Likely cause of boiler transformer failure?
 

I have an Ideal Icos HE15 heat-only boiler which, by all accounts judging by plumbing/heating forums on the Internet, appears to be unwanted child of the boiler world. That said, this one is 12 years old now and has given sterling performance for the 9 years since we adopted it.

Until now that is. Today the house was cold and the boiler was dead. Many years ago I'd bought a spare PCB and control panel as I was aware these were its Achilles heal and, sure enough, replacing the PCB has brought it back to life.

First thing I noticed with the failed PCB was that the plastic case had a small area that was dark and slightly warped on the outside:

http://www.newtonnet.co.uk/permanent/icospcb1.jpg
http://www.newtonnet.co.uk/permanent/icospcb2.jpg

Opening up the case revealed that the board looked quite healthy however the transformer, which is situated right beneath where the warped plastic is, was a little dark and the label showed signs of what I guess could be heat stress:

http://www.newtonnet.co.uk/permanent...ansformer1.jpg
http://www.newtonnet.co.uk/permanent...ansformer2.jpg

Measuring the primary coil revealed it was open circuit.

Any ideas what could cause the transformer to fail? Do I dare rejoice that I've fixed the boiler, only to find out soon (Christmas Day probably) that there is an external component (e.g. fan?) that might be overloading the transformer causing it to fail? Or could it just be age / poor design?

Likely cause of boiler transformer failure?
 

Well, obviously I do not know the boiler specifically, but it sounds to me
like a thermal link has blown due to overheating of the transformer. It is
likely that something in the power supply circuit has put a short on the
secondary, or the transformer merely has broken down with shorted turns.
I'd have thought if there had been a fan or other bad component then you
might actually see it or hear it, ie lack of sound if its failed, so short
of trying to get a transformer and replacing the old board, I'd imagine just
checking every so often for overheating might be all one can do.
When this happened to a different appliance here, it turned out to be a
capacitor and a bridge rectifier which had gone, and one could actually
measure this on the old pcb. It was a shame nobody thought to fit a hi tech
device like a fuse in the low voltage side of the ac from the transformer.
grin.
Brian

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"Mathew Newton" wrote in message
...
I have an Ideal Icos HE15 heat-only boiler which, by all accounts judging by
plumbing/heating forums on the Internet, appears to be unwanted child of the
boiler world. That said, this one is 12 years old now and has given sterling
performance for the 9 years since we adopted it.

Until now that is. Today the house was cold and the boiler was dead. Many
years ago I'd bought a spare PCB and control panel as I was aware these were
its Achilles heal and, sure enough, replacing the PCB has brought it back to
life.

First thing I noticed with the failed PCB was that the plastic case had a
small area that was dark and slightly warped on the outside:

http://www.newtonnet.co.uk/permanent/icospcb1.jpg
http://www.newtonnet.co.uk/permanent/icospcb2.jpg

Opening up the case revealed that the board looked quite healthy however the
transformer, which is situated right beneath where the warped plastic is,
was a little dark and the label showed signs of what I guess could be heat
stress:

http://www.newtonnet.co.uk/permanent...ansformer1.jpg
http://www.newtonnet.co.uk/permanent...ansformer2.jpg

Measuring the primary coil revealed it was open circuit.

Any ideas what could cause the transformer to fail? Do I dare rejoice that
I've fixed the boiler, only to find out soon (Christmas Day probably) that
there is an external component (e.g. fan?) that might be overloading the
transformer causing it to fail? Or could it just be age / poor design?

Likely cause of boiler transformer failure?
 

On 28/11/2019 21:43, Mathew Newton wrote:

Any ideas what could cause the transformer to fail? Do I dare rejoice
that I've fixed the boiler, only to find out soon (Christmas Day
probably) that there is an external component (e.g. fan?) that might
be overloading the transformer causing it to fail? Or could it just
be age / poor design?

Hard to say from here... might be worth having a chat with the guys at
CET and see what the likely causes are. (you can also send em your dead
PCB and get a recon in its place for the next time!)

https://www.cetltd.com/



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Likely cause of boiler transformer failure?
 

On Thursday, 28 November 2019 21:43:18 UTC, Mathew Newton wrote:
I have an Ideal Icos HE15 heat-only boiler which, by all accounts judging by plumbing/heating forums on the Internet, appears to be unwanted child of the boiler world. That said, this one is 12 years old now and has given sterling performance for the 9 years since we adopted it.

Until now that is. Today the house was cold and the boiler was dead. Many years ago I'd bought a spare PCB and control panel as I was aware these were its Achilles heal and, sure enough, replacing the PCB has brought it back to life.

First thing I noticed with the failed PCB was that the plastic case had a small area that was dark and slightly warped on the outside:

http://www.newtonnet.co.uk/permanent/icospcb1.jpg
http://www.newtonnet.co.uk/permanent/icospcb2.jpg

Opening up the case revealed that the board looked quite healthy however the transformer, which is situated right beneath where the warped plastic is, was a little dark and the label showed signs of what I guess could be heat stress:

http://www.newtonnet.co.uk/permanent...ansformer1.jpg
http://www.newtonnet.co.uk/permanent...ansformer2.jpg

Measuring the primary coil revealed it was open circuit.

Any ideas what could cause the transformer to fail? Do I dare rejoice that I've fixed the boiler, only to find out soon (Christmas Day probably) that there is an external component (e.g. fan?) that might be overloading the transformer causing it to fail? Or could it just be age / poor design?

the only thing that kills transformers is too much heat due to too much current or voltage. So current overload on the 2ndary side is the answer. Post the schematic.


NT

Likely cause of boiler transformer failure?
 

Mathew Newton pretended :
Measuring the primary coil revealed it was open circuit.

Any ideas what could cause the transformer to fail? Do I dare rejoice that
I've fixed the boiler, only to find out soon (Christmas Day probably) that
there is an external component (e.g. fan?) that might be overloading the
transformer causing it to fail? Or could it just be age / poor design?

It was probably inadequate design or inadequate rating it was such a
common fault. You can actually buy, or could, identical replacement
transformers to avoid the cost of a new PCB. I repaired one that way,
but added extra ventilation around the transformer.

Another regular fault, is the fan and especially the wiring to to the
fan, which runs up the rear of the boiler. The heat from the boiler
melts the insulation.

Likely cause of boiler transformer failure?
 

On Thu, 28 Nov 2019 13:43:15 -0800 (PST), Mathew Newton wrote:

Measuring the primary coil revealed it was open circuit.

Internal thermal fuse has given up.

Or could it just be age / poor design?

I'd tend towards age and border line design. It takes quite a while
for plastic to change colour under heat without getting smelly.
Especially when there is an air gap like for the cover. The
transformer case was blue but is now mostly and evenly dark.

As you have a working board how warm/hot does the transformer on that
one run?

--
Cheers
Dave.

Likely cause of boiler transformer failure?
 

On Friday, 29 November 2019 17:05:41 UTC, Dave Liquorice wrote:
On Thu, 28 Nov 2019 13:43:15 -0800 (PST), Mathew Newton wrote:

Measuring the primary coil revealed it was open circuit.

Internal thermal fuse has given up.

Or could it just be age / poor design?

I'd tend towards age and border line design. It takes quite a while
for plastic to change colour under heat without getting smelly.
Especially when there is an air gap like for the cover. The
transformer case was blue but is now mostly and evenly dark.

As you have a working board how warm/hot does the transformer on that
one run?

50Hz transformers normally run no more than hand warm. To turn anything black it must have been well overloaded.


NT

Likely cause of boiler transformer failure?
 

On Fri, 29 Nov 2019 09:10:20 -0800 (PST), wrote:

As you have a working board how warm/hot does the transformer on
that
one run?

50Hz transformers normally run no more than hand warm. To turn anything
black it must have been well overloaded.

Or hand warm for a long time, like 12 years...

--
Cheers
Dave.

Likely cause of boiler transformer failure?
 

Everything else appears to be working fine, and the fan in particular - which I thought could be a likely suspect - is nice and quiet in operation. I'm thinking it'd down to a poor quality transformer.

On Friday, 29 November 2019 07:51:24 UTC, Brian Gaff (Sofa 2) wrote:
It is
likely that something in the power supply circuit has put a short on the
secondary, or the transformer merely has broken down with shorted turns.
I'd have thought if there had been a fan or other bad component then you
might actually see it or hear it, ie lack of sound if its failed, so short
of trying to get a transformer and replacing the old board

Likely cause of boiler transformer failure?
 

On Friday, 29 November 2019 09:53:20 UTC, John Rumm wrote:

Hard to say from here... might be worth having a chat with the guys at
CET and see what the likely causes are. (you can also send em your dead
PCB and get a recon in its place for the next time!)

As soon as it failed I thought of Geoff!

I've actually bought another transformer so will give that a go.

Likely cause of boiler transformer failure?
 

On Friday, 29 November 2019 14:55:28 UTC, wrote:

the only thing that kills transformers is too much heat due to too much current or voltage. So current overload on the 2ndary side is the answer. Post the schematic.

Unfortunately I don't have a schematic.

Likely cause of boiler transformer failure?
 

On Friday, 29 November 2019 16:43:15 UTC, wrote:

It was probably inadequate design or inadequate rating it was such a
common fault. You can actually buy, or could, identical replacement
transformers to avoid the cost of a new PCB. I repaired one that way,
but added extra ventilation around the transformer.

Yes, just bought one. One other company I contacted (YHDC in China) so they don't keep one as a stock item but would make me one in 3-4 weeks!

Another regular fault, is the fan and especially the wiring to to the
fan, which runs up the rear of the boiler. The heat from the boiler
melts the insulation.

That's not good to hear, but good to know - thanks!

Likely cause of boiler transformer failure?
 

On Friday, 29 November 2019 17:05:41 UTC, Dave Liquorice wrote:

I'd tend towards age and border line design. It takes quite a while
for plastic to change colour under heat without getting smelly.
Especially when there is an air gap like for the cover. The
transformer case was blue but is now mostly and evenly dark.

As you have a working board how warm/hot does the transformer on that
one run?

Good question; I'll do some testing. I did wonder about the location of the PCB as whilst it is underneath the combustion chamber it is never the less inside the casing and so it wouldn't surprise me if it got close to, or exceed, the 50C rating that I've seen printed on some replacement transformers.

Likely cause of boiler transformer failure?
 

On Friday, 29 November 2019 17:13:56 UTC, Dave Liquorice wrote:
On Fri, 29 Nov 2019 09:10:20 -0800 (PST), tabbypurr wrote:

As you have a working board how warm/hot does the transformer on
that
one run?

50Hz transformers normally run no more than hand warm. To turn anything
black it must have been well overloaded.

Or hand warm for a long time, like 12 years...

I don't know any material that's charred or blackened by being hand warm for 12 years. You're outdoing yourself.


NT

Likely cause of boiler transformer failure?
 

Mathew Newton was thinking very hard :
That's not good to hear, but good to know - thanks!

It might be worth your while if you intend to keep the boiler a while,
to take those cables out and replace the centre section with heat
resistant wires. Its a short loom, of four or five wires, which unplugs
at each end. Just snip close to the plugs, then solder in and sleeve
heat resistant wires. I suspect that cable failing, might be the cause
of the transformer burning out..

Likely cause of boiler transformer failure?
 

Mathew Newton explained :
That's not good to hear, but good to know - thanks!

I have a couple of spare fans for that boiler in my hut, if they might
be of use to you. One is a used working one, the other brand new
unused. I bought one when the boiler suggested a fan fault, before I
found the over heated and shorted fan loom running behind the boiler.

They are free for collection.