Hot water circulation (for taps)

[moyesboy]

Previously my system had a hot water circulation pump and pipe stat wired to a point that was live when the hot water was on even when the cylinder stat was hot (hot water scheduled on but switched off by the the cylinder stat.)
Now i don't have that switched live available because I have a WiFi cylinder stat and the relay switches off with that.
Circ pump wired to the relay will only circ when the hot water us on but below tempature (not often enough to be worth it).
Crculation pump must not be on when hot water is off or the circulation cools it down while it's not heating.
So I can't see how to make it work unless I can go back to the mechanical cylinder stat and have the hot water relay switches on whenever the hot water is timed to be on. I'm not sure if it will work like that though.
Any suggestions?
Theory says there us an energy saving from a hot water circ pump if the pipe runs are long enough, as you run less cold water waiting for it to run hot (the lagged hot tap circuit becomes an extension of the hot water tank).

[Richard]

There is no way to have a secondary hot water circ pump with evohome already using a hot water kit for the cylinder. This would have to be put on a separate timer or Wi-Fi switch.