anti back flow device

[sarg]

He would install the cut off valve upstream from the expansion tank typically.

For me to better understand ..... You have the heater and then a shut-off valve and then the expansion tank ? and that is the norm?
So if one is working on their toilet and has the water turned off at the described valve ... and the heater is left "on" .... the expansion tank is then excluded for the duration?

 

[Twowaxhack]

The expansion tank is usually placed downstream toward the water heater from the water heater cold water valve.

But it doesn’t have to be. The expansion tank can be any place in the closed system. A shut off valve being turned off for maintenance isn’t considered by the code.

 

[TomFOhio]

If your just replacing the water heater it is nice to be able to shut the valve off and to be able to replace the tank without
shutting off the main.

 

[Twowaxhack]

If your just replacing the water heater it is nice to be able to shut the valve off and to be able to replace the tank without
shutting off the main.

Isn’t that how it’s done everywhere ? Each appliance has a stop valve ?

 

[Rossando]

What size heater? If it's a 40 or 50 you can use the 2.5 gallon unit but I have seen the 5 gallon for 50/75 gallon water heater installed work better. I did a insurance job and this guy's pressure was so high around what you stated of 120psi and the smaller 2.5 gallon unit couldn't help so I swapped it out for the 5 gallon and problem solved no more pressure rise.

 

[TomFOhio]

Isn’t that how it’s done everywhere ? Each appliance has a stop valve ?

He was talking about putting it below the exp tank I think