Some Assistance Please

[icehouse]

I could use some assistance on the wiring of FB-7 relay.
I haven't worked on Oil Heat in 15 years, but remembered this relay that mounts on Hot Water heater. What it does is it is wired if the Boiler & Hot Water Heater try to come on at the same time it lets the Hot water Heater fire, otherwise the Heater locks out and has to be reset. This is with one oil line from the tank and teed off at the boiler. Thanks for any help.

[icehouse]

Well I see none had a clue what I was talking about, so I called my old service manager(oil heat) actually remembered me all these years.
This is called a "preferance relay", and if anyone is interested it is wired the following:
Coil of relay is wired to
Motor power lead & neutral
(orange & white) of the water
heater, and the normally closed
contacts are wired to the thermostat
terminals(TT)on the Boiler relay.
This keeps the Boiler off until the
Water heater is satisfied, thus
preventing lock-out of HWH