Replacing expansion tank

bobar

I have a gas-fired Vitodens 200 for radiant floor heating and DHW.  It was installed 4 years ago and the expansion tank has sprung a leak, actually several pinhole leaks from internal corrosion.  The tank is an Amtrol model 30.  I have little confidence in the installer, and for that reason and to save some $$ would prefer to do it myself.  It's very hard to get competent technicians here in New Mexico.  I am considering using an Amtrol Extrol RX-30 as it has a plastic liner for corrosion resistance and is said to be designed for high efficiency radiant systems.  My question is, what is the procedure for replacing the tank?  It would appear that one would shut off the boiler, shut off the water, unscrew that old tank, screw on the new tank with some teflon tape... and then what?  Is it just a matter of turning on the water and opening up the manual air bleed valve at the top of the unit until all the air seems purged?  Any help would be appreciated.  I have some mechanical skills but would not hesitate to hire help if I think it's needed.

thanks much

Bob

Big Ed_4

Expansion Tank

Shut off the water to the system , shut off any isolation valves to heating zones , attach hose to boiler drain or drain valve that is not isolated from the tank . Adjust air charge of new expansion tank to match normal system charge .. Prepare tank with pipe dope .. Drop system water pressure ..Remove old tank with a 7/8" open end wrench . Expect ruptured tank to be weighed with water ..Spin on new tank ... Tank should be hanging down and wet , tap up .. Tank up can catch air and rust out ....



My concern why so much rot... Was a oxogen barrier pex used ?

IndianaJones

expansion tank pinhole leak

I have an Amtrol 60 Extrol expansion tank installed on my hot water house heating system.  It's only 5 years old, but has already sprung a pinhole leak (I've attached a photo of the hole).  It was installed (by a professional) about 3' above the boiler, facing down, so I suspect air was trapped inside it, and suspect that may have sped up the rusting process.  (Your post seems to confirm this because you suggest the tank should be hung down so air in the tank can bleed out the top.)  Am I correct that hanging it the wrong way caused it to rust out early?  5 years seems like an awfully short life span for this tank.  It is possible the tank was also touching the wall on one side, and perhaps rubbing against it.  The wall had sound absorbing tiles on it, with nothing metal to scratch, so I'm doubtful the wall to tank contact point could have caused the leak, but its curious the leak was on the side that was very near the wall.  Is that a possible cause of the leak?  If so, should I ask the installer why he allowed the tank to rub against the wall, in addition to asking why he installed it upside down?  Any other words of wisdom as to why the tank only lasted 5 years would be appreciated.  The installer charged me $284 for the tank alone, so I'm not anxious to spend that every 5 years.  Thanks!

SWEI

Oops