Replace expansion tank?

[DIYorBust]

My hot water heater has an expansion tank off its feed. The water supply is municipal with a prv. The other day I turned on the water heater when the house was about 50 degrees. I observed later water on the kitchen floor. It appears to me the water blew by the compression fittings on the sink supply, its a hard supply line. Perhaps not the worst thing that could have happened. Now I checked the expansion tank and found the charge at 12psi. The bladder appears intact, no water comes out the valve only air, and it accept a charge to 60psi. The Tank probably dates to about 2012, I was not the owner then but that's when the water heater was installed. Do I need to replace the tank or just check the charge more often?


Thanks

Diy

 

[Tuttles Revenge]

Theres not much downside to using it. I've only seen one expansion tank actually leaking water (homeowner tried patching the hole with scotch tape!) one time. Perhaps a more frequent monitoring of its condition. Thud on the water side Tink on the air side when you flick it with your finger.

 

[Sponsor]

 

[DIYorBust]

Cool. I don't want to replace what I don't need to, but I often set back the thermostat and turn off the water heater, and then activate them remotely so I'll arrive at a warm house. We're on oil so the setback save me thousands, but a leak could really cost me. Should I consider putting a relief valve in the cellar near a drain?

 

[WorthFlorida]

Even with an expansion tank, it may not be able to absorb all the pressure the expanding water can apply especially when its at 50 degree water temp. The compression ring failure could have been just a bad fitting or it was not tighten enough. Most water appliances and fittings are designed for 150 PSI max. To be sure the next time put a tattletail pressure gauge on a hose fitting or spigot. Fire up the WH and do not run any water as it gets to the set temperature. The red needle will be pushed to the highest reading. Is this a separate WH from the furnace used for heating?

 

[DIYorBust]

Ok I'm going to give that a try this weekend, although the recharged tank may reduce the pressure. The water heater is a stand alone oil fired cylinder, and there is a separate boiler with its own burner.

 

[Jadnashua]

There's no downside to having a larger ET than necessary...the larger it is, the less pressure gain you'll see when you heat the water, but obviously, it will take up more space, and cost a little more. Being larger also means it won't flex as much, and that may let it last longer, which may offset the slightly larger cost.

You need three numbers to size an ET properly:
- incoming water temp
- outgoing water temp
- volume of water being heated

There are numerous on-line calculators that will tell you the minimum sized tank you need, or, you can look up the equations and do it yourself.

You can think of the ET as a tire when it comes to holding air. The air valve itself isn't perfect, and the cap is actually the better seal than the valve itself. Over time, you might get a little air to migrate through the bladder, but it would be very slow and very small as long as it's intact. BUt, like a tire, you may need to pump it back up again, eventually.