Thermal expansion tank needed?


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Old 11-18-14, 08:05 AM
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Thermal expansion tank needed?

My pressure relief valve on my water seems to be failing (Or operating perfectly). I have a good flow of water coming from it, also before shutting it out, water seemed to be leaking from the threads as well. I'm assuming I need to install a thermal expansion tank, but before doing so I seen in researched it should be required in all homes hooked to a city water supply. I however am not, I use well water and a water pressure tank. Everything I've read has stated thermal expansion tanks are needed because of check valves, I however don't have any check valves in my system.

So although evidence says my water heater pressure is expanding with no where to go, I just wanted to know what is more likely. Valve failure, or pressure being too high without the thermal expansion tank?
 
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Old 11-18-14, 03:11 PM
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Welcome to the forums! Thermal expansion tanks are required in some jurisdictions, and are a good idea at any rate. When the water in your system expands due to being heated, it needs somewhere to go, so the tank takes up that slack. Replacing the T&P valve may be good, especially if it has age on it. How old is the water heater?
 
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Old 11-18-14, 09:48 PM
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I'd start by just replacing the valve.
The pressure tank you may be referring to that is near the pump has nothing to do with the hot water tank.
Checked the temp. of the water at a faucet?
Should not be higher then 120 Deg.
Over temp. can cause pressure build up.
 
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Old 11-19-14, 06:48 AM
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I think I'd start by checking the pressure in the hot water system before, during and after a heating cycle. It is quite possible that you need a new T&P relief valve, but I wouldn't start replacing parts till I knew what pressure I was working with. It's also possible that your pump is providing much higher pressure than it should, but you'll never know if you don't check the pressure.
 
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Old 11-19-14, 04:37 PM
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Replacing the T & P valve tomorrow. The pump pressure, and the water pressure tank are right where they should be. Heater is only 5 years old.
 
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Old 11-19-14, 04:47 PM
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Yes the well bladder tank will take up the thermal expansion...

Replace the relief valve and see how it goes...

Have you noticed high hot water temps?

What is the max well pressure set too just for reference?
 
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Old 11-20-14, 03:14 AM
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Missed the well thingy. Sorry about that. My comments referred to municipal water supply.
 
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Old 11-22-14, 08:16 PM
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Turned out the tank failed right where the T&P valve would screw in. Under warranty, replaced with a new one. Thanks for the input guys.
 
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Old 11-22-14, 08:19 PM
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Just for kicks, haven't noticed any high water temps, was 101 degrees (with the tank leaking) at the faucet. Pressure switch is a 40|60 switch, bladder gauge verified. Was an American Water Heater. Real quick about the warranty as well.
 
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Old 11-23-14, 05:32 AM
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Thank you for the reply on the outcome.. Glad it all worked out...
 
 

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