Expansion Tanks,,,,

Unknown

I see many installers favoring pre-charged tanks.



Other than a "cleaner install" , what`s the difference?,,,, if tied-in at the right place(with proper air-keeper protection) both do the same thing,,,, am I missing something?



I have seen osmosis play havoc on some inexpensive pre-charged tanks,,,, but not any joist mounted with a proper air-keeper.



Thoughts?



Kinda like an air-separator(down below) on a Prestige, EH Tony S?





 

Al Roethlisberger

Interested as well....

My old converted(to closed circ) gravity system currently has a 30G air-cushion tank suspended in the joists, but was never installed correctly, gets water logged, and is pretty rusty.



As part of my planed boiler repipe I was sizing a new diaphragm tank and based on the 380G capacity of my system, CI radiators, the B&G conversion chart sized out their(sourced with Amtrol, same size) 160V tank.  It's about $500 retail.



And I'm not even sure that original 30G tank was sufficient, but I bet even at a larger size it would be cheaper as I already have some airtrol fittings.



But I do like the ease of installation and "zero" maintenance of the newer diaphragm units.



So I too am curious to hear some thoughts on the pros/cons of the "old" air cushion tanks and "new" diaphragm units.



Al

Unknown

Al,,,

a 30 Gal. tank provides alot of system expansion,,,,, my advice is, if you can apply the appropriate fittings(B&G Airtrol),  connected to "the proper" air-scoop or the like, you should have no problems. 

TonyS

I still tie into tanks

that are riveted. Before welding was invented! The tanks are probably going to last longer than me. As long as they have the airtrol tank fitting to stop thermal convection they work fine. And even if it does go bad in another 5 years, so what. I isolate them with full port valves. I think for the most part they just got a bad rap because so many were piped in wrong. In Dans book...Pumping away he talks  quite a bit about air traps in boilers and the proper fittings and piping detail for expansion tanks. When you think about it, why would I want to install a tank with a rubber bladder? Something I know is going to fail. A regular tank with air will always last alot longer and they kinda hang up out of the way in the joist. Any oxygen in the air inside is soon attached to the ferrous walls and only nitrogen remains.

Al Roethlisberger

Longevity of modern bladder tanks?

That's a question I've wondered:  What is the average lifespan of the latest generations of bladder based tanks?



Al

EricAune

Longevity?

For the relatively low cost associated with standard size bladder expansion tanks I think most would consider the life span to be sufficient.  Failure of these tanks is mostly due to the improper sizing "that size seemed to work for the last job" technique.  Placement of the tank and water quality could play a role too.   



I jump at the chance to re-use an existing tank if it and its fittings check out, but to replace it with another of the same would seem like a bad idea.  When I install a bladder tank, and at the first sign of a leaky relief valve or noise in the system, there are no valves for the a curious "tinkerer"  to mess with tank which has been the origin of many water logged tanks upon arrival to a no heat call.