"Simon Hawthorne" wrote in message
...


I thought it was a 'gravity'
system.
.......................................

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal? Where
is the water going? ..............................................


This operation appears to be the same as my 1980s bungalow CH which it is
not a gravity system. It is fully pumped.

Below the thermostat set temperature, the 2- port valve is open, so water is
pumped to both radiators and the DHW coil.

When the thermostat set temperature is reached, the 2-port valve is closed,
so water is pumped to the DHW coil only.

That is the pump runs continuously. After the pump, the pipe Tees off to the
2-port valve and to the DHW coil(via a stop cock).

The DHW cylinder does not have a thermostat.

The timer also allows either DHW or DHW with CH or both off.

Hope that makes sense


Keith G. Powell