Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller. Now the instructions for the C27 show kindly
show a table for converting the wiring for the EP2000 to the C27.
However, having opened up the EP2000, the wiring isnt as straight
forward as I thought. The Ep2000 is connected to a Potterton NettaHeat
conventional cast iron boiler (circa mid-late 80s), both of which are
currently working fine.

Now only having very basic electrician skills, it looks as if this is
possible to wire (from the instructions), but since seeing the wiring
its now clear that I may need assistance from some experienced/wise
bod. ( as the EP2000 instructions werent in the house when I bought
it. )

I've included a couple of pics to help explanation.

The EP2000 to C27 conversion table and the EP2000 basic-wiring sticker
shown here http://81.106.39.40/boiler/back.jpg
The crazy wiring can be seen here http://81.106.39.40/boiler/front.jpg
(ive labelled the wries with letters to aid means of description if
anyone can shed any light !)

Alas Ive no idea to what each of the 4 cables attaches (as I have
precisely zero knowledge of boilers) as I was expecting the wiring to
be a tad simpler.

My current visual observations a
1) The Lives of cables D & B seem to be wired together, but route to
via terminal 5, which isnt listed in the conversion table (it only
goes 1-4). This doesnt seem to be doing anything.
2) terminals 1 & 2 dont currently have any cables attached, (which
according to the conversion table should supply the control signals
for HW OFF and CH OFF ). Ive no idea why - perhaps the controller only
needs to enable leccy flow when the units it is ON.
3) terminal 3 (which should be HW ON according to the C27 conversion
table) has the Earth of cable A connected. Strange ??????

If anyone could advise on how I should wire up the existing 4 cables
to the new C27 controller (to L N E, HW OFF, HW ON, CH OFF, CH ON )
then Id be very appreciative.

Many thanks in advance ....

J.

On Sat, 18 Sep 2004 11:02:24 -0700, JE wrote:

Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller. Now the instructions for the C27 show kindly
show a table for converting the wiring for the EP2000 to the C27.
However, having opened up the EP2000, the wiring isnt as straight
forward as I thought. The Ep2000 is connected to a Potterton NettaHeat
conventional cast iron boiler (circa mid-late 80s), both of which are
currently working fine.

Now only having very basic electrician skills, it looks as if this is
possible to wire (from the instructions), but since seeing the wiring
its now clear that I may need assistance from some experienced/wise
bod. ( as the EP2000 instructions werent in the house when I bought
it. )

I've included a couple of pics to help explanation.

The EP2000 to C27 conversion table and the EP2000 basic-wiring sticker
shown here http://81.106.39.40/boiler/back.jpg
The crazy wiring can be seen here http://81.106.39.40/boiler/front.jpg
(ive labelled the wries with letters to aid means of description if
anyone can shed any light !)

Alas Ive no idea to what each of the 4 cables attaches (as I have
precisely zero knowledge of boilers) as I was expecting the wiring to
be a tad simpler.

My current visual observations a
1) The Lives of cables D & B seem to be wired together, but route to
via terminal 5, which isnt listed in the conversion table (it only
goes 1-4). This doesnt seem to be doing anything.
2) terminals 1 & 2 dont currently have any cables attached, (which
according to the conversion table should supply the control signals
for HW OFF and CH OFF ). Ive no idea why - perhaps the controller only
needs to enable leccy flow when the units it is ON.

Only a few systems and controls need a powered OFF signal.
(mainly those with non Honeywell style zone valves and 3-port valves).


3) terminal 3 (which should be HW ON according to the C27 conversion
table) has the Earth of cable A connected. Strange ??????


If anyone could advise on how I should wire up the existing 4 cables
to the new C27 controller (to L N E, HW OFF, HW ON, CH OFF, CH ON )
then Id be very appreciative.

Many thanks in advance ....


As you can see from the wiring diagrams the two controllers are almost
identical.

The wiring for N L 1 2 3 4 is the same in both cases.
The C27 unit does not need the extra wire from L to 5 as its '5' is
internally connectd to L. The brown wire from cable B will go to L.


Terminal B is just a spare connector
Cales B&D are live as you say.

The person who wired this up committed the great sin of using the green
and yellow wire in cable as the HW demand.

To avoid the sort of crap you have here I have just spent £30 on a reel of
six core mains cable. It means not only do you not have a stack of blue
and brown wires doing several things but often less cables as well...

Read the main FAQ on CH controls. It will help you a lot.

--
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

So basically just to get things clear in my mind

1) The Cable A Earth (green and yellow) isnt being used as earth, but
as a live cable to supply terminal 3 (from god knows where)?

2) The join between Cable A Neutral (blue) -Cable C Live (brown)
needs to maintained and permanently connected with connector strip
within the new C27 ?

3) Cable D must be the mains supply, (as it's the only cable with all
three wires going to the corresponding EP2000 Earth, Line and Neutral
terminals. Any idea on what the other 3 cables could be used for by
looking at the picture? (note there is also a fused single switch for
the controller to the right of the EP2000, but I assume this is just
in series and supplies the power to the controller and therefore
doesnt supply any other cables in the controller)


If 1 is correct, then Id never had thought that people would use spare
wires without at least putting the correct colured insulating tape
over them. Good idea on the 6 core - if u do this thing regularly.

Thanks for the FAQ link too - I now know what the 10/16 EP2000 switch
is for.

Cheers,

J.

"Ed Sirett" wrote in message on.co.uk...
On Sat, 18 Sep 2004 11:02:24 -0700, JE wrote:

Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller. Now the instructions for the C27 show kindly
show a table for converting the wiring for the EP2000 to the C27.
However, having opened up the EP2000, the wiring isnt as straight
forward as I thought. The Ep2000 is connected to a Potterton NettaHeat
conventional cast iron boiler (circa mid-late 80s), both of which are
currently working fine.

Now only having very basic electrician skills, it looks as if this is
possible to wire (from the instructions), but since seeing the wiring
its now clear that I may need assistance from some experienced/wise
bod. ( as the EP2000 instructions werent in the house when I bought
it. )

I've included a couple of pics to help explanation.

The EP2000 to C27 conversion table and the EP2000 basic-wiring sticker
shown here http://81.106.39.40/boiler/back.jpg
The crazy wiring can be seen here http://81.106.39.40/boiler/front.jpg
(ive labelled the wries with letters to aid means of description if
anyone can shed any light !)

Alas Ive no idea to what each of the 4 cables attaches (as I have
precisely zero knowledge of boilers) as I was expecting the wiring to
be a tad simpler.

My current visual observations a
1) The Lives of cables D & B seem to be wired together, but route to
via terminal 5, which isnt listed in the conversion table (it only
goes 1-4). This doesnt seem to be doing anything.
2) terminals 1 & 2 dont currently have any cables attached, (which
according to the conversion table should supply the control signals
for HW OFF and CH OFF ). Ive no idea why - perhaps the controller only
needs to enable leccy flow when the units it is ON.

Only a few systems and controls need a powered OFF signal.
(mainly those with non Honeywell style zone valves and 3-port valves).


3) terminal 3 (which should be HW ON according to the C27 conversion
table) has the Earth of cable A connected. Strange ??????


If anyone could advise on how I should wire up the existing 4 cables
to the new C27 controller (to L N E, HW OFF, HW ON, CH OFF, CH ON )
then Id be very appreciative.

Many thanks in advance ....


As you can see from the wiring diagrams the two controllers are almost
identical.

The wiring for N L 1 2 3 4 is the same in both cases.
The C27 unit does not need the extra wire from L to 5 as its '5' is
internally connectd to L. The brown wire from cable B will go to L.


Terminal B is just a spare connector
Cales B&D are live as you say.

The person who wired this up committed the great sin of using the green
and yellow wire in cable as the HW demand.

To avoid the sort of crap you have here I have just spent £30 on a reel of
six core mains cable. It means not only do you not have a stack of blue
and brown wires doing several things but often less cables as well...

Read the main FAQ on CH controls. It will help you a lot.

On Mon, 20 Sep 2004 05:43:55 -0700, JE wrote:

So basically just to get things clear in my mind

1) The Cable A Earth (green and yellow) isnt being used as earth, but
as a live cable to supply terminal 3 (from god knows where)?

Yes. Better put as terminal 3 supplies the HW demand signal to the G&Y core
of cable A (which goes TO god knows where).


2) The join between Cable A Neutral (blue) -Cable C Live (brown)
needs to maintained and permanently connected with connector strip
within the new C27 ?

Yes.
Best practice is not to use the C27 back plate as a mini
wiring centre. A wiring centre can be purpose bought or
easily made using a single or double patress with a choc strip inside.
I suspect there may also be a wiring centre or junction box elsewhere.
You actually only need 4 wires + Earth to wire the time switch, L & N
and one core from 3 for HW demand and one from 4 for CH demand.


3) Cable D must be the mains supply, (as it's the only cable with all
three wires going to the corresponding EP2000 Earth, Line and Neutral
terminals. Any idea on what the other 3 cables could be used for by
looking at the picture? (note there is also a fused single switch for
the controller to the right of the EP2000, but I assume this is just
in series and supplies the power to the controller and therefore
doesnt supply any other cables in the controller)

I'm sure the switch (containing 13A fuse should be 3A) runs one of
cable B or D.

You cant say if Cable B or D is the supply since both their cores are
effectivly connected to LN&E. The other cable of B&D likely goes
to the boiler to provide a permanent power supply.


If 1 is correct, then Id never had thought that people would use spare
wires without at least putting the correct colured insulating tape
over them.
You have a lot to learn about the depth, breadth and creativity
of corner cutting...

Good idea on the 6 core - if u do this thing regularly.

Thanks for the FAQ link too - I now know what the 10/16 EP2000 switch
is for.

Yes the 10/16 is very arcane. 8-)

A wild guess based on what I see form the photos plus experience:

The system is operated in '10' or gravity mode there is just a hint that
the photo shows the EP2000 in 10 mode. You can't have HW off
when the CH on. There is a zone valve for the CH.
The boiler is a modern unit requiring a permanent supply. The earth wire
was probably reassigned when the boiler was replaced. It might even go all
the way to the boiler as is. Somewhere along cable A between the timer and
the boiler the wall thermostat joins brown to blue.

Cable B&D are mains, one is supply likely D, and the other goes to the
boiler as a permanent supply.
Cable A takes CH and HW demand out on brown and G&Y. The blue cable is
likely the return from a wall thermostat. The G&Y operates the boiler
demand terminal. Either the boiler works the pump or the G&Y also does
that.

Cable C likely goes to the CH zone valve to put the radiators on. The
micro switch in the zone valve (cable cores orange and grey) is not used.

Boiler is a Potterton Suprima or Baxi Solo? The EP2000 is an older bit of
kit which predates the boiler?


--
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

In message .uk, Ed
Sirett writes

A wild guess based on what I see form the photos plus experience:

The system is operated in '10' or gravity mode there is just a hint that
the photo shows the EP2000 in 10 mode.

The cam looks to be in the vertical (16) to me

--
geoff

Thanks for the advice.

Erm by "connector strip" I acutally meant chocolate strip. ( Ill get
the terminology one day. ) Glad to know that I wasnt going completely
crazy with the G&Y wire on Terminal 3. Thanks for making me a little
more confident in my elecrical knowledge. BTW, the fused switch I
mentioned does contain a 3A fuse.

FYI, the boiler is a Potterton Netaheat 10-16. And the controller
setting seems to be set to 16 (and not 10) by my judgement (of both
the twisty control on the right and the sliding switch on the bottom).

As im in the middle of refitting my kitchen, Im taking the time to fit
the new controller and patch the bad plaster around the old, which
prompted this whole thread. With the kitchen stripped bare, now might
have been the time to replace and fit a new conventional boiler, but
it would cost about 2k to buy and get fitted, which seems alot
considering the Potterton Netaheat seems to be working fine.

Ive not had the boiler serviced since i moved in 2 1/2 yrs ago - is
this something I should sort out ASAP, in your opinion (and then
serviced at what intervals )?

Im impressed with your knowledge and also the effort you've taken to
help me stop blowing myself up.

Thanks again.

J.





"Ed Sirett" wrote in message on.co.uk...
On Mon, 20 Sep 2004 05:43:55 -0700, JE wrote:

So basically just to get things clear in my mind

1) The Cable A Earth (green and yellow) isnt being used as earth, but
as a live cable to supply terminal 3 (from god knows where)?

Yes. Better put as terminal 3 supplies the HW demand signal to the G&Y core
of cable A (which goes TO god knows where).


2) The join between Cable A Neutral (blue) -Cable C Live (brown)
needs to maintained and permanently connected with connector strip
within the new C27 ?

Yes.
Best practice is not to use the C27 back plate as a mini
wiring centre. A wiring centre can be purpose bought or
easily made using a single or double patress with a choc strip inside.
I suspect there may also be a wiring centre or junction box elsewhere.
You actually only need 4 wires + Earth to wire the time switch, L & N
and one core from 3 for HW demand and one from 4 for CH demand.


3) Cable D must be the mains supply, (as it's the only cable with all
three wires going to the corresponding EP2000 Earth, Line and Neutral
terminals. Any idea on what the other 3 cables could be used for by
looking at the picture? (note there is also a fused single switch for
the controller to the right of the EP2000, but I assume this is just
in series and supplies the power to the controller and therefore
doesnt supply any other cables in the controller)

I'm sure the switch (containing 13A fuse should be 3A) runs one of
cable B or D.

You cant say if Cable B or D is the supply since both their cores are
effectivly connected to LN&E. The other cable of B&D likely goes
to the boiler to provide a permanent power supply.


If 1 is correct, then Id never had thought that people would use spare
wires without at least putting the correct colured insulating tape
over them.
You have a lot to learn about the depth, breadth and creativity
of corner cutting...

Good idea on the 6 core - if u do this thing regularly.

Thanks for the FAQ link too - I now know what the 10/16 EP2000 switch
is for.

Yes the 10/16 is very arcane. 8-)

A wild guess based on what I see form the photos plus experience:

The system is operated in '10' or gravity mode there is just a hint that
the photo shows the EP2000 in 10 mode. You can't have HW off
when the CH on. There is a zone valve for the CH.
The boiler is a modern unit requiring a permanent supply. The earth wire
was probably reassigned when the boiler was replaced. It might even go all
the way to the boiler as is. Somewhere along cable A between the timer and
the boiler the wall thermostat joins brown to blue.

Cable B&D are mains, one is supply likely D, and the other goes to the
boiler as a permanent supply.
Cable A takes CH and HW demand out on brown and G&Y. The blue cable is
likely the return from a wall thermostat. The G&Y operates the boiler
demand terminal. Either the boiler works the pump or the G&Y also does
that.

Cable C likely goes to the CH zone valve to put the radiators on. The
micro switch in the zone valve (cable cores orange and grey) is not used.

Boiler is a Potterton Suprima or Baxi Solo? The EP2000 is an older bit of
kit which predates the boiler?

On Mon, 20 Sep 2004 20:40:55 +0000, raden wrote:

In message .uk, Ed
Sirett writes

A wild guess based on what I see form the photos plus experience:

The system is operated in '10' or gravity mode there is just a hint that
the photo shows the EP2000 in 10 mode.

The cam looks to be in the vertical (16) to me

OK. In which case there are probably two zone valves.


--
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 Mon, 20 Sep 2004 15:03:33 -0700, JE wrote:

Thanks for the advice.

Erm by "connector strip" I acutally meant chocolate strip. ( Ill get
the terminology one day. ) Glad to know that I wasnt going completely
crazy with the G&Y wire on Terminal 3. Thanks for making me a little
more confident in my elecrical knowledge. BTW, the fused switch I
mentioned does contain a 3A fuse.

OK that's encouraging.


FYI, the boiler is a Potterton Netaheat 10-16. And the controller
setting seems to be set to 16 (and not 10) by my judgement (of both
the twisty control on the right and the sliding switch on the bottom).

OK in which case there is likely two zone valvesa and a cylinder
thermostat elsewhere.

As im in the middle of refitting my kitchen, Im taking the time to fit
the new controller and patch the bad plaster around the old, which
prompted this whole thread. With the kitchen stripped bare, now might
have been the time to replace and fit a new conventional boiler, but
it would cost about 2k to buy and get fitted, which seems alot
considering the Potterton Netaheat seems to be working fine.

Yes I have many customers with a Netaheat The units are fairly efficient
and very reliable. The arguments for replacement are ambiguous with only a
10-15% saving likely in gas bills the pay back period is lengthy.

Ive not had the boiler serviced since i moved in 2 1/2 yrs ago - is
this something I should sort out ASAP, in your opinion (and then
serviced at what intervals )?

All official sources are going to tell you the boiler should be serviced
annually and if you rented your house this would legally be required.
I would say an annual safety check and expect to do a major service
every three years.



--
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

[quote=JE]Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller.

Like you I am attempting to replace my Potterton EP2000 with a C27, but I am unable to get past first base. I can't work out how to remove the front cover of the Potterton. There are no screw fixings and as far as I can see no simple clip fixings?

The timer came with the house 18 years ago, less instructions.

Can any one out there help?

Andy G.

On Sat, 23 Jul 2005 17:27:34 UTC, AndyG
wrote:

JE Wrote:
Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller.

Like you I am attempting to replace my Potterton EP2000 with a C27, but
I am unable to get past first base. I can't work out how to remove the
front cover of the Potterton. There are no screw fixings and as far as
I can see no simple clip fixings?

The timer came with the house 18 years ago, less instructions.

Can any one out there help?

Didn't see the original post, and Andy's appears to have a null reply,
but...

These are usually held by two screws UNDERNEATH. The screws are
vertical, and probably recessed. You loosen them (two), then pull the
front of the controller forward, lift it slightly and it comes off the
backplate. There is no front cover to remove - it all comes off at once
(apart from the connection backplate).

Isolate the circuit first, of course - there will be largish exposed
pieces of metal at mains potential.

Thanks for the reply, this is exactly what I would expect, however there are no screws!

In message , AndyG
writes

JE Wrote:
Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller.

Like you I am attempting to replace my Potterton EP2000 with a C27,
but
I am unable to get past first base. I can't work out how to remove
the
front cover of the Potterton. There are no screw fixings and as far
as
I can see no simple clip fixings?

The timer came with the house 18 years ago, less instructions.

The screw is underneath

There are two "hinges" at the top of the backplate

You rotate the time clock upwards to release it


--
geoff

In message , Bob Eager
writes
On Sat, 23 Jul 2005 17:27:34 UTC, AndyG
wrote:

JE Wrote:
Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller.

Like you I am attempting to replace my Potterton EP2000 with a C27, but
I am unable to get past first base. I can't work out how to remove the
front cover of the Potterton. There are no screw fixings and as far as
I can see no simple clip fixings?

The timer came with the house 18 years ago, less instructions.

Can any one out there help?

Didn't see the original post, and Andy's appears to have a null reply,
but...

These are usually held by two screws UNDERNEATH. The screws are
vertical, and probably recessed. You loosen them (two), then pull the
front of the controller forward, lift it slightly and it comes off the
backplate.

No you don't

--
geoff

In message , AndyG
writes

Bob Eager Wrote:
On Sat, 23 Jul 2005 17:27:34 UTC, AndyG
wrote:
-
JE Wrote:-
Im attempting to replace my aging potterton EP2000 controller with a
Horstmann C27 controller.

Like you I am attempting to replace my Potterton EP2000 with a C27,
but
I am unable to get past first base. I can't work out how to remove
the
front cover of the Potterton. There are no screw fixings and as far
as
I can see no simple clip fixings?

The timer came with the house 18 years ago, less instructions.

Can any one out there help?--

Didn't see the original post, and Andy's appears to have a null reply,
but...

These are usually held by two screws UNDERNEATH. The screws are
vertical, and probably recessed. You loosen them (two), then pull the
front of the controller forward, lift it slightly and it comes off the
backplate. There is no front cover to remove - it all comes off at
once
(apart from the connection backplate).

Isolate the circuit first, of course - there will be largish exposed
pieces of metal at mains potential.

Thanks for the reply, this is exactly what I would expect, however
there are no screws!


Then just rotate it upwards - i.e. thumbs under the bottom, fingers on
the top, pull outwards with your thumbs

Maybe the screw has got lost in the depths of time


--
geoff

Update: I have since found some more help and have now been able to remove the timer from the wall.

For info. There is a small slot about 10mm X 3 mm on the lower RH side within the groove that runs all the way round the timer. Insert a flat screwdriver into this slot, push upwards to release the "finger catch" that holds the timer to the back plate. The timer can then be tilted upwards and away from the wall.
Regards
Andy.

In message , AndyG
writes

AndyG Wrote:
Thanks for the reply, this is exactly what I would expect, however there
are no screws!

Update: I have since found some more help and have now been able to
remove the timer from the wall.

For info. There is a small slot about 10mm X 3 mm on the lower RH side
within the groove that runs all the way round the timer. Insert a flat
screwdriver into this slot, push upwards to release the "finger catch"
that holds the timer to the back plate. The timer can then be tilted
upwards and away from the wall.


Bugger, You're right, I forgot about that

--
geoff