Leaking Presssure Relief Valve / Expansion Tank


Old 03-03-15, 11:50 AM
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Leaking Presssure Relief Valve / Expansion Tank

My just-under-3-year-old FWH single-zone system (that some on this forum assisted me in choosing) recently developed a leaking pressure relief valve. The technician could find nothing obviously wrong. He zeroed out the pressure on the system, checked the #60 Extrol tank, which had been installed in late 2012,(6 months after the original installation of the system, replacing the #30 Extrol tank).

Everything seemed OK, but it still ran up to 30 PSI, and leaked.

It is an old home, about 2800 SF/2-story, converted steam system with huge radiators, huge cast iron piping, much water volume. Six months after the installation, at the new heating season, the #30 was blowing the PRV, so they put in the #60. It ran at 25-lbs, but it did the trick until recently.

Just for fun today, when he could find nothing glaringly wrong, the technician decided to try a new expansion tank. When he was taking the old one off after depressurizing it, he slowly unscrewed it, holding it there momentarily as it more-or-less finished leaking. As he finished unscrewing it, and then while slowly lowering it, it suddenly and instantly sprayed a fair amount of highly-pressurized water for 3 or 4 seconds, like a gusher, sending a stream of water to the ceiling, as well as getting fairly soaked himself. He was shocked and indicated that that had never happened before.

The new tank (HTX #60) seems to be holding at 25-lbs at full operating temperature—so I hope the problem is solved. Does anyone have any opinions on what happened, and if the problem is likely fixed?

I have been charged $95- for the “diagnostic fee” and $133- for a “Misc. Repair”. $228- total. Have I been mis-treated? The Extrol tanks seem to have a 5-year limited warranty, but it is unclear how that all works.

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Old 03-03-15, 12:07 PM
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The 5 yr. warranty is exactly what it says. If it fails within that time it's covered. That is the part, not the labor.
An honest contractor would have charged you a service call to install the free tank replacement.
There apparently not enough money there for him to get drenched.
If you're not going to use him again I would call Amtrol and explain the situation to them.
My best guess is that this guy charged you for a new tank, then took the defective one and will turn it in under the warranty for a new one for himself to sell again at 100% pure profit.
You might want to call him and get your tank back and see about turning it in yourself.

When you have cast iron radiation #60 extrol should in most cases be the minimum tank size but depending on your system and it sounds like it's good size could require a larger one.
I did one a while back similar to yours, maybe a bit larger with radiators converted to hot water andit took a #90 extrol because of the large water content.
Old 03-03-15, 02:42 PM
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while slowly lowering it, it suddenly and instantly sprayed a fair amount of highly-pressurized water for 3 or 4 seconds, like a gusher, sending a stream of water to the ceiling, as well as getting fairly soaked himself.
The only way I can envision something like that happening is if the diaphragm got 'stuck' to the inside wall of the tank. Then, with the pressure released from the water side and being jostled around, it got 'unstuck' and spewed it's guts...

Seems unlikely to me, but SOMETHING had to cause that and I can't think of any other reason...

I have heard of something similar, actually the OPPOSITE happening on two occasions. The new tank was installed and did not fix the problem. Turns out that the diaphragm was in fact 'stuck' to the top of the tank, and wouldn't let water in. Letting the air out of the tank while installed unstuck the diaphragm and when repressurized, it was OK afterward.

One of the occasions was a poster on here... who as I recall had called tech support and they told him that was the problem.

I've just never heard of it happening in reverse. Glad it wasn't me that got the shower! (as much as I usually need one!)

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