does the navien npe-240a tankless require an expansion tank?

[smartAutomation]

Hi,

I would like to check if does npe-240a tankless require an expansion tank?
I have installed NavieCirc at the farest faucet and I did install Navien Link Lite WiFi Sytem.
I was able to get the hot water really fast instancely base on the schedule that I set at my Navi LInk App via my phone.

However, whenever the hot water circulator is running the water pressure went up from 65 to 81 PSI.

 

[Breplum]

The NaviCirc doesn't determine need for exp device. What does is if you have a over 85 psi from the street and PRV on the dwelling that does not have "bypass" feature, or a check valve on the cold water side, creating a closed system.
Do you have isolation valve kit for descaling...just can't see.

 

[Sponsor]

 

[GReynolds929]

If you have recirculation Navien wants an expansion tank installed. We usually install one of the little mini tanks about the size of a softball.

 

[ptalar]

If you have recirculation Navien wants an expansion tank installed. We usually install one of the little mini tanks about the size of a softball.

Where do you install it? Anywhere in the cold water supply line or near the tankless water heater?

 

[GReynolds929]

Cold water line near the unit. Usually right below the service valve.