I have a problem with my rather old Ravenheat NSF20/20ET (RSF20/20ET)combi boiler. I aquired this boiler with my house back in 1999.
I have had to change the divert valve because the rubber diaphram had torn of so I ended up buying the complete valve back in 2001 I think it cost £180 plus a new pump another £60. I also changed the pump as it was sometimes not starting.
All has been fine all this time from 2001 onwards, then suddenly the boiler has been making a loud grinding noise when shutting the hot water tap.
Now suddenly I cannot get hot water, basically the burner does not light up nor does the fan start when opening the hot water tap.
I have done some diagnostics and I hope someone can point me to the problem.
If I start the heating the everything is fine, the flame fires, the fan start and the boiler starts to heat the water, I have also checked the 4 neon lamps on the electronic circuit behind the timer unit, first the 2 neons light up followed by the 3 and finally the 4 neon which indicates the HT for the pilot/burner piezo is working as the boiler lights up.
With the heating working if I open the hotwater tap, all the 4 neon indicators turn off and the burner is extinguished and the fan also stops running. I can confirm the pump is working perfectly and so is the diaphram, the divert valve pin is pushing the two micro switches when opening and shutting the hot water tap.
The fact that the heating works perfectly, can I conclude the Gas Valve etc is working properly?
If I shut the hot water tap while in heating mode, the burner ignites again and the boiler starts heating in this mode.
I have turned the hotwater thermostat fully UP but this doesn't seem to make any difference.
Is there a sensor or pressure switch somewhere in the heat exchanger which controls the hotwater start/stop signal?
What could be wrong? Is this going to be something to do with the Heat Exchanger having got scaled up inside?
Your advice and comments will be greatly appreciated.
Mike
London, Middlesex
I have had to change the divert valve because the rubber diaphram had torn of so I ended up buying the complete valve back in 2001 I think it cost £180 plus a new pump another £60. I also changed the pump as it was sometimes not starting.
All has been fine all this time from 2001 onwards, then suddenly the boiler has been making a loud grinding noise when shutting the hot water tap.
Now suddenly I cannot get hot water, basically the burner does not light up nor does the fan start when opening the hot water tap.
I have done some diagnostics and I hope someone can point me to the problem.
If I start the heating the everything is fine, the flame fires, the fan start and the boiler starts to heat the water, I have also checked the 4 neon lamps on the electronic circuit behind the timer unit, first the 2 neons light up followed by the 3 and finally the 4 neon which indicates the HT for the pilot/burner piezo is working as the boiler lights up.
With the heating working if I open the hotwater tap, all the 4 neon indicators turn off and the burner is extinguished and the fan also stops running. I can confirm the pump is working perfectly and so is the diaphram, the divert valve pin is pushing the two micro switches when opening and shutting the hot water tap.
The fact that the heating works perfectly, can I conclude the Gas Valve etc is working properly?
If I shut the hot water tap while in heating mode, the burner ignites again and the boiler starts heating in this mode.
I have turned the hotwater thermostat fully UP but this doesn't seem to make any difference.
Is there a sensor or pressure switch somewhere in the heat exchanger which controls the hotwater start/stop signal?
What could be wrong? Is this going to be something to do with the Heat Exchanger having got scaled up inside?
Your advice and comments will be greatly appreciated.
Mike
London, Middlesex