Worcester 28i RSF - Tap Sensor ?

28 Feb 2011
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United Kingdom
Hi chaps

Really hope someone can help?

My boiler seems to work fine apart from when I’m using the hot tap in the bathroom which is furthest from the boiler pipe wise in the house, sometimes half way through a shower the boiler switches off, but if I then turn on the hot tap in the sink ( next to the shower ) it fires up again..I’m pretty sure the fault has to do with the water pressure detector sensor ( i.e the tap being turned on ) but I have no idea where that is on the boiler ?

The other thing which happened yesterday is when I had the hot tap on in the sink ( right next to the boiler ) and then I turned the cold tap on again the boiler turned off the heating..again I think this was because turning on the cold tap dropped the water pressure of the pipe going into the boiler so it thinks I had turned the hot tap off.

Any ideas ?
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When you turn on a hot water tap / shower outlet your boiler should fire up once the flow of water reaches 3 litres per minute ,or more. A device in your boiler called a turbine senses this rate of flow and starts up the boiler. So its not the water pressure but the rate of flowing water that brings the boiler on. Does your shower start up the boiler ,every time , but during showering then switches off ?? And if so does this happen every time the shower is used ?
Thanks for reply

Yes the boiler fires up as soon as the hot tap in the shower is turned on but sometimes not always it switches off half way through...I can fix it by running the sink hot tap slightly and this fires the boiler back up again..it’s only started doing it recently with no changes to any of the plumbing, so I’m assuming the water detection flow rate in the boiler is beginning to fail ?
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Good morning , is it only your shower that is problematic ? Do all other hot taps work fine ? And what type of shower is it ?
The shower is just a simple hot tap and cold tap ( no mixer ) with a pipe that runs off to a shower head , I have the same issue with the sink in the same bathroom..infact yesterday I had the hose on in the back garden and it was impossible to get the hot water on as the drop in pressure to the hot tap flow meant the boiler wouldn’t fire up ..could the flow rate detector in the boiler be failing ?

The water pressure to our building is extremely high ( garden Flat ) but when the cold tap is on, it greatly affects the flow to the hot tap which I guess makes sense as it’s sharing the feed.

Nothing has changed in my plumbing apart from the boiler seems be getting more picky with when it realises the hot tap has been turned on.

Thanks for helping :)
Time to call in an engineer to establish what's going on. If any hot water tap is turned on ,and delivers more than 3 litres per minute ,the boiler should fire and continue to supply hot water . if you are getting that flow then the boiler is at fault. Probably the turbine.
Any idea which component in the boiler might have failed or has the turbine sensor ?

I replaced the motherboard on it a few years ago when a relay failed, so I’m happy to work on it as there are plenty of spare parts on EBay :)
The boiler technician will be able to advise.
I guess I was hoping someone on this forum could advise ? I appreciate a boiler engineer could help but what’s the point in joining an internet forum if people just advise I call the engineer ? I’m much fonder of trying to fix this myself plus I’d learn something new along the way :) last time I replaced the motherboard in this boiler when someone on this forum helped intentify a failed relay..I was hoping to do the same again ?

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