Ideal Icos HE 18 troubles

[Harry Bloomfield]

Some years ago, it failed and it turned out to be PCB failure, the onboard transformer. It was expedient to get a replacement PCB (#2) at the time, then I later sourced, fitted and tested it with a replacement transformer. Complete PCB worked fine, my repaired one (#1) did not, but I never investigated further - it didn't even light the display.

Heating system failed again, yesterday evening, it had tripped the circuit MCB. I reset that, then it blew the spur unit 3amp fuse. Replaced that and the boiler panel came on, showing 2 then E, H, E, H....

I then closely inspected PCB #1 and found a blown apart 100nF cap, replaced that, tested it in the boiler. I got exactly the same fault codes as above, which looking it up in the manual, it suggests it must be the HE fault code, a PCB failure. On this first attempt with #1 installed, it tripped the MCB, but when reset it has not tripped again.

Closely inspecting PCB #2, I found a blown and splattered 102 surface mount resistor, but did not attempt a repair.

I tracked down a replacement (refurbed) PCB supplier, he sounded as if if was very familiar with the HE18 range problems and suggested it might be the fan damaging the PCB. He suggests both fan and PCB may need replacement, though it might have other issues.

The fan runs on DC, but the gentleman above suggests it is some flow sensing components in the fan, which most often damage the PCB.

Anyone aware of any component level diagnostic I can carry out first, rather than blindly buying another PCB?

[Brian Gaff]

Its probably something like a brushed fan where the comutator is wearing and causing momentary shorts over stressing whatever drives it. This sort of thing used to happen to some equipment rack fans where I used to work. it was just nobody had thought of what might happen if a crappy old motor shorted out. Brian

[Harry Bloomfield]

Brian Gaff explained :

Twirling the fan blades inside its cast alloy casing, it doesn't have the feel of having a commutator. That plus the extra wires into it, suggest it might be a brushless type, using the switching sensors to prove air flow - motor turning, there almost certainly is air flow. Four terminals, with 100 Ohm across one pair seems to suggest the motor is probably OK. It is a variable speed, to cope with variable demand for heat from the boiler. I read or found somewhere that it runs on around 320v DC, so maybe it uses the rectified 240v mains voltage.

Where ever the fault was which was tripping the MCB/blowing fuses, it has cleared and the fault being displayed by both PCB's is a PCB/controller failure. I have therefore flipped a coin and decided to risk it by ordering a new PCB. I found one on ebay, new in its box, which is a later version V10 (versus the V9) I had, for £60. Usual cost for a new item is around £300.

[tabbypurr]

200ohm on one pair certainly doesn't prove a motor ok. It might have a shor ted turn, insulation that arcs over at full voltage, or other faults that c ould taken out an mcb.

NT

[Harry Bloomfield]

[e-mail] laid this down on his screen :

The replacement Control PCB arrived early this morning. Installed, it doesn't pop any fuses, doesn't complain of PCB faulty, now it complains that the fan is faulty. I am trying to source one of those at a reasonable cost at the moment. Before it decides it has an incurable problem, the fan motor give a buzz, a rest, another buzz and so it goes on to the point where it gives up and decides it has a hard fault.

In the meantime, I have pulled the fan apart to take a look. As I guessed earlier, it is a brush-less design. Four coils, with a sensor close to the intended to rotate magnetic rotor. A very basic design. Bearings are absolutely fine, no sign of damage to the coils, so my best guess now is that the 'sensor' thingummy bob has failed. My further guess is that it is a Hall Effect switch, feeding back to the control PCB, to prove both rotation and switch the DC alternate positive, negative, to drive the motor round.

I will try to identify the Hall Switch to source a replacement, to make a good working spare fan, when I get a round tuit.

My further guess, is that the PCB suffered a major fault and took the fan out with it, rather than the fan damaging the PCB.

[Harry Bloomfield]

Harry Bloomfield formulated on Saturday :

The new replacement fan behaved exactly the same, so I investigated the loom passing behind the boiler. It had suffered some heat damage, so I parted the wires and to see if that might be the cause, ran them up the front of the boiler - at that point the new control board blew, so that is it, time to look at a new boiler. See my later thread looking for boiler advice.

[tabbypurr]

not another ideal :/

NT

[Harry Bloomfield]

[e-mail] submitted this idea :

Too be fair, it has not been that bad....

Installed 2007, transformer on PCB failed around 2012.

New PCB installed, transformer sourced for original PCB.

Then the latest batch of issues, where it blew the repaired PCB, then a new PCB - which I am now almost satisfied myself, was due to a faulty fan loom rather than fan faulty.

At some time the ignition spark points/ 'spark plug' burnt out, maybe 5 years ago.

From 2007 until 2015 that boiler was really hammered night and day, winter and often summer too, due to my late partners need to be kept warm.

[Dave Plowman (News)]

I feel for you. So near, yet so far. A horrid situation.

[Dave Plowman (News)]

If it helps, my Viessmann has all the external bits fed via soldered in fuses on the PCB. Not mentioned as being replaceable in the service manual, but obviously are.

Mine had a stupid failure. The heat exchanger has a 'rubber' pipe feeding it. Probably added to reduce noise or vibration - as earlier versions of the same model don't show it. And it split, spilling water over both the igniter and gas valve. The igniter being a sealed unit survived this - the gas valve didn't. But when it burnt out, it took out its fuse on the PCB. And they were only a few pence from CPC. Unlike the gas valve. ;-)

I'd guess if BG had fixed it, the bill would have been not far short of the cost of a new boiler.