Ideal Mini C24 fires up when not switched on

[ATG]

My C24 combi has worked perfectly until recently, but it now fires up at odd times when there is no call on it. Sometimes for 5 sec, sometimes up to 2 mins. The rads do not start to get hot, and so far as I am aware there is no pre-heat on the DHW side to have been accidentally switched on.

As I see there are three reasons why this is:

1. Flow temp thermistor sending figure below frost stat threshold (but it ain't that cold in my place!)

2. Timer on the blink (it's the incomprehensible digital one)

3. PCB on the blink

How would I prove which one is the culprit and is it easy to fix?

Could it be a minor leak inside which has dripped onto something?

Thanks in advance,

ATG

 

[45yearsagasman]

Do you get any of the lights on the front panel flashing or any combination of lights when the boiler fires up when it shouldn't?

 

[Slugbabydotcom]

I'd say it sounds more like a frost stat operation.
The other 2 are highly unlikely.

What I would look out for is a small leak on a DHW pipe, enough to operate the flow switch when the mains pressure could build up on a night when no water is being used.
Try isolating the cold supply to the boiler for a night and see if it stops.

Try and see whether its a call for heat or a call for HW thats causing the boiler to light to give you a clue where to look.[ As per 45yr's post ]

 

[Agile]

He has already said that the rads dont get hot when this firing up occurs.

That would seem to indicate that its an apparent demand for DHW.

A leak would have to be over 2 li/min to normally trigger the flow sensor.

Just to elimimate a genuine DHW demand sensing you could remove the Hall effect sensor overnight and see what effect that has. Ideally remove the plug from it too.

My Ideal Mini C24 combi has worked perfectly until recently,

ATG

I need one of the metal clips used to hold the instrument panel in place on my Turbomax Plus 824 E.

ATG

Hi people, just joined the forum.

We have a Vokera Linea 24 boiler with 3 rads in the timber chalet in our garden (installed by the previous owners)

ATG

In our house we have a ten year old Ecomax 828E lpg fired combi which works perfectly.

ATG

Now your posts say that you have FOUR boilers at your property.

I do have to say that whenever we see people posting about having so many different boilers it always turns out that they are really doing boiler repairs and mostly illegally because they are not gas registered.

Tony

 

[Stamina]

Well spotted Tony.The authenticity of alot of threads on this site is questionable

 

[45yearsagasman]

I got sucked in.Doh! Well spotted. He'll be back under another name.

 

[ATG]

The spirit of Sherlock Holmes lives on, obviously. No need for such flaming though.

I will come clean and say that the the C24 combi is in a flat which we rent out, so I have not been able to look at the leds to see what array of flashing might occur when the firing up takes place. The tenant says that it happens randomly so it's not really sensible for me to take up residence in her bathroom (where the boiler is) long term.

But it is absolutely true that we have 3 boilers at our house, one in the main building (Vaillant 828), one in the annexe (Vaillant 824) and one in the chalet (Vokera), so no porkies there.

For the benefit of your consciences (and my legal obligations as a landlord), I have all four boilers (and two others) serviced and repaired regularly by a Gas Safe Registered engineer.

But thanks for the advice anyway, just wanted to know if it was something I could tweak without bothering my man. If it was lack of heat or hot water he would have fixed it already.

ATG

 

[ATG]

And I won't be back under another name, but I promise to state the facts exactly in future.....

ATG