I have a swimming pool pump that I'd like to turn on if either one (or both)
of two conditions exist:

Presently the pump's power cord can be plugged into either a clock/timer so
it will turn on at certain times of the day that I choose,

OR

The pump's 240vac power cord can be plugged into a socket attached to a
'computer' on a solar heating system, and that socket will be turned on when
the computer decides the solar panel temperature is not hot enough to heat
the pool water. This allows a gas heater to turn on and heat the pool.

I would like to have the pump turn on if either one (or both) of the
conditions exist, but I need some advice. What I envision is that the pump
power cord will be plugged into some kind of back box containing a couple of
relays. The black box will have two inputs, one from the clock/timer and
the other from the solar computer. It either (or both) of the inputs has
voltage, the output to the pump power cord will have voltage. If neither
has voltage, there would be no voltage to the pump power cord.

I have the pump (750 watt), the clock/timer, and the solar computer. I need
to build the black box.

I suspect this is not rocket science but choosing and connecting the relays
is beyond me. I'd welcome any advice.

Please let me now if this is unclear and I will elaborate.

Thanks,
Clark
(in Melbourne, Australia)

"cb" wrote in message
...
I have a swimming pool pump that I'd like to turn on if either one (or
both)
of two conditions exist:

Presently the pump's power cord can be plugged into either a clock/timer
so
it will turn on at certain times of the day that I choose,

OR

The pump's 240vac power cord can be plugged into a socket attached to a
'computer' on a solar heating system, and that socket will be turned on
when
the computer decides the solar panel temperature is not hot enough to heat
the pool water. This allows a gas heater to turn on and heat the pool.

I would like to have the pump turn on if either one (or both) of the
conditions exist, but I need some advice. What I envision is that the
pump
power cord will be plugged into some kind of back box containing a couple
of
relays. The black box will have two inputs, one from the clock/timer and
the other from the solar computer. It either (or both) of the inputs has
voltage, the output to the pump power cord will have voltage. If neither
has voltage, there would be no voltage to the pump power cord.

I have the pump (750 watt), the clock/timer, and the solar computer. I
need
to build the black box.

I suspect this is not rocket science but choosing and connecting the
relays
is beyond me. I'd welcome any advice.

Please let me now if this is unclear and I will elaborate.

Thanks,
Clark
(in Melbourne, Australia)

Clark Try putting this on (sci.electronics.design ) Lots of wizards
on that site. Warren