L9 fault code, ideal isar HE24

Called out to boiler fault, nothing working when arrived, client advised diaplay panel had not been working for several months. I changed display to get faults codes but nothing happened, so i then changed pcb as well. All seemed ok when i left, client then called to say 'L9' appeared and manual referred to possible blockage in heat exchanger.

I then returned to check all posibilities that the manual mentioned and all seemed fine except for the blocked heat exchanger. The thermistors were checked and all ok and the diverter valve was checked for debris and function and all ok. I then tried changing the plate heat exchanger but still getting 'L9', I'm thinking of going back tomorrow to powerflush the boiler, there was a little brown debris in the plate connections within the boiler but nothing too much. AM I DOING THE RIGHT THING, ITS DRIVING ME MAD? I have also spoke with ideal several times who don't seem to be much help.

Any help will be much appreiciated. Nick.

I tend to stay away from Ideals that are newer than the classic, so can't help you much there.
But I do have some very good advice for you. If you are a RGI, get access to the Combustion Chamber on this forum.

Faulty pump.

how sure can you be about the pump, this was checked and seemed to be spinning strongly? The boiler will run for several minutes and start to heat the rads and then cuts out to L9 (pressure gauge also fluctuates eractically up and down).

Its driving me crazy!!

Make sure you take the boiler serial number as there are 2 pumps for these.

pump or blocked main heat exchanger, or all the radiators are closed.

it will be the pump tho.

change 1 a day for exactly the same problem

Definitely pump! L9 normally due to pump sticking or seized causing it to overheat.

Had it several times before so my first port of call is the pump

feeltheheat said:

I have also spoke with ideal several times who don't seem to be much help.

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nothing ever changes does it!! why numpties keep installing their crap is beyond me!

L9 is a low overheat, H9 is the high overheat with either i would suspect a blockage or lack of water flow
if this was a heat only boiler Icos or Evo and over 60,000btu then it would need 28mm pipework for at least a metre on flow and return.