replying to fftt, dp3 wrote:
Even if the system is closed I would ask of the expansion of the steel tank
itself somewhat matches any water expansion? additionally if there is a
anti-water-hammer device (i.e., shock absorber) anywhere in the system (often
found at washing machine or shower or sometimes whole house - simply a
vertical pipe filled with air) then I wuold think a thermal expansion tank is
not actually needed.

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