A problem strarted occuring a week or so ago and is as follows :
Whenever the cold mains water supply re-pressurises (e.g. after the washing machine, dishwasher or toilets have finished taking in water) there is a banging noise followed by some pipe rattle upstairs.
At first it was suspected that there was air in the system somewhere that was causing the problem.
Further investigation has found the pipework to be sound and no evidence of air. The banging noise is coming from the boiler (Bosch 28Si) and this then causes the rattle back down the DHW cold inlet pipe.
Having looked at the boiler more closely I can see that the DHW cold inlet pipe simply runs in to the water flow switch, on to the heat exchanger and then out to the DHW flow. if I turn off the DHW cold inlet on the boiler banging no longer occurs.
From deduction I can only assume its the water flow switch thats on its way out. I don't think its its the heat exchanger as if it was surely I'd see a leak of some sort or I would see the pressure of the closed system gradually rise (internal break in the exchanger).
I can see as the hot taps are turned (i.e. the DHW flow increases) the spring (on the top of the switch) does correctly move and have the desirved effect on the micro-switch that is attached.
I've looked for kits for the water flow switch but it appears to only be sold as a single unit.
1) Can anyone advise if I am along the right line?
2) In addition to this, from a heat-exchanger perspective am I ok to run the central heating with the DHW cold inlet turned off in the meantime to prevent banging (but get the missus moaning at me about no hot water) or could that cause damage?
Apart from this the boiler is running fine.
Whenever the cold mains water supply re-pressurises (e.g. after the washing machine, dishwasher or toilets have finished taking in water) there is a banging noise followed by some pipe rattle upstairs.
At first it was suspected that there was air in the system somewhere that was causing the problem.
Further investigation has found the pipework to be sound and no evidence of air. The banging noise is coming from the boiler (Bosch 28Si) and this then causes the rattle back down the DHW cold inlet pipe.
Having looked at the boiler more closely I can see that the DHW cold inlet pipe simply runs in to the water flow switch, on to the heat exchanger and then out to the DHW flow. if I turn off the DHW cold inlet on the boiler banging no longer occurs.
From deduction I can only assume its the water flow switch thats on its way out. I don't think its its the heat exchanger as if it was surely I'd see a leak of some sort or I would see the pressure of the closed system gradually rise (internal break in the exchanger).
I can see as the hot taps are turned (i.e. the DHW flow increases) the spring (on the top of the switch) does correctly move and have the desirved effect on the micro-switch that is attached.
I've looked for kits for the water flow switch but it appears to only be sold as a single unit.
1) Can anyone advise if I am along the right line?
2) In addition to this, from a heat-exchanger perspective am I ok to run the central heating with the DHW cold inlet turned off in the meantime to prevent banging (but get the missus moaning at me about no hot water) or could that cause damage?
Apart from this the boiler is running fine.