"Wainscotting" wrote in message
...
When heating is on it takes an age to draw hot water. The diaphragm is new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).


I'm no expert but I've an idea what it is. It's a 242 right? There is a
valve/actuator thingy fairly central behind the panel. There is a pressure
activated lever emerging from it, which should actuate a red microswitch
within a few seconds, but it takes ages on knackered actuators, and you can
watch this lever arm inching slowly towards the microswitch. You won't get
hot water until it activates the microswitch, I suspect you're waiting 30-45
seconds for water? Sorry not to be technically accurate, others may give
a better explanationj, but have a look with the panel off, identify the
actuator/lever/microswitch assembly then get someone to turn on the hot tap
and see how long it takes to work. Solution? Probably get a new atuator
assembly, it may be all corroded/scaled up anyway.

PS. If you search for uk.d-i-y on Google ( search for 'Google groups' using
the options provided on Google's page ) you will get the uk.d-i-y archive,
and youcan search within this for more info on this problem, it has come up
within the last year at least once I believe.

Andy.

"Wainscotting" wrote in message
...

"Ed Sirett" wrote in message
news
On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm is
new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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


Thanks Ed. I will have a llok in my instalation manual to try and locate
it
(and the microswitch mentioned in Andy's post).


If it's not a 242 then disregard what I said - I had a 242 and it had the
same
symptoms as your combi, but I have no idea what your combi looks like
inside, unless Vaillant use a largely common design. Ed Sirrett is a
professional and has more of an idea than I do!

Andy.

When heating is on it takes an age to draw hot water. The diaphragm is new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).

On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm is new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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

"andrewpreece" wrote in message
...

"Wainscotting" wrote in message
...
When heating is on it takes an age to draw hot water. The diaphragm is
new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).


I'm no expert but I've an idea what it is. It's a 242 right? There is a
valve/actuator thingy fairly central behind the panel. There is a pressure
activated lever emerging from it, which should actuate a red microswitch
within a few seconds, but it takes ages on knackered actuators, and you
can
watch this lever arm inching slowly towards the microswitch. You won't get
hot water until it activates the microswitch, I suspect you're waiting
30-45
seconds for water? Sorry not to be technically accurate, others may give
a better explanationj, but have a look with the panel off, identify the
actuator/lever/microswitch assembly then get someone to turn on the hot
tap
and see how long it takes to work. Solution? Probably get a new atuator
assembly, it may be all corroded/scaled up anyway.

PS. If you search for uk.d-i-y on Google ( search for 'Google groups'
using
the options provided on Google's page ) you will get the uk.d-i-y archive,
and youcan search within this for more info on this problem, it has come
up
within the last year at least once I believe.

Andy.


Tanks for the reply Andy. It is actually a VCW T3W (either 20/1, 25/1 or
18). I will investigate tomorrow and see if I can locate the parts you
mention. Thanks for the Google archive info as well.

"Ed Sirett" wrote in message
news
On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm is
new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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


Thanks Ed. I will have a llok in my instalation manual to try and locate it
(and the microswitch mentioned in Andy's post).

Wainscotting wrote:
When heating is on it takes an age to draw hot water. The diaphragm
is new so what else could be the cause? The boiler is about 15-20
years old (VWSine).

I used to have a Vaillant VCW25 Sine which did this!
If yours is this type, You'll need to take off the front door, boiler 'stat
knob, front panel and left hand side panel to get at the DHW flow switch,
which is at the rear of the boiler, low down on the left, behind the "silver
tank" which is the DHW heat exchanger. As another poster has said, the DHW
flow switch operates a couple of microswitches which fire up the boiler when
hot water (tap) is required.

In my case, the actuator rod had become very stiff through time and was
hardly moving - thus no hot water. I cured it by squirting a small amount of
WD40 at the point where the rod comes out of the flow switch body. You can
get a pair of pliers onto the bar and move it up and down to get the WD40 to
do its stuff. I then cleaned all the gunge off with paper towels, and a
final short squirt of WD40 again. Never had any more problems after that.

HTH
--

Reply address is spamtrapped. Remove theobvious for valid e-mail address

"Paul King" wrote in message
news:1097786351.2BWD3IA2pSU1qusXQkAzqQ@teranews...
Wainscotting wrote:
When heating is on it takes an age to draw hot water. The diaphragm
is new so what else could be the cause? The boiler is about 15-20
years old (VWSine).

I used to have a Vaillant VCW25 Sine which did this!
If yours is this type, You'll need to take off the front door, boiler
'stat
knob, front panel and left hand side panel to get at the DHW flow switch,
which is at the rear of the boiler, low down on the left, behind the
"silver
tank" which is the DHW heat exchanger. As another poster has said, the DHW
flow switch operates a couple of microswitches which fire up the boiler
when
hot water (tap) is required.

In my case, the actuator rod had become very stiff through time and was
hardly moving - thus no hot water. I cured it by squirting a small amount
of
WD40 at the point where the rod comes out of the flow switch body. You can
get a pair of pliers onto the bar and move it up and down to get the WD40
to
do its stuff. I then cleaned all the gunge off with paper towels, and a
final short squirt of WD40 again. Never had any more problems after that.

HTH
--

Reply address is spamtrapped. Remove theobvious for valid e-mail address


Yep..that's the boiler. I will have a look at what you suggest tomorrow.
Thanks.

In message 1097786351.2BWD3IA2pSU1qusXQkAzqQ@teranews, Paul King
writes
Wainscotting wrote:
When heating is on it takes an age to draw hot water. The diaphragm
is new so what else could be the cause? The boiler is about 15-20
years old (VWSine).

I used to have a Vaillant VCW25 Sine which did this!
If yours is this type, You'll need to take off the front door, boiler 'stat
knob, front panel and left hand side panel to get at the DHW flow switch,
which is at the rear of the boiler, low down on the left, behind the "silver
tank" which is the DHW heat exchanger. As another poster has said, the DHW
flow switch operates a couple of microswitches which fire up the boiler when
hot water (tap) is required.

In my case, the actuator rod had become very stiff through time and was
hardly moving - thus no hot water. I cured it by squirting a small amount of
WD40 at the point where the rod comes out of the flow switch body. You can
get a pair of pliers onto the bar and move it up and down to get the WD40 to
do its stuff. I then cleaned all the gunge off with paper towels, and a
final short squirt of WD40 again. Never had any more problems after that.

WD40 really isn't the best long term fix

I would suggest silicone grease, until someone else picks me up on this
--
geoff

"raden" wrote in message
...
In message 1097786351.2BWD3IA2pSU1qusXQkAzqQ@teranews, Paul King
writes
Wainscotting wrote:
When heating is on it takes an age to draw hot water. The diaphragm
is new so what else could be the cause? The boiler is about 15-20
years old (VWSine).

I used to have a Vaillant VCW25 Sine which did this!
If yours is this type, You'll need to take off the front door, boiler
'stat
knob, front panel and left hand side panel to get at the DHW flow switch,
which is at the rear of the boiler, low down on the left, behind the
"silver
tank" which is the DHW heat exchanger. As another poster has said, the
DHW
flow switch operates a couple of microswitches which fire up the boiler
when
hot water (tap) is required.

In my case, the actuator rod had become very stiff through time and was
hardly moving - thus no hot water. I cured it by squirting a small amount
of
WD40 at the point where the rod comes out of the flow switch body. You
can
get a pair of pliers onto the bar and move it up and down to get the WD40
to
do its stuff. I then cleaned all the gunge off with paper towels, and a
final short squirt of WD40 again. Never had any more problems after that.

WD40 really isn't the best long term fix

I would suggest silicone grease, until someone else picks me up on this

Maxie, you are right. WD40 is a water repellent NOT a lubricant.

Paul King wrote:
Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm
is new so what else could be the cause? The boiler is about 15-20
years old (VWSine).


I used to have a Vaillant VCW25 Sine which did this!
If yours is this type, You'll need to take off the front door, boiler 'stat
knob, front panel and left hand side panel to get at the DHW flow switch,
which is at the rear of the boiler, low down on the left, behind the "silver
tank" which is the DHW heat exchanger. As another poster has said, the DHW
flow switch operates a couple of microswitches which fire up the boiler when
hot water (tap) is required.

In my case, the actuator rod had become very stiff through time and was
hardly moving - thus no hot water. I cured it by squirting a small amount of
WD40 at the point where the rod comes out of the flow switch body. You can
get a pair of pliers onto the bar and move it up and down to get the WD40 to
do its stuff. I then cleaned all the gunge off with paper towels, and a
final short squirt of WD40 again. Never had any more problems after that.

HTH

Had this about 6 months ago and replaced the flow switch. I could not
find a 'repair kit' though it looks a doddle to refurbish if I'd been
able to do so. I got a new switch for around £105.

You could test whether it's a sluggish flow switch by removing the front
cover, the cover of the switch box and lifting the switches with a long
insulated screwdriver. It should fire up immediately.

Phil.

IMM wrote:
"raden" wrote in message
...
In message 1097786351.2BWD3IA2pSU1qusXQkAzqQ@teranews, WD40 really
isn't the best long term fix

I would suggest silicone grease, until someone else picks me up on
this

Maxie, you are right. WD40 is a water repellent NOT a lubricant.

I'm not disagreeing with either of you - just telling what I did. I used the
WD40 not to lube the actuator rod, but as a solvent to dissolve all of the
crud and gunge which had accumulated through time.

It worked, and I never had any more problems in the further 13 years I lived
at the house.
--

Reply address is spamtrapped. Remove theobvious for valid e-mail address

"andrewpreece" wrote in message
...

"Wainscotting" wrote in message
...

"Ed Sirett" wrote in message
news
On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm
is
new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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


Thanks Ed. I will have a llok in my instalation manual to try and locate
it
(and the microswitch mentioned in Andy's post).


If it's not a 242 then disregard what I said - I had a 242 and it had the
same
symptoms as your combi, but I have no idea what your combi looks like
inside, unless Vaillant use a largely common design. Ed Sirrett is a
professional and has more of an idea than I do!

Andy.


No problem - appreciate the reply

In message , IMM writes

"raden" wrote in message
...
In message 1097786351.2BWD3IA2pSU1qusXQkAzqQ@teranews, Paul King
writes
Wainscotting wrote:
When heating is on it takes an age to draw hot water. The diaphragm
is new so what else could be the cause? The boiler is about 15-20
years old (VWSine).

I used to have a Vaillant VCW25 Sine which did this!
If yours is this type, You'll need to take off the front door, boiler
'stat
knob, front panel and left hand side panel to get at the DHW flow switch,
which is at the rear of the boiler, low down on the left, behind the
"silver
tank" which is the DHW heat exchanger. As another poster has said, the
DHW
flow switch operates a couple of microswitches which fire up the boiler
when
hot water (tap) is required.

In my case, the actuator rod had become very stiff through time and was
hardly moving - thus no hot water. I cured it by squirting a small amount
of
WD40 at the point where the rod comes out of the flow switch body. You
can
get a pair of pliers onto the bar and move it up and down to get the WD40
to
do its stuff. I then cleaned all the gunge off with paper towels, and a
final short squirt of WD40 again. Never had any more problems after that.

WD40 really isn't the best long term fix

I would suggest silicone grease, until someone else picks me up on this

Maxie, you are right. WD40 is a water repellent NOT a lubricant.

Of course

--
geoff

On Wed, 13 Oct 2004 22:09:13 +0100, andrewpreece wrote:


"Wainscotting" wrote in message
...

"Ed Sirett" wrote in message
news
On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm is
new
so what else could be the cause? The boiler is about 15-20 years old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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


Thanks Ed. I will have a llok in my instalation manual to try and locate
it
(and the microswitch mentioned in Andy's post).


If it's not a 242 then disregard what I said - I had a 242 and it had the
same
symptoms as your combi, but I have no idea what your combi looks like
inside, unless Vaillant use a largely common design. Ed Sirrett is a
professional and has more of an idea than I do!


Vaillants of this era are somewhat unique in their design features.
I am very familiar with 242s this is a slightly earlier model called a
Sine.
It could be the diverter valve and the HW performance is still there
at a reduced level
because some water goes through the secondary heat exchanger.
I rather assumed this might be the case.

This model has a cold/hot standby switch (this can make the difference of
around 30 seconds for hot HW to arrive at the tap). It might be that the
switch or some of the control gear has turned off this facility.

As you rightly say the DHW flow sensor whilst newly diaphragmed is sticky
in some other way (this can certainly happen on 242s - but I don't know
whether it's the same kit on Sines).


--
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

On Fri, 15 Oct 2004 15:15:18 +0100, Paul King wrote:



It worked, and I never had any more problems in the further 13 years I lived
at the house.

.... further 13 years... we'd see a Puma,Ocean,Wickes etc. put in and
removed during that time.

--
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

"Ed Sirett" wrote in message
news
On Wed, 13 Oct 2004 22:09:13 +0100, andrewpreece wrote:


"Wainscotting" wrote in message
...

"Ed Sirett" wrote in message
news On Thu, 14 Oct 2004 16:36:26 +0100, Wainscotting wrote:

When heating is on it takes an age to draw hot water. The diaphragm
is
new
so what else could be the cause? The boiler is about 15-20 years
old
(VWSine).

Failed diverter valve.
The diaphragm you refer to is presumably the HW flow sensor?
I think they are sub £70 quid.

--
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


Thanks Ed. I will have a llok in my instalation manual to try and
locate
it
(and the microswitch mentioned in Andy's post).


If it's not a 242 then disregard what I said - I had a 242 and it had
the
same
symptoms as your combi, but I have no idea what your combi looks like
inside, unless Vaillant use a largely common design. Ed Sirrett is a
professional and has more of an idea than I do!


Vaillants of this era are somewhat unique in their design features.
I am very familiar with 242s this is a slightly earlier model called a
Sine.
It could be the diverter valve and the HW performance is still there
at a reduced level
because some water goes through the secondary heat exchanger.
I rather assumed this might be the case.

This model has a cold/hot standby switch (this can make the difference of
around 30 seconds for hot HW to arrive at the tap). It might be that the
switch or some of the control gear has turned off this facility.

As you rightly say the DHW flow sensor whilst newly diaphragmed is sticky
in some other way (this can certainly happen on 242s - but I don't know
whether it's the same kit on Sines).


--
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


Even in the summer I have to keep the radiator switch in the on position and
shut off all the radiator thermostats, plus, keep the cold/hot standby
switchin the "instant" position if I am to guarantee hot water. This time of
the year, with the heating on, if hot water is coming out of the tap and I
turn the cold/hot standby switch into the other position (not instant) the
boiler will shut off.
To recap....in the summer with the rad switch off I can't get any hot water
(most of the time). With the rad switch on I only get hot water if the
standby switch is in the "instant" position. With the heating on, hot water
takes up to 5 mins to come out of the tap and only then, with the standby
switch in the "instant" position. I will never get hot water if the standby
switch is not in the "instant" position. Perhaps it's time for a new boiler?

On Sat, 16 Oct 2004 11:41:50 +0100, Wainscotting wrote:


Even in the summer I have to keep the radiator switch in the on position and
shut off all the radiator thermostats, plus, keep the cold/hot standby
switchin the "instant" position if I am to guarantee hot water. This time of
the year, with the heating on, if hot water is coming out of the tap and I
turn the cold/hot standby switch into the other position (not instant) the
boiler will shut off.
To recap....in the summer with the rad switch off I can't get any hot water
(most of the time). With the rad switch on I only get hot water if the
standby switch is in the "instant" position. With the heating on, hot water
takes up to 5 mins to come out of the tap and only then, with the standby
switch in the "instant" position. I will never get hot water if the standby
switch is not in the "instant" position. Perhaps it's time for a new
boiler?

1) From completely cold with the instant switch off does the boiler fire
when you run a tap? If no then the problem is with the DHW flow sensor
(diaphragm) or more likely with the micro switch this sensor triggers or
its operating mechanism.

2) If the boiler starts the pump but does not fire the gas it can still be
the DHW microswitch not making prolonged and steady contact.

3) If the boiler makes a poor amount of HW and then only when the
heating is on then the diverter valve is the prome suspect.

Obviously 90% of the kit is fine or you'd get no heating.

If this is a balanced flue model (IIRC Sines were also made with fanned
flues) the there is something to be gained by replacing it.
I strongly suspect that Vaillant will be bringing the prices of the Ecomax
range down by a few hundred before next April else they won't be selling
many boilers so you could wait till then if you can get it fixed.


--
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

"Ed Sirett" wrote in message
news
1) From completely cold with the instant switch off does the boiler fire
when you run a tap? If no then the problem is with the DHW flow sensor
(diaphragm) or more likely with the micro switch this sensor triggers or
its operating mechanism.


Just tried this and no, with the instant hot water switch in the "off"
position and hot tap running, the boiler will not fire up and there is no
evidence of the pump running. If I switch to instant hot water whilst the
tap is running the boiler will fire up no problem.

On Mon, 18 Oct 2004 17:06:43 +0100, Wainscotting wrote:


"Ed Sirett" wrote in message
news
1) From completely cold with the instant switch off does the boiler fire
when you run a tap? If no then the problem is with the DHW flow sensor
(diaphragm) or more likely with the micro switch this sensor triggers or
its operating mechanism.


Just tried this and no, with the instant hot water switch in the "off"
position and hot tap running, the boiler will not fire up and there is no
evidence of the pump running. If I switch to instant hot water whilst the
tap is running the boiler will fire up no problem.

OK. The problem is definitely with the DHW flow sensor.
This is a differential pressure type with a rubber diaphragm.
1) This could have split.
2) The pin it pushes could be stuck
3) the microswitch it moves could be duff.
4) the wires to the switch are broken.

When you put the instant (hot standby) switch on the boiler fires because
it is trying to preheat the innards, as you draw HW the preheating is
thwarted and the boiler delivers HW after a fashion.

--
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

"Ed Sirett" wrote in message
news
On Mon, 18 Oct 2004 17:06:43 +0100, Wainscotting wrote:


"Ed Sirett" wrote in message
news
1) From completely cold with the instant switch off does the boiler
fire
when you run a tap? If no then the problem is with the DHW flow sensor
(diaphragm) or more likely with the micro switch this sensor triggers
or
its operating mechanism.


Just tried this and no, with the instant hot water switch in the "off"
position and hot tap running, the boiler will not fire up and there is
no
evidence of the pump running. If I switch to instant hot water whilst
the
tap is running the boiler will fire up no problem.

OK. The problem is definitely with the DHW flow sensor.
This is a differential pressure type with a rubber diaphragm.
1) This could have split.
2) The pin it pushes could be stuck
3) the microswitch it moves could be duff.
4) the wires to the switch are broken.

When you put the instant (hot standby) switch on the boiler fires because
it is trying to preheat the innards, as you draw HW the preheating is
thwarted and the boiler delivers HW after a fashion.

--
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


Thanks for all your help and advice Ed. I will investigate the DHW flow
sensor. Much appreciated.

"Ed Sirett" wrote in message
news
On Mon, 18 Oct 2004 17:06:43 +0100, Wainscotting wrote:


"Ed Sirett" wrote in message
news
1) From completely cold with the instant switch off does the boiler
fire
when you run a tap? If no then the problem is with the DHW flow sensor
(diaphragm) or more likely with the micro switch this sensor triggers
or
its operating mechanism.


Just tried this and no, with the instant hot water switch in the "off"
position and hot tap running, the boiler will not fire up and there is
no
evidence of the pump running. If I switch to instant hot water whilst
the
tap is running the boiler will fire up no problem.

OK. The problem is definitely with the DHW flow sensor.
This is a differential pressure type with a rubber diaphragm.
1) This could have split.
2) The pin it pushes could be stuck
3) the microswitch it moves could be duff.
4) the wires to the switch are broken.

When you put the instant (hot standby) switch on the boiler fires because
it is trying to preheat the innards, as you draw HW the preheating is
thwarted and the boiler delivers HW after a fashion.

Update - The cold water section diaphragm seems to work ok. When drawing
water the pin lifts straight away and the microswitch contact is made. Are
you referring to the actual flow switch? The one that has two microswitches?
There is a metal lever that rises and falls depending on whether you are
using hot water. When the lever is in the down position it makes the right
hand microswitch and the boiler comes on for water. When water is turned off
the lever reverses it's action and moves away from one switch and makes the
other. It seems to take about 2-3 mins to move from radiators position to
hot water. Can the flow switch be refurbished or does it have to be replaced
as a unit?

On Wed, 03 Nov 2004 18:07:27 +0000, Wainscotting wrote:


"Ed Sirett" wrote in message
news
On Mon, 18 Oct 2004 17:06:43 +0100, Wainscotting wrote:


"Ed Sirett" wrote in message
news 1) From completely cold with the instant switch off does the boiler
fire
when you run a tap? If no then the problem is with the DHW flow sensor
(diaphragm) or more likely with the micro switch this sensor triggers
or
its operating mechanism.


Just tried this and no, with the instant hot water switch in the "off"
position and hot tap running, the boiler will not fire up and there is
no
evidence of the pump running. If I switch to instant hot water whilst
the
tap is running the boiler will fire up no problem.

OK. The problem is definitely with the DHW flow sensor.
This is a differential pressure type with a rubber diaphragm.
1) This could have split.
2) The pin it pushes could be stuck
3) the microswitch it moves could be duff.
4) the wires to the switch are broken.

When you put the instant (hot standby) switch on the boiler fires because
it is trying to preheat the innards, as you draw HW the preheating is
thwarted and the boiler delivers HW after a fashion.

Update - The cold water section diaphragm seems to work ok. When drawing
water the pin lifts straight away and the microswitch contact is made. Are
you referring to the actual flow switch? The one that has two microswitches?
There is a metal lever that rises and falls depending on whether you are
using hot water. When the lever is in the down position it makes the right
hand microswitch and the boiler comes on for water. When water is turned off
the lever reverses it's action and moves away from one switch and makes the
other. It seems to take about 2-3 mins to move from radiators position to
hot water. Can the flow switch be refurbished or does it have to be replaced
as a unit?

I'm less familiar with Sines than other Vaillant combis. I'm fairly sure
that the switches should go back and forth between the modes in a second
or two. I know that 242s have a three position diverter valve unit which
has CH-neutral-DHW positions. However they are indrectly servo operated
by pump pressure.

You'll have to ask at a heating spares shops if they have a 'service kit' for
the unit. A new unit which sounds like its a DHW flow + diveter valve
unit is likely to be pushing £100.
Incidently I notice that the cheaper the boiler the more expensive the
spare. This part is £140 for an Alpha, and £110 for a Pott. Lynx.
A possible cause of failure is spindles getting sticky on the O-ring
glands, or a load of gunk in the primary circuit part preventing free
movement of the valve.

--
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

"Ed Sirett" wrote in message
news
On Wed, 03 Nov 2004 18:07:27 +0000, Wainscotting wrote:


"Ed Sirett" wrote in message
news
On Mon, 18 Oct 2004 17:06:43 +0100, Wainscotting wrote:


"Ed Sirett" wrote in message
news 1) From completely cold with the instant switch off does the boiler
fire
when you run a tap? If no then the problem is with the DHW flow
sensor
(diaphragm) or more likely with the micro switch this sensor
triggers
or
its operating mechanism.


Just tried this and no, with the instant hot water switch in the
"off"
position and hot tap running, the boiler will not fire up and there
is
no
evidence of the pump running. If I switch to instant hot water whilst
the
tap is running the boiler will fire up no problem.

OK. The problem is definitely with the DHW flow sensor.
This is a differential pressure type with a rubber diaphragm.
1) This could have split.
2) The pin it pushes could be stuck
3) the microswitch it moves could be duff.
4) the wires to the switch are broken.

When you put the instant (hot standby) switch on the boiler fires
because
it is trying to preheat the innards, as you draw HW the preheating is
thwarted and the boiler delivers HW after a fashion.

Update - The cold water section diaphragm seems to work ok. When drawing
water the pin lifts straight away and the microswitch contact is made.
Are
you referring to the actual flow switch? The one that has two
microswitches?
There is a metal lever that rises and falls depending on whether you are
using hot water. When the lever is in the down position it makes the
right
hand microswitch and the boiler comes on for water. When water is turned
off
the lever reverses it's action and moves away from one switch and makes
the
other. It seems to take about 2-3 mins to move from radiators position
to
hot water. Can the flow switch be refurbished or does it have to be
replaced
as a unit?

I'm less familiar with Sines than other Vaillant combis. I'm fairly sure
that the switches should go back and forth between the modes in a second
or two. I know that 242s have a three position diverter valve unit which
has CH-neutral-DHW positions. However they are indrectly servo operated
by pump pressure.

You'll have to ask at a heating spares shops if they have a 'service kit'
for
the unit. A new unit which sounds like its a DHW flow + diveter valve
unit is likely to be pushing £100.
Incidently I notice that the cheaper the boiler the more expensive the
spare. This part is £140 for an Alpha, and £110 for a Pott. Lynx.
A possible cause of failure is spindles getting sticky on the O-ring
glands, or a load of gunk in the primary circuit part preventing free
movement of the valve.

--
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


Thanks once again Ed. I might try removing it and ceaning it as best I can
before I think about buying another.