Sensor on front of Ariston Eurocombi A27 diverter valve

[Dimebar]

I'm looking at replacing my diverter valve on my Euro Combi A27 boiler because it has sezied enough to prevent it operating the micro switch for the hot water.

Anyway, can anybody tell me what the sensor is on the front of the diverter valve (pictured below)? I want to replace this too because the screws are rusted in due to a previous leak so rather than remove it I'll just replace it too.

 

[Agile]

I think that you are planning to do more or different things than you need.

But at the end of the day its your boiler!

 

[gas_man_gaz]

are ya sure the diverter is seized? have you separated the flow valve (which houses the dhw diaphragm) from the diverter and checked by manually pushing the pin across?
whilst they are separated i would also check the correct operation of the flow valve by turning the hw tap on and ensuring the pin moves in and out. norm it isn't the diverter what is seized, norm its the diaphragm that is damaged or the differential tubes that are blocked.

 

[Dimebar]

If things cost just a few quid extra to replace then often it makes life easier just to replace rather than dismantle. As the screws are rotten it's less hassle to not have to struggle with them.

The HW only works when the heating is on. The pin on the diverter only moves across to the micro switch when the heating is on. It moves a little when the heating is off but not enough.

What are the dfferential tubes? Are those the two small pipes leading to the diverter?

 

[gas_man_gaz]

from what you are saying you haven't checked the operation of the flow valve and you are just guessing the diverter valve is seized?
guessing and replacing this part will end up costing a few quid, wasting ya time, wont fix the problem and probably cause ya more problems with the boiler.
start by slackening the two screws securing the flow valve to the diverter, this will allow you to separate the 2 parts. gently pull them apart, then run the hw and check the pin is moving. if it isn't you will most likely need a diaphragm

 

[Dimebar]

You are 100% correct that I'm guesing.
Is the flow valve the large disc shaped part on the left hand side? This has the differential pipes running to it?

The pin hardly moves at the moment when the heating is off. It does contact the switch when the HW is switched on with the heating on.

If my assumption above is correct if I remove the flow valve and switch the HW on the pin on the right should shoot across?

Please excuse my ignorance when it comes to the terminology for the parts. I cant find a parts diagram anywhere.

Does the diaphragm sit in the flow valve?

 

[gas_man_gaz]

you've got it!

 

[Dimebar]

Excellent. I'll start by testing that. Job for next weekend i think.

Just to complete my education do you know what the sensor is on the front of the valve? Some internet pictures show it fitted, others don't. None of them describe what it does.

 

[gas_man_gaz]

just to confirm the pin on the flow-valve should shoot out (but wont if the diaphragm is shot),
the diverter wont move as it will be separated from the valve that controls it.

 

[Dimebar]

Understood.

Don't know if these flow switches are a work/don't work thing but the diverter pin does move fully when the heating is on.

It moves a little when the heating is off but not enough to trigger the HW microswitch.

All will hopefully be answered next weekend.

 

[gas_man_gaz]

the part with the rusted screws is ya primary flow switch, which is ok or the boiler wouldn't fire up