Britony combi SE: where's the flow switch hiding?

Morning.

Quick explanation of why I'm looking for this elusive little gadget:

DHW only fires when the hot water tap is turned to delivery quickly, but under those conditions the water passes too quickly through the exchanger to get much heat in it. Any slower and the boiler shuts off the DHW.

So, after much reading, I'm looking at the flow switch.

Thing is, where is it? The documents I got with the combi (in 2001) only show the device in a schematic diagram - it shows no pictures. A quick google (and eBay) shows a neat looking gadget which looks simple enough to find, you would think.

Interestingly, my doco says the following about replacing the flow switch:

14. DHW Flow Switch
Disconnect the electrical connections undo the securing clip and remove the microswitch; reassemble in reverse order.

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The pics I found around the globe suggest that there's more to a flow switch than just the microswitch - possibly involving a piston?

Here are the pics I just took of the combi.

Where's the removable flow switch?










This is what I found on eBay, part number (600)81471




Can anybody help me find my flow switch?

Thanks.


21/12/2011: edited title to replace "80" with "SE"

follow the cold inlet pipe into the boiler(make sure electric and water are isolated--!!!) that will lead you to flow switch. these types of switches normally only require to be cleaned out as the magnet inside gets built up with deposits but either way cheap part, easy job

BARNY78BG said:

... these types of switches normally only require to be cleaned out ...

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Thanks for the quick reply, but my question remains... where is this switch? I cannot locate it.

As for cleaning it out (if I find it) if the eBay part I pictured is anything to go by, it doesn't look like it comes apart.

Diaphragm probably needs replacing...middle of the second picture down. Your ebay part is for a completely different boiler.

by the looks of it the part ya got is for britony 80, the boiler ya got is a se

flow regulator will be the problem ,knurled plactic black piece hed in with a clip on the front follow the water inlet up ,turn cold off open tap and remove it will have fallen apart

Thanks for all the replies. Looks like I got a few things to look at, starting with the clipped-in thing with a fallen-apart diaphragm

gas_man_gaz said:

by the looks of it the part ya got is for britony 80, the boiler ya got is a se

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I didn't order that part but very nearly did; this forum just saved me £21! My doco says I have an "80" but as you say, the internals say its an "SE". Brilliant.

gordongas said:

flow regulator will be the problem ,knurled plactic black piece hed in with a clip on the front follow the water inlet up ,turn cold off open tap and remove it will have fallen apart

Click to expand...

Bob on.

Removing and dismantling this




Showed me the white spring retaining piece had sheared




Tried eBay and a few other online stores, cannot find a single source

You will probably be forced to get it from Parts Center where they are both expensive and in most branches not very helpful.

Tony

Agile said:

You will probably be forced to get it from Parts Center where they are both expensive and in most branches not very helpful.

Tony

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I'll check them out if they're online. Thanks for the pointer (and the warning)

Got good results using the actual part number 1301952. Around £15 delivered. Result.

I know this thread is old now, but to add my experience....

I had the same symptoms, couldn't get DHW without high flow rate, but I could turn it down afterwards to get the temperature up. And then on Sunday it must have 'gone' completely as nothing could persuade the old bastard Britony SE 100 to fire up DHW. I could see the hydraulic actuator was not moving down to call for DHW, so might have been the diaphragm or....ah this flow switch is in the path....bit of searching done...

Drained down DHW. Took the flow regulator out, completely knackered. Found most of the plunger and the spring, but the end-piece (X shaped piece of plastic on the opposite end to the knurled end) was completely gone ! I wonder where...come away in bits and out through a tap perhaps.

Any how, got a new one of those....from PartsCentre now costing 21quid plus VAT for the SE100 version. Very easy to replace. Remove old one, clear-out a bit of perished o-ring, and used silicone grease on the o-rings of the new one. I notice the X end piece seems to be of a different type of plastic to the rest of it, might explain why that disintegrated as opposed to the main body. Not an item in stock, had to wait overnight and pick up in store today.

Also renewed the diaphragm because that was looking worn, although still in one piece. Replaced and greased the actuator which pokes out of the bottom of the diaphragm assembly and moves the 3 port valve including pressing on the 'DHW demand' microswitch. Careful reassembly of the diaphragm and renewal of the o-rings...no leaks. Perhaps I could have got away with not replacing the diaphragm but the actuator was quite stiff and probably needed cleaning up and greasing.

Cheers to gordongas and people in other threads who documented this one.

Whenever I get a fault with this joyous heap it spurs me to think about getting a new one, but then I fix it and feel a bit more attached to it. If the gas side starts playing up it will be out !