On Jun 6, 1:04*pm, "Heliotrope Smith" wrote:
wrote in message

...



Background info:
Potterton *Suprima 80 boiler 5 yr old
Honeywell Timer St6400
Honeywell 3 way valve V 4073A 1039
Pump Grunfos Selectric UPS 15-50
wired to Y plan
normal operation allows separate H/water from Heating or both together
all rads have thermostats

Problem:
Central Heating and water both switched off at timer yet yesterday
evening the pump was running and continued to run until we slightly
turn the white control anti-clock on the side of the Grunfos pump, the
pump then stops running.
Switch the Honeywell timer to hot water the boiler lights up but the
pump does NOT operate until we turn the white control back slightly
clockwise to the 90* setting mark on the pump.
So is this another 3 way valve issue or the pump not receiving the
correct signal ?

Any ideas or suggestion most welcome, some years ago we were able to
replace the 3 way valve after good advice from Roger Mills.

Happy to provide more info if required.
Steve

Could be a sticky 3 port. Switch off mains going to boiler and check the
manual arm on the valve head, if *you can push it side to side with no
resistance then the valve is jammed. If however there is a strong resistance
and the arm returns automatically when released then the valve is probably
ok.

The symptoms you describe suggest to me that the pump overrun is faulty and
not switching off in which case a new *control board would seem to be the
only cure.

*The white control on the pump is in fact the pump speed selector and it is
not a good idea to switch off the pump by setting between speeds as this
would allow the boiler to fire up with no circulation and can cause damage
to the boiler.

Ok here 's the very latest _ the pump stayed back on after the mid day
hot water cycle had finished, so I took the cover off the 3 way valve
and found the earth wire was off inside the 4073A unit , re-attached
the earth wire switched off the circuit tested the value operation as
you suggested and found:
the 4073A 3 way valve lever was in the central position ie the middle,
when I pushed against it to the right there is resistance and then the
lever returned to the centre position [presumably on the return
springs inside the unit]
Does this suggest the valve itself is OK and its just the Honeywell
4073A unit with a malfunction ( this one has been on since 2005).
Hope this piece of info helps with the issue at hand.

PS thanks for the info on the pump itself the speed control seems to
be variable , we just turned it off last night.
I would not leave the cent heating on with the pump speed turned down/
off