C & M Brittony boiler hot water problem.

[Gees]

I am having the following problem.
C.H. works fine with no problem at all.
However the DHW is doing strange things...
I need to have the hw tap on a very fast flow before the boiler responds with the lights running across the front and the flame light lit. It I then drop the flow rate to a point where the water is hot ( not scalding hot ) the boiler responds by reverting back to CH mode ( or off if the ch is not on ) This results in cold water at the hot tap... Not what is required !
If i give it another go with the flow rate the whole sequence repeats.
Could this have anything to do with the sold water pressure as I have recently had a new stopcock fitted. Or is there a more sinister fault lurking...

The temp control is fully clockwise.

 

[past3bar]

Shatt use the name Britony for more than one boiler. Do you have any more information on model?
From what you wrote it sounds like a later SE ?
flow switch?

 

[holty]

80se by any chance

 

[Gees]

Its an 80 SE

 

[Gees]

I have had a close look at the boiler today and think I have figured out the problem... The diverter valve spindle comes down VERY slowly and only when the tap is on almost full flow. If I then throttle back the flow the spindle rises up again and unmakes the flow switch. If I manually hold in the flow switch the water gets as hot as it ever did. Have I got a leaking diaphram !!! This only started after I had a new stopcock fitted and the pressure is now quite high. If this is the problem how difficult is it to replace ?

 

[Gees]

Thanks to All the help I have received, I have now solved the problem. The "o" ring below the diaphragm was VERY tight fit on the shaft making it very difficult to slide up and down. I replaced the diaphragm and the plunger and "o" ring and now all is well.
It took me a little time to figure out how the diaphragm water bleed worked but got it all working now

Changing is a doddle, drain DHW system remove flow switch wires ( 2 ). remove the two retaining clips, lift off the housing, change the bits , reassemble and bleed the diaphragm water feed.

 

[Agile]

Does anyone remember which old C&M model you surprisingly need to depressurise the heating side to replace the diaphragm?

Was it the Celtic?

Tony

 

[Gees]

I'm pleased it wasnt this one

 

[kevplumb]

it was the celtic mr glazier

if you didn't the spindle blew out then you did

showing your age now

 

[cyclonebri2]

it was the celtic mr glazier

if you didn't the spindle blew out then you did

showing your age now

Hi Plumbob

 

[kevplumb]

crawl back under your rock troll View media item 14326

 

[Gees]

I thought It was too good to be true.... My hot water stopped completly today and on investigation I found the flow contol valve was in little bits inside the housing.. The little white plastic valve thing that sits on the end of a spring inside the valve had disintergrated and was not restricting the flow of water at all. this meant the diaphragm was getting very little pressure diffrence and hence no DHW.

I have done a temp fix but I need to know where to get either the little white plastic part or the whole valve..

[/img]