Our boiler (Baxi Combi 105 HE) has developed a leak. I think it has been slowly weeping for a while, but seems to be leaking faster now (I increased the pressure in the system this morning).
The leak is coming from a a little plunger mechanism, indicated in this picture: .
What part is that? Is there some way to relieve the pressure in the system? It's at 2.5bar at the moment.
Thanks,
Daniele
Looks as if it might be a pressure switch, there to ensure the boiler turns off if the system loses pressure. But I would have thought you could lose a bit of pressure. There'll be a drain point somewhere - or if it's leaking faster now, the pressure will drop anyway....
Here's one which had been leaking worse for longer:
Looks like the diverter valve to me, the pin moves out when you call for hot water if so? I had a Baxi Eco 80 which had a very similar one which I fixed by dismantling and placing an o-ring with a little silicon grease round the "plunger". Worked fine but then something else failed and given the thing was built like a tin can I change it for a Vaillant and have never looked back (it looks like something from the future inside in comparison).
You can relieve the pressure by draining some water out the radiators, best thing to use is the drain c*ck which will be located at the (near) lowest point in the pipework (hopefully). Otherwise you could loosen a radiator valve slightly and drain that way but it is likely to be a bit messier.
That's exactly the one.
Before doing that, presumably I need to drain the system and/or isolate it from the cold water supply.
Daniele
From memory that boiler has quarter turn taps on all pipes into the boiler so you should just have to turn them and only lose a very small amount of water.
Use the valves to isolate the boiler from the radiators so you don't lose water from the latter, but you'll still get a lot of water discharged from the boiler as the expansion vessel pushes out what's in it.
Reminds me I've got to do the same job on a Poxi/Batterton of the standard-efficiency generation, so looks like they've got a stock fault that's been around for many years if the same thing's happening on your HE model.
I'm no plumber, but as I remember the pin is pushed in and out by a diaphragm, the back of which has the pressurised central heat loop, and the front is the mains pressure hot water. When you turn on a tap the pressure in the front drops and pushes out the pin which tells the boiler water is being drawn. Now the fresh water and the central heat loop are completely isolated, so I don't think you have to drain down at all as the diaphragm will hold the water in the loop, you do however have to turn off the mains water and drain the hot water pipework. The leak you are seeing is fresh water as I recall.
I also found the supplied filling loop was absolute rubbish and was passing water on both the non-return valve and the mains water tap, so you had to keep the loop connected otherwise the non-return leaked, and since the main tap passed the pressure kept on rising which may be how you have got to 2.5 bar. A new filling loop solved that, but of course you do have to drain down to fit it.
Ignore me, if a pressure switch was leaking from where you arrowed, the diaphragm would have failed and the switch wouldn't work.
Thanks for the advice, I've successfuly repaired it, without a flood, electric shock or gas explosion.
Daniele
That's always a good sign.
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