# Expansion tank keeps failing????



## Smitten_kitten (Sep 8, 2011)

So today at work we had a service call from a women whose T+P kepts spluttering and spraying everytime the t-stat called for heat. The Tech and I hopped into the truck and headed over. On the way he told me that this wass the 3rd time the company had been over their for T+P problems. It was both our first. They have replaced the Expansion tank twice before this the last time less than 1 year ago (april 2011). Everytime the diaphragm was ruptured, waterlogged, not functioning and not allowing for heated water to expand safley We arrived and sure enough the new expansion tank installed on April 2011 was waterlogged. It was also installed on the horizontal and on a dead end both something the manufacture does not reccommend. 

We tested the boiler pressure it was fine it stayed static at 19psi, we tested the temp, it was fine. It cut off at 180 degrees. The boiler was oil fired with a beckett AFG burner and Genisys controls and natural drafting. The boiler also heated the domestic potable water. 

The tech determined that the problem was with the location of the the expansion tank. The tank was located about 1inch from the Flue stack which operates at about 600 degrees. He presumed that the heat from the stack was being absorbed by the expansion tank and thus ruining the rubber diaphragm. So we Replaced the T+P and moved the Expansion tank about 24" past the vent connector. It was also installed correctly in the vertical position but still on a dead end. (this boiler was most likley piped 30 years ago its a one pump system fyi).

Now i disagreed with him on this as the proper correction I dont think it could have been an overheating of the rubber material inside the tank. 

1. The expansion tank is tested and approved up to 240 degrees I dont think a Vent connector could transfer that much heat to the expansion tank via radiation to wipe it out.
2. The Vent doesn't stay hot that long it cools fairly quickly after the boiler is done satisfy a heating demand.

I don't think moving it will fix the problem. I could be wrong though. 
However We didn't size the Tank nor did we really pre-pressurize it we took it at factory setting and just filled it up. I am really intrested in what could ruin three expansion tanks in such a short time. Any input would be great. 

Thanks!


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## rjbphd (Feb 5, 2010)

2 things... is it Scamtrol tank?? 2nd.. tank undersized??


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## Smitten_kitten (Sep 8, 2011)

by scamtrol you mean amtrol then yes it is ha. and yeah im guessing its undersized how the keeps rupturing the bladder i don't quite know. But it was an amtrol 30 i would have put in a 60. I dont think we even checked out how much baseboard their was up there


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## rjbphd (Feb 5, 2010)

Smitten_kitten said:


> by scamtrol you mean amtrol then yes it is ha. and yeah im guessing its undersized how the keeps rupturing the bladder i don't quite know. But it was an amtrol 30 i would have put in a 60. I dont think we even checked out how much baseboard their was up there


 Well that's one mistake, not checking what kind of radiation you have on the system.. huge difference from tube finned radiator with old fashoined standing cast iron system ( better have by-pass)...


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## theplumbinator (Sep 6, 2012)

Boilers Don't have a p&t relief valve only a "p" relief valve. Water heaters have a p&t. Sounds like expansion tank is undersized to me also. I had also had an experience where the pipe was clogged with crap between tank and boiler, but that wouldn't cause tank bladder to rupture, tankless coil could be leaking into boiler causing excessive pressure also but that would be all the time wether boiler was running or not. Bad pressure reducing valve would do same thing, so u can rule them out for now. Are you sure the tridacator guage you have on the boiler is accurate? Try using a pressure guage you trust is accurate on boiler drain and compare readings. Sometimes those guages are off.


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## Smitten_kitten (Sep 8, 2011)

Thanks guys,

Hey RJ could you elaborate on what you mean by "by-pass" thanks

Plumb- yeah idk why i always call boiler blow offs t+p's bad habit i guess. Yeah their were no debris in between it had one of those auto shut offs that come with it that in my opinon are a POS we switch that out with just a ips ballvalve much better as that little rubber always gets gunked and malfunctions. And the coil was functioning fun no holes atleast none indictated and no call backs, the pressure never jumped up past 20psi even when hot. But good call on the throwing on gauges have had that mess me upo before many times. sometimes its the simple little things that i forget to do that can make a big difference so im definatley going to throw a gauge in my bag from now on to help me remember. 

Just really puzzled at what could keep rupturing the tank. I think it has something to do with incorrectly sizing the tank. We didn't even check the upstairs for baseboard wont do that again. Maybe well get a call back soon and i can further investigate what could be rupturing the bladder????


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