On Fri, 2 Jan 2004 16:00:04 -0000, "JH" wrote:
Hi,
I'm preparing to add a room stat to an existing gas central heating system
and need some help with the installation.
The current system consists of
o Boiler: Ideal Elan 2, conventional fan assist gas boiler
o All radiators have TRV's
o Timer is a Horstmann 527 (electronic 7 day, 3events/day, for independent
heating and water control)
o Based upon the FAQ, I believe the system is a Type C or S-plan
installation
o There a two motorised valves
I've taken a couple of photos of the controls to help (which are located
with the hot water tank - a bit unusual, oh well)
timer.jpg - http://www.jjh1.demon.co.uk/timer.jpg showing the timer
rest.jpg - http://www.jjh1.demon.co.uk/rest.jpg with all the other controls,
including a wire box with its cover off.
From the photos, assuming that the motorised valve in the foreground
is for the CH, this is an S-plan system.
They appear to be Honeywell valves as well.
The wiring should be as
http://content.honeywell.com/uk/homes/files/pag110.pdf
You may find that the boiler has a permanent and a switched live, in
which case the pump may be wired to a separate live output from the
boiler for over-run purposes.
You need to figure out which you have, although it doesn't make a huge
difference to implementing this solution.
I assume that you'll leave the existing programmer in place to time
the hot water.? You could replace the whole caboodle with the
wireless cylinder thermostat and an RX-2 receiver but there doesn't
seem much point.
If so, all you need to do is to disconnect the timed live from the
existing controller from the brown motor wire of the CH motorized
valve. Connect the receiver switch common contact to a permanent
live and the make contact to the MV brown wire. Connect the receiver
electronics terminals to a permanent live and neutral.
I'm planning on adding the Danfoss TP7000-RF + RX1 7 day wireless
programmable room thermostat.
The main unknown is how to wire the unit into the existing system. Logically
it appears straightforward i.e. simple wire AC power to the RX1 and then the
boiler off/on/com wires in series with the timer and that's it.
No,, look at the S plan wiring diagram. The boiler should be fired
up by the use of the auxilliary microswitches on the motorised valves.
You shouldn't need to touch this part. The new receiver should
provide a timed and temperature controlled live to the CH MV and that
is all.
So to the questions
1. Any opinions, good or bad on the Danfoss TP7000-RF + RX1? I was thinking
of buying from http://www.rkm-heating-controls.co.uk/danfoss.htm , any other
places worth a try?
This is a new product. The existing one has been the TP5000-RF and
TP75-RF.
Make sure you are buying what you think you are buying,
There are wiring diagrams on
www.danfoss-randall.co.uk
2. What is the correct way of wiring the receiver to the mains.
Do I simply add the live and neutral terminals in the existing wiring box
in the picture above (rest.jpg)?
A bit more - see above and refer to the Danfoss Randall web site.
3. I have no installation manuals for the boiler or existing timer unit so I
don't know which three wires are on/off/con for the heating.
What's the best way of deducing this information (I've got a Maplins
multimeter to hand)?
Trace back from the motorised valve leads and the diagram. It should
become obvious from the cable colours.
BTW - I've had the timer unit off the wall and it has the following
legend for each terminal on its back
Off C ON OFF C ON L N
4. Once I know which wires are on/off/c for the heating, how do I correctly
wire the unit in series with the timer?
You don't. Simply take the CH part of the existing timer out of
circuit and use the timing function of the new controller. It can do
more things like optimised start and night setback anyway.Retain the
old one to time the heating unless you fancy replacing it with the
wireless version.
Many thanks in advance
Jules
..andy
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