My Keston boiler seems nothing but trouble. In the two years since I
have had it installed, it has failed in the following ways

The main PCB failed (just stopped working)

The Keston system kit (expansion tank) failed- the membrane went

and now the cabinet overheats

Surprisingly the keston does not have a reset switch. Instead you have
to replace the 'thermal fuse' which is set at £4.50

This is just to get the boiler to re-ignite. Then I surpose you have
to test it and see why the boiler overheated. Proably blowing one or
more of these thermal fuses. My local supplier tells me they do not
stock these items. Keston naturally do not supply direct, and I am
left with having to wait a week for this non stock item to appear (at
a charge of £18.50! (£14 small order carrage!) )

Therefore I am forced to call on Keston themselves to fix the problem.
It is going to be a very expensive repair (their MINIMUM is £150) as
at least their engineer will have the parts to hand, and will not be
on an endless cycle of get part, fit it , blow it discover real
underlying fault, get part fit it etc etc. I cannot wait weeks in this
weather.

So in conclusion. I cannot recomment kestion celcius 25s. Too flaky
Richard

In article ,
Richard writes:
My Keston boiler seems nothing but trouble. In the two years since I
have had it installed, it has failed in the following ways

The main PCB failed (just stopped working)

The Keston system kit (expansion tank) failed- the membrane went

and now the cabinet overheats

Surprisingly the keston does not have a reset switch. Instead you have
to replace the 'thermal fuse' which is set at £4.50

They're around 50p each from CPC if this is the one on the transformer
connector block, but you'll have to know what the fusing temperature is,
and I've never looked at it that closely. Manual mentions 82ºC, but the
nearest standard values for thermal fuses seem to be 72ºC and 84ºC.

This is just to get the boiler to re-ignite. Then I surpose you have
to test it and see why the boiler overheated. Proably blowing one or
more of these thermal fuses. My local supplier tells me they do not
stock these items. Keston naturally do not supply direct, and I am
left with having to wait a week for this non stock item to appear (at
a charge of £18.50! (£14 small order carrage!) )

Therefore I am forced to call on Keston themselves to fix the problem.
It is going to be a very expensive repair (their MINIMUM is £150) as
at least their engineer will have the parts to hand, and will not be
on an endless cycle of get part, fit it , blow it discover real
underlying fault, get part fit it etc etc. I cannot wait weeks in this
weather.

Well, the thermal fuse failure is just a symptom of something
potentially more serious.

Let's try to guess what might cause the temperature in the cabinet to
overheat. Perhaps blocked air intake or flue, burst/split/disconnected
internal flue pipe, burst/split/disconnected internal condensate pipe
before U-trap (would also show up as water leaking from casing), failed
burner gasket, failed heat exchanger insulation (internal or external),
excessive combustion rate.

Also, are there any external influences which might heat up the boiler
casing, such as positioned over a radiator or some other heat source?
This could have blown the thermal fuse by overheating the boiler when
it's not running and there's no airflow through it.

So in conclusion. I cannot recomment kestion celcius 25s. Too flaky
Richard

--
Andrew Gabriel

(Andrew Gabriel) wrote:

In article ,
Richard writes:
My Keston boiler seems nothing but trouble. In the two years since I
have had it installed, it has failed in the following ways

The main PCB failed (just stopped working)

The Keston system kit (expansion tank) failed- the membrane went

and now the cabinet overheats

Surprisingly the keston does not have a reset switch. Instead you have
to replace the 'thermal fuse' which is set at £4.50

They're around 50p each from CPC if this is the one on the transformer
connector block, but you'll have to know what the fusing temperature is,
and I've never looked at it that closely. Manual mentions 82ºC, but the
nearest standard values for thermal fuses seem to be 72ºC and 84ºC.

This is just to get the boiler to re-ignite. Then I surpose you have
to test it and see why the boiler overheated. Proably blowing one or
more of these thermal fuses. My local supplier tells me they do not
stock these items. Keston naturally do not supply direct, and I am
left with having to wait a week for this non stock item to appear (at
a charge of £18.50! (£14 small order carrage!) )

Therefore I am forced to call on Keston themselves to fix the problem.
It is going to be a very expensive repair (their MINIMUM is £150) as
at least their engineer will have the parts to hand, and will not be
on an endless cycle of get part, fit it , blow it discover real
underlying fault, get part fit it etc etc. I cannot wait weeks in this
weather.

Well, the thermal fuse failure is just a symptom of something
potentially more serious.

Let's try to guess what might cause the temperature in the cabinet to
overheat. Perhaps blocked air intake or flue, burst/split/disconnected
internal flue pipe, burst/split/disconnected internal condensate pipe
before U-trap (would also show up as water leaking from casing), failed
burner gasket, failed heat exchanger insulation (internal or external),
excessive combustion rate.

Also, are there any external influences which might heat up the boiler
casing, such as positioned over a radiator or some other heat source?
This could have blown the thermal fuse by overheating the boiler when
it's not running and there's no airflow through it.

yep, whole host of possible causes. Hence:-

So in conclusion. I cannot recomment kestion celcius 25s. Too flaky
Richard

Richard wrote:

(Andrew Gabriel) wrote:

In article ,
Richard writes:
My Keston boiler seems nothing but trouble. In the two years since I
have had it installed, it has failed in the following ways

The main PCB failed (just stopped working)

The Keston system kit (expansion tank) failed- the membrane went

and now the cabinet overheats

Surprisingly the keston does not have a reset switch. Instead you have
to replace the 'thermal fuse' which is set at £4.50

They're around 50p each from CPC if this is the one on the transformer
connector block, but you'll have to know what the fusing temperature is,
and I've never looked at it that closely. Manual mentions 82ºC, but the
nearest standard values for thermal fuses seem to be 72ºC and 84ºC.

This is just to get the boiler to re-ignite. Then I surpose you have
to test it and see why the boiler overheated. Proably blowing one or
more of these thermal fuses. My local supplier tells me they do not
stock these items. Keston naturally do not supply direct, and I am
left with having to wait a week for this non stock item to appear (at
a charge of £18.50! (£14 small order carrage!) )

Therefore I am forced to call on Keston themselves to fix the problem.
It is going to be a very expensive repair (their MINIMUM is £150) as
at least their engineer will have the parts to hand, and will not be
on an endless cycle of get part, fit it , blow it discover real
underlying fault, get part fit it etc etc. I cannot wait weeks in this
weather.

Well, the thermal fuse failure is just a symptom of something
potentially more serious.

Let's try to guess what might cause the temperature in the cabinet to
overheat. Perhaps blocked air intake or flue, burst/split/disconnected
internal flue pipe, burst/split/disconnected internal condensate pipe
before U-trap (would also show up as water leaking from casing), failed
burner gasket, failed heat exchanger insulation (internal or external),
excessive combustion rate.

Also, are there any external influences which might heat up the boiler
casing, such as positioned over a radiator or some other heat source?
This could have blown the thermal fuse by overheating the boiler when
it's not running and there's no airflow through it.

yep, whole host of possible causes. Hence:-

So in conclusion. I cannot recomment kestion celcius 25s. Too flaky
Richard
Thanks for your advice
Man acme today, fitted new fuse and after 30 mins spooted micro leak
in seal where flue attached to boiler. This is the black rubber
gasket. It seems it is sealed by just silicon from a gun. If it lets
water out, then it can cause a build up of steam in the cabinet thus
causing thermal cut out.

So all working again. Must say next time its serviced I will get them
to check the silicon seal.

Richard

In article ,
Richard writes:
Thanks for your advice
Man acme today, fitted new fuse and after 30 mins spooted micro leak
in seal where flue attached to boiler. This is the black rubber
gasket. It seems it is sealed by just silicon from a gun. If it lets

I can't picture a black gasket in the flue path.
Was this the burner gasket -- the large rectangular
gasket on top of the rectangular heat exchanger box?
A leak at this point would be very hot, whereas a
leak in the flue would be much less so.

I did replace the burner gasket on mine during servicing as
a) it was impossible to get it off in less than about
10 pieces because it had been glued on, and
b) it had hairline cracks through at several of the
mounting holes (although I couldn't actually see any
sign of leaking there).
I didn't silicone in the replacement gasket as the instructions
don't say this is necessary. I did check it again a week later
to make sure it still looked OK with no sign of leaks/cracks.
I bought a couple of them -- can't remember the price but
it was under a tenner each.

water out, then it can cause a build up of steam in the cabinet thus
causing thermal cut out.

Hum, did it look like it had corroded anything in the
boiler (the steam is acidic)? The thermal trip probably
caught it before it had a chance to do so.

So all working again. Must say next time its serviced I will get them
to check the silicon seal.

If it is the burner gasket, this is supposed to be open at
each service anyway, to clean the burner and surrounding
area.

--
Andrew Gabriel

(Andrew Gabriel) wrote:

In article ,
Richard writes:
Thanks for your advice
Man acme today, fitted new fuse and after 30 mins spooted micro leak
in seal where flue attached to boiler. This is the black rubber
gasket. It seems it is sealed by just silicon from a gun. If it lets

I can't picture a black gasket in the flue path.
Was this the burner gasket -- the large rectangular
gasket on top of the rectangular heat exchanger box?
A leak at this point would be very hot, whereas a
leak in the flue would be much less so.

I did replace the burner gasket on mine during servicing as
a) it was impossible to get it off in less than about
10 pieces because it had been glued on, and
b) it had hairline cracks through at several of the
mounting holes (although I couldn't actually see any
sign of leaking there).
I didn't silicone in the replacement gasket as the instructions
don't say this is necessary. I did check it again a week later
to make sure it still looked OK with no sign of leaks/cracks.
I bought a couple of them -- can't remember the price but
it was under a tenner each.

my teminology is not really accurate. it is a black ribbed tube going
up to the flue outlet. The base of the tube should be sealed with
silicone otherwise flue gasses/water can leak into the cabinet. The
flue gasses are i guess not hot enuf to trip the overheat but the
water can be turned to steam by the hot surfaces and im told fill the
cabinet with steam and this would clearly trigger the overheat.

On Tue, 18 Jan 2005 20:07:52 +0000, Richard wrote:

(Andrew Gabriel) wrote:

In article ,
Richard writes:
My Keston boiler seems nothing but trouble. In the two years since I
have had it installed, it has failed in the following ways

The main PCB failed (just stopped working)

The Keston system kit (expansion tank) failed- the membrane went

and now the cabinet overheats

Surprisingly the keston does not have a reset switch. Instead you have
to replace the 'thermal fuse' which is set at £4.50

They're around 50p each from CPC if this is the one on the transformer
connector block, but you'll have to know what the fusing temperature is,
and I've never looked at it that closely. Manual mentions 82ºC, but the
nearest standard values for thermal fuses seem to be 72ºC and 84ºC.

This is just to get the boiler to re-ignite. Then I surpose you have
to test it and see why the boiler overheated. Proably blowing one or
more of these thermal fuses. My local supplier tells me they do not
stock these items. Keston naturally do not supply direct, and I am
left with having to wait a week for this non stock item to appear (at
a charge of £18.50! (£14 small order carrage!) )

Therefore I am forced to call on Keston themselves to fix the problem.
It is going to be a very expensive repair (their MINIMUM is £150) as
at least their engineer will have the parts to hand, and will not be
on an endless cycle of get part, fit it , blow it discover real
underlying fault, get part fit it etc etc. I cannot wait weeks in this
weather.

Well, the thermal fuse failure is just a symptom of something
potentially more serious.

Let's try to guess what might cause the temperature in the cabinet to
overheat. Perhaps blocked air intake or flue, burst/split/disconnected
internal flue pipe, burst/split/disconnected internal condensate pipe
before U-trap (would also show up as water leaking from casing), failed
burner gasket, failed heat exchanger insulation (internal or external),
excessive combustion rate.

Also, are there any external influences which might heat up the boiler
casing, such as positioned over a radiator or some other heat source?
This could have blown the thermal fuse by overheating the boiler when
it's not running and there's no airflow through it.

yep, whole host of possible causes. Hence:-

So in conclusion. I cannot recomment kestion celcius 25s. Too flaky
Richard

Alas you seem to have got the lemon. I have now installed 3 C25s the
oldest is nearly 3 years ago. None have had any trouble although the C40
had loads (But mostly suphide dust getting into the gas valve whcich was
not Kestons's fault).

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

In article ,
(Andrew Gabriel) writes:

Let's try to guess what might cause the temperature in the cabinet to
overheat. Perhaps blocked air intake or flue, burst/split/disconnected
internal flue pipe, burst/split/disconnected internal condensate pipe
before U-trap (would also show up as water leaking from casing), failed
burner gasket, failed heat exchanger insulation (internal or external),
excessive combustion rate.

I just checked the fault finding section, and it gives another
possible cause as pump overrun not working although I'm not sure
what you could do about that as it's controlled by the fan
control board. You could perhaps have a system design which had
no water path for overrun (e.g. no 3-way valve and no bypass) or
the bypass loop is too short to absorb the required energy.

Also, are there any external influences which might heat up the boiler
casing, such as positioned over a radiator or some other heat source?
This could have blown the thermal fuse by overheating the boiler when
it's not running and there's no airflow through it.

Another thought -- has the thermal fuse actually failed at all?
Check it, and if not, look for a broken wire connecting it back
to the fan control board. It could also be a fault on the board
itself.

--
Andrew Gabriel

I bought a new Keston C25 boilers which was installed and commissioned
in late December 05. The installation was inspected in January 2006 by
a Keston engineer, and the boiler has been running well for the last
four months, but more recently it appeared to be losing efficiency.

This evening I noticed a dark stain in the grouting in the tilework
fronting the room space space in which the boiler was installed. I
investigated and found that condensate had been dripping out of the
boiler casing for what was clearly some time, judging by the highly
evident level of corrosion to the flow control valves, pipe work,
boiler casing and damage to the room space area beneath the boiler.

I am an engineer by trade, so I felt confident in investigating
further. I removed the casing to find condensate dripping out of the
fluted rubber vent tube to the right hand side of the combustion
chamber. There was also a pool of rusty-coloured liquid in the bottom
of the boiler which spilled out when I pulled back the casing.

I investigated further and found the rubber flue tube to be completely
corroded and brittle - the inner sides of the flutes have split so it
is possible to stretch the pipe out like a slinky spring. I ran the
boiler with the casing open and was shocked to see a huge amount of
flue gas coming back into the boiler itself. The boiler casing is
corroded in parts and very rusty looking, yet it is not even six months
old. It - not surprisingly - runs very hot, too.

The boiler casing is not properly sealed, either. A quick check with a
smoke can showed that the positive pressure of the flue gas was pushing
the flue gas out of the casing into the room cavity in which the boiler
is installed. This boiler room space is not vented to the outside - my
installer informed me that the boiler is self-venting, allowing it to
be installed in domestic spaces such as kitchen cupboards etc.

It is obviously a known design fault. I note - with a little bit of
investigation on the internet, including posts in this thread
describing a cracked 'gasket pipe' from January '05 - that the latest
version of the C25 boilers no longer contains this rubber pipe and has
been redesigned with a solid one. This can only be because someone
realised there was a serious problem.

My conclusion is that the model of boiler I have had installed is
actually dangerous. Keston has shipped boilers of this design for
nearly a year so there must be a lot of them out there. I have
contacted Keston to inform them of my findings. And I have informed
Corgi. I will post their response to this forum when I get it.

Richard Wrote:
The Keston system kit (expansion tank) failed- the membrane went and now
the cabinet overheats
Richard


--
worriedconsumer

In article .com,
worriedconsumer .com writes:

I bought a new Keston C25 boilers which was installed and commissioned
in late December 05. The installation was inspected in January 2006 by
a Keston engineer, and the boiler has been running well for the last
four months, but more recently it appeared to be losing efficiency.

Why did Keston inspect it only a month after installation?

I investigated further and found the rubber flue tube to be completely
corroded and brittle - the inner sides of the flutes have split so it
is possible to stretch the pipe out like a slinky spring. I ran the
boiler with the casing open and was shocked to see a huge amount of
flue gas coming back into the boiler itself. The boiler casing is
corroded in parts and very rusty looking, yet it is not even six months
old. It - not surprisingly - runs very hot, too.

There's a non-resettable case over temperature sensor which
people have reported blows if the flue splits and discharges
back into the case. It's mounted on the transformer.

The boiler casing is not properly sealed, either. A quick check with a
smoke can showed that the positive pressure of the flue gas was pushing
the flue gas out of the casing into the room cavity in which the boiler
is installed. This boiler room space is not vented to the outside - my
installer informed me that the boiler is self-venting, allowing it to
be installed in domestic spaces such as kitchen cupboards etc.

It is obviously a known design fault. I note - with a little bit of
investigation on the internet, including posts in this thread
describing a cracked 'gasket pipe' from January '05 - that the latest
version of the C25 boilers no longer contains this rubber pipe and has
been redesigned with a solid one. This can only be because someone
realised there was a serious problem.

My 2002 model has the black consertina pipe. I recall someone
saying earlier ones had a blue flexible flue pipe which Keston
swapped out. The black pipe in mine is still flexible (I had
to disconnect it to clear a blockage in the condensation
outlet). However, I have almost never run my boiler very hot;
the temperature knob pretty much only went past pointing straight
up (about 60C flow) during commissioning. In normal running, it
is set pointing to the left (about 45C flow). I'm curious what
position/temperature yours is normally set to -- maybe this has
a significant effect on the flue pipe life?

--
Andrew Gabriel

On Wed, 24 May 2006 01:22:36 +0100, worriedconsumer wrote:


I bought a new Keston C25 boilers which was installed and commissioned
in late December 05. The installation was inspected in January 2006 by
a Keston engineer, and the boiler has been running well for the last
four months, but more recently it appeared to be losing efficiency.

This evening I noticed a dark stain in the grouting in the tilework
fronting the room space space in which the boiler was installed. I
investigated and found that condensate had been dripping out of the
boiler casing for what was clearly some time, judging by the highly
evident level of corrosion to the flow control valves, pipe work,
boiler casing and damage to the room space area beneath the boiler.

I am an engineer by trade, so I felt confident in investigating
further. I removed the casing to find condensate dripping out of the
fluted rubber vent tube to the right hand side of the combustion
chamber. There was also a pool of rusty-coloured liquid in the bottom
of the boiler which spilled out when I pulled back the casing.

I investigated further and found the rubber flue tube to be completely
corroded and brittle - the inner sides of the flutes have split so it
is possible to stretch the pipe out like a slinky spring. I ran the
boiler with the casing open and was shocked to see a huge amount of
flue gas coming back into the boiler itself. The boiler casing is
corroded in parts and very rusty looking, yet it is not even six months
old. It - not surprisingly - runs very hot, too.

The boiler casing is not properly sealed, either. A quick check with a
smoke can showed that the positive pressure of the flue gas was pushing
the flue gas out of the casing into the room cavity in which the boiler
is installed. This boiler room space is not vented to the outside - my
installer informed me that the boiler is self-venting, allowing it to
be installed in domestic spaces such as kitchen cupboards etc.

It is obviously a known design fault. I note - with a little bit of
investigation on the internet, including posts in this thread
describing a cracked 'gasket pipe' from January '05 - that the latest
version of the C25 boilers no longer contains this rubber pipe and has
been redesigned with a solid one. This can only be because someone
realised there was a serious problem.

My conclusion is that the model of boiler I have had installed is
actually dangerous. Keston has shipped boilers of this design for
nearly a year so there must be a lot of them out there. I have
contacted Keston to inform them of my findings. And I have informed
Corgi. I will post their response to this forum when I get it.

Richard Wrote:
The Keston system kit (expansion tank) failed- the membrane went and now
the cabinet overheats
Richard

My own is a 2003 model and has not had a problem in this area.
I installed one the other week and this has a thicker solid
un-reinforced one piece rubber hose from the bottom of the heat exchanger
to the flue outlet spigot. It makes a slight deviation around the gas
supply pipe.

When in operation with the cover on the internal air pressure is always
less than ambient (although severe weather could alter this on a very
temporary basis). This would be true even if the flue outlet hose splits
within the boiler casing (a bad fault). As AG posted if it got so bad that
there was a serious problem the boiler would shutdown.

The only condition which would make the outlet hose get subject to an over
temperature would be running the boiler with no water in it (there is a
low pressure cut out against this).

I agree that this is a real bummer but you should be able to get the
replacement part fitted by Keston under warranty.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards