2003 LS100 CH working ok! ask for DHW the pipe from the 3 way valve up to the heat exchanger gets very hot within 15 seconds and flame cut's off, tries to re-ignite it's self then Flame fail light on! Checked the DHW & CH sensors both reading 12.8 ohms. AAV rattles and seems ok but cant hear any hissing with inner cover on. Checked Thermister for continuity and ok! could it be the 3 way valve diaphram? anything I can do to check its operations before I strip it.

strawbear, May 2012

Boiler Ravenheat LS100 2003
Started going intermittent two weeks ago then just kept tripping Flame Fail device?
1: Checked readings of DCH & HW sensorsboth reading between 3.8 & 15.6 khoms so they are ok. Was told it could be the ignition board so brought one and didn’t help “Ouch it was expensive”
2: Decided to check the diverter valve and found it more or less solid with build up. Stripped it and cleaned it used a full Alpha repair kit installed it (diaphragm/seals and replaced them all). Checked its operation to make sure it switched direction correctly before replacing it.
3: Rebuilt the boiler and fired it up on DHW started full gas worked for about 30 seconds and stopped burning, It tried to relight itself but Flame fail light comes on, Same thing happens with C/H but will keep working for a little longer.
4: Decide as it had been working for 8 years to go back to the start and removed all the Radiators and pipe work flushed them all out. Stripped and cleaned heat exchange pump etc. Reassembled, refilled and re-installed?
5: When I tried the DHW the pipe down from the heat exchanger gets very hot and the diverter valve gets hot and some warm water came through the tap but only about 10 seconds then back to cold with FFD, felt the return pipe and it’s still cool. Tried central heating and boiler worked for about 3 minutes outward pipes went warm about for about 2 meters, but nothing seemed to be coming back, when it tries to restart the FFD kicks in, press it and same again!
Getting desperate took the pump off tonight as I was thinking if the water is not circulating properly either round the boiler or the CH system then the pump could be faulty, it does get a little hot round the motor part! fixed it up outside with a pipe feed and it pushed water out of the hose up to 8ft. Thought it must be ok put it back on but still the same symptoms.
This is getting a major problem no money left to spend no hot water no shower and 2 kids and a not happy wife, any suggestions will be welcome!!!!

fedupandbroke, June 2012

Hope I have a result stripped the 3 way valve and the diverter was well seized up with carbon and the rubbber was looking very perished. Will get a repair kit today and hopfully it will do the trick. I did clean inside the part beyond the circlip do I need to drill out what looks like 2 grub screws the other end to get at the other side of the slider valve??

strawbear, May 2012