have the system tapping located at the bottom and your shreader valve in the top with isolation from the system and drain valve, with a charge less than your system static cold temp all will work fine. In 20 story buildings I have seen non-pressurized open tanks at the tops of the building and the non-bladder tanks mounted correctly in the basement/boiler rm of the building. Isolate,drain and charge. The true manufactured old ones came with a isolatable sight glass.
Cheers

 

[jdboy9]

Well I guess we will find out in years how it affects the system. I would like to believe it has no effect All in all its a heck of a lot better than an OWB even if the gasification boiler needs replaced after x amount of years.