Appreciate some help. The clock in this central heating timer stopped
going round and having spent hours trying to find a way to get into
the timer I broke the plastic lugs off. I'm not too bothered as I
wanted to replace it with a modern one anyway. It one with the old two
on and two off pegs around a circular clock.

Having got inside, it hasn't helped and now I'm stuck. The metal piece
at the back won't come away from the wall and it needs to to get to
the wiring which I need to do to fit a replacement. I still haven't
worked out how it was meant to come to bits but it looks like screws
from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

Some clues would be appreciated. I have replaced a timer in a previous
house but that was dead easy - nothing like this!

TIA

G.

The Wallport wrote:

from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

Often there is a small screw top or bottom that secures the front to the
mounting plate. However if someone has tiled round it that may be obscured.

If all else fails, turn off the boiler, and clomp the switch on the side
with a club hammer! ;-)

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

Assuming it just turns the boiler on and off at preset times, and does
not have separate controls for differentiating between hot water and
central heating, most are pretty standard. If you have the manual for
the boiler it may show some typical wiring diagrams.

Usually all a timer does is close switch when its in the "on" part of
the cycle, and open it otherwise.

So you may have two, three, or four wires. A four wire setup would be
Live, neutral and earth to the timer - this gives it power to run. Plus
a switched live which it will connect to the supply live when it is set
to "on". It may not have earth, it may not have neutral (although that
would normally require it to have a battery to keep its clock running)

Some clues would be appreciated. I have replaced a timer in a previous
house but that was dead easy - nothing like this!

This is probably as easy once you get it off the wall.

It might even be worth removing the switch altogether and replacing the
room stat with a programmable one. That way you not only get the
programmable on/off switching throughout the day (or week) but also the
ability to vary the temperature throughout the day at the same time.

After recommendations from this group, I fitted one of these the other
day, since my new boiler did not have any timer of its own:

http://www.screwfix.com/app/sfd/cat/...12157&ts=45911

Works very well.

--
Cheers,

John.

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

On 26 Mar 2004 12:44:46 -0800, in uk.d-i-y
(The Wallport) strung together this:

Appreciate some help. The clock in this central heating timer stopped
going round and having spent hours trying to find a way to get into
the timer I broke the plastic lugs off. I'm not too bothered as I
wanted to replace it with a modern one anyway. It one with the old two
on and two off pegs around a circular clock.

Having got inside, it hasn't helped and now I'm stuck. The metal piece
at the back won't come away from the wall and it needs to to get to
the wiring which I need to do to fit a replacement. I still haven't
worked out how it was meant to come to bits but it looks like screws
from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

Without looking difficult to tell if it is bodged on or mounted
correctly. It should be fitted with 2 screws on the bottom holding the
unit on to the baseplate, remove\slacken these and withdraw the front
of the unit bottom first.

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

A new Horstmann H21 will fit back on as a direct replacement amongst
others.
--

SJW
A.C.S. Ltd.

Thanks both. Had to wrench it off - now I can see where the screws
were but there was just no access. Must have been tiled after it was
fitted.

The backplate might be slightly damaged so I may have to replace it
anyway. Have figured the wiring out with a continuity tester.
Interestingly, the heating "Off" terminal is not wired but the water
"Off" is. What does this mean?

Thanks for the advice about a direct replacement but I really want to
move to a 7 day timer to have different times at the weekend. As for a
combined timer and thermostat - the wiring is in the wall with no easy
access and the current thermostat is upstairs. It would have been good
to move this but not easy due to the wiring not being where it's
needed.

I'm now going off to B&Q to see what I can get.

Thanks again

G.

(Lurch) wrote in message ...
On 26 Mar 2004 12:44:46 -0800, in uk.d-i-y
(The Wallport) strung together this:

Appreciate some help. The clock in this central heating timer stopped
going round and having spent hours trying to find a way to get into
the timer I broke the plastic lugs off. I'm not too bothered as I
wanted to replace it with a modern one anyway. It one with the old two
on and two off pegs around a circular clock.

Having got inside, it hasn't helped and now I'm stuck. The metal piece
at the back won't come away from the wall and it needs to to get to
the wiring which I need to do to fit a replacement. I still haven't
worked out how it was meant to come to bits but it looks like screws
from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

Without looking difficult to tell if it is bodged on or mounted
correctly. It should be fitted with 2 screws on the bottom holding the
unit on to the baseplate, remove\slacken these and withdraw the front
of the unit bottom first.

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

A new Horstmann H21 will fit back on as a direct replacement amongst
others.

The Wallport wrote:

Thanks both. Had to wrench it off - now I can see where the screws

Satisfaction huh ;-)

The backplate might be slightly damaged so I may have to replace it
anyway. Have figured the wiring out with a continuity tester.
Interestingly, the heating "Off" terminal is not wired but the water
"Off" is. What does this mean?

Does this timer have separate channels for water and CH then?

The off terminals are often just the other half of a changeover switch -
i.e.

*======== On
Live In /
==============*

*======== Off

This lets you switch things so they occur when the switch turns either
the heating or water off.

Thanks for the advice about a direct replacement but I really want to
move to a 7 day timer to have different times at the weekend. As for a
combined timer and thermostat - the wiring is in the wall with no easy
access and the current thermostat is upstairs. It would have been good
to move this but not easy due to the wiring not being where it's
needed.

There is no need to move anything usually. The combined timer/stat is a
direct replacement for the current stat - not the current timer. The
current timer would be removed - or left permanently switched to "on"
leaving the stat to control the heating (timing and temperature).

I'm now going off to B&Q to see what I can get.

Depressed?

--
Cheers,

John.

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

In an earlier contribution to this discussion,
The Wallport wrote:


The backplate might be slightly damaged so I may have to replace it
anyway. Have figured the wiring out with a continuity tester.
Interestingly, the heating "Off" terminal is not wired but the water
"Off" is. What does this mean?

I assume that you have a Y-plan fully pumped system, with a 3-port valve to
direct the primary water to the HW or CH (or both) circuits?

This type of arrangement requires a HW not required connection from the
programmer, and also requires the cylinder stat to be of the change-over
type - so that a different wire becomes live once the hot water demand is
satisfied. Have a look at the Y-plan wiring diagram in
http://content.honeywell.com/uk/homes/systems.htm - when all should become
clear(ish).

Without these connections, there is nothing to drive the valve to the CH
position when the HW is off or satisfied - and until the valve gets to the
CH position, it doesn't switch the boiler and pump on - so cold house! [The
boiler and pump are fed from the HW side until the HW demand is satisfied].

Your replacement programmer must, of course also have a HW Off connection -
but they virtually all do, anyway.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

In an earlier contribution to this discussion,
John Rumm wrote:


There is no need to move anything usually. The combined timer/stat is
a direct replacement for the current stat - not the current timer. The
current timer would be removed - or left permanently switched to "on"
leaving the stat to control the heating (timing and temperature).

Except that a programmable room stat will only control the heating - *not*
the hot water. A more usual arrangement would be to:
* keep a normal 2-channel programmer, and use it to programme the hot water
* switch the CH control on this programmer to "permanently on"
* Use a programmable room stat to control both the timing and the
temperature required for the heating

This is what I did, and it works fine. Additional features of this
arrangement a
* Everything can be switched off from a single point (original programmer)
* If any future occupier can't cope with a programmable stat, they can use
it in manual mode and revert to programming the heating with the original
programmer.

--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

Set Square wrote:

There is no need to move anything usually. The combined timer/stat is
a direct replacement for the current stat - not the current timer. The
current timer would be removed - or left permanently switched to "on"
leaving the stat to control the heating (timing and temperature).


Except that a programmable room stat will only control the heating - *not*

Hence my question about if it actually controls the water heating, or it
is it a case the timer has an unused channel for water but someone has
just used on of the terminals to "park" and unused wire?



--
Cheers,

John.

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

OK - I have installed a Drayton Tempus 7 and it seems to be working.
Wasn't backplate compatible so had to rewire but this was fairly
simple. Of course there was no wire to connect to the heating off
connection - I hope this is OK but can't see how it's any different to
before.

Don't understand the full meaning of the term "Two channels" but if
this means ability to control hot water on/off and heating on/off then
yes it could do this but there was only one set of times available for
on/off.

Don't fully understand the Y plan but I did trace the wires to a
junction box and the hot water off wire does connect to a valve which
I presume directs the boiler output away from the hot water circuit
when it's off. I don't understand what happens when the heating is
switched off but the water is switched on.

Anyway, all seems well for the moment - unless anyone is going to warn
me of something I've not realised!

G.

(The Wallport) wrote in message . com...
Appreciate some help. The clock in this central heating timer stopped
going round and having spent hours trying to find a way to get into
the timer I broke the plastic lugs off. I'm not too bothered as I
wanted to replace it with a modern one anyway. It one with the old two
on and two off pegs around a circular clock.

Having got inside, it hasn't helped and now I'm stuck. The metal piece
at the back won't come away from the wall and it needs to to get to
the wiring which I need to do to fit a replacement. I still haven't
worked out how it was meant to come to bits but it looks like screws
from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

Some clues would be appreciated. I have replaced a timer in a previous
house but that was dead easy - nothing like this!

TIA

G.

The Wallport wrote:

Don't understand the full meaning of the term "Two channels" but if
this means ability to control hot water on/off and heating on/off then
yes it could do this but there was only one set of times available for
on/off.

Two channels means as you suspect - the ability to control hot water and
heating independently. Your older timer may only have the ability to
have one or two sets of on/off times that can be used for both CH and
HW. The modern digital beasties will usually allow CH and HW to be
switched on and off independently at different times if required.

Don't fully understand the Y plan but I did trace the wires to a

Y plan is where you have the flow pipe from the boiler going to a three
port valve. From there it connects to two pipes - one to the HW cylinder
heating coil, the other to the radiators.

junction box and the hot water off wire does connect to a valve which
I presume directs the boiler output away from the hot water circuit
when it's off. I don't understand what happens when the heating is
switched off but the water is switched on.

Depends on the type of valve - the modern 3 port "mid position" valves
can be switched to 3 positions - A, B and A+B - so you can have the
boilers flow directed to either the HW, the CH, or split between both.
You can normally spot these since they will have a cable with five wires
going to the valve.

The other type you may find is a simpler diversion valve which has only
3 wires and only supports A or B but not both. With this type of valve
the HW is usually wired to take priority - it gets the full boiler flow
until its thermostat is satisfied. At which point either the boiler
shuts down, or the valve switched to the CH position if the CH is on at
the timer and the room stat is demanding heat.

Anyway, all seems well for the moment - unless anyone is going to warn
me of something I've not realised!

You will find out soon enough ;-)


--
Cheers,

John.

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

In an earlier contribution to this discussion,
The Wallport wrote:

OK - I have installed a Drayton Tempus 7 and it seems to be working.
Wasn't backplate compatible so had to rewire but this was fairly
simple. Of course there was no wire to connect to the heating off
connection - I hope this is OK but can't see how it's any different to
before.

Don't understand the full meaning of the term "Two channels" but if
this means ability to control hot water on/off and heating on/off then
yes it could do this but there was only one set of times available for
on/off.

Don't fully understand the Y plan but I did trace the wires to a
junction box and the hot water off wire does connect to a valve which
I presume directs the boiler output away from the hot water circuit
when it's off. I don't understand what happens when the heating is
switched off but the water is switched on.

Anyway, all seems well for the moment - unless anyone is going to warn
me of something I've not realised!

G.

You don't need a CH connection but you *do* need a HW off connection if it's
a Y-plan.

Yes, 2 channel refers refers to independent switching of HW and CH - albeit
at the same times, because there is only one clock. But it does usually
allow you to have (say) 3 on's and off's for the CH but "all day" (first on
'til last off) for HW - or vice versa - or to have one or other or both on
constantly, ignoring the clock. Hence if you have a programmable thermostat
for the heating, you can have CH on at completely independent times from
HW - using the original programmer clock for HW amd the clock in the stat
for CH.

With HW on and CH off, the 3-port valves sits at its rest (unpowered)
position - where it directs the boiler output only to the heating coil in
the HW cylinder. In this position, the boiler and pump are powered from the
programmer and cylstat - rather than from the microswitches in the valve
actuator.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is Black Hole!

In message , The
Wallport writes
Appreciate some help. The clock in this central heating timer stopped
going round and having spent hours trying to find a way to get into
the timer I broke the plastic lugs off. I'm not too bothered as I
wanted to replace it with a modern one anyway. It one with the old two
on and two off pegs around a circular clock.

Having got inside, it hasn't helped and now I'm stuck. The metal piece
at the back won't come away from the wall and it needs to to get to
the wiring which I need to do to fit a replacement. I still haven't
worked out how it was meant to come to bits but it looks like screws
from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

When I do get to the back, what model can I replace it with? Are these
things fairly standard?

Some clues would be appreciated. I have replaced a timer in a previous
house but that was dead easy - nothing like this!

TIA

The ST1000 has two screws on the top which hold it to the backplane.
Once undone, you can rotate it downwards to remove it. It requires a
bit of force to remove it as the spade connectors on the back are
stiffly held. The front of the clock is held to the back of the clock by
four crossheaded screws. If you touch the live and neutral pins when it
has just been removed, expect a small electric shock as you discharge
the motor capacitor.

The ST1000 has volts free contacts, so if you replace it, you might have
to replace it with another volts free contact timer
--
geoff

In message , Lurch
writes
On 26 Mar 2004 12:44:46 -0800, in uk.d-i-y
(The Wallport) strung together this:

Appreciate some help. The clock in this central heating timer stopped
going round and having spent hours trying to find a way to get into
the timer I broke the plastic lugs off. I'm not too bothered as I
wanted to replace it with a modern one anyway. It one with the old two
on and two off pegs around a circular clock.

Having got inside, it hasn't helped and now I'm stuck. The metal piece
at the back won't come away from the wall and it needs to to get to
the wiring which I need to do to fit a replacement. I still haven't
worked out how it was meant to come to bits but it looks like screws
from the rear and if so these are completely inaccessible. The people
who did this have cut a hole in a wall tile and so you cant get to the
very back of it. Anyone know how it is mounted?

Without looking difficult to tell if it is bodged on or mounted
correctly. It should be fitted with 2 screws on the bottom

top

holding the
unit on to the baseplate,

--
geoff