Stuart Turner shower pump problem.

[dobbslc]

Help!
My 3.0 bar negative head shower pump is playing silly ****'s and I can't work out what's wrong with it.
I switched it off and isolated the water to finish some pipework off and when I turned it back on it was dead.
I ended up with a second hand pcb and it will now just cycle off and on when the shower is turned on.
It stays off when the shower is off so it's not leaking pipework etc.
The reed switches are ok, the pressure vessel seems ok and is pumped up to 0.9 bar, could it be a dodgy pressure switch?
They ain't cheap so I don't want to replace it if it's not that!
Help!!!

 

[Pigeon_Droppings2]

On mine it was the stupid magnet things...they basically rusted away...so even though the flow bits were there the little tiny magnets had mostly gone so it wouldn't work properly .

Seem to remember theres a quick test...if you plug in (unplumbed) and flip it upside down and back upright and the pump fires and stops then the flow switches are probably OK.

Mine isn't negative head so I know diddly squat about those!

 

[Seadog]

There's a plastic shuttle valve that disintegrates, so it never builds sufficient pressure to activate the cut-off switch. I made one for a 25 yo pump from Delrin.

 

[dobbslc]

The magnets look fine and seem to switch perfectly every time.

 

[dobbslc]

There's a plastic shuttle valve that disintegrates, so it never builds sufficient pressure to activate the cut-off switch. I made one for a 25 yo pump from Delrin.

I think mine is the opposite to that as it shuts off when it should stay on.

 

[dobbslc]

An update, I've replaced pressure switch and it's no different
All the other sensors are ok ie reed switches.
If I turn down the valves on the supply side of the pump it works ok BUT I obviously loose some flow, I thought it could be blocked filters in the shower bar and on inspection found this.



I cleaned them out thinking it's solved but it made no difference
It's like the pump thinks the shower has been turned off and shuts down then when the back pressure in the pipes has dropped it starts up again.
Weird but does anyone think the pump might just be too powerful for the pipework?

 

[Seadog]

Weird but does anyone think the pump might just be too powerful for the pipework?

It used to work, did it not? If you've not changed any pipework why would it be that?

 

[Onoff]

There are often mesh filters similar to that in the shower bar / mixer itself. If flow is low it won't kick the pump in. Skip to 2m25s:

 

[Pigeon_Droppings2]

I started with 3bar...replaced with 1.5...we are on a water meter and it made a noticeable difference to the water bill.

I switched from Stuart turner to salamander. One of my (many!) 3bar pumps failed when the impellers got stuck. Worth checking they turn freely....you can spin them thro the pipe holes.

 

[dobbslc]

It used to work, did it not? If you've not changed any pipework why would it be that?

When I think back those valves were not fully open before I started work on the pipes, it's a long time ago I fitted it so it might have been like this for a few years.

I started with 3bar...replaced with 1.5...we are on a water meter and it made a noticeable difference to the water bill.

I switched from Stuart turner to salamander. One of my (many!) 3bar pumps failed when the impellers got stuck. Worth checking they turn freely....you can spin them thro the pipe holes.

Everything is free, no funny noises etc.
It's literally like it thinks the taps have been shut.

 

[Pigeon_Droppings2]

Take it all apart and post pics I reckon...it'll be like a forum equivalent of chat gpt .

On mine I went thro all sorts of nonsense...there was a point where I thought maybe it was an air lock!

I now always buy exactly the same pump....I have a set of old spares and a couple good pumps ready to go it when it breaks again!

 

[dobbslc]

I have a spare positive head pump with one knackered brass end and if I ever finish the ensuite I'll have another one spare that's currently feeding the bathroom.

 

[dobbslc]

The poxy thing woke me up this morning pulsing off and on when the youngest had a shower
I've ripped into it tonight and took the shower bar off and pulled out the none return valves to check for a blockage and it was clear, I even ran the pump with the shower bar off and it works fine with plenty of flow so I don't think it's a blocked pipe etc.
I swapped it with the identical one from downstairs and its made no difference.
It'll only work if I really turn down the cold valve on the supply side of the pump
I'm getting to the point where I might have to spend money and buy a smaller 1.5 or 2.0 bar pump to see if it's just the pump pushing too much water.
Arrrgghhh

There are often mesh filters similar to that in the shower bar / mixer itself. If flow is low it won't kick the pump in. Skip to 2m25s:

It starts fine every time it, what it's doing is stopping during a shower every few seconds unless I turn the supply cold water down.

 

[Pigeon_Droppings2]

Are you sure both magnets were intact when you stripped the flow valve....sounds a lot like mine until it eventually stopped working entirely.

 

[dobbslc]

I did some experimenting last week
I tested the old pressure switch and found it is operating (turning off) at 1.3 bar!
They are rated at 1.5 bar .




I took it apart and added an extra spring under the diaphragm and slightly stretched the original spring and got it to work at about 1.8 bar.
The thing is, why would they fit a 1.5 bar pressure switch to a 3 bar pump? This switch is also listed for just about all of the older Monsoon pumps up to 4 bar!
I've also fitted and tested a brand new original Stuart Turner pressure switch and that was operating at about 1.4 bar.
I then fitted a pressure gauge to the pump and tested what it's actually producing.
Bang on 3 bar with the pressure switch linked out so the pump runs constantly and just over 2 bar with the shower valves turned on and flowing water.

So it looks like the pump is working fine but due the back pressure whilst in use being higher than the pressure switch setting is just turning off

 

[dobbslc]

I've now got an adjustable pressure switch to see if this will fix the pulsing if I can turn it up a bit more than 2 bar.
Feeling too rough today to bother with it though.

 

[dobbslc]

I set the new switch to 2.4 bar and tried it.

It's better but the pump still pulses so I turned the adjuster another 1/4 turn and it's now passable but I still have the inlet valves turned down slightly.
What a pain in the arris!

 

[voipio]

Has the shower head been changed, by any chance? I changed one recently, and the flow rate was quite a bit lower (smaller individual shower head nozzles). Ended up buying another head, but the nozzles on it are big enough to result in a relatively low nozzle pressures so, when showering, the flow feels a bit on the feeble side (the shower is not pump-assisted, by the way). More like a rainfall shower. The nozzles didn't look any bigger when looking at the head in the shop, but under a magnifying glass, they went from something like 0.7mm diameter nozzles on the original head, to 0.8mm, so quite a big difference is cross sectional area.

 

[dobbslc]

No it's the same as ever, I did swap the whole shower bar etc with the downstairs one and cleaned out the filters but it made no difference. A rainfall head might help though!