Need for an expansion tank for well system with water treatment/softener?

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beren

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We have a well that goes to 2 (parallel) bladder pressure tanks and then to a water treatment system (2 neutralizers in parallel) and then a softener. So: Well-->pressure tanks-->neutralizers->softener--> water heater. There are no check valves after the pressure tanks.

A few years ago we replaced our 80 gallon HW heater with a 55 gallon (largest available) and since then we run out of hot water all the time unless we really space out our showers. I am planning on adding a thermostaic mixing valve (like the Cash Acme) to the WH to allow us to increase the WH temperature in the tank. I'm worried that the hotter water will lead to more expansion.

The water heater does not have an expansion tank and never has (50 years). I was told the well pressure tanks would handle any expansion. We have had a history of leaks, but I think most of those were caused by very acidic well water before the neutralizers were maintained (and even after when we couldn't get the right mix of chemicals to reduce the pH). But now I wonder if thermal expansion pressure contributed to the leaks. All the plumbing in the house is copper (except where it has been replaced due to leakage).

Question 1: although there are no 'extra' check valves in the system, isn't there essentially a check valve in the neutralizers and/or the softener that would keep the 'expansion' from ever getting back to the well pressure tanks?

Question 2: Even if #1 isn't true, isn't an expansion tank at the WH a good idea anyway?

Thanks much.
 

Reach4

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If there is no check valve, then no need for the expansion tank.

If there is enough pipe between the WH and the softener, then expansion should not drive significant hot water into the softener. The water that does pass thru the softener on the way to the pressure tank is going to rotate the metering turbine the other way, but it still generates pulses that get counted as gallons used. This is called phantom flow.

You could prevent the phantom flow with a check valve after the softener, and then add a big-enough expansion tank. There are online calculators and tables to help you figure out what big-enough is.
 

beren

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Thank you, you just saved me some money. There's about 50 feet of 1 inch pipe between the water treatment and the hot water heater, so I'm assuming that is enough. I'm not overly concerned about the phantom flow so I think I'll skip the check valve.
 

Fitter30

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The hotter the water the more mineral will be released in the hot water heater. Here's a calculator for how much more hw you will get by raising the tank temp with mixing valve. Just change settings to gpm.
 
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