Ariston Eurocombi a/23 diverter valve / diaphragm help pls

[ghockley1981]

Hi There

I have the above combi boiler which has begun to heat the rads when I ask for hot water from the taps. However the central heating doesn't turn off so I have to turn it off manually by the power switch.

It also turns the rads on randomly throughout the day and does not shut down. I believe this is because the boiller does do this but due to the faulty part it's not switching off properly.

From my research into it on the forum I believe it's the diverter valve thats faulty, but im led to believe that to solve this problem I can just change the diaphragm inside this which is much cheaper.

Can anyone help me by confirming this for me, and would anyone have a part number to use to get this as there seem to be many diaphragms for ariston, my manual doesn't have this part mentioned in it.

Many many thanks for your help

Glenn

 

[Terrywookfit]

When you open a hot tap does it activate the micro switch on the R/H side of divertor ? and when you turn off does switch plunger return?? If so its not diaphragm!
Random switching of heating could be due to a faulty thermistor acting as frost stat!!
Is the shuttle in divertor valve stuck in mid position?
Would suggest contacting a RGI who does repairs!!

 

[gas4you]

I don't know this particular boiler but most new combis don't use diaphragms, but instead some form of flow switch. If this was faulty I doubt you would get any hw when the tap is opened.

As the rads are getting hot then it sounds like the DV stuck mid position.

The random warming of the rads could be due to the boiler having a pre heat function for the hw which will fire every now and again to keep the plate heat exchanger warm.

 

[ghockley1981]

This is an old boiler, about 5 years old im guessing

The microswitch is being operated i've seen it, but it returns straight away.

It doesn't operate it again after, maybe i'l have to have a another look to see the exact operation of it.

Does this mean as it's moving that propably the diverter valve is getting stuck in it's mid postion somehow.

It doens't happen all the time but is becoming more and more frequent, would flushing the system sort it out? I've read about people doing this before ?

 

[Agile]

There were a lot of boilers called Eurocombis, Chris thinks 11 !

There were also several I think called A23 which is usually followed by a string of meaningless letters MFFI being a common string.

If its that one then it does have a diaphragm but the problem is going to be something different from the symptoms described.

A leaking DHW switch gland is a distinct possibility perhaps coupled with a faulty diaphragm as well.

Tony

 

[gas4you]

Now checked the parts breakdown for this and it does have a diaphragm for the main flow switch and could possibly have one in the housing on the left of the valve group.

The diaphragm should be simple to change as a starter.

Note that with these several parts are different depending upon the boiler serial number, so if you attempt this fix yourself you will need to supply this to your supplier.

 

[Terrywookfit]

You possibly could have two faults! ie diaphragm on way out and faulty NTC!
Did problems occur at same time??

 

[Terrywookfit]

Just read Agiles post and agree !!check for water shorting microswitch!!

 

[ghockley1981]

Cheers for the quick responses everyone

It is an MFFI version

The issues of the rads turning on when i use the hot water, appeard to happen first with the boiler then not turning off happening after. however this could just be because it became more noticable as it happened more often

The Main Flow diaphragm i have seen for sale on the net for the ariston so i can get this, would this be an easy job? im fairly diy handy so am not afraid of getting my hands dirty

A leaking DHW switch gland and water shorting microswitch I haven't heard of, what do these elements exactly do then? And why would they be causing the boiler not to turn off.

Many thanks for all your help, it's appreciated

 

[Terrywookfit]

If the gland on Dv leaks into microswitch and shorts it !(ie current will flow through the water) The boiler will think there is a demand for hot water and fire!!
However the divertor valve at rest is in the heating position and so the water will be pumped through that circuit instead!!
Obviously as the boiler thinks it is a demand for H/W the radiators will continue to get hot!!

 

[ghockley1981]

Looks like it's getting more complicated as i look into it.

im not worried about it turning on and off now as aristons have a fire up mechansim built in so thats made me feel easier about it.

sooo.....

Is the diaphragm something inside the diverter that choses between hot water and radiators ?

and is this different to the diaphragm in the main flow switch

apologies if this is a stupid question. i won't pretend to know what im talking about. i know what it looks like but not what it does.

if this is the case and it's warn and gets stuck this could be possibly causing the problem from what you've told me

where would i find the DHW switch / dv gland

and are there any signs i can look for or test on this

thanks again

 

[Terrywookfit]

Diphragm is at L/H side inside a round brass casing with about ten screws holding it together.Two thin pipes(pressure differential) that come from other side of boiler are connected to it!!
Gland and switch are at opposite end of manifold!!

 

[gas4you]

Main flow switch diaphragm looks as though it is at the front of DV valve

 

[Terrywookfit]

Main flow switch diaphragm looks as though it is at the front of DV valve

It is (although it is called a circulator consent switch) or some other obscure term.
But what has it got to do with the DH/W flow switch and gland??

 

[gas4you]

Nothing other than op saying he thinks heating is not turning off/operating properly.