Following on from a previous thread...
I too would like to change my knackered mechanical programmer (15 years old)
for a shiny digital version

I really like the sound of reusing the backplate - saves hassle

I have a Smith Meters Ltd Switchmaster 400 - a search on Google suggests
this is now made by Drayton???

Only trouble is I don't know which programmer to replace it with
If possible I would like one from Screwfix as it's cheap and just across the
road !!! but they only do Horstmann or danfoss

Also the old switch only does HW on or HW plus CH on
I would also like just CH at different times
Would I be able to achieve this with the existing wiring? (I can open it up
if anyone needs to know what's there

--
Regards

Hays

T610 Housings in stock now!!
www.phonepro.go.to


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hays wrote:
Following on from a previous thread...
I too would like to change my knackered mechanical programmer (15
years old) for a shiny digital version

I really like the sound of reusing the backplate - saves hassle

I have a Smith Meters Ltd Switchmaster 400 - a search on Google
suggests this is now made by Drayton???

Only trouble is I don't know which programmer to replace it with
If possible I would like one from Screwfix as it's cheap and just
across the road !!! but they only do Horstmann or danfoss

Also the old switch only does HW on or HW plus CH on
I would also like just CH at different times
Would I be able to achieve this with the existing wiring? (I can open
it up if anyone needs to know what's there


There are only 4 or 5 wires connected to most programmers - so it's not a
big deal to re-wire if the new one doesn't have the same backplate.

As to whether you can have CH without HW, most programmers support this -
but your plumbing may not. If you have a fully pumped system with either a
mid-position valve to control the HW/CH flow [Y-plan] or two zone valves
doing the same job [S-plan], it is possible to achieve. Have a look at the S
& Y plan details in http://content.honeywell.com/uk/homes/systems.htm when
all should become clear. You may need some minor wiring changes. In
particular, for Y-plan, you will need to connect the HW-OFF terminal in the
programmer to the appropriate connections on the cylinder stat and
mid-position valve.

If your system *isn't* fully pumped (e.g. gravity HW and pumped CH) you can
still achieve what you want - but only by installing an additional zone
valve and thermostat, and re-wiring in accordance with Plan-C.
--
HTH,
Set Square
Please reply to newsgroup. Reply address is Black Hole!

hays wrote:
Following on from a previous thread...
I too would like to change my knackered mechanical programmer (15
years old) for a shiny digital version

I really like the sound of reusing the backplate - saves hassle

I have a Smith Meters Ltd Switchmaster 400 - a search on Google
suggests this is now made by Drayton???

Only trouble is I don't know which programmer to replace it with
If possible I would like one from Screwfix as it's cheap and just
across the road !!! but they only do Horstmann or danfoss
They are both ok.
Also the old switch only does HW on or HW plus CH on
I would also like just CH at different times
Depends on the system more than the wiring.
Would I be able to achieve this with the existing wiring? (
More than likely..
Don't be afraid of using a different make. The install instructions are very
comprehensive and refer to most old models.

Generally the wiring has:-
mains in to the programmer.
CH demand
HW demand
HW satisfied ( for a 3 way valve)

In message , hays
writes
Following on from a previous thread...
I too would like to change my knackered mechanical programmer (15 years old)
for a shiny digital version

I really like the sound of reusing the backplate - saves hassle

I have a Smith Meters Ltd Switchmaster 400 - a search on Google suggests
this is now made by Drayton???

Only trouble is I don't know which programmer to replace it with
If possible I would like one from Screwfix as it's cheap and just across the
road !!! but they only do Horstmann or danfoss

Also the old switch only does HW on or HW plus CH on
I would also like just CH at different times
Would I be able to achieve this with the existing wiring? (I can open it up
if anyone needs to know what's there

As far as I know there is no current equivalent programmer which will
fit on the Switchmaster backplate
--
geoff

You might want to consider leaving the CH on 24 hours and controlling it
from a programmable thermostat instead. Much better control imho.

Colin M