Hot water fault with Worcester 25si

[Yanni]

I have a Worcester 25si around 7 years old.

When the hot water tap is fully open, the spindle on the water flow switch lifts up and you can hear the little microswitch clicking and thus having hot water.

However, if the tap is half way open, the spindle doesn't move enough to let the microswitch make contact.

I've thought it was the water flow switch and bought a new one for £60..replaced it...same fault !!

I get a good pressure to the boiler and good pressure from the hot water tap. Central Heating is fine and hot water is fine too when boiler is on CH.

Any suggestions ? ...A plumber suggested( without seen it) it could be the diverter valve but was wondering how can the diverter valve affect the spindle of the water flow switch since the WFS is fed from the cold water supply so pressure to the WFS can only be affected by the mains cold water pressure ????

The problem started when last year I've changed all copper pipes in the house to plastic JG speedfit. It could be a coincidence though !

Sorry, I'm not an expert but trying to make sense.


I have attached an image of the WFS and of the boiler...

P.S Where would be the diverter valve on this boiler as I can only see a pressure relief valve next to the pump ?

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• 13 May 2008
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[Agile]

The diverter valve is the part which most boilers use as a water flow switch. Yours has the seperate water flow switch instead.

If it has been replaced by a new one then I would expect there is a cross over and cold water is leaking to the hot tap without going through the boiler.

However if that was the case the hot water would be luke warm.

Tony



EDIT... Just read your post again and seen the fact it started when you replumbed your house!

That makes the crossed pipes the obvious cause of your problem! Or a mixer tap with no non return valves fitted.

Tony

 

[superdupergasman]

there are two adjustment screws on the water valve as I just changed one last week. Now if you speak to worcester there may be a spring pretention or something you can set to adjust the min flow rate at which it operates??? Worth a phone call.

 

[Yanni]

Spot on Tony for your answer.

Just looked at my photos before putting plasterboard in the kitchen and realised I have connected the hot and cold to the boiler other way round. The cold water was connected to the DHW flow and the hot to the DHW Cold Inlet.

Arghhhh !...I just have to take the fleeping ceiling down to change the connections.

Anyway, many thanks for your replies guys...I'll read the manual next time !

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• 13 May 2008
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[Agile]

You could have saved yourself £60 by asking me first!