Got a fully pumped system, with cylinder thermostat and 3 way valve (no
room therm)

HW seems to work OK - Heats up, cylinder themostat cuts off and boiler/pump
switch off.

However have got problem with valve (or rather the way it has been wiring!)

When HW & CH are selected (programmer only allows HW only or CH&HW) valve
remains in B position (HW only), boiler and pump power up and tank heats.
When the tank reaches temp the thermostat switches off.

At this point the motor powers up and moves to the AB position, the
microswitch is activated and the motor stalls in the AB position, The boiler
and pump however dont run and so the heating is in the off state.

If I manually slide the lever on the 3way valve over to the A position
(heating) then the boiler and pump switch on again

Which wires are connected incorrectly?

Any suggestions?

"John" wrote in message
...
Got a fully pumped system, with cylinder thermostat and 3 way valve (no
room therm)

HW seems to work OK - Heats up, cylinder themostat cuts off and
boiler/pump
switch off.

However have got problem with valve (or rather the way it has been
wiring!)

When HW & CH are selected (programmer only allows HW only or CH&HW) valve
remains in B position (HW only), boiler and pump power up and tank heats.
When the tank reaches temp the thermostat switches off.

At this point the motor powers up and moves to the AB position, the
microswitch is activated and the motor stalls in the AB position, The
boiler
and pump however dont run and so the heating is in the off state.

If I manually slide the lever on the 3way valve over to the A position
(heating) then the boiler and pump switch on again

Which wires are connected incorrectly?

Any suggestions?



Have a look at http://content.honeywell.com/uk/homes/systems.htm and scroll
down to the wiring diagram for a Y-plan system.

Yours should be like this, except for replacing the room stat with a link
between 4 and 5 in the 10-way junction box.

The most likely candidates are either a missing live feed for Hot Water OFF
from the programmer to terminal 7, or one of the connections to the cylinder
stat missing. The grey wire to the 3-position valve *must* have a live feed
when hot water is off or satisfied - otherwise the whole thing won't work.

Roger