"Clive" wrote in message
...


Naive question. Are the 2-port valves on the boiler / supply side
of the circuit or the “demand” side of the circuit? I am thinking they
should be on the demand side to enable either circuit to be switched
independently – giving independent HW and CH. I can understand the
operation of a 2-port valve on the sealed loop that goes around the
radiators but I can't understand how such a valve would work on the HW
side. Surely the DHW just comes off the top of the HW cylinder – and
the water removed is replaced by cold water supplied from the tank in
the loft. So what flow is the second 2-port valve controlling?


*****

My setup is:
Boiler flow pump 2-port valves HW/CH boiler return.

The HW 2-port valve is controlling flow of water from the boiler through the
indirect coil in the HW tank.

The lever that you mention in your other post is to manually open the valve.
They latch in the open position. If the valve is already opened by the
system the lever moves freely, otherwise a bit of force is required. When
the valve is open the boiler should fire.