Gents
Have been experiencing problems with my CB28 boiler
If I give you symptoms and some of the parts I have changed over the last couple of years perhaps it may help with diagnosis.
1. Boiler is about 9 years old
2. At around 6 years old I had the rads and underfloor pipes replaced, chemically cleaned and serviced
3. At around 7 years old I replaced the DHW heat exchanger
4. Last year I replaced the diverter valve assembly which included the diaphrgam VV
Im getting a tail off in hot water temp when a tap is opened. I have mostly mixers but all have single check isolation valves fitted. However the down stairs loo has separate taps and opening the hot tap I get hot water which fluctuates very hot to stone cold. Flow hasnt been measured but it is excellent.
At the boiler itself I initially get the flashing 5 second green B light with the Red A light not illumianted.
When I get the missus to open the hot tap the boiler fires up straight away then after about 5 seconds the pressure starts to rise and then what appears a relief blowing down and the red A light is constantly illuminated.
The hot water is still deliverered but fluctuates hot and cold.
I have checked the DHW switch and pressing the white microswitch whilst the meter is connected it goes from open circuit to closed circuit. I have a good spare DHW switch but havent fitted it yet as the existing appears to be working.
With the cover off and my hand on the DV outlet to CH but with the boiler only on DHW the pipe to CH does get hot.
I tried closing the supply vv to the CH but the symptoms above persisted.
Im thinking diverter valve, possibly perished diaphragm. Ive ordered a kit as well as a new valve. The aim being to replace the DV with the new vv and then rebuild the old one as a spare.
However is it likely to be the DHW heat exchanger? Im unsure as it was replaced only a couple of years ago and I wouldnt have thought that scale would form at DHW temps?
There is little to no sludge in the system as new pipes and rads have just been fitted. Indicated by the cristal clear water when I drain down.
So my question is, am I on the right track or is this a indiscriminate replacement of parts!
Any help would be greatly recieved!
Russ
Have been experiencing problems with my CB28 boiler
If I give you symptoms and some of the parts I have changed over the last couple of years perhaps it may help with diagnosis.
1. Boiler is about 9 years old
2. At around 6 years old I had the rads and underfloor pipes replaced, chemically cleaned and serviced
3. At around 7 years old I replaced the DHW heat exchanger
4. Last year I replaced the diverter valve assembly which included the diaphrgam VV
Im getting a tail off in hot water temp when a tap is opened. I have mostly mixers but all have single check isolation valves fitted. However the down stairs loo has separate taps and opening the hot tap I get hot water which fluctuates very hot to stone cold. Flow hasnt been measured but it is excellent.
At the boiler itself I initially get the flashing 5 second green B light with the Red A light not illumianted.
When I get the missus to open the hot tap the boiler fires up straight away then after about 5 seconds the pressure starts to rise and then what appears a relief blowing down and the red A light is constantly illuminated.
The hot water is still deliverered but fluctuates hot and cold.
I have checked the DHW switch and pressing the white microswitch whilst the meter is connected it goes from open circuit to closed circuit. I have a good spare DHW switch but havent fitted it yet as the existing appears to be working.
With the cover off and my hand on the DV outlet to CH but with the boiler only on DHW the pipe to CH does get hot.
I tried closing the supply vv to the CH but the symptoms above persisted.
Im thinking diverter valve, possibly perished diaphragm. Ive ordered a kit as well as a new valve. The aim being to replace the DV with the new vv and then rebuild the old one as a spare.
However is it likely to be the DHW heat exchanger? Im unsure as it was replaced only a couple of years ago and I wouldnt have thought that scale would form at DHW temps?
There is little to no sludge in the system as new pipes and rads have just been fitted. Indicated by the cristal clear water when I drain down.
So my question is, am I on the right track or is this a indiscriminate replacement of parts!
Any help would be greatly recieved!
Russ
