Circulation pump on solar system.

With regard to a circulation pump on a solar system should it be on all the time. I haven't seen the system yet myself but am having a look at it later in the week and the client recons that it should be on constantly. Has any one any experience with these. Also there is a back up element that they are telling me is on constantly! I have not got any drawings as yet but certainly does not sound right.

There's no point having the circulation pump on when the panel is not providing a heat gain. In fact, you will lose heat if it is. Some systems use a photovoltaic panel to power the circulation pump.

By back up element, do you mean immersion heater?
Leo

Leo said:

There's no point having the circulation pump on when the panel is not providing a heat gain. In fact, you will lose heat if it is. Some systems use a photovoltaic panel to power the circulation pump.

By back up element, do you mean immersion heater?
Leo

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Yes. However I have found out since that this is not a requirement as we have a Nilan heat exchanger tied into the system.
The client has since come back to me and told me that the pump is only for a towel rad. So I will wire it through a time clock.
In your experience does the Nilan and solar provide enough hot water or would should I wire the back up emmersion?