I've recently replaced a Honeywell T6360 thermostat with a CM907
Chronostat and I am generally very happy with it.

There is one downside though. To give total control of the heating
over to the CM907 the main programmer/timer unit (a Potterton EP2001)
has to be set to continous for the heating. Due to the restrictions of
the EP2001 this also means that the hot water has to be set to continous.
If fact the act of setting the heating to continous on the EP2001 causes
the EP2001 to set the ho****er to continous too.

So what I'd ldeally like is a tank thermostat with a bult in timer as
for much of the time we don't need hot water but would still like a
warm house!

The system is a pumped Y plan BTW.

Any pointers?

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd

On 2007-10-31, Guy Dawson wrote:
I've recently replaced a Honeywell T6360 thermostat with a CM907
Chronostat and I am generally very happy with it.

There is one downside though. To give total control of the heating
over to the CM907 the main programmer/timer unit (a Potterton EP2001)
has to be set to continous for the heating. Due to the restrictions of
the EP2001 this also means that the hot water has to be set to continous.
If fact the act of setting the heating to continous on the EP2001 causes
the EP2001 to set the ho****er to continous too.

Instead of taking the live feed to the CM907 switch (pin A probably)
from the timed "CH on" pin of the EP2001 (pin 4 I think) why not take
this live feed from a non-timed, permanent live?

Then the timer applies only to the HW and the temperature profile of
the CM907 takes care of the timing for the CH.

--
John Phillips

John Phillips wrote:
On 2007-10-31, Guy Dawson wrote:
I've recently replaced a Honeywell T6360 thermostat with a CM907
Chronostat and I am generally very happy with it.

There is one downside though. To give total control of the heating
over to the CM907 the main programmer/timer unit (a Potterton EP2001)
has to be set to continous for the heating. Due to the restrictions of
the EP2001 this also means that the hot water has to be set to continous.
If fact the act of setting the heating to continous on the EP2001 causes
the EP2001 to set the ho****er to continous too.

Instead of taking the live feed to the CM907 switch (pin A probably)
from the timed "CH on" pin of the EP2001 (pin 4 I think) why not take
this live feed from a non-timed, permanent live?

That would involve running new wires. The boilder and controller are
in new extension (well, new in 1990) while the CM907 is the original
(and current) hall.

Then the timer applies only to the HW and the temperature profile of
the CM907 takes care of the timing for the CH.

I guess if I would rewire the switched live at the EP2001 to be a
non-switched live then this might be enough.

Guy, who feels guess is not good enough!
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd

On 2007-10-31, Guy Dawson wrote:
John Phillips wrote:
On 2007-10-31, Guy Dawson wrote:
I've recently replaced a Honeywell T6360 thermostat with a CM907
Chronostat and I am generally very happy with it.

There is one downside though. To give total control of the heating
over to the CM907 the main programmer/timer unit (a Potterton EP2001)
has to be set to continous for the heating. Due to the restrictions of
the EP2001 this also means that the hot water has to be set to continous.
If fact the act of setting the heating to continous on the EP2001 causes
the EP2001 to set the ho****er to continous too.

Instead of taking the live feed to the CM907 switch (pin A probably)
from the timed "CH on" pin of the EP2001 (pin 4 I think) why not take
this live feed from a non-timed, permanent live?

That would involve running new wires. The boilder and controller are
in new extension (well, new in 1990) while the CM907 is the original
(and current) hall.

Then the timer applies only to the HW and the temperature profile of
the CM907 takes care of the timing for the CH.

I guess if I would rewire the switched live at the EP2001 to be a
non-switched live then this might be enough.

Yes - that's exactly what I wanted to suggest. Sorry if it wasn't clear
which end of the thermostat cable I was writing about.

It should just need the thermostat switch wire moved at the EP2001 from
the "CH on" pin (pin 4 I think) to the L pin (or pin 5 if the installer
link from L to 5 is there). BTW I'm going on a diagram from the web so
please do check your EP2001 documentataion for correctness and safety.

Of course a programmable cylinder stat would also do if available,
but the above seems simpler if it can be safely done.

--
John Phillips

John Phillips wrote:
On 2007-10-31, Guy Dawson wrote:
John Phillips wrote:

[snip]

I guess if I would rewire the switched live at the EP2001 to be a
non-switched live then this might be enough.

Yes - that's exactly what I wanted to suggest. Sorry if it wasn't clear
which end of the thermostat cable I was writing about.

It should just need the thermostat switch wire moved at the EP2001 from
the "CH on" pin (pin 4 I think) to the L pin (or pin 5 if the installer
link from L to 5 is there). BTW I'm going on a diagram from the web so
please do check your EP2001 documentataion for correctness and safety.

There's my main problem - no documentation for the EP2001.

Of course a programmable cylinder stat would also do if available,
but the above seems simpler if it can be safely done.

Indeed.

--
Guy

On 2007-10-31, Guy Dawson wrote:
There's my main problem - no documentation for the EP2001.

http://www.gtts.co.uk/EP2001/

There's an installer and a user guide.

I see Ed S. suggests it can be put into separate HW and CH control mode
by switching from 10- to 16-program mode. See the installer guide section
12. Note that this seems to be done with the battery disconnected (see
section 13).

If so, that would be an easier solution still ...

--
John Phillips

In message , Guy Dawson
writes
John Phillips wrote:
On 2007-10-31, Guy Dawson wrote:
John Phillips wrote:

[snip]

I guess if I would rewire the switched live at the EP2001 to be a
non-switched live then this might be enough.
Yes - that's exactly what I wanted to suggest. Sorry if it wasn't
clear
which end of the thermostat cable I was writing about.
It should just need the thermostat switch wire moved at the EP2001
from
the "CH on" pin (pin 4 I think) to the L pin (or pin 5 if the installer
link from L to 5 is there). BTW I'm going on a diagram from the web so
please do check your EP2001 documentataion for correctness and safety.

There's my main problem - no documentation for the EP2001.

Of course a programmable cylinder stat would also do if available,
but the above seems simpler if it can be safely done.

What do you need to know about the 2001 that isn't on the back of the
programmer ?

I prolly have a user guide somewhere
--
geoff

On Wed, 31 Oct 2007 14:05:32 +0000, Guy Dawson wrote:

I've recently replaced a Honeywell T6360 thermostat with a CM907
Chronostat and I am generally very happy with it.

There is one downside though. To give total control of the heating
over to the CM907 the main programmer/timer unit (a Potterton EP2001)
has to be set to continous for the heating. Due to the restrictions of
the EP2001 this also means that the hot water has to be set to continous.
If fact the act of setting the heating to continous on the EP2001 causes
the EP2001 to set the ho****er to continous too.

So what I'd ldeally like is a tank thermostat with a bult in timer as
for much of the time we don't need hot water but would still like a
warm house!

The system is a pumped Y plan BTW.

Any pointers?

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd



You should be able to set the CH to continuous and the HW to once or twice.

You may need to reset the device and/or move a mechanincal interlock
and/or move a jumper from Gravity/10 to Full/Pumped/16 .



--
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