On Mon, 23 Jan 2006 10:26:39 +0000, Set Square wrote:
In an earlier contribution to this discussion,
Geronimo W. Christ Esq wrote:
Hi all,
I recently moved into a house which has a traditional CH and HW
system, ie cylinder/header tank/gas boiler, but no controls which
allow me independent control of either or both - there is one
timeswitch that turns the whole thing on or off. I would like to
upgrade this to add a proper control digital programmer that will
allow me to program various on/off times for the hot water and
heating independently, as I'm finding there are many times when I
need one but not the other and it's clearly not efficient to keep a
cylinder of water warm all day in the winter (and in the summer, I
don't want to have to go around the house and turn down all the TRVs
manually when I just need water).
My understanding is that this is a matter of adding two motorized
valves, one to open the HW circuit and one to open the CH circuit -
then drop in the programmer and bob's your uncle. However, I
recognize that this means a control cables will need to be run to
each of these valves. Because the cylinder (where the valves will
need to go near) is upstairs and the boiler and present timeclock are
downstairs, this will mean gouging out of walls, requiring lots of
tiling and replastering that I don't want to contemplate at the
moment.
What would be really great would be a way to add this wirelessly. This
way I could stick the box on the wall, and then have it talk over a
radio link to the two motorized valves as required.
Alternatively, the present timeswitch obviously sends a control signal
up to switch on the pump which is right beside the cylinder. I guess
it just switches mains onto it. I wonder could that arrangement be
reversed; I could put the new programmer beside the cylinder, have it
control the two valves from there, and then have it use the wire
currently used to operate the pump to switch mains downstairs which
fires the boiler ?
Advice greatly appreciated ..
Depending to some extent on how many conductors there are in the cable
running between the boiler and airing cupboard, and on where the whole lot
is powered from, what you want to do is probably possible.
It makes sense to concentrate as much of the electrics as you can in the
airing cupboard. The pump is already there. The cylinder stat needs to go
there. It's the best [only viable?] place for the motorised valves. The only
items which need to be somewhere else are the boiler and the room stat. You
already have a cable going to the boiler. You can use a wireless room stat,
with the actual switching bit in or near the airing cupboard, and with the
wireless sensor/programming unit anywhere you like.
You will, of course, need a source of mains power in the airing cupboard. If
the cable from the boiler has enough conductors you may be able to use
that - otherwise you'll need to spur an FCU off a nearby power point.
Whatever happens, put a proper 10-way junction box in the airing cupboard
and wire it all up as per standard S-Plan stuff.
Your main constraint - if there is one - is going to be the existing cable
between airing cupboard and boiler - particularly if the boiler needs to
control the pump in order to provide pump over-run. You could potentially
need five conductors in this cable - Live, Neutral, Earth, Switched Live,
and Pump Control. If the boiler doesn't need to control the pump, and
doesn't need a permanent live, you can get away with three conductors.
Anyone know if you can get a plain wireless switch for use in any
application not just heating?
I expect it would be quite easy to modify a a wireless cylinder stat to do
this but I would like to know if there is an off the shelf product?
--
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