I've just installed a Stuart Turner Monsoon Twin pump (3-bar, positive
head) and it's misbehaving: starts fine, but the hot side will not
switch off in normal use. Instead, it continues to run unless either I
cut the power, or turn off the isolating valve.

Looking at the ST website suggests this may be either a dodgy reed
switch or PCB (switch is in the right place and seems to test OK with a
fridge magnet), or a leak in the pipework. None of the outlets are
letting by, and I don't think I've got leaks elsewhe nor does the
pump restart of its own accord.

Being, um, parsimonious, this is a second-hand unit but at least
cosmetically is in perfect condition. I've got no reason to believe the
pump itself is faulty but suspect it's something about the interaction
with my pipework: I'm pumping the whole house (well, bathroom and
kitchen) not just a shower.

I'll call ST after Easter, but meantime any advice about what to try,
test or change would be appreciated.

--

John

On 3 Apr, 17:49, "jsabine" wrote:
I've just installed a Stuart Turner Monsoon Twin pump (3-bar, positive
head) and it's misbehaving: starts fine, but the hot side will not
switch off in normal use. Instead, it continues to run unless either I
cut the power, or turn off the isolating valve.

Looking at the ST website suggests this may be either a dodgy reed
switch or PCB (switch is in the right place and seems to test OK with a
fridge magnet), or a leak in the pipework. None of the outlets are
letting by, and I don't think I've got leaks elsewhe nor does the
pump restart of its own accord.

Being, um, parsimonious, this is a second-hand unit but at least
cosmetically is in perfect condition. I've got no reason to believe the
pump itself is faulty but suspect it's something about the interaction
with my pipework: I'm pumping the whole house (well, bathroom and
kitchen) not just a shower.

I'll call ST after Easter, but meantime any advice about what to try,
test or change would be appreciated.

--

John

If shutting the isolator stops the pump it suggests that water is
going somewhere and your reed switch remains "on" as a result. Have
you got a hot water leak somewhere which shows up when the pressure
rises due to the pump running. This might be from the hot into the
cold system in a mixer valve which is letting by.