Heating?

In some old style systems the water tank was heated by gravity ( a throw back from the back boiler fireplace) the c/heating by a pump,one way to test is to put the programmer on to "hot water only" in gravity fed systems the pump does not run but the boiler does

toptrish
September 2014

I think that there will be a 3 port mid position valve (diverter) but I can't imagine it being fitted under the floor.

The valve directs the heated water either to the cylinder or to the radiators or both - as required. The pump just continuously circulates the heated water - as directed by the diverter valve - as far as I know.

Follow the route of the hot water outflow from your boiler - or the control wires that run to it - they will eventually take you to the valve - I think they usually put the valve close to the hot cylinder.

I am not qualified to answer you with any confidence.

Good luck...

I K Brunel
September 2014