Ideal Mini C Pilot cuts out during heating cycle

[Rookie2k]

We have an intermittent problem with our inherited combi boiler - Ideal Mini C (about 3 years old we think), and would be grateful for any suggestions.

Sometimes during the heating cycle the pilot/flame cuts out leaving the fan running. We usually find out because we can't get any hot water or notice the radiators have gone cold. We have a wireless thermostat and can get the boiler running again by using the wireless controller to switch the boiler off and then on again. What we don't know is why it happens. We do have water pressure issues, which we're aware of and working on, but this problem seems to happen even when we've topped up the water. We've not been able to recreate this problem for our central heating engineer (as its intermittent) and he can't find any obvious problem. Do you have any ideas?

 

[Agile]

I have the idea that your heating engeer is not very clever!

That fault indicates a failure of the APS to operate.

Its more common on long or vertical flue systems. It can also be an indication that the flue seals are out of position ( or missing ).

That would need a competent CORGI to examine the fan, APS and flue.

All that you could do is check the plugs are in the test point on the top of the boiler and that the flue outlet is not damaged or obstructed.

Tony

 

[Rookie2k]

Thanks for suggestions, we'll investigate further

 

[gas4you]

Change the flame rectification electrodes. Reasonably common problem on these.

Tony, I had to change an exp tank on a mini and had to remove the flue obviously to do this.

To my horror the flue seals had totally hardened and disintegrated after about 3 years

 

[Agile]

The electrodes only failed on about 100 out of 100,000 boilers so it was not a very common problem.

The effect it produced was totally unexpected and unexplainable. The flame lit for just 0.3 sec and then the gas valve closed. There was nothing you could see or measure on faulty electrodes.

The flue seals only harden and disintegrate if they are out of position in the flue gases.

Tony

 

[gas4you]

As I haven't seen 100,000 of these boilers I wouldn't know, But I had 3 under warranty calls that Ideal engineer changed them and it cured the fault. Boiler used to fire for around 30- 45 secs before failing,

As I only fitted around 20 of the mini series I work out that that is a 15% failure rate

 

[Agile]

As I haven't seen 100,000 of these boilers I wouldn't know, But I had 3 under warranty calls that Ideal engineer changed them and it cured the fault. Boiler used to fire for around 30- 45 secs before failing,

That would have been a different fault and probably where the wire was not welded on to the electrode. Heats up and expands and no longer makes contact!

Tony