# hot water heater



## tuffy (Nov 26, 2017)

I have a reliance 501 hot water heater model 64020RS with 2 4500watt heating elements and only 1 thermostat which is on the bottom element. Problem is we have to keep the thermostat at the lowest setting or the pressure relieve valve pops off. which gives us almost no hot water. would this be the thermostat or pressure relieve valve?


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## JoeD (Nov 26, 2017)

The thermostat seems to be working since adjusting it lowers the temp.
It could be the TPR valve or you could need a pressure tank. When water heats up it expands. If you have a pressure reducing valve(PRV) the pressure of the water in your will rise.


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## tuffy (Nov 26, 2017)

What is a pressure tank? Is that what the TPR goes into? In that case I need a new water heater? I don't have a PVR.


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## joecaption (Nov 26, 2017)

Here is a picture of how a pressure tank would be plumbed in.
https://www.anthonyphc.com/kansas-city-water-heaters/
If it mine I'd start by removing and replacing the TPR valve with an exact replacement.
Most have a tag on them making it simple to find the right one.
Shut off the incoming water, shut off the heater, open up any hot water side of a faucet to lower the pressure, leave it open, then connect a hose up to the valve to the drain valve on the bottom of the tank and let it drain for about a min. (there is 0 need to drain the whole tank!)
Remove and replace the valve.
Once changed open up the main water valve first, let the water run out of that open faucet valve until you get a steady flow of water, then turn the heater back on.


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## JoeD (Nov 26, 2017)

tuffy said:


> What is a pressure tank? Is that what the TPR goes into? In that case I need a new water heater? I don't have a PVR.


If you don't have a PVR then the TPR could be defective. They should cost less than $20 so I would try replacing it.


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## tuffy (Nov 26, 2017)

I will go out and get a TPR.thanks for all your help.Joecaption thanks for the picture now I know what a PVR is and thank you for the play by by play of changing it.


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## joecaption (Nov 27, 2017)

If it's an older heater (over 5 years old) I make a habit of also changing the Anode rod at the same time.
Simple enough to do if you have the right tools.
Everyone I've changed was so tight I ended up using a air impact wrench.
http://www.waterheaterrescue.com/Longevity/water-heater-anodes.html


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