2 x RGI's and even IDEAL cannot fathom this. ICOS HE24 system. Jedi Master required

[Defence Engineer]

Happy Thursday. I do hope you can help ?

Yes, I know this boiler is old (ICOS System Boiler HE24) but it has been surprisingly reliable. I also know a lot of you professionals hate them... Looking to engage the hive mind here.

Our faithful boiler packed up 5 weeks ago and has given us many yrs. of stirling service. It just stopped
No, I do not want a new boiler... (just saying) - yet.


New Gas Valve in June - fully calibrated
New Fan in March
New spark plug - same (2nd one over its life)
New Flame detection (2nd one over its life)
Sump clear
Trap clear
Burner Insulation new 2 yrs ago
All new gaskets... always.. all the time
Boiler Vent valve (4yrs ago)
Heat Xch - deep cleaned in march
New pump 3 yrs ago
New User Control panel - Feb (flickering display)
New Loom from PCB to User controller
All parts new - IDEAL except :-
1 x reconditioned PCB about 8yrs ago.

Failure mode.
It was purring like a kitten - no noise... no sounds... just "normal". Then, it just stopped. No display, nothing. No warning codes. No leaks. Wiring loom tested everywhere for continuity. Power traced right up to input plug of boiler - all fine. Fuse intact.
Earth intact.

Emergency service via insurance = 2 visits... 2 PCB's - reconditioned
Power going in... both permanent and switched - nothing coming out. Display dead
Disconnected all i/p's and o/p's - i.e. just mains in and user controller... no joy. Nothing
That company just said "cannot fix" and left the scene (!)

This week
New (local and trusted) heating engineer:- "100% it is the PCB, see them dead all the time"
Got a new one in from IDEAL...
fitted and...
...Still dead.

IDEAL tech service tracking this failure - quite responsive..
Could be a faulty, PCB from new ?

IDEAL looking to advise what voltages to expect where when powered up.
I've also established a faulty user control panel will not (has never in IDEAL's experience) caused the failure of the main PCB.
Loom from PCB to control panel - perfect - reads well on meter
Gas valve checked.. coil value is per specification
Fan reads perfect - no shorts / coil values fine
No earth leakage
No water leakage
No shorted pins

I left the end of my wits several days / weeks ago. Sure, I will need a new boiler eventually, but even with all these new parts we have had excellent value so far.

So, any clues ??
My new RGI is clutching at straws

I'm heading to a Divorce - please save me.

FYI - I'm fully time served, qualified and practical and used to dealing in / designing the most sophisticated control systems on the planet for defence applications... there is almost nothing in this boiler ! it has to be the main PCB - of course, I need (for legal reasons) to depend on RGI's for service, but... "how can it be so hard" ?

 

[endecotp]

I've also established a faulty user control panel will not (has never in IDEAL's experience) caused the failure of the main PCB.

On a totally different boiler, I had a short on the display/controls board that caused it to blow up the low voltage (5V?) power supply on the main PCB.

Replacing the main PCB would of course result in the new one being blown up too. Somehow I worked out the issue before doing that - I think maybe I spotted scorching on the display board, or something. It's a while ago.

Good luck.

 

[jj4091]

FYI - I'm fully time served, qualified and practical and used to dealing in / designing the most sophisticated control systems on the planet for defence applications... there is almost nothing in this boiler ! it has to be the main PCB - of course, I need (for legal reasons) to depend on RGI's for service, but... "how can it be so hard" ?


I am not GSE nor have any experience of your boiler, but given your experience I wonder if you have suggested they connect the input to the pcb. and measure the voltage at all the outputs before connecting anything. It seems to me they need to identify if there are other faulty parts before throwing new circuit boards at it. Surely if it blows as soon as power is applied to the boiler it is something that is activated at power on, like a display or it's controls, as endecotp suggests. Rather than something in the actual heating side of the boiler. Also what are you doing your insulation tests with.
My ideal logic instalation manual has a flow chart for all the component resistances and supply voltages, don't know if the same is applicable to yours.

 

[Defence Engineer]

One of the earlier ( not mentioned) tests was to power up with nothing connected (except the user control panel).. still nothing. Since I have written this, have confirmed the fan reads ok with 111 ohms. (Figures given by IDEAL). Ideal also confirmed the correct values for the Honeywell gas valve at 4.2 kohms… perfect reading. There are only “big” 3 outputs… the valve, pump and the fan. Everything else is low voltage or an input.

The start sequence (even when no heating is called for) is to spin the fan to purge, for a couple of seconds and then settle down to a “0” on the display and a single led. This part of switch on! Does not sequence pump or gas valve. The output to the spark generator is not a part of this sequence either so even if that was faulty, the boiler would go through its initialisation sequence.

Incidentally, the spark generation system is very recently changed… so we can eliminate that.

It has to be the fan killing the PCB (it is the first thing Idea, suggested) but we do not even get a flicker of a flicker… and that reading suggests it is not broken in any case.