Sharkbite thermal relief valve?

[James23912]

Hi I asked the other day about the distance needed between water heater and water softener, reach4 dug into his memory banks for a thread from 2012, lots of info, so I started looked at expansion tanks and found this sharkbite unit that says it eliminates need for exp tank by allowing expanded water to drain out, wonder if anyone has used this? Runs about 50 bucks

https://www.sharkbite.com/products/thermal-expansion-relief-valve

 

[Bannerman]

Because that drain valve will cause water to be eliminated to drain whenever a specific pressure is exceeded, a suitable drain with an air gap connection will also be needed.

An expansion tank will be a simpler installation as it will not discard water so no drain will be needed. No water will be wasted as the higher pressure water that is absorbed by the expansion tank, will be returned to the system when the pressure is again reduced such as when a faucet is opened or a toilet is flushed.

 

[Sponsor]

 

[James23912]

thanks, that makes sense, tho I have a sump pump and drain right there, sometimes getting too many options and too much info makes me just about freeze up. I guess I should ask how often backflow happens, like is it every time water is heated or is it just an occasional thing?

 

[hj]

It COULD be every time the heater is activated. It depends on how much hot water you use.

 

[Bannerman]

Since you were questioning the distance between a water hester and water softener, I am assuming you were advised to install a check valve after the WS, which then lead to discussion about an expansion tank for your WH.

Water expands as it is heated. Water cannot be compressed so as cold water enters the WH and is heated, once no water is further being consumed, expansion will commonly push back into the cold inlet line to be absorbed by either the city water main or, if well water, into the well pressure tank.

Placing a check valve after the WS, creates a closed system as the water expansion from the WH can no longer flow backward through the WS to the water main or pressure tank. With nowhere for the expansion to be absorbed, the system pressure after the check valve will rise sharply above the usual system pressure, and often above the usual safe limit for the plumbing system. Once the pressure rises to 150 psi, as a safety device, the WH's T&P valve will typically begin to seep to drain off some water to prevent the pressure from rising further.

The amount of expansion is dependant on the quantity of cold water being heated, the initial temperature of that water, and the amount of temperature rise.

A thermal expansion tank will provide space for the expanded water to be absorbed without causing the system pressure to rise excessively.

 

[James23912]

Thanks guys, I will go with the tank, what a relief!

 

[James23912]

Sorry, I have yet another question. If I use the exp tank and a check valve, do I still need the 10' between the wh and filter?

 

[Bannerman]

By filter, I assume you are referring to the water softener.

The recommended minimum piping distance between the water heater and a water softener, filter or other temperature sensitive device, is intended to ensure no hot water can back flow into the device and damage it. The 10' minimum piping distance is recommended when no check valve is utilized as that distance should allow opportunity for any backflow from the WH to cool somewhat so it will be less likely to damage the device.

Because the check valve will prevent back flow to the WS or filter, the 10' minimum piping distance is not essential.