Roger Mills wrote:
In an earlier contribution to this discussion,
Mike Barnard wrote:

Hi all.

Any CH design guru's aid me in my small dilemma please?

I have a 1960's mid terrace Wimpy (spit) three bed house. It had no
CH at all untill a couple of years ago when I put a new combi boiler
in [1]. I also put a couple of rads in. It was not a complete system,
DHW was what I needed mostly. Now the time has finally come to finish
the job.

The dilemma is whether to zone off the rear two rooms upstairs. The
bathroom and bedroom 2 are north facing and in winter they can be much
colder than the rest of the house. The thremostat and timing controls
are in the open plan lounge; see description below. If the lounge is
nice and toasty, then the thermostat will not be telling the boiler to
fire up. Therefore the water in the pipes will not be heated and
under circulation. No matter how far the TRV's in these rooms open
they will recieve no heat.


With a properly designed and balanced system (with radiators of an
appropriate size in each room/space to balance the heat loss - and with the
lockshields adjusted to give the same temperature differential across each
radiator) there's no reason why one room should be significantly hotter or
colder than any other.

There speaks a man of theory..with respect Roger, in the real world, in
my north rooms when the north wind blows, so does your theory. MUCH more
heatloss from them then...


Zoning comes into its own if you want to heat different parts of the house
at different times. Otherwise there's not all that much point. If it's easy
to do, do it anyway - because it gives slightly better control over
different areas (with a room stat for each area) - but if it's a pain,
plumbing-wise, don't bother.


If I had my time again I'd zone every single room. With a motorised
valve, and run a ****load of cables back to the timer and pumps etc.

We have a lot of rooms we don't use all the time, and it would be far
more economical to simply flick a switch and have them go to 'frost
stat' settings when not in use.