On Mon, 15 Dec 2003 16:23:12 +0000, Ian wrote:

Hello All,

I have been following the recent excellent threads and am now coming
out of my confusion, I think.
Our existing solid fuel boiler is not going to cope with the
additional requirement of our extension and will be replaced by oil in
the nearish future. This will allow some degree of control (yippee).
My original plan was simple DHW stat and TRV's on all rads, but this ,
I now see, has difficulties in achieving 'boiler interlock'

From pointers given by various recent posters I believe I want:
1) two CH zones, since I have identified that all our rooms fall into
one of two distinct heating requirement patterns.
2) separate control of hot water.

Now... someone (BillR, I think) mentioned the Honeywell CM67's. Having
investigated, these look excellent, allowing each heating zone to be
controlled to different temperature levels throughout six different
periods of the day. I particularly like the look of the RF versions
and, AIUI, by linking to an additional HC60NG to be used as the
boiler/pump controller - as per honeywell installation guide - I
could then have TRV's on all the radiators except those in the 2 rooms
(1 room in each zone) where the CM67's are installed and this would
provide the required 'boiler interlock'. I think I'm OK with this so
far (?) Someone tell me if I'm not!

Then I come to the DHW....
I cannot see an equivalent beast to the CM67 for DHW purposes....
I guess I can use a simple cylinder thermostat - although I don't
necessarily want to have a tank full of hot water permanently. Even if
I did, how do I get this stat to talk to the HC60NG that is
controlling the boiler?? I am sure I am missing something very simple
here but cannot put my finger on it.
It may become clearer when I have the boiler installation information
to hand but in the meantime, I'd really appreciate if some kind soul
can enlighten me.

I think that a better and more convenient solution to this would be
the Danfoss Randall TP75-RF (about to be replaced by TP7000-RF) for
the heating zones and a WP75-RF for the hot water. This would give
you completely independent time and temperature operation for each
zone and the hot water.

www.danfoss-randall.co.uk

These have a common receiver type and you can get up to 3 channel
receivers, although probably to order.

www.controlscenter.co.uk should be able to or any heating supplier.

You would sit the receiver at the boiler position and hook all the
demand outputs to the switched input of the boiler and possibly the
pump if the boiler doesn't have an overrun output for the pump.

If the motorised zone valves need to be in a position remote from the
boiler and you can get power there, then you could have additional
single channel receivers if you wanted. The receivers are trained to
the transmitted signal during installation and you can have multiple
receivers listening to one transmitting programmer.

Obviously this would cost a bit more to implement, but the trade off
is against wiring convenience and time .






Perhaps there is something to be said for the old anthracite boiler...
a) light it once a year - DHW control is sorted
b) switch on the pump when you want the CH
c) twiddle with the TRV's
d) switch the pump off at bedtime
e) heat leak rad keeps the bathroom warm for the overnight tinkles and
f) the heatloss from the boiler keeps it warm for breakfast!
arhhh the simplicity!

TIA
Ian


..andy

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