Replacing my hot water tank, do I need an expansion tank?

Old 07-22-11, 02:30 PM
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Replacing my hot water tank, do I need an expansion tank?

I have a State brand hot water tank that is probably 20 years old, it's been gurgling for a while. I only have 38# or water pressure, #40 on a good day (I have a gauge). Do I need an expansion tank and/or a check valve? I have no expansion tank now and I wonder if I need one with my low pressure? I live at the top of a hill, therefore the pressure is always low.

What do you think of State brand tanks? I had such good luck with the last one, I figured I'd buy another one.
Old 07-22-11, 02:54 PM
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State brand is good IMO. Made by AO Smith.

Mike NJ
Old 08-04-11, 08:50 PM
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Fit that expansion tank!

I would fit an expansion tank even at the low incoming pressure you've stated. Without an expansion tank, you will be stressing the tank and plumbing fittings and reduce the longevity of your water heater.

Since the Clean Water Act, water utility companies have been fitting check valves on water meters making household plumbing 'closed' systems.

As water is heated it expands; typically 50 gallons may expand buy two gallons when heated to 120f. Previously, this expansion was accommodated by pushing a column back into the water mains, thus contaminating drinking water with water from the water heater.

Check your incoming water pressure over a 24 hour period (water pressure gauge with a static hand) and make a note of the highest pressure - between 50 and 60 PSI is an acceptable range for incoming water. The expansion tank should be pressurised at the same PSI as your highest recorded incoming pressure. Fit the tank on the cold water line feeding your heater within a foot or so of the heater. The expansion tank is fitted with a Schrader valve as fitted to automobiles. Pressurise the thermal expansion tank as you would with your car tyres.

Job done.
Old 08-06-11, 12:08 PM
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There is probably nothing wrong with your hot water tank.
Being on top of a hill you have low water pressure especially at times of high demand.
The solution is to fit a high level feeder tank, preferably with a water level more than 10 feet above your highest outlet. (higher means more pressure) (this will also allow your hot water to expand)
This will top up at times of low demand and you will then have 50 gallons of water to draw on as required.
Old 08-15-11, 07:15 PM
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the cycling of the cold water into the tank during make up is enough to defuse the pressure worry on a normal day of stuff being washed and showers

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