Hi all. After experiencing issues with luke warm hot water and reading about the relative simplicity of refurbishing the diverter valve in the Baxi 105 he I went ahead and did the job (with some trepidation)
To my relief the boiler is now working much better, however it is also leaking a fair bit. The refurb kit came with a small pouch of grease and I applied this as well as I could where it seemed sensible to do so. Mainly on the actuator pins that contact the microswitches.
Clearly it was insufficient though as the leak is not one that can be ignored.
I'm not really clear as to where/how much grease to apply. One leak is coming from one of the unoccupied screw holes that hold the diverter vale assy on. there are 4 holes but only 2 screws (from online vids this seems normal). The leak is around the actator pin, can I liberally apply grease in the diaphragm cavity? I assumed water circulated through here, so would wash grease away. Am I missing somewhere else to put the grease? EG between the diverter itself and the main body (the cavity into which the four screw holes go?)
It's disappointing after summoning the courage to tackle the issue (and doing so successfully) to find this small but not ignorable problem remains.
The leak will be coming from the small o ring on the diverter valve body - as the domestic hot water pressure switch assembly moves forward and backward when you open and close a hot tap, heating water will squirt past the o ring.
Its a simple fix if you fancy it.
Isolate electrical supplies to the boiler.
Drain the boiler using the drain point on the RHS of the boiler, whilst you're at it top up the pre-charge in the expansion vessel to 0.8bar, then check the Schrader valve isn't letting-by using some leak detector fluid. NB No not touch the heating isolation valves, leave them well alone.
Remove the DHW micro switch from the diverter valve/pressure switch by unscrewing the Phillips screw and push the switch to the side out of the way.
Isolate the cold mains inlet to the boiler (this one is usually fine to use) and open a hot tap (ideally one lower than the boiler), leave the hot tap open.
Now remove both of the small copper pipes from the top of the DHW pressure switch assembly and carefully lift the pipes up.
Then remove the two retaining screws which hold the pressure switch to the diverter valve (where you mentioned water is dripping from). Also, its normal to have two holes there, it gives you the option of where to place the screws.
The pressure switch assembly should now come off, exposing the leaking o ring on the diverter valve.
Place a bucket under the LHS of the boiler in preparation to catch any water which may dribble out of the boiler.
Now use a large spanner to remove the gland nut from the diverter valve (its not hexagonal, but an adjustable spanner will work. NB they are tight as hell. You can also use some grips placed through the cut out on the bottom of the boiler. It may also come off with part of the diverter valve spindle attached, don't worry this is normal, but make a mental note of its orientation.
Once you've removed this, take the spindle in your hand separate it from the nut and use a bit of wire wool and remove any black deposits on the spindle. It should be chrome in colour, yours will probably be black.
Then get the gland nut in your hand. You'll notice that it has a white plastic packer on the inside, that packer retains the o ring. To remove it and get access to the o ring, take one of the two screws from the boiler case front fascia (you will have removed these to get the front case off) and screw it into the white bit of plastic a couple of turns. Then use a pair of pliers and pull on the screw, the white plastic packer will follow and you'll have exposed the o ring, use a small screwdriver to poke to o ring out.
The o rings aren't to my knowledge available as a spare part from Baxi, but are available online if you look, however you get the same sized o ring in their diagram repair kit so I usually pinch one from there.
Replace the O ring and with the plastic packer still attached to the screw, lightly tap the screw and the packer back into place.
Put some grease on the spindle and push it back into the gland nut (remember which way it went?)
Put a couple of turns of PTFE around the thread/oring of the gland nut prior to putting it all back together as you took it off.
I usually hold off on reattaching the differential pressure switch and turning on the cold water mains until I've pressurised the boiler and used a screwdriver to push the pin in and out a few times on the diverter valve to check for leaks.
Finally, when you reattach the two small copper pipes back, be extremely careful not to cross thread them and dont over tightened them!
Hope that helps, as it took ages to write!
Regards, Guy
