Britony Combi SE stuck on DHW

I've a fault with my Britony SE100

Once the hot tap has been turned off, the boiler appears to stay in hot water mode (the LED light sequence continues as per DHW demand). Boiler is firing, but there's no flow to the taps as they are turned off, but the CH is then heated. The CH is not on (i.e. no demand from thermostat).

If I reset the boiler, the fault stops - i.e. boiler goes to ready state. However the fault has recurred.

From the little I know, I guess this is something to do with the three way valve, the diaphram (?), and or the DHW flow switch.

Supplementary - when I replace this heap in the spring, what should I get instead ?

So taking a closer look, the microswitch looks OK, and is actuated properly when the hot tap is run. However there seems to be some rusty sludge inside the body of this thing - which you can see into through the gap.


I guess the sludge is damping the mechanism- it may have been gumming up the microswitch just enough before I cleaned it a little.

I'm not sure where the leak is coming from or how to fix it. Can someone give me a hint ?

Thanks

If youre losing pressure the leak is likely to be from the diverter valve,if yore not losing pressure it will be the diaphragm housing.The cartridge in the 3 way valve can be changed quite easily,as can diaphragm housing.

Its losing pressure gradually - its been leaking for about a month and needed topping up about once a week.

From what you said, this means its the diverter valve. How do I go about fixing this ? I haven't taken it apart yet (apart from removing the microswitch to clean it up and have a look) so the innards are a mystery to me at the moment !

Ah OK a bit more digging and I have found the exploded parts view of these boilers.

http://www.aroundtownflats.com/manuals/Boilers/Chaffoteaux/britony se spare parts list 2002 - on.pdf

I assume the cartridge is the valve assembly which sits below the diaphragm on page 157.


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Key number 509,drain boiler,turn off cold inlet,remove diaphragm housing(2 clips,1 below microswitch,1 on the left of dia/housing)valve cartridge is removed by twisting anti clockwise&pulling up at same time,a sort of bayonet type fixing.You may also need a new microswitch if this is sticking&causing boiler to stay on.

Thanks ihatemyjob, I'll get the parts tomorrow and fix this.

The microswitch did get gummed up and stick a couple of times so I think I will replace it even though I have cleaned it up fairly well. The failure mode when it sticks is potentially disastrous (continuously heating the CH circuit) so I'm not going to risk it.

Got a new valve and microswitch, retail with next day 12pm delivery total about 40quid.

After isolating everything and draining the CH and DHW as far as possible, I took the motor head off and then the valve head. The valve body was not very easy to turn, and attention to gripping and twisting the right part is needed. Here's a photo for future reference of forum users. The arrow shows the bayonet lug where the valve body locates into the water block, and the body needs gripping and twisting anticlockwise.
This needed a little force.

However no amount of force could persuade the valve body to come up and out of the housing. Different tools, angles of attack and amounts of force were tried for about an hour ! I asked my neighbour who is a professional familiar with this boiler if he could have a go since I didn't want to take the whole water section out. He couldn't get it to budge either and in the end, the whole water section had to come off and the valve body pushed out from the other side, which he very kindly did. As well as having a top bloke for a neighbour, there was also the Christmas miracle of none of the joints leaking when it was put back together !

Thanks to my neighbour and ihatemyjob for the advise and help. Apologies for above detail but its sometimes useful if someone has written up their experiences when searching on some topic.