Boiler locks out on central heating

[m112]

Hello.

I've got rather old Ariston micrombi boiler which worked well for number of years.

In the last couple of nights boiler started to lock out when C/H is on. It happens randomly without any pattern.

We did have occasional lock out last winter but maybe once per week max. I did happen on DHW but even less often (once a month)

Usually I wake up and could only hear the fan - with red light on the boiler. When the boiler is reset it could work for a day or so but last night it locked out 3 times.

What could it be?

I checked the manual https://www.freeboilermanuals.com/assets/pdf/ariston/Microcombi_23-&27.pdf and it says it could be detection electrode?

If it would be a detection electrode I reckon it should lock out more often on H/W too.

pcb?

thanks for help in an advance

 

[HERTS P&D]

Have you thought about calling someone out???

Andy

 

[75pete]

When was it lasted serviced?
Might be worth now having a service before the winter kicks-in.

 

[m112]

It's been serviced 18 months ago.

As the fault is intermittent and difficult to recreate, im worried that i will spend money on it and never got to the problem fixed.

If i will not get any tips i would rather go for new boiler

 

[m112]

This is a gas issue so no tips. A service should be done every year.

Defo gas?

Would it not be the same with dhw though?

 

[Dan Robinson]

Gas/flue/combustion, all comes under the same rule.

 

[lemon_1]

Could be a number of things. Usual suspect is plate heat exchanger blocked up. But could be other things so needs diagnostics. Maybe thermistor sensor or maybe gas valve?... My bet is on plate heat exchanger. Do come back and update us when it gets diagnosed.

What's the water quality like in the central heating? Bleed one of the radiators a little bit into a plastic bottle take a pic and post it here.

Do you have a magnetic filter installed? Make a video of your boiler in operation and post it here

 

[nwgs]

How does the plate heat exchanger cause a problem with Central Heating?

 

[nwgs]

gordon bennet we got a live one.. are you an RGI? god help us all if you are.

Plate heat exchange is purely for hot water.

 

[nwgs]

seriously are you an RGI?

both go through plate heat exchanger. go and read up on it. you plonk.

Quality!!!

It’s comedy gold in here

The boiler the OP is referring to doesn’t even have a plate heat exchanger. It’s got a twin pass one.

Perhaps you meant “main heat exchange” ? It’s been noted your English is lacking.

 

[ianmcd]

seriously are you an RGI?

both go through plate heat exchanger. go and read up on it. you plonk.

which plate heat exchanger would that be ? this boiler doesnt have a plate heat exchanger

 

[lemon_1]

Thought he was referring to another model! Lol

 

[Dan Robinson]

Yeah right We believe you. Thousands wouldn't.

 

[m112]

Yeah right We believe you. Thousands wouldn't.

I've arranged an engineer to have a look at the boiler early next week.
Today ive increased the pressure from 1.2 to 1.5bar boiler now locks much more often?
Why would the pressure had an effect on the ignition.

Ive also noticed when I open hot tap boiler ignites straight away but she CH comes on i can see sparks for for 2-3 seconds. Why the ignition have a different ?

 

[Dan Robinson]

My quote was referring to Lemon, not you, if that was what you were thinking.

Today ive increased the pressure from 1.2 to 1.5bar boiler now locks much more often?

That will be a coincidence.

Why the ignition have a different ?

Again, coincidence or over analysing the situation.