My central heating only comes on when the HW circuit is turned on. With
both off, if I turn on the CH circuit via the programmer, the motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The status
light does not change colour when I turn on the CH alone. Another thing
that's weird is the reset button doesn't seem to do anything, on my old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on. With
both off, if I turn on the CH circuit via the programmer, the motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The status
light does not change colour when I turn on the CH alone. Another thing
that's weird is the reset button doesn't seem to do anything, on my old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.

Your two port valve is stuck.

Andy

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on. With
both off, if I turn on the CH circuit via the programmer, the motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The status
light does not change colour when I turn on the CH alone. Another thing
that's weird is the reset button doesn't seem to do anything, on my old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.


Actually, belay that diagnosis, I didn't read your post carefully enough :0(

Andy

On Tue, 16 Jan 2007 22:39:05 +0000, Andy wrote:

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on. With
both off, if I turn on the CH circuit via the programmer, the motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The status
light does not change colour when I turn on the CH alone. Another thing
that's weird is the reset button doesn't seem to do anything, on my old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.


Actually, belay that diagnosis, I didn't read your post carefully enough :0(


I think your original diagnosis is correct the 2 port valve is stuck half
open, enough that the rads warm up but not enough to close the conacts to
fire the boiler.

As for the reset problem it's a Suprima. I'd get buy a recon'ed PCB in
in readiness if I were you.

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

In an earlier contribution to this discussion,
Chris wrote:

My central heating only comes on when the HW circuit is turned on.
With both off, if I turn on the CH circuit via the programmer, the
motorised valve turns on and winds open but the boiler does not fire
up. If I then turn on the HW circuit via the programmer the boiler
fires up and heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The
status light does not change colour when I turn on the CH alone.
Another thing that's weird is the reset button doesn't seem to do
anything, on my old boiler this used reset the boiler if I pressed it
when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.

It's an electrical problem in the CH's 2-port valve's actuator. There is an
additional switch inside the actuator which switches the boiler on when the
valve is open. The motor is opening the valve ok, but this secondary switch
isn't making.

[You have an S-Plan system. See
http://content.honeywell.com/uk/homes/systems.htm and scroll down to the
S-Plan wiring diagram to get a better understanding of how it's supposed to
work].

You may be able to replace just the switch - but it's easier (albeit a bit
more expensive) to replace the whole actuator.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Ed Sirett" wrote in message
...
On Tue, 16 Jan 2007 22:39:05 +0000, Andy wrote:

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on. With
both off, if I turn on the CH circuit via the programmer, the motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The status
light does not change colour when I turn on the CH alone. Another thing
that's weird is the reset button doesn't seem to do anything, on my old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.


Actually, belay that diagnosis, I didn't read your post carefully enough
:0(


I think your original diagnosis is correct the 2 port valve is stuck half
open, enough that the rads warm up but not enough to close the conacts to
fire the boiler.

Ah, well I've learned something the I wasn't sure about the way the
two-port valve signalled the boiler it was allowed to fire.

cheers

Andy

"Andy" wrote in message
...

"Ed Sirett" wrote in message
...
On Tue, 16 Jan 2007 22:39:05 +0000, Andy wrote:

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on.
With
both off, if I turn on the CH circuit via the programmer, the
motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The
status
light does not change colour when I turn on the CH alone. Another
thing
that's weird is the reset button doesn't seem to do anything, on my
old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.


Actually, belay that diagnosis, I didn't read your post carefully
enough
:0(


I think your original diagnosis is correct the 2 port valve is stuck
half
open, enough that the rads warm up but not enough to close the conacts
to
fire the boiler.

Ah, well I've learned something the I wasn't sure about the way the
two-port valve signalled the boiler it was allowed to fire.

You should have a lever to manually open the valve. See if this fires the CH
when the HW is off.

"PM" wrote in message
...

"Andy" wrote in message
...

"Ed Sirett" wrote in message
...
On Tue, 16 Jan 2007 22:39:05 +0000, Andy wrote:

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on.
With
both off, if I turn on the CH circuit via the programmer, the
motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up
and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The
status
light does not change colour when I turn on the CH alone. Another
thing
that's weird is the reset button doesn't seem to do anything, on my
old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.


Actually, belay that diagnosis, I didn't read your post carefully
enough
:0(


I think your original diagnosis is correct the 2 port valve is stuck
half
open, enough that the rads warm up but not enough to close the conacts
to
fire the boiler.

Ah, well I've learned something the I wasn't sure about the way the
two-port valve signalled the boiler it was allowed to fire.

You should have a lever to manually open the valve. See if this fires the
CH
when the HW is off.

Not sure about Myson but on a Honeywell 2 port that does not work. Only the
synchron motor can do that and a failure mode I have experienced is that a
failing synchron motor opens the valve but does not operate the contacts.

Jim A

In an earlier contribution to this discussion,
Jim Alexander wrote:


You should have a lever to manually open the valve. See if this
fires the CH
when the HW is off.

Not sure about Myson but on a Honeywell 2 port that does not work. Only
the synchron motor can do that and a failure mode I have
experienced is that a failing synchron motor opens the valve but does
not operate the contacts.
Jim A

Are you saying that the motor (when working properly) moves the valve
*further* than the lever does - and that the lever doesn't move it quite far
enough to operate the secondary contacts? Interesting!

To clarify what I wrote earlier about the secondary contacts being duff,
requiring the actuator to be replaced - as others have pointed out, there is
also the possibility that the valve isn't opening fully but that the
contacts are ok and *would* make if the valve did open fully. This could be
due either to a problem with the motor or to the mechanical part of the
valve being partially seized. So it needs to be bottomed out before rushing
out and buying bits unnecessarily.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
Jim Alexander wrote:


You should have a lever to manually open the valve. See if this
fires the CH
when the HW is off.

Not sure about Myson but on a Honeywell 2 port that does not work. Only
the synchron motor can do that and a failure mode I have
experienced is that a failing synchron motor opens the valve but does
not operate the contacts.
Jim A

Are you saying that the motor (when working properly) moves the valve
*further* than the lever does - and that the lever doesn't move it quite
far enough to operate the secondary contacts? Interesting!


Can't say *exactly* that. Would have known when I investigated the problem.
Can't remember the internals but I remember the valve was operating freely
throughout its travel. It may just be the contact travel that is different.
May take a look later. The effect was definately as I describe. Got me the
first time but not the second time. Circumstantially I have a suspicion
the synchron motor "failure" was cause by switching transients on the
incoming mains.

Jim A

On Wed, 17 Jan 2007 16:16:15 +0000, Jim Alexander wrote:

"PM" wrote in message
...

"Andy" wrote in message
...

"Ed Sirett" wrote in message
...
On Tue, 16 Jan 2007 22:39:05 +0000, Andy wrote:

"Chris" wrote in message
ups.com...
My central heating only comes on when the HW circuit is turned on.
With
both off, if I turn on the CH circuit via the programmer, the
motorised
valve turns on and winds open but the boiler does not fire up. If I
then turn on the HW circuit via the programmer the boiler fires up
and
heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The
status
light does not change colour when I turn on the CH alone. Another
thing
that's weird is the reset button doesn't seem to do anything, on my
old
boiler this used reset the boiler if I pressed it when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.


Actually, belay that diagnosis, I didn't read your post carefully
enough
:0(


I think your original diagnosis is correct the 2 port valve is stuck
half
open, enough that the rads warm up but not enough to close the conacts
to
fire the boiler.

Ah, well I've learned something the I wasn't sure about the way the
two-port valve signalled the boiler it was allowed to fire.

You should have a lever to manually open the valve. See if this fires the
CH
when the HW is off.

Not sure about Myson but on a Honeywell 2 port that does not work. Only the
synchron motor can do that and a failure mode I have experienced is that a
failing synchron motor opens the valve but does not operate the contacts.

It depends on the make.

The Honeywell ones won't close the contacts
with the lever, but if you move the lever quickly enough (but not so hard
the gears slip!) the valve can be briefly thrown to the contact point.
This can serve of something of a touchstone on the health of the valve: if
it can do this, it is not jammed.

The Horstmann ones will close the contact with the lever.



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

On Tue, 16 Jan 2007 23:38:09 +0000, Roger Mills wrote:

In an earlier contribution to this discussion,
Chris wrote:

My central heating only comes on when the HW circuit is turned on.
With both off, if I turn on the CH circuit via the programmer, the
motorised valve turns on and winds open but the boiler does not fire
up. If I then turn on the HW circuit via the programmer the boiler
fires up and heats HW and CH.

This used to work perfectly until recently. Nothing has (knowingly)
been changed since it was working.
There was a room thermostat but I bypassed this during renovations by
joining both brown wires (L and SL) and insulating the earth and
neutral. This was bypassed long before this fault developed.

I have a Potterton Suprima 60 boiler for CH and HW which are
individually controlled by the programmer.
I have a Myson motorised 2-port valve at the boiler (for CH) and same
next to the upstairs cylinder.

The boiler and programmer are about a year old, the valves etc. were
installed by the previous owner.

A picture of my boiler can be seen here
http://84.203.164.145/boiler.jpg

Does this sound like an electrical or perhaps a PCB problem? The
status light does not change colour when I turn on the CH alone.
Another thing that's weird is the reset button doesn't seem to do
anything, on my old boiler this used reset the boiler if I pressed it
when running.

I'd rather not have to get my plumber out if I can avoid it so any
advice would be much appreciated.

Cheers,
Chris.

It's an electrical problem in the CH's 2-port valve's actuator. There is an
additional switch inside the actuator which switches the boiler on when the
valve is open. The motor is opening the valve ok, but this secondary switch
isn't making.

[You have an S-Plan system. See
http://content.honeywell.com/uk/homes/systems.htm and scroll down to the
S-Plan wiring diagram to get a better understanding of how it's supposed to
work].

You may be able to replace just the switch - but it's easier (albeit a bit
more expensive) to replace the whole actuator.

Except in my experience the valve is as likely to be mechanically
stuck/stiff/jammed as the microswitch defective.


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

Thanks for all the replies. You won't believe it but it has started
working properly again as mysteriously as it stopped! However I suspect
it will stop again one of these cold frosty mornings!
From reading the posts I gather the problem is almost certainly with
the 2-port valve. I did try manually opening the valve but the boiler
still would not fire up until I turned on the HW circuit. The valve
always closes quickly with a 'whizz' sound but is quite slow opening
with more of a quiet creak than a whizz. Not sure if this is normal,
sounds like during opening it is tightening a spring loaded coil or
something like that.

Is it tricky to replace the motorised valve? I know how to drain the
system and basic plumbing. Might be a job for my plumber though. Thanks
for all the help which has been very informative.

Cheers,
Chris.

In an earlier contribution to this discussion,
Chris wrote:

Thanks for all the replies. You won't believe it but it has started
working properly again as mysteriously as it stopped! However I
suspect it will stop again one of these cold frosty mornings!
From reading the posts I gather the problem is almost certainly with
the 2-port valve. I did try manually opening the valve but the boiler
still would not fire up until I turned on the HW circuit. The valve
always closes quickly with a 'whizz' sound but is quite slow opening
with more of a quiet creak than a whizz. Not sure if this is normal,
sounds like during opening it is tightening a spring loaded coil or
something like that.

Is it tricky to replace the motorised valve? I know how to drain the
system and basic plumbing. Might be a job for my plumber though.
Thanks for all the help which has been very informative.

Cheers,
Chris.

It's not difficult - especially if you've got any manual gate or lever
valves which enable you to isolate the motorised valve. Otherwise, it's at
least a partial drain down job.

From what you now say, it sounds as if the valve is just a bit stiff rather
than seized. You may be able to free it up by removing the actuator and
turning the exposed spindle (of the valve itself) back and forth a few
times. You should be able to rotate it through 90 degrees with finger and
thumb - but may initially need to use pliers if it is stiff. You don't need
to drain anything to do that. Don't disturb the electrical connections to
the actuator.

To get an idea of what it's supposed to sound like, open the valve manually
and operate the actuator while it is off the valve. If you call for heating,
the motor will turn in order to think it's opening the valve - and will wind
up the return spring. When it gets to the end of its travel, the motor will
simply stall and - hopefully - the contacts will close and turn the boiler
on (which is why you need to make sure that the valve is physically open
before doing this). When you turn the heating off, power will be removed
from the motor, and the return spring will move the actuator shaft back to
the valve closed position.

When the valve is moving freely, the opening and closing sounds will be the
*same* as the sounds made by the detached actuator.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!