ideal isar with random lf fault

[mudlux]

hi
ive got an old isar m30100 combi.
i get an l/f error 1-5 times a day! for the last few months
it seems to happen randomly, but have recently noticed that its more likely when boiler is hot/been working hard.
if i happen to be near it when it fails and reset itright away, it fires, goes out and refires 3 times then lf faults this sequence can be repeated 3/4 times, but usually restarts properly by then.

if it fails and its left 2 mins or so (ie cools) it will reset and work for ages!

engineer has recently replaced flame sensor & checked condensate, ive also changed pcb (s/hand) with identical results

fan is often noisy...but has been for years...also loud whining/whistling noise noticeable from outside, again...for years

any advice appreciated

 

[Dan Robinson]

PCB.

Had this recently. Replaced with a NEW board and it is working as well as any Ideal POS can be expected to.

 

[dcawkwell]

Needs a good clean out first.
Probably hasn't been touched and the condensate is blocked solid
with bits of the heat exchanger.

You engineer probably didn't touch the condensate because it's so damn awkward to get at. Typical ideal design really.

 

[Gaspt]

Spark gen , they are a common fault on these

 

[mudlux]

PCB.

Had this recently. Replaced with a NEW board and it is working as well as any Ideal POS can be expected to.

thats what i was thinking, but having swapped it out already for (albeit a secondhand) one, with exactly the same symptoms....only option is to try a new one i suppose - thanks

 

[mudlux]

Needs a good clean out first.
Probably hasn't been touched and the condensate is blocked solid
with bits of the heat exchanger.

You engineer probably didn't touch the condensate because it's so damn awkward to get at. Typical ideal design really.

condensate was removed and cleaned last autumn, exchanger & diverter removed and cleaned in jan, so i dont think its a maintenance issue

 

[mudlux]

Spark gen , they are a common fault on these

been replaced in jan...i was wondering if its worth replacing flame sensor again, in case the new one was faulty...anyone had that?

 

[shambolic]

*********************
But really you shouldn't be checking anything inside the combustion chamber, or changing pcbs, unless you are a qualified gas engineer!!
After changing pcb you should take dynamic pressure, has rate and combustion performance, this should also be done after combustion cover has been removed.

 

[mudlux]

....

yes, the old detection probe did have cracked insulation, and was suspected, but was replaced with no improvement

 

[petit_pablo]

Check the detection probe lead as these can crack and "short onto hex".

+1 Seems to be becoming a common problem at the moment. Ive found thy are going low down near the grommit in the casing.

 

[shambolic]

Check the ************

**********************

 

[Dan Robinson]

Relying on a NEW Ideal PCB for this boiler is risky enough as it is.

Hoping the boiler Gods are smiling down on you with a USED one is bonkers.

 

[mudlux]

****

 

[mudlux]

Relying on a NEW Ideal PCB for this boiler is risky enough as it is.

Hoping the boiler Gods are smiling down on you with a USED one is bonkers.

before getting a new pcb, i thought it was a useful test to try a different (though used, but free) pcb to see if this slightly unusual problem persisted. the fact that the particular problem does persist suggests either the 2nd pcb is also faulty in the same way, or the problem is not with the pcb?