(another) Ideal Isar fault.

[chris2922]

For the second time in 2 years, my Ideal Isar m30100 combi boiler has developed a fault.

Last winter the PCB went and 'H / E' errors were displayed. Costly little fix that was.

This time i have an alternating fault display. First 'F.' then 'L'.

If i hold reset for 5 second here's what happens:

Boiler display shows '5'
Display shows 'd' and gas starts arriving to the boiler.
Boiler lights gas
'Burner' light goes green.
Lots of steam starts coming out of the exhaust outside.
Gas/steam suddenly stops and Burner light goes out after about 5 seconds and it goes quiet.
This is repeated a further 2 times automatically, and finally it gives up and displays F. / L again.

Heres what i have looked at:

Condensate pipe coming out of the bottom is not blocked. Its a bit grubby inside, but it isnt blocked.

I've taken the unit apart and looked at the electrode that tells the PCB there is a flame present. It isn't coroded and looks like a picture of a new one i found online.
I was going to buy a replacement element but this seems pointless as the one already in there looks fine.

All connections are ok that i can see.

Does this sound like yet another PCB change?

 

[gas4you]

You need to check the actual condensate trap is not blocked, not just the condensate pipe.

Just because the flame detection electrode looks like new, doesn't mean it is ok.

 

[chris2922]

I've read the servicing / installation booklet and looked at the condesate trap in the unit, but i cant get at it without taking the whole thing apart. This is not something i am skilled enough to do.

Getting the PCB into the servicing position and having a look at the flame detection electrode was ok, but i cant even get at the screw, or even see the 'elongated bolt' required to remove the trap.

At this point i can either get a replacement flame detection electrode for about £13 and give it a try, or im going to have to call a professional.

Ideal quoted me £318 today.

Is it worth trying the replacement flame detection electrode? While waiting for this to arrive via post ill obviously be freezing my ass off so would rather not do this unless it stands a chance of working.

 

[Garfeild]

When it does light,is there a sort of gurgling noise to suggest it may be struggling to "breathe"?
Ive had some of these make an obvious bubbling noise,to suggest the sump is full,wereas others dont do it,same fault though.
I wouldnt remove the trap without knowing what you are doing,you risk getting water in pcb,gas valve,wiring loom,mains electric etc etc.

Might be worth getting Ideal in,if i go to a non contract repair,i ALWAYS check the boiler from top to bottom,and replace any suspect parts,irrespective what the original fault was.

 

[chris2922]

Hi,
I did listen for a gurgling sound, but other than a slightly louder ignition sound (i presume due to more gas to ignite than normal due to the frequent failed starts) it seems to behave normally.

I dont think the flame detection electrode is the problem, because the 'burner' light goes green when it starts up - so the electrode must be feeding that info to the PCB.

Perhaps it is the trap thats blocked and its just not making a gurgling sound for whatever reason.

 

[Joe 2017]

i went to one today, took the trap out --- full of crap, it should not take you longer than 30mins.

 

[adlplumbing]

try britsh gas if can`t get sole trader to do it as their dirt cheap as bg at the mo

 

[gas4you]

A proper full service that includes removing the trap and cleaning should cost around £60 + VAT.

Use an electricians screwdriver to undo the right hand long bolt that holds the trap in place.

There is also an electrical component you have to drop (can't remember its name) to access the trap on this model.

 

[chris2922]

Hi all,

Removed the condensate trap and took it apart over the sink. Running water through it did clear out a bit of black stuff, but not a lot.

Filled it with water as per the instruction/service guide and replaced it.

The same error occurs after i reset the system:

Boiler display shows '5'
Display shows 'd' and gas starts arriving to the boiler.
Boiler lights gas
'Burner' light goes green.
Lots of steam starts coming out of the exhaust outside.
Gas/steam suddenly stops and Burner light goes out after about 5 seconds and it goes quiet.
This is repeated a further 2 times automatically, and finally it gives up and displays F. / L again.

So its not the condensate trap.

Worth buying a new flame detection electrode next or something else?

 

[plummerman]

Lf. is the flame detection probe or its wiring harness, this sits right on the heat ex and over time melts and sticks to the heat ex so looses continuty.

To check if the detection probes faulty, get a multimeter pull the wiring off the probe stick one end of multimeter on probe connection, other end to the wiring plug, set your multimeter to mirco volts. fire boiler up. you want more than 1.5MV's or probes is knakered! Check continuity of wiring, also check wiring is full pushed in to the white molex connector too.

 

[shambolic]

L F . Is detection shorting after lighting whereas LF no dot is open circuit or failure to light.
I would look at detection lead or even flue seal.

 

[screech]

LF can also be caused by a faulty gas valve

 

[Paul from BG]

Get BG out £168 fixed price and they'll check the insulation board retaining pins are still intact (VERY IMPORTANT!) Ridiculously low price to repair an isar

 

[chris2922]

Thanks, i will phone British Gas as soon as i get home.

Further info to post while im on.

When removing the condesate trap yesterday my dad had a look in the small window to the left of the flame detection electrode to see if the flame was indeed lighting when the boiler fired up. When it did he noticed the back corners of the 'burner box' (for lack of a better description) seemed burnt and rounded. Bot sure if this is heat damage or normal for this boiler.

Also, the light from the flame was leaking out the side of the box and lighting the outside slightly. There was also a smell of combustion. This smell had been noticable for a day before the boiler packed up. I thought it was car fumes from the outside main road at the time.

Very strangley though, the system fired up and did not give an error without the metal case or the white facia on the front of the boiler. It operated normally, returned to the '0' status when not needed and to 'd' when i opened the hot water tap.

Obviously this is a job for the pro's now - but does this extra information help anyone diagnose what the problem might be?

 

[brutaldeluxe1]

best turn it off mate looks like the insulation boards have failed and its burning through the heat engine. At the very least a new heat ex is required not sure what a fixed price off Ideal would be but i would be looking at a replacement boiler.

There is a photo on here of the damage that can be done when the insulation boards fail.