W-B 28i Junior slow hot water
 

It's about two years old, non-condensing, and recently is taking a
long time to come up with hot water. It fires up about five or six
seconds after opening the tap, then it's anything up to about five
minutes before the water gets warm, not counting the time it takes
to get to the tap. The more recently it has been used, the less
time it takes. It doesn't seem to depend on the water flow rate.
The red light is on the whole time, but it's difficult to tell from
the sound how much gas it's burning. The CH pipes stay cold.

Does that ring any bells?

W-B 28i Junior slow hot water
 

"Joe" wrote in message
...
It's about two years old, non-condensing, and recently is taking a
long time to come up with hot water. It fires up about five or six
seconds after opening the tap, then it's anything up to about five
minutes before the water gets warm, not counting the time it takes
to get to the tap. The more recently it has been used, the less
time it takes. It doesn't seem to depend on the water flow rate.
The red light is on the whole time, but it's difficult to tell from
the sound how much gas it's burning. The CH pipes stay cold.

Does that ring any bells?

I have the same problem with a 24i, waiting with anticipation for helpful
replies.............

Tom

W-B 28i Junior slow hot water
 

On Sun, 18 Feb 2007 13:58:15 +0000, Joe wrote:

It's about two years old, non-condensing, and recently is taking a
long time to come up with hot water. It fires up about five or six
seconds after opening the tap, then it's anything up to about five
minutes before the water gets warm, not counting the time it takes
to get to the tap. The more recently it has been used, the less
time it takes. It doesn't seem to depend on the water flow rate.
The red light is on the whole time, but it's difficult to tell from
the sound how much gas it's burning. The CH pipes stay cold.

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if you're
in a hard water area).

The non-condensing 24/28i Juniors have combined heat exchangers rather
than separate plate heat exchangers and diverter valves so if the boiler
is firing up straight away it must be heating DHW straight away: you
should be able to feel the DHW pipework inside and just outside the boiler
getting hot and follow the pipework getting hot.

W-B 28i Junior slow hot water
 

John Stumbles wrote:
On Sun, 18 Feb 2007 13:58:15 +0000, Joe wrote:

It's about two years old, non-condensing, and recently is taking a
long time to come up with hot water. It fires up about five or six
seconds after opening the tap, then it's anything up to about five
minutes before the water gets warm, not counting the time it takes
to get to the tap. The more recently it has been used, the less
time it takes. It doesn't seem to depend on the water flow rate.
The red light is on the whole time, but it's difficult to tell from
the sound how much gas it's burning. The CH pipes stay cold.

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if you're
in a hard water area).

No, sorry, it's running as fast as it did a month or two ago, when the
problem wasn't there. I expect a slightly slower warm-up in winter, when
the incoming water is colder, but this is excessive. As I say, if I use
hot water again within half an hour, there's no problem, and the flow
rate hasn't changed. It's almost as if there's a huge heatsink that has
to warm up before the water gets any heat.

The non-condensing 24/28i Juniors have combined heat exchangers rather
than separate plate heat exchangers and diverter valves so if the boiler
is firing up straight away it must be heating DHW straight away: you
should be able to feel the DHW pipework inside and just outside the boiler
getting hot and follow the pipework getting hot.

Not obviously. I did wonder where all the heat was going, and I must
assume the burner is throttled back to minimum during the waiting period.

W-B 28i Junior slow hot water
 

On Mon, 19 Feb 2007 15:20:59 +0000, Joe wrote:

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if you're
in a hard water area).

No, sorry, it's running as fast as it did a month or two ago, when the
problem wasn't there. I expect a slightly slower warm-up in winter, when
the incoming water is colder, but this is excessive. As I say, if I use
hot water again within half an hour, there's no problem, and the flow
rate hasn't changed. It's almost as if there's a huge heatsink that has
to warm up before the water gets any heat.

... I did wonder where all the heat was going, and I must
assume the burner is throttled back to minimum during the waiting period.

If you watch the gas meter (clock dial) while someone else turns on a hot
tap can you see if the boiler is starting up at a low rate and then
getting to full rate much later?

W-B 28i Junior slow hot water
 

John Stumbles wrote:
On Mon, 19 Feb 2007 15:20:59 +0000, Joe wrote:

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if you're
in a hard water area).
No, sorry, it's running as fast as it did a month or two ago, when the
problem wasn't there. I expect a slightly slower warm-up in winter, when
the incoming water is colder, but this is excessive. As I say, if I use
hot water again within half an hour, there's no problem, and the flow
rate hasn't changed. It's almost as if there's a huge heatsink that has
to warm up before the water gets any heat.

... I did wonder where all the heat was going, and I must
assume the burner is throttled back to minimum during the waiting period.

If you watch the gas meter (clock dial) while someone else turns on a hot
tap can you see if the boiler is starting up at a low rate and then
getting to full rate much later?


That could be difficult. We have an old style meter literally on the
floor under the stairs. I may get curious enough to try, but I assume
I'll have to get the proverbial Man In to fix the boiler anyway. I was
hoping to get some idea of the problem, as this seems a reasonably
popular model, but it doesn't look as if anyone has seen this before.

W-B 28i Junior slow hot water
 

"Joe" wrote in message
...
John Stumbles wrote:
On Mon, 19 Feb 2007 15:20:59 +0000, Joe wrote:

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if
you're
in a hard water area).
No, sorry, it's running as fast as it did a month or two ago, when the
problem wasn't there. I expect a slightly slower warm-up in winter, when
the incoming water is colder, but this is excessive. As I say, if I use
hot water again within half an hour, there's no problem, and the flow
rate hasn't changed. It's almost as if there's a huge heatsink that has
to warm up before the water gets any heat.

... I did wonder where all the heat was going, and I must
assume the burner is throttled back to minimum during the waiting
period.

If you watch the gas meter (clock dial) while someone else turns on a hot
tap can you see if the boiler is starting up at a low rate and then
getting to full rate much later?


That could be difficult. We have an old style meter literally on the
floor under the stairs. I may get curious enough to try, but I assume
I'll have to get the proverbial Man In to fix the boiler anyway. I was
hoping to get some idea of the problem, as this seems a reasonably
popular model, but it doesn't look as if anyone has seen this before.

Sorry Joe but our boiler has seemed to cure itself! I wont believe until we
have at least a week of trouble free hot water supplies.

Tom

W-B 28i Junior slow hot water
 

Joe wrote:
John Stumbles wrote:
On Mon, 19 Feb 2007 15:20:59 +0000, Joe wrote:

Is the water coming out at a dribble that's taking a long time to get
through the pipework? In that case it's likely to be scaled up (if
you're
in a hard water area).
No, sorry, it's running as fast as it did a month or two ago, when the
problem wasn't there. I expect a slightly slower warm-up in winter, when
the incoming water is colder, but this is excessive. As I say, if I use
hot water again within half an hour, there's no problem, and the flow
rate hasn't changed. It's almost as if there's a huge heatsink that has
to warm up before the water gets any heat.

... I did wonder where all the heat was going, and I must
assume the burner is throttled back to minimum during the waiting
period.

If you watch the gas meter (clock dial) while someone else turns on a hot
tap can you see if the boiler is starting up at a low rate and then
getting to full rate much later?


That could be difficult. We have an old style meter literally on the
floor under the stairs. I may get curious enough to try, but I assume
I'll have to get the proverbial Man In to fix the boiler anyway. I was
hoping to get some idea of the problem, as this seems a reasonably
popular model, but it doesn't look as if anyone has seen this before.

More information: I confirmed that no pipes get hot during the dead
period, and being an electronics engineer, I gave the cabinet a few
thumps was rewarded with a blinking 'computer crashed' light.

Turned off the tap, reset it and tried again. Again the pipes stayed
cold, and the flue showed only a very slight heat haze. Then after
about twenty seconds, the sound started to fluctuate slightly and
then the pipe got hot.

So this looks like a flame-failure device fault. Does anyone know
whether this is purely thermo-mechanical, or whether it's an electric
valve and sensor? The latter would seem to imply that the computer
crash was the result of a dodgy joint, and it might be worth reseating
everything. I would assume if it's purely mechanical then it needs
replacing.

W-B 28i Junior slow hot water
 

In message , Joe
writes

So this looks like a flame-failure device fault. Does anyone know
whether this is purely thermo-mechanical, or whether it's an electric
valve and sensor? The latter would seem to imply that the computer
crash was the result of a dodgy joint, and it might be worth reseating
everything. I would assume if it's purely mechanical then it needs
replacing.


It's not a computer, it's a very naughty boy

That's why it's called junior

the 28i Jnr uses purely electronic sensing, nothing magic about that,
the pcb just detects a small rectified current from the flame

Now, this is where it gets embarrassing ...

I'm the boiler pcb expert and I have a W-B 28i Jnr, and I can't remember
whether the pcb senses the flame over the HT lead or a separate sensing
lead, I think the latter (It will be in the manual, which I am too lazy
to go and check)

Sources of flame sense failure are

1) pcb fault (prolly not much you can do about tis unless you are fairly
clued up, engineer or not) the 28i Jnr isn't so prone to cracked solder
joiints, but worth checking around the HT transformer area

2) Broken flame sensing lead

3) Flame sense electrode not in the flame

4) earthing problems - without a good earth, flame sensing will fail


--
geoff

W-B 28i Junior slow hot water
 

raden wrote:
In message , Joe
writes

So this looks like a flame-failure device fault. Does anyone know
whether this is purely thermo-mechanical, or whether it's an electric
valve and sensor? The latter would seem to imply that the computer
crash was the result of a dodgy joint, and it might be worth reseating
everything. I would assume if it's purely mechanical then it needs
replacing.


It's not a computer, it's a very naughty boy

That's why it's called junior

the 28i Jnr uses purely electronic sensing, nothing magic about that,
the pcb just detects a small rectified current from the flame

Now, this is where it gets embarrassing ...

I'm the boiler pcb expert and I have a W-B 28i Jnr, and I can't remember
whether the pcb senses the flame over the HT lead or a separate sensing
lead, I think the latter (It will be in the manual, which I am too lazy
to go and check)

Sources of flame sense failure are

1) pcb fault (prolly not much you can do about tis unless you are fairly
clued up, engineer or not) the 28i Jnr isn't so prone to cracked solder
joiints, but worth checking around the HT transformer area

2) Broken flame sensing lead

3) Flame sense electrode not in the flame

4) earthing problems - without a good earth, flame sensing will fail


Thanks for your time. I can expect The Man to tell me I need a new PCB,
then. I'll have a quick look at any accessible wiring and connectors,
but I have no interest in dismantling anything with a seal.