Worcester Bosch 24i RSF Problem with hot water

[nobbyumbnut]

Hello all,
I would really appreciate any advice that may help me find out what is the matter with my boiler.

Here we go then:
About two Months ago I noticed that when someone was using the shower upstairs afetr about 10 minutes the boiler was constantly firing up then cutting out. I could hear the relays clicking on and off. The boiler was constantly firing up, stopping, firing, etc etc.

I suspected that one of the relays may have been faulty so I replaced the entire PCB. Unfortunately the problem still exsists. I also notice that the HWS temperatue is very very hot. The water pressure from the hot tap in the kitchen is slightly less that the cold.

I took the silver screw out of the pump in the boiler and ran the hot tap. Rather oddly the pump never ran all the time that he hot tap was running however the pump did run for a few seconds when I turned the tap off.

Someone has suggested that I replace the heat exchanger. Is this a job that could be tackled by a novice or is this covered under the gas safe regs.

Please help. I am worried that with the HWS water being so hot I will cause more damage

 

[Agile]

You could check the resistance of the sensors with the boiler totally cold.

But they can fail just when they get hot.

As a test you could replace them one at a time with a fixed resistor and see what effect that has on the fault.

Replacing a PCB when its not faulty is an expensive exercise and a professional would probably have been cheaper.

Tony

 

[nobbyumbnut]

Tony,
Thank you for your reply. I wonder if you wouldn't mind helping me a little more by answering a couple of questions.

What should the value of resistance be on each sensor?
How many sensors are there and where do I find them?

I appreciate you comments and yes, I agree I may have been a bit naive to replace the PCB without consulting a professional first.