Stuart turner monsoon shower pump not turning off...

[oldbuffer]

1. Which Stuart Turner pump is it. Monsoon range you can get spares, Showermate range you can't (except hoses).
2. Sounds like a sticking flow switch.
3. If its a Monsoon:
3.1 The flow switch is a brass bobbin with a rubber seal around it. The water coming up (there is one in each output) pushes it up inside its housing,, a magnet then operates a reed switch to turn the pump on. When the flow stops the bobbin should fall and the magnet breaks the contact and turns the pump off. The seals tend to stick after a time, but not by much, so sometimes the pump stays on, sometimes it doesn't. Worse in hard water areas.
3.2 The warranty on these pumps is five years, and if younger than that Stuart Turner are usually pretty good about providing replacement.
3.3 If out of warranty, you have to buy the whole bobbin assembly, which from memory is about £35. Bit steep when all that is really needed is a new seal which should cost pence.
3.4 Fitting is not difficult provided the isolation valves on the pump inlet are in good order.
4. If its a Showermate, then unless under warranty (which I think is 1 year) it may well be new pump time. If forced that route, replace with a Monsoon.

 

[YorkshireMidge]

Agree with previous answer from @oldbuffer

What you're seeing isn't as strange as it sounds either. Normally, the bog would be on mains pressure but it sounds like yours is pumped low pressure? If what you're saying is correct, flush the bog, and the flow eases off very gradually as the cistern nears it's fill - and is more likely to show up a sticking flow switch in a pump. Whereas opening and shutting a tap will give a sharper stop to the water flow which might make a sticky switch shut off correctly.

For clarity, the attached is what you've probably got on your Stuart Turner pump. If so and you have a spare replacement cable tie handy, when the pump is stuck on, clip the black cable tie off, remove the black collar away from the outlet, and I would fully expect your pump will shut off which will prove its a flow switch issue beyond doubt. The black collar contains a reed switch which is activated by a magnetic field - so you are simply moving it well away from the magnet that operates it normally.

The problem is the black thing with three legs which lives inside the pump outlet and has a magnet in it, which moves in the flow of water. You might be lucky and find its just gunge causing it to stick but there are also cases where it is problem seals and I notice someone further up the thread had found some replacement silicone ones on ebay in the past (lot no longer active) - removing the need to buy the whole flow switch body.

 

[mobile73]

Agree with previous answer from @oldbuffer

What you're seeing isn't as strange as it sounds either. Normally, the bog would be on mains pressure but it sounds like yours is pumped low pressure? If what you're saying is correct, flush the bog, and the flow eases off very gradually as the cistern nears it's fill - and is more likely to show up a sticking flow switch in a pump. Whereas opening and shutting a tap will give a sharper stop to the water flow which might make a sticky switch shut off correctly.

For clarity, the attached is what you've probably got on your Stuart Turner pump. If so and you have a spare replacement cable tie handy, when the pump is stuck on, clip the black cable tie off, remove the black collar away from the outlet, and I would fully expect your pump will shut off which will prove its a flow switch issue beyond doubt. The black collar contains a reed switch which is activated by a magnetic field - so you are simply moving it well away from the magnet that operates it normally.

The problem is the black thing with three legs which lives inside the pump outlet and has a magnet in it, which moves in the flow of water. You might be lucky and find its just gunge causing it to stick but there are also cases where it is problem seals and I notice someone further up the thread had found some replacement silicone ones on ebay in the past (lot no longer active) - removing the need to buy the whole flow switch body.

Thanks. Have checked and it is Monsoon and is around 10 years old. What you describe sounds right. Our house has very low pressure, so toilets and all upstairs taps are on the pump. This happens when either a normal tap is turned on or the toilet is flushed. I attach images of the pump in situ. Is this something that needs the water and electric turned off first? Do I need a plumber or is this something I should be able to do myself? (I am not great at DIY but can normalluy folow simple instructions!). Thanks for any help

 

[YorkshireMidge]

Dual impeller pump so you're pumping hot too?

In that case, there is a reed switch on both outlets wired in parallel - so flow in EITHER hot or cold will start the pump. But it sounds from your description that it is the one in the cold side causing the problem. The test I suggested to you of removing the reed from the outlet just to make sure the pump shuts off has to be done with the mains on (obviously) and the reed switch is fully insulated, and pretty certain from memory it isn't mains through that reed anyway.

As for draining, it's a hot and cold drain down UNLESS there are service valves on the pipework as you can see circled in red on my Monsoon shower pump which are a quarter turn with a screwdriver OR the same sort of valve built into the pump tails (the mesh covered hoses). But even then, it might not be straight forward as service valves that have been in years undisturbed often leak after they have been used - leaving you doing a drain down and valve replace. If you have service valves, and there is any sign they might already have been weeping in the past (white powdery deposits around the screw head), then prepare yourself for a bit more work, or go straight for a full drain down and ignore the valves.

The pump tails on mine are a push fit onto the pipes, so it is a grey ring you press down to release the push fit - but even with my service valves shut, there will still be some water needing to be caught with towels so the pump needs to be unplugged from the mains when that is done in case you accidentally get water on the pump control box. Can't see what's at the top of the pump tails on yours.

As for whether you need a pro, only you know the answer. But If you know how to drain your system down and have done it before, then the job itself is pretty straight forward - accepting that you still don't know if you will need a flow switch body until you find what the problem is, whether you can get washers separately, or whether it's just limescale and a clean will be enough. Obviously, with a dual pump that has been in that long, it will make sense to do whatever you find is necessary to the cold, to the hot side as well.

 

[oldbuffer]

1. Its a universal, so has a pressure vessel.
2. First step is to check the air charge in the pressure vessel:
2.1 Turn off the pump electrically and close the isolation valves at the top of the inlet flexible (braided) hoses. They are often quite stiff so use a screwdriver big enough to fill the slot so you don't spoil the slot. Slot at right angles to pipe = off.
2.2 Open a hot and cold tap to relieve system pressure.
2.3 Unscrew the Schrader valve cap in the centre of the back of the black pressure vessel on top of the pump. Measure the pressure with a tyre pressure gauge. Should be 1.3 bar (18.5 psi). If lower, bring up to required pressure with a car tyre pump or similar. Leave taps open while doing this.
2.4 When done, replace cap, close taps and open isolation valves. Open taps and allow water to run through under gravity to prime pump.
2.5 Turn pump back on and see if its done the trick.
3. Changing the flow switches is a straightforward DIY job provided the isolation valves work. If they don't you might be more comfortable getting someone to do it.
4. Before going to the expense, turn a tap on then off. When you do this and the pump keeps running, gently tap the flow switches with something wooden or plastic. The flow switches are on the outlet of the pump (hoses furthest from the centre of the pump's diameter. If tapping causes the pump to stop it is an indication (only) that the flow switch is faulty. You might like to repeat for both switches in case only one is a problem.
5. The spare parts come with good fitting instructions.
6. Have a look at https://www.stuart-turner.co.uk/contentfiles/Monsoon-Universal-21269-IG.pdf for instructions.

 

[YorkshireMidge]

@oldbuffer Not used a negative head pump before but I thought the pressure vessel was just to switch the pump on initially, and the flow switches then keep it running, and stop it (or perhaps not in this case).

 

[oldbuffer]

You are probably right, but checking it costs nothing. Those flow switches aren't cheap, so worth checking any low cost options first.

 

[YorkshireMidge]

You are probably right, but checking it costs nothing. Those flow switches aren't cheap, so worth checking any low cost options first.

True. It's odd, I was just reading the troubleshooting bit of the guide and it does actually list the pressure vessel in the pump staying on/hunting section, so maybe I am missing something!

I was having a rummage around to see if I could find those silicone washers referred to earlier in the thread, and finally located a lot that has just finished as they are out of stock. These seem to refer to the washers distorting and causing flow switch sticking mainly on the hot side - and that is entirely possible in @mobile73 case. Beats the cost of the flow switches if it is this.

Stuart Turner Monsoon pumps 2 x high temp silicone flow switch washers + O rings | eBay

Find many great new & used options and get the best deals for Stuart Turner Monsoon pumps 2 x high temp silicone flow switch washers + O rings at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[jimmybuckrogers]

I fitted those washers last year after my flow switch kept sticking and it's been perfect ever since. They're made from silicone so are very tolerant of extreme temperatures and won't warp like the original ones do. You can still find them on ebay if you search for 'stuart turner monsoon washers'.

 

[JSorz]

Thanks for all your responses. I had the same issue. Managed to resolve it by turning the power on and off rapidly (via a isolating switch put in). Hopefully that will resolve it if it happens again.