Pump does not switch on until both heating and hot water are

[bowler01]

I have a Danfloss FP715 Si 2 channel programmer.
If I switch on central heating only the light comes on but the pump does not come on and the rads stay cold.
If I then switch on the water as well, the pump comes on and the rads heat up.
I am assuming that I should be able to switch on heating and water individually.
Any advice please?

 

[JohnD]

when was this programmer fitted? Who by? Did the system wok properly before that? How long have you had this problem? It can be set for gravity HW.

How old is your boiler, and what make and model?

Is yours a Housing Association home, or private rental? When was the boiler and programmer last serviced? this is an SI programmer, which is designed to stop working properly if it is not regularly serviced and reset.

 

[bowler01]

Thanks for your reply.
I dont know the full history but I live in a private house.
The boiler is an Alpha CD18R.
The controller and timers work fine apart from this oddity.

 

[45yearsagasman]

More than likely a fault in something like these:- View media item 30391 View media item 38425

 

[bowler01]

A bit more info-

Pump (primaflow)

3 way valve (cant see a name)

Is it possible that the controller is wired incorrectly?

 

[Whitespirit66]

Is it possible that the controller is wired incorrectly?

When did everything last work correctly? Has anything been touched before it started playing up?

If the fault just started happening by itself, not a wiring fault.

Could be programmer, but more likely to be 45years' suggestion of motorised valve.

 

[Andy128]

It's probably set up that way so the water tank is used as a bypass, unless of course you cannot get hot water separately without running the CH at the same time. As mentioned, that would point to a fault either with the programmer or the MV.

Some of the Danfoss programmers only have a two-way rocker switch either for Water & Heating or Water only (no option to run CH separately), often depending on the system layout (plan).

 

[JohnD]

when was this programmer fitted? Who by? Did the system wok properly before that? How long have you had this problem? (etc)

 

[bowler01]

when was this programmer fitted? Who by? Did the system wok properly before that? How long have you had this problem? (etc)

I did mention above that I did not know the history of the system.

I may have to live with it.

 

[Agile]

For us just reading this you seem to be very economical with the information.

You say you dont know but dont explain why.

Have you only just bought the property?

If so then the advice is to get a gas reg engineer to service the boiler and inspect the system and see if its working as designed or if there is a fault.

Tony