Our gas boiler has decided of course that this is the week to breakdown

It's an Ideal Mexico Super CF4120, this is a floor standing open flued boiler,
it's a pretty basic boiler with nothing in the way of fancy electronics. The
only control is water temp thermostat.

When required to fire up, it has a pilot ignited by a spark , which then
lights the mian burner.

So it stopped lighting up. Though I could hear the spark clicking.

As I've done a couple of times before when this happened removed the burner
unit and gas the pilot light burner and igniter a good clean and blow out
with a compressed air can. Unfortunately this did not sort the problem :-(

The gas valve is one of these

https://www.tradeboilerparts.co.uk/I...Part-no-170664.

I've tested the solenoid resistance on the left with my cheapo multimeter at it
is showing open circuit , so has presumably failed. Are there any other checks
I should do?.

Or is that pretty conclusive? I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

Thanks (and glad to see some old faces still here :-))

--
Chris French

Chris French wrote:

I've tested the solenoid resistance on the left with my cheapo multimeter at it
is showing open circuit , so has presumably failed. Are there any other checks
I should do?.

Or is that pretty conclusive?

Sounds it.

I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

Mine's a permanent pilot, and yes the solenoid valve supplies it
(controlled by thermocouple) ... hope my gas valve keeps hanging on in
there ...

On 17/12/2020 03:08, Chris French wrote:
Our gas boiler has decided of course that this is the week to breakdown

It's an Ideal Mexico Super CF4120, this is a floor standing open flued boiler,
it's a pretty basic boiler with nothing in the way of fancy electronics. The
only control is water temp thermostat.

Classic symptoms of the thermocouple failing. To light the pilot light
you manually override The pilot light heats the thermocouple



When required to fire up, it has a pilot ignited by a spark , which then
lights the mian burner.

So it stopped lighting up. Though I could hear the spark clicking.

As I've done a couple of times before when this happened removed the burner
unit and gas the pilot light burner and igniter a good clean and blow out
with a compressed air can. Unfortunately this did not sort the problem :-(

The gas valve is one of these

https://www.tradeboilerparts.co.uk/I...Part-no-170664.

I've tested the solenoid resistance on the left with my cheapo multimeter at it
is showing open circuit , so has presumably failed. Are there any other checks
I should do?.

Or is that pretty conclusive? I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

Thanks (and glad to see some old faces still here :-))



--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 17/12/2020 08:29, alan_m wrote:

Classic symptoms of the thermocouple failing.Â* To light the pilot light
you manually override The pilot light heats the thermocouple


Ignore - I pressed send instead of delete.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Thu, 17 Dec 2020 08:13:52 +0000, Andy Burns wrote:

I've tested the solenoid resistance on the left with my cheapo
multimeter at it is showing open circuit , so has presumably
failed.
Are there any other checks I should do?.

Or is that pretty conclusive?

Sounds it.

High up the list that's for sure.

I don't know much about the gas valves, does the solenoid control
the
flow of gas to the pilot as well?

Mine's a permanent pilot, and yes the solenoid valve supplies it
(controlled by thermocouple) ...

This boiler doesn't have a permanent pilot. Logic/safety would
suggest that the gas for the pilot is not supplied without incoming
mains and the spark generator running (possibly with a time out).
Once the pilot lights it heats the thermocouple that operates the
main gas valve solenoid. Loss of mains causes the main and pilot gas
valves to close shutting of the boiler and pilot.

In theory... See if the service manula can be found on the 'net to
find out how/what it is supposed to be doing.

--
Cheers
Dave.

On 17/12/2020 03:08, Chris French wrote:

Our gas boiler has decided of course that this is the week to breakdown

It's an Ideal Mexico Super CF4120, this is a floor standing open flued boiler,
it's a pretty basic boiler with nothing in the way of fancy electronics. The
only control is water temp thermostat.

(drop me an email if if you need a copy of the install/service manual
for this boiler)

There is also a down draft detecting thermostat near the base of the
flue inlet as well. That is designed to cut power to the boiler if
there are adverse weather conditions that would risk pushing combustion
products out into the room. If that fails open circuit, then the boiler
will not fire. (you would get no spark either - since its inline with
the boiler power supply).

When required to fire up, it has a pilot ignited by a spark , which then
lights the mian burner.

So it stopped lighting up. Though I could hear the spark clicking.

I presume the pilot is not lighting either?

As I've done a couple of times before when this happened removed the burner
unit and gas the pilot light burner and igniter a good clean and blow out
with a compressed air can. Unfortunately this did not sort the problem :-(

The gas valve is one of these

https://www.tradeboilerparts.co.uk/I...Part-no-170664.

I've tested the solenoid resistance on the left with my cheapo multimeter at it
is showing open circuit , so has presumably failed. Are there any other checks
I should do?.

I would verify that mains voltage is appearing on the contacts when the
controls are calling for heat - that way you eliminate any other
possible cause in the controls prior to that point.

Or is that pretty conclusive?

As long as there is actually gas getting to the valve, yup.

I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.




--
Cheers,

John.

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

On 17/12/2020 09:51:58, John Rumm wrote:
On 17/12/2020 03:08, Chris French wrote:

Our gas boiler has decided of course that this is the week to breakdown

It's an Ideal Mexico Super CF4120, this is a floor standing open flued
boiler,
it's a pretty basic boiler with nothing in the way of fancy
electronics. The
only control is water temp thermostat.

(drop me an email if if you need a copy of the install/service manual
for this boiler)

There is also a down draft detecting thermostat near the base of the
flue inlet as well. That isÂ* designed to cut power to the boiler if
there are adverse weather conditions that would risk pushing combustion
products out into the room. If that fails open circuit, then the boiler
will not fire. (you would get no spark either - since its inline with
the boiler power supply).

When required to fire up, itÂ* has a pilot ignited by a spark , which then
lights the mian burner.

So it stoppedÂ* lighting up. Though I could hear the spark clicking.

I presume the pilot is not lighting either?

As I've done a couple of times before when this happened removed the
burner
unit and gas theÂ* pilot lightÂ* burner and igniter a good clean and
blow out
with a compressed air can. Unfortunately this did not sort the problem
:-(

The gas valve is one of these

https://www.tradeboilerparts.co.uk/I...Part-no-170664.


I've tested the solenoid resistance on the left with my cheapo
multimeter at it
is showing open circuit , so has presumably failed. Are there any
other checks
I should do?.

I would verify that mains voltage is appearing on the contacts when the
controls are calling for heat - that way you eliminate any other
possible cause in the controls prior to that point.

Or is that pretty conclusive?

As long as there is actually gas getting to the valve, yup.

I don't know much about the gas valves, does the
solenoid control the flow of gas to theÂ* pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.

After checking power is getting to at least one of the solenoids on the
gas valve you might be able to do the following.

I don't know the layout of this boiler but if the pilot is blocked, or
the pilot solenoid side faulty, it may be possible to use an extended
gas lighter to heat the thermocouple for the main burner to then light.

John Rumm wrote:
On 17/12/2020 03:08, Chris French wrote:

Our gas boiler has decided of course that this is the week to breakdown

It's an Ideal Mexico Super CF4120, this is a floor standing open flued
boiler,
it's a pretty basic boiler with nothing in the way of fancy electronics. The
only control is water temp thermostat.

(drop me an email if if you need a copy of the install/service manual
for this boiler)

Thanks for the offer John, I have a copy.

There is also a down draft detecting thermostat near the base of the
flue inlet as well. That is designed to cut power to the boiler if
there are adverse weather conditions that would risk pushing combustion
products out into the room. If that fails open circuit, then the boiler
will not fire. (you would get no spark either - since its inline with
the boiler power supply).

Yup, I discovered that one windy winters night :-)


When required to fire up, it has a pilot ignited by a spark , which then
lights the mian burner.

So it stopped lighting up. Though I could hear the spark clicking.

I presume the pilot is not lighting either?

Nope


As I've done a couple of times before when this happened removed the burner
unit and gas the pilot light burner and igniter a good clean and blow out
with a compressed air can. Unfortunately this did not sort the problem :-(

The gas valve is one of these


https://www.tradeboilerparts.co.uk/I...Part-no-170664.

I've tested the solenoid resistance on the left with my cheapo multimeter at
it
is showing open circuit , so has presumably failed. Are there any other
checks
I should do?.

I would verify that mains voltage is appearing on the contacts when the
controls are calling for heat - that way you eliminate any other
possible cause in the controls prior to that point.

Yep, got voltage

Or is that pretty conclusive?

As long as there is actually gas getting to the valve, yup.

Yep, disconnected the union to check for gas.


I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.


Yep, that@s exactly what seems to happen

Thanks John

--
Chris French

"Dave Liquorice" wrote:
On Thu, 17 Dec 2020 08:13:52 +0000, Andy Burns wrote:

I've tested the solenoid resistance on the left with my cheapo
multimeter at it is showing open circuit , so has presumably
failed.
Are there any other checks I should do?.

Or is that pretty conclusive?

Sounds it.

High up the list that's for sure.

I don't know much about the gas valves, does the solenoid control
the
flow of gas to the pilot as well?

Mine's a permanent pilot, and yes the solenoid valve supplies it
(controlled by thermocouple) ...

This boiler doesn't have a permanent pilot. Logic/safety would
suggest that the gas for the pilot is not supplied without incoming
mains and the spark generator running (possibly with a time out).
Once the pilot lights it heats the thermocouple that operates the
main gas valve solenoid. Loss of mains causes the main and pilot gas
valves to close shutting of the boiler and pilot.

In theory... See if the service manula can be found on the 'net to
find out how/what it is supposed to be doing.


Thjanks Dave, yeah I've got a copy of the install and maintenance manual.

That's the gist of it, but This one doesn't have thermocouple. The spark
electrode acts as a sensor for when the pilot is alight. The PCB then opens the
main gas valve.

--
chris French

On 17/12/2020 13:39, Chris French wrote:
John Rumm wrote:


I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.


Yep, that@s exactly what seems to happen

Thanks John

In which case, I would have to concur, shagged gas valve...

(have seen this on other mexico boilers - although normally the manual
pilot type. One that failed to fire at all, and one that failed shortly
after main burner ignition as the valve warmed up).



--
Cheers,

John.

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

On 17/12/2020 13:45, Chris French wrote:
"Dave Liquorice" wrote:
On Thu, 17 Dec 2020 08:13:52 +0000, Andy Burns wrote:

I've tested the solenoid resistance on the left with my cheapo
multimeter at it is showing open circuit , so has presumably
failed.
Are there any other checks I should do?.

Or is that pretty conclusive?

Sounds it.

High up the list that's for sure.

I don't know much about the gas valves, does the solenoid control
the
flow of gas to the pilot as well?

Mine's a permanent pilot, and yes the solenoid valve supplies it
(controlled by thermocouple) ...

This boiler doesn't have a permanent pilot. Logic/safety would
suggest that the gas for the pilot is not supplied without incoming
mains and the spark generator running (possibly with a time out).
Once the pilot lights it heats the thermocouple that operates the
main gas valve solenoid. Loss of mains causes the main and pilot gas
valves to close shutting of the boiler and pilot.

In theory... See if the service manula can be found on the 'net to
find out how/what it is supposed to be doing.


Thjanks Dave, yeah I've got a copy of the install and maintenance manual.

That's the gist of it, but This one doesn't have thermocouple. The spark
electrode acts as a sensor for when the pilot is alight. The PCB then opens the
main gas valve.

Its an odd design in a way - more sophisticated controls (spark ignition
etc) that many mexico models - but not room sealed...


--
Cheers,

John.

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

On Thu, 17 Dec 2020 13:45:20 GMT, Chris French wrote:

That's the gist of it, but This one doesn't have thermocouple. The spark
electrode acts as a sensor for when the pilot is alight. The PCB then
opens the main gas valve.

It hasn't lost it's earth (as in real) has it? Don't know the
mechanisum but there are post mentioning boilers not starting when
run from a genset that doesn't have neutral tied to earth somewhere.

--
Cheers
Dave.

On 17/12/2020 14:04, Dave Liquorice wrote:
On Thu, 17 Dec 2020 13:45:20 GMT, Chris French wrote:

That's the gist of it, but This one doesn't have thermocouple. The spark
electrode acts as a sensor for when the pilot is alight. The PCB then
opens the main gas valve.

It hasn't lost it's earth (as in real) has it? Don't know the
mechanisum but there are post mentioning boilers not starting when
run from a genset that doesn't have neutral tied to earth somewhere.

That's for ones that use flame rectification to sense ignition. Even
when that mechanism fails the main burner will still light, but then it
fails to "prove" and the controls shut it off again.


--
Cheers,

John.

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

Fredxx wrote:

After checking power is getting to at least one of the solenoids

Is there much point, given the solenoid valve is known to be O/C ?

On Thu, 17 Dec 2020 15:38:51 +0000, Andy Burns wrote:

After checking power is getting to at least one of the solenoids

Is there much point, given the solenoid valve is known to be O/C ?

Wouldn't the main solenoid be OC unless the pilot solenoid was
engaged? The fail safe lot get very fussy about gas...

--
Cheers
Dave.

John Rumm wrote:
On 17/12/2020 13:39, Chris French wrote:
John Rumm wrote:


I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.


Yep, that@s exactly what seems to happen

Thanks John

In which case, I would have to concur, shagged gas valve...

(have seen this on other mexico boilers - although normally the manual
pilot type. One that failed to fire at all, and one that failed shortly
after main burner ignition as the valve warmed up).



Ok, new gas valve on it's way.

A couple of small queries.

The boiler manual says of the pressure testing points on the gas valve, to
loosen the scews in them to test the pressure. Except there are no screws in
them, just a threaded hole.

I presume I need to use a pressure test nipple in them? Are these likely to be
the common 1/8 BSP size? I can't find any info on it .

Is the feed pipe likley to be hard to remove? It's threaded in and the other
end is the female part of the union, so no nut or anything to use a spanner on?

Thanks

--
Chris French

On 18/12/2020 00:35, Chris ?French wrote:
John Rumm wrote:
On 17/12/2020 13:39, Chris French wrote:
John Rumm wrote:


I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.


Yep, that@s exactly what seems to happen

Thanks John

In which case, I would have to concur, shagged gas valve...

(have seen this on other mexico boilers - although normally the manual
pilot type. One that failed to fire at all, and one that failed shortly
after main burner ignition as the valve warmed up).



Ok, new gas valve on it's way.

A couple of small queries.

The boiler manual says of the pressure testing points on the gas valve, to
loosen the scews in them to test the pressure. Except there are no screws in
them, just a threaded hole.

I presume I need to use a pressure test nipple in them? Are these likely to be
the common 1/8 BSP size? I can't find any info on it .

I have never tried it on one of those, but I would expect so.

Is the feed pipe likley to be hard to remove? It's threaded in and the other
end is the female part of the union, so no nut or anything to use a spanner on?

IME yup it takes a fair amount of oompf to get it free (taper steel pipe
thread into ali casting ISTR). On the bright side there is usually a
bend in the pipe, which gives you some leverage. However gas valve
clamped up in a vice and a big stilson wrench on the pipe will do it
(YMMV). Refitting is much easier I expect!



--
Cheers,

John.

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

John Rumm wrote:
On 18/12/2020 00:35, Chris ?French wrote:
John Rumm wrote:
On 17/12/2020 13:39, Chris French wrote:
John Rumm wrote:


I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.


Yep, that@s exactly what seems to happen

Thanks John

In which case, I would have to concur, shagged gas valve...

(have seen this on other mexico boilers - although normally the manual
pilot type. One that failed to fire at all, and one that failed shortly
after main burner ignition as the valve warmed up).



Ok, new gas valve on it's way.

A couple of small queries.

The boiler manual says of the pressure testing points on the gas valve, to
loosen the scews in them to test the pressure. Except there are no screws in
them, just a threaded hole.

I presume I need to use a pressure test nipple in them? Are these likely to
be
the common 1/8 BSP size? I can't find any info on it .

I have never tried it on one of those, but I would expect so.

Is the feed pipe likley to be hard to remove? It's threaded in and the other
end is the female part of the union, so no nut or anything to use a spanner
on?

IME yup it takes a fair amount of oompf to get it free (taper steel pipe
thread into ali casting ISTR). On the bright side there is usually a
bend in the pipe, which gives you some leverage. However gas valve
clamped up in a vice and a big stilson wrench on the pipe will do it
(YMMV). Refitting is much easier I expect!


Unfortunately, just a short length (20cm?) of straight pipe.

On the brightside I do have a big FO lighweight stillson wrench left behind by
the chaps who changed the gas mater a few years back :-)

Thanks John

--
Chris French

Chris ?French wrote in
news

The boiler manual says of the pressure testing points on the gas
valve, to loosen the scews in them to test the pressure. Except there
are no screws in them, just a threaded hole.

I presume I need to use a pressure test nipple in them? Are these
likely to be the common 1/8 BSP size? I can't find any info on it .

Are the threaded holes in the cast-in posts on the gas valve?

If so I'd expect the screw to be deeply recessed within the posts and the
posts to be sized to be a fit for the manometer hose, no nipple reqd.

That's certainly the case here but mine's not an ideal or mexico.

No need to remove the screw, just open a 1/4 turn or so as no major flow
reqd.

On 17/12/2020 22:57, Dave Liquorice wrote:
On Thu, 17 Dec 2020 15:38:51 +0000, Andy Burns wrote:

After checking power is getting to at least one of the solenoids

Is there much point, given the solenoid valve is known to be O/C ?

Wouldn't the main solenoid be OC unless the pilot solenoid was
engaged? The fail safe lot get very fussy about gas...


No. It's just a coil of wire with a finite impedance. If the impedance
is infinite, it's stuffed!

Depending on the gas valve, the OP may be able to buy a new coil without
having to replace the whole valve.
--
Cheers,
Roger

John Rumm wrote:
On 18/12/2020 00:35, Chris ?French wrote:
John Rumm wrote:
On 17/12/2020 13:39, Chris French wrote:
John Rumm wrote:


I don't know much about the gas valves, does the
solenoid control the flow of gas to the pilot as well?

On this boiler there appears to be two live connections to the gas valve
- one presumably for the pilot and another for the main valve. The PCB
may sequence these, and possibly turn off the pilot once the ignition
electrode detects the main burner firing.


Yep, that@s exactly what seems to happen

Thanks John

In which case, I would have to concur, shagged gas valve...

(have seen this on other mexico boilers - although normally the manual
pilot type. One that failed to fire at all, and one that failed shortly
after main burner ignition as the valve warmed up).



Ok, new gas valve on it's way.

A couple of small queries.

The boiler manual says of the pressure testing points on the gas valve, to
loosen the scews in them to test the pressure. Except there are no screws in
them, just a threaded hole.

I presume I need to use a pressure test nipple in them? Are these likely to
be
the common 1/8 BSP size? I can't find any info on it .

I have never tried it on one of those, but I would expect so.

I was talking rubbish, there is a screw lurking at the bottom of the hole.


Is the feed pipe likley to be hard to remove? It's threaded in and the other
end is the female part of the union, so no nut or anything to use a spanner
on?

IME yup it takes a fair amount of oompf to get it free (taper steel pipe
thread into ali casting ISTR). On the bright side there is usually a
bend in the pipe, which gives you some leverage. However gas valve
clamped up in a vice and a big stilson wrench on the pipe will do it
(YMMV). Refitting is much easier I expect!


Actually, in the end it came out easily enough, witht he stilsons.

Then I noticed that the indie of the union on the other end had an allen key
fitting, for one of those big allen keys.

Back together, and now working :-)

Household harmony resumes.

Thanks for your help John

--
Chris French

Roger Mills wrote:
On 17/12/2020 22:57, Dave Liquorice wrote:
On Thu, 17 Dec 2020 15:38:51 +0000, Andy Burns wrote:

After checking power is getting to at least one of the solenoids

Is there much point, given the solenoid valve is known to be O/C ?

Wouldn't the main solenoid be OC unless the pilot solenoid was
engaged? The fail safe lot get very fussy about gas...


No. It's just a coil of wire with a finite impedance. If the impedance
is infinite, it's stuffed!

Depending on the gas valve, the OP may be able to buy a new coil without
having to replace the whole valve.

I did look a bit to see if I could get the solenoid , but I couldn't find one,
and it's winter and we are all at home. Just wanted it fixed :-)

--
Chris French

Peter Burke wrote:
Chris ?French wrote in
news

The boiler manual says of the pressure testing points on the gas
valve, to loosen the scews in them to test the pressure. Except there
are no screws in them, just a threaded hole.

I presume I need to use a pressure test nipple in them? Are these
likely to be the common 1/8 BSP size? I can't find any info on it .

Are the threaded holes in the cast-in posts on the gas valve?

If so I'd expect the screw to be deeply recessed within the posts and the
posts to be sized to be a fit for the manometer hose, no nipple reqd.

That's certainly the case here but mine's not an ideal or mexico.

No need to remove the screw, just open a 1/4 turn or so as no major flow
reqd.

Yep, mine was like that, once I looked more closely :-)