My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

Power cycled, and it showed 0.6 bar, and fired, but still wouldn't
accept any more filling. Let a bit of water out through the prv - no
change of reading, but it would then admit a small amount to refill.

It sounds like a faulty pressure sensor to me, but I suppose it could be
a circuit board fault.

Can the pressure sensor be tested other than by substitution? Can any
dummy load be applied to the circuit board to give a nominal pressure
reading?

Pressure sensors seem to be around the £70 mark, so he'd rather not buy
one if the fault's more likely to be elsewhere. Glow-worm part
2000801911, GC E83997.

Any ideas, please?

--
Kevin Poole
****Use current date to reply (e.g. )****

"Kevin Poole" wrote in message
...
My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of 0.4bar,
so he opened the filling valve. He heard some water flow in, but the
pressure barely changed, and the flow soon stopped.

Power cycled, and it showed 0.6 bar, and fired, but still wouldn't accept
any more filling. Let a bit of water out through the prv - no change of
reading, but it would then admit a small amount to refill.

It sounds like a faulty pressure sensor to me, but I suppose it could be a
circuit board fault.

Can the pressure sensor be tested other than by substitution? Can any
dummy load be applied to the circuit board to give a nominal pressure
reading?

Pressure sensors seem to be around the £70 mark, so he'd rather not buy
one if the fault's more likely to be elsewhere. Glow-worm part 2000801911,
GC E83997.

Any ideas, please?

--
Kevin Poole
****Use current date to reply (e.g. )****

Are both valves opened when you fill it?

John wrote:
"Kevin Poole" wrote in message
...
My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of 0.4bar,
so he opened the filling valve. He heard some water flow in, but the
pressure barely changed, and the flow soon stopped.
snip

Are both valves opened when you fill it?


Yes - and we tried both the internal and external filling loops.

--
Kevin Poole
****Use current date to reply (e.g. )****

Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

Power cycled, and it showed 0.6 bar, and fired, but still wouldn't
accept any more filling. Let a bit of water out through the prv - no
change of reading, but it would then admit a small amount to refill.

It sounds like a faulty pressure sensor to me, but I suppose it could be
a circuit board fault.

Can the pressure sensor be tested other than by substitution? Can any
dummy load be applied to the circuit board to give a nominal pressure
reading?

Pressure sensors seem to be around the £70 mark, so he'd rather not buy
one if the fault's more likely to be elsewhere. Glow-worm part
2000801911, GC E83997.

Any ideas, please?

It sounds like you have pretty poor mains pressure. A typical result of
opening a filling loop and leaving it on would be to raise the pressure
to the point the PRV operates. Have you got an gauge on the external;
filling loop?

--
Cheers,

John.

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

On Mon, 03 Nov 2008 23:37:34 +0000 Kevin Poole wrote :
Yes - and we tried both the internal and external filling loops.

Until you said this, I would have suspected the internal filling tap.
On my Cxi this broke internally so that turning it on did nothing. In
the best tradition of spare parts, a replacement cost £21 - for a
little all-plastic tap.

--
Tony Bryer, 'Software to build on' from Greentram
www.superbeam.co.uk www.superbeam.com www.greentram.com

John Rumm wrote:
Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for
3 years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

snip

It sounds like you have pretty poor mains pressure. A typical result of
opening a filling loop and leaving it on would be to raise the pressure
to the point the PRV operates. Have you got an gauge on the external;
filling loop?


No mechanical gauge at all, I'm afraid. The question of why the prv
didn't operate is one that's been bothering me in the dark watches of
the night. Starting fault-finding at 10pm in someone else's house is
not ideal for a day-person, so I didn't think to check the flow rate at
his cold tap, either. The prv isn't stuck - I manually released it OK,
so what pressure do they normally blow off at?

Mains pressure is _normally_ fine - he's at about the lowest point in
the county.

--
Kevin Poole
****Use current date to reply (e.g. )****

"Kevin Poole" wrote in message
...


John Rumm wrote:
Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

snip

It sounds like you have pretty poor mains pressure. A typical result of
opening a filling loop and leaving it on would be to raise the pressure
to the point the PRV operates. Have you got an gauge on the external;
filling loop?


No mechanical gauge at all, I'm afraid. The question of why the prv
didn't operate is one that's been bothering me in the dark watches of the
night. Starting fault-finding at 10pm in someone else's house is not
ideal for a day-person, so I didn't think to check the flow rate at his
cold tap, either. The prv isn't stuck - I manually released it OK, so
what pressure do they normally blow off at?

Mains pressure is _normally_ fine - he's at about the lowest point in the
county.

--
Kevin Poole
****Use current date to reply (e.g. )****


I thought it best not to use PRV as it can lead to them weeping if grit gets
into seating.

"Kevin Poole" wrote in message
...


John Rumm wrote:
Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

snip

It sounds like you have pretty poor mains pressure. A typical result of
opening a filling loop and leaving it on would be to raise the pressure
to the point the PRV operates. Have you got an gauge on the external;
filling loop?


No mechanical gauge at all, I'm afraid. The question of why the prv
didn't operate is one that's been bothering me in the dark watches of the
night. Starting fault-finding at 10pm in someone else's house is not
ideal for a day-person, so I didn't think to check the flow rate at his
cold tap, either. The prv isn't stuck - I manually released it OK, so
what pressure do they normally blow off at?

Mains pressure is _normally_ fine - he's at about the lowest point in the
county.

--
Kevin Poole
****Use current date to reply (e.g. )****

If the pressure sensor is £70 then yiou need a pressure tester.
http://www.screwfix.com/search.do;js...hbutton=submit

Fit a washing machine tap on the CH return pipe and use this as the test
point for the system. Use a 3/4" BSP brass cap on the washing machine tap.

You can test the water mains pressure with this too, from the garden tap or
the washing machine tap. This will determine if the internal gauge is
faulty, or if it is faulty and the boiler still works then use this gauge to
set the CH system pressure at 1 bar and save £70.

Doctor Drivel wrote:


Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly
for 3 years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow
in, but the pressure barely changed, and the flow soon stopped.

snip



If the pressure sensor is £70 then yiou need a pressure tester.
http://www.screwfix.com/search.do;js...hbutton=submit


Fit a washing machine tap on the CH return pipe and use this as the test
point for the system. Use a 3/4" BSP brass cap on the washing machine tap.

You can test the water mains pressure with this too, from the garden tap
or the washing machine tap. This will determine if the internal gauge is
faulty, or if it is faulty and the boiler still works then use this
gauge to set the CH system pressure at 1 bar and save £70.


Thanks for the suggestion - a gauge like this, or one I mackle up to do
the same job, would certainly establish what the pressure in the system
really was, but if the built-in sensor is faulty it would only be a
permanent solution if I bypassed the sensor completely - at the moment
the sensor, or rather its processed output, does two things: it gives a
reading on the display, and if it thinks the pressure is too low, it
locks out the boiler from firing.


--
Kevin Poole
****Use current date to reply (e.g. )****

"Kevin Poole" wrote in message
...

Doctor Drivel wrote:

Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for
3 years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

snip

If the pressure sensor is £70 then you need a pressure tester.
http://www.screwfix.com/search.do;js...hbutton=submit
Fit a washing machine tap on the CH return pipe and use this as the test
point for the system. Use a 3/4" BSP brass cap on the washing machine
tap.

You can test the water mains pressure with this too, from the garden tap
or the washing machine tap. This will determine if the internal gauge is
faulty, or if it is faulty and the boiler still works then use this gauge
to set the CH system pressure at 1 bar and save £70.

Thanks for the suggestion - a gauge like this, or one I mackle up to do
the same job, would certainly establish what the pressure in the system
really was, but if the built-in sensor is faulty it would only be a
permanent solution if I bypassed the sensor completely - at the moment the
sensor, or rather its processed output, does two things: it gives a
reading on the display, and if it thinks the pressure is too low, it locks
out the boiler from firing.

I did make the point that if the boiler still runs, and the pressure is not
being displayed, all you need do is attach the pressure gauge and set it to
1 to 1.25 bar. If it locks out on pressure out then you need a new
assembly. But check that you have enough pressure from the mains first and
this gauge can do that. Your mains may have dropped.

wrote in message ...
On 4 Nov,
Kevin Poole wrote:

No mechanical gauge at all, I'm afraid. The question of why the prv
didn't operate is one that's been bothering me in the dark watches of
the night. Starting fault-finding at 10pm in someone else's house is
not ideal for a day-person, so I didn't think to check the flow rate at
his cold tap, either. The prv isn't stuck - I manually released it OK,
so what pressure do they normally blow off at?

I've almost never had enough pressure to lift my PRV which is set at 3.5
bar.
My mains pressure seems to top out at 2.5bar. At one time (before they
built
a local service reservoir) it would occasionally get high enough in the
dead
of night to lift the PRV.

Do you keep the filling loop tap permanently on?

Kevin Poole wrote:

his cold tap, either. The prv isn't stuck - I manually released it OK,
so what pressure do they normally blow off at?

Approx 3 to 3.5 bar typically.

--
Cheers,

John.

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

John Rumm wrote:
Kevin Poole wrote:

his cold tap, either. The prv isn't stuck - I manually released it
OK, so what pressure do they normally blow off at?

Approx 3 to 3.5 bar typically.

Thanks for that, John - higher than I was expecting. Checking again in
daylight, I confirmed that the supply pressure is (unquantified)
reasonably high; that the prv does just start to dribble if the filling
loop valves are left open; and that the boiler display reads the same
0.4 bar regardless of the pressure in it, from very near zero to mains
water pressure. The only way to get a lower reading is to disconnect
the sensor from the main board, when it briefly shows 0 before giving
the expected F9 fault code.

It's looking like the sensor, I reckon. What on earth possessed them to
use such a sensor instead of a mechanical gauge and pressure switch?


--
Kevin Poole
****Use current date to reply (e.g. )****

Kevin Poole wrote:


John Rumm wrote:
Kevin Poole wrote:

his cold tap, either. The prv isn't stuck - I manually released it
OK, so what pressure do they normally blow off at?

Approx 3 to 3.5 bar typically.

Thanks for that, John - higher than I was expecting. Checking again in
daylight, I confirmed that the supply pressure is (unquantified)
reasonably high; that the prv does just start to dribble if the filling
loop valves are left open; and that the boiler display reads the same
0.4 bar regardless of the pressure in it, from very near zero to mains
water pressure. The only way to get a lower reading is to disconnect
the sensor from the main board, when it briefly shows 0 before giving
the expected F9 fault code.

Sounds like a sensor or PCB fault then...

It's looking like the sensor, I reckon. What on earth possessed them to
use such a sensor instead of a mechanical gauge and pressure switch?

Probably because the boiler would need a low pressure detection
capability of some sort anyway, so it was cheaper to use that twice
rather than provide a separate gauge!

--
Cheers,

John.

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

Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for 3
years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.
snip


To conclude the tale:

Much checking around found prices for a new sensor varying by a factor
of more than 4. MJT Controls in Bristol (http://www.mjtcontrols.co.uk)
were by far the cheapest at £21.58 plus delivery and VAT, and they gave
an excellent service.

The tip of the old pressure sensor was covered in rusty gunge, and I
suppose a through clean may have unblocked its most intimate passages,
but with a new one to hand, I just fitted it. All is now well.

Moral: when, a few days after installing a heating system, you hand your
son a bottle of inhibitor and tell him to add it to his system (and how
to do so), don't assume he will do it. I think it's now due for a dose
of X400 or similar.

But I still don't know how the sensor works.

--
Kevin Poole
****Use current date to reply (e.g. )****

"Kevin Poole" wrote in message
...

To conclude the tale:

Much checking around found prices for a new sensor varying by a factor of
more than 4. MJT Controls in Bristol (http://www.mjtcontrols.co.uk) were
by far the cheapest at £21.58 plus delivery and VAT, and they gave an
excellent service.

The tip of the old pressure sensor was covered in rusty gunge, and I
suppose a through clean may have unblocked its most intimate passages, but
with a new one to hand, I just fitted it. All is now well.

Was it the gunge causing the problem?

Moral: when, a few days after installing a heating system, you hand your
son a bottle of inhibitor and tell him to add it to his system (and how to
do so), don't assume he will do it. I think it's now due for a dose of
X400 or similar.

As long as heat comes out they don't care, so ignore it. Then, when it is
clogged up and they find out how much it will cost to unclog it, they get a
wake up call. Like those who run around in cars with warning lights on and
ignore them, then get upset when a big garage bill comes in.

The Glow-worm 30cxi condensing combi is a good boiler. The older one with
the plastic hydro block were a little dodgy - Glow Worm replaced them for
free. The later models are brass and far better. If this combis has the
weather compensation option, have it connected. They really perform well.

I like the new Broags. Quality, great value and highly specced to.

Doctor Drivel wrote:

"Kevin Poole" wrote in message
...

To conclude the tale:

snip

The tip of the old pressure sensor was covered in rusty gunge, and I
suppose a through clean may have unblocked its most intimate passages,
but
with a new one to hand, I just fitted it. All is now well.

Was it the gunge causing the problem?

I don't particularly want to disturb the boiler again to make certain,
but I strongly suspect so. At first, I thought the old sensor might be
of slightly different construction to the new, with some sort of
deliberate constriction at the "wet" end, perhaps to dampen
fluctuations, but then I dropped it and a plug of rusty gunge fell out.
So I guess we may have wasted 33 quid.



The Glow-worm 30cxi condensing combi is a good boiler.

We've been pleased enough till now. Easier to fit than the Buderus I
was recently involved with, and the Buderus needed three warranty calls
in the first 4 months.

If this
combis has the weather compensation option, have it connected. They
really perform well.

I don't think it has, and in the totality of circumstances of its use, I
don't think I could justify the cost.


--
Kevin Poole
****Use current date to reply (e.g. )****

"Kevin Poole" wrote in message
...

We've been pleased enough till now. Easier to fit than the Buderus I was
recently involved with, and the Buderus needed three warranty calls in the
first 4 months.

That is odd. Buderus are generally well made and "well designed " boilers.
The heat exchangers clip in and out.