The pressure was fairly steady at 45 psi. However the hot faucet in the 2nd fl bath was steady while the shower cycled from normal to about 10F higher. The bathroom was done by the previous owner in ~90 so I wouldn’t think that the shower valve would be anything other than simple a mixing valve…guess not. Thanks for your help. I’ll order a flex combo rod for my old HWH from you guys since I haven’t been able to get that hex rod out.