On Mon, 2 Apr 2007 23:28:09 UTC, Neil Barker wrote:

I have one of these:-

http://www.zen58589.zen.co.uk/st699.pdf

controlling my central heating/hot water.

Works OK, but it will not allow independant hot water/heating, just
both together and therefore I want to fit a different kind, which I
already have.

Problem is that I can't manage to release it from its sub-base which is
mounted on the wall - the manual says that, "it can be removed if
required by depressing the locking catch with a screwdriver".

All fine and dandy, but where is the locking catch ?

Don't know this particular model, but it's usually underneath. Some
(presumably not thi, as it says 'catch', but you never know) have a
small recessed screw.

Look for a hole or slot underneath into which you can poke a thin
screwdriver or thick paper clip.

--
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On 2 Apr 2007 23:34:03 GMT, "Bob Eager" wrote:

On Mon, 2 Apr 2007 23:28:09 UTC, Neil Barker wrote:

I have one of these:-

http://www.zen58589.zen.co.uk/st699.pdf

controlling my central heating/hot water.

Works OK, but it will not allow independant hot water/heating, just
both together and therefore I want to fit a different kind, which I
already have.

Problem is that I can't manage to release it from its sub-base which is
mounted on the wall - the manual says that, "it can be removed if
required by depressing the locking catch with a screwdriver".

All fine and dandy, but where is the locking catch ?

Don't know this particular model, but it's usually underneath. Some
(presumably not thi, as it says 'catch', but you never know) have a
small recessed screw.

Look for a hole or slot underneath into which you can poke a thin
screwdriver or thick paper clip.

Apart from how to get into the unit, isn't there an apparent question
about the system itself?

If the Honeywell won't control DHW and CH seperately, a replacement is
unlikely to do so, because the fault lies in the controls available to
the programmer, not the programmer? A lack of control valves to be
turned on and off?

Just an idle thought and probably wrong.

The message
from Neil Barker contains these words:

If the Honeywell won't control DHW and CH seperately, a replacement is
unlikely to do so, because the fault lies in the controls available to
the programmer, not the programmer? A lack of control valves to be
turned on and off?

No, the problem is purely with the programmer - the system can happily
do hot water or heating or both, manually. The programmer simply cannot
operate the two individually.

I have no knowledge of that particular programmer but programmers
traditionally have been designed to work both with fully pumped and
pumped central heating/gravity driven domestic hot water systems.

Given that your programmer won't cooperate has it been set for gravity DHW?

--
Roger Chapman

In article ,
Neil Barker wrote:
If the Honeywell won't control DHW and CH seperately, a replacement is
unlikely to do so, because the fault lies in the controls available to
the programmer, not the programmer? A lack of control valves to be
turned on and off?

No, the problem is purely with the programmer - the system can happily
do hot water or heating or both, manually. The programmer simply cannot
operate the two individually.

Then it's wired up incorrectly. It does precisely that here. Unless you
want different on off times.

--
*We are born naked, wet, and hungry. Then things get worse.

Dave Plowman London SW
To e-mail, change noise into sound.

In an earlier contribution to this discussion,
Neil Barker wrote:

In article ,
says...

If the Honeywell won't control DHW and CH seperately, a replacement
is unlikely to do so, because the fault lies in the controls
available to the programmer, not the programmer? A lack of control
valves to be turned on and off?

No, the problem is purely with the programmer - the system can happily
do hot water or heating or both, manually. The programmer simply
cannot operate the two individually.

Can you please define what you mean by "individually". The programmer has
separate sliders for CH and HW - each of which can be set independently at
off, once per day, twice per day or constant. What does it *not* do?

To answer that myself, maybe you want to time both the CH and HW but have
them going on and off at *different* times from each other? If that is the
case, this programmer *won't* do that, 'cos it's only got one timer. You
would thus need to replace it with one having *two* independent timers.

OR - and possibly a better solution - replace your room stat with a
programmable stat. You can then leave the CH control on your existing
programmer set to 'constant' and do the *actual* timing on the programmable
stat. This has the advantage of being able to select different temperatures
for different times of day (or different days of the week if it's a 7-day
jobby) as well as things like providing an automatic frost stat (and usually
other goodies too).
--
Cheers,
Roger
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In message , Neil Barker
writes
In article ,
says...

If the Honeywell won't control DHW and CH seperately, a replacement is
unlikely to do so, because the fault lies in the controls available to
the programmer, not the programmer? A lack of control valves to be
turned on and off?

No, the problem is purely with the programmer - the system can happily
do hot water or heating or both, manually. The programmer simply cannot
operate the two individually.

Sorry, but the exact opposite is true

the two channels are independent of each other

--
geoff

In article ,
raden wrote:
If the Honeywell won't control DHW and CH seperately, a replacement is
unlikely to do so, because the fault lies in the controls available to
the programmer, not the programmer? A lack of control valves to be
turned on and off?

No, the problem is purely with the programmer - the system can happily
do hot water or heating or both, manually. The programmer simply cannot
operate the two individually.

Sorry, but the exact opposite is true

the two channels are independent of each other

Given it has separate controls for each I'd have thought this was obvious,
but since the OP hasn't replied I wonder if he meant different timings?

--
*Never put off until tomorrow what you can avoid altogether *

Dave Plowman London SW
To e-mail, change noise into sound.