In my previous post I described how I've messed with my current CH &
HW system to make it fully pumped (S plan). I think I've messed up a
perfectly good system but it is totally undo-able. What I need to know
is from the following information would the old system have worked
successfully so I had HW only when I needed it, CH only when I needed
it, and or both. And would it have been fully pumped?

the diagram: http://www.facebook.com/album.php?ai...f&id=544791297

this is definately how the old system was piped up. when HW only was
called the HW valve opened, the pump started running, and the boiler
fired - although the valve was knackered so this actually couldn't be
tested (the valve was set to manual open). when CH was called the CH
valve opened, the pump started running, and the boiler fired. when
both CH and HW was needed both valves opened, the pump started running
and the boiler fired. on all cases the system stopped when the
approriate thermostat(s) were satifsfied (and there is NO pump
overrun).

can you tell me how this system worked unless the valves were on the
return. i have no idea. can you also label pipes 1-3 with where they
are going/coming from. they run under the floorboards so i have no
idea.

my theory is the valves are on the return. pipe 1 comes from the rads
(pipe 1 definately heats up with the CH but the rads seem to be hotter
than this pipe, suggesting a return?). pipe 2 goes back to the boiler
(pumped for both HW and CH) and pipe 3 is the flow to the HW tank, to
the coil and then to the HW valve (also the expansion tank).
underneath the floorboard i think is a T piece which splits the water
from the boiler between the HW tank and rads and can only flow if the
valves on the return are open. is this feasible? any other ideas?

Cheers,
Paul.