Is there going to be any problem with this set up?
At the moment theres a basic two channel mechanical timeswitch in the
kitchen and a wired 'stat on the first floor landing. The timer
switches both water and heating on together but manual over-ride
allows them to be operated independently. There are two motorised
valves in the airing cupboard with the boiler.
I want to put a ACL Tempus2 7 day timeswitch in the airing cupboard to
control hot water (i figure with a 7 day timer manual override will be
rare) and use an ACL Wireless Digistat3i to control the heating. IME
a 'stat is far more useful placed in your primary living space (ie the
living room) than a draughty hallway with few rad's.
Are there any pitfalls I haven't thought of? The boiler is a
Keston130. I figure it's going to take a bit of time to work out
what's what in the boiler cupboard but all the new wiring will be in
Firstly, use a 2 channel programmer and wire the new programmable stat
through the CH side. There is almost no difference in price. You don't use
the programmer for actual timing, but it is very useful as a central
location to turn everything off and on without having to traipse round to
the room stat. The CH side is usually set to 24H (or Off). It is
particularly useful if you have multiple heating zones, or your room stat
doesn't have a simple "Off" feature, as many don't.
Secondly, ensure that you have a cylinder thermostat. It sounds like you
have an S plan system. If no cylinder stat is present, you need to insert it
in series between the programmer "HW On" output and the hot water zone valve
motor live (normally brown) wire.
Several reasons. Basically, the advantages of using a programmable stat over
a separate stat and programmer are:
1. Controls are in the living area rather than in a manky undersink cupboard
or inaccessible airing cupboard. This enables manual override and
programming to be easily achieved.
2. Rather than turning off completely, the stat can just turn down the
temperature, to say, 12C, ensuring that the house doesn't get freezing
overnight, or whilst you are out.
3. Complex control laws can be used that can predict the house's response to
heat, enabling temperature overshoot to be controlled and enabling the
device to predict how long before the required start period the heating
needs to be on.
The spur will also turn off the hot water, which may not be desired. If you
are fiddling around with the system whilst testing, you don't want to have
to frequently disappear down the stairs to turn the thermostat on and off
when the nearby programmer can do the same function for pennies more than a
On Wed, 14 Jan 2004 11:48:20 -0000, "Christian McArdle"
I was actually going more for the two programmers in series, a
programmable roomstat is a good idea in my opinion.
Fair enough, but if it's set up correctly you don't really need to
alter the timing. Although it's all up to the individual.
You've lost me there, you can turn the temp up and down regardless of
where the stat and programmer are.
O.k. then, I'll let you off with that one!
I personally only test my heating systems once and then thats it, it
generally doesn't break down that often.
So in general then to the OP, yes, your way would work but there are
other ways, a good programmable room stat would be my choice coupled
with a single channel on the water, but it's a free country!
Unfortunately, when setting the timer in January, you don't know that a
couple of mates are coming over on July 14th until 2am. A handy nearby
"boost" button could be useful here, rather than searching for a torch
because in the low light you can't see the programmer in its cubbyhole and
can't remember which button boosts the heating (and the manufacturer decided
to scratch the legend in rather than using high contrast printing, but you
don't read braille).
What I mean is that a programmable room stat doesn't turn off and on, it
just changes temperature. My "off" temperature is 10C. My "on" temperature
is 22C. If you had a separate programmer, the "off" temperature is -273C, as
it just cuts the power totally, with no ability to just keep it ticking
along for the benefit of your furniture and pipework.
You could always put a switch for the CH side. But then twin channel
programmers are basically the same price as single channel ones, so it would
be cheaper and neater just to use a twin channel programmer. OTOH, it isn't
that important on a single zone heating system. On multiple zones, it is far
I think he got confused who said what...
Whether to use a single or twin channel programmer is a minor point. The
important thing is to check that you have a functioning cylinder stat. If
not, it is very simple to add.
Which is exactly what I agreed with. In esscence my answer was- yes,
that will work perfectly satisfactorily. The problem with ba simple
question is it has many complex answers.
A 2 channel programmer coupled with a programmable room stat would
offer you more control and an increase in performance.
If you are doing it the latter way just make sure that the settings
are all at the optimum for your living situation and that you use a
quality stat, some of the cheaper ones aren't as accurate on the
ACL's good stuff, I use them quite a bit. Decent price too. Fitted a
few RF3i's on combi's, not had any complaints yet. Some have been in
for 6/7 years.
The Tempus 7 would be the 2 channel clock you would want instead if
you're going to do it that way.
Indeed. I've come to the conclusion that it's worth paying for the top
end controllers as the premium is'nt great. Tempus 7 even has a holiday
mode - tell it you'll be back in a fortnight and it will have the
house nice and warm for your return.
It's just that I prefer not to cut the power completely when "off". I don't
want it getting too cold (i.e. below 10C), even when I'm not there. My prog
room stat is on the approximate equivalent of "twice" on weekdays, the
middle of which can be filled in by pressing a single button, if required. I
suppose some stats may have more complicated manual overrides.
Nah, it doesn't. In fact, despite lack of wall insulation, it doesn't drop
that much during the day. However, during the night, it could well go below
10C. Wall insulation isn't practical. It has solid walls and original
features that would get seriously disturbed. However, as it is a terraced
house, the overall heat loss really isn't that bad in practical terms.
Much the same as mine, then. But I'm not intererested too much in the
nighttime temp as I'm in bed. ;-) Obviously, if it can't come up to
temperature after the switch on time and I get up, then that's when I'd
leave it on all night - controlled to the nighttime temp of the stat. But
it's not many times a year.
*I don't know what your problem is, but I'll bet it's hard to pronounce
Dave Plowman email@example.com London SW 12
I've had one on a combi for the last 3 years so can confirm:
Generally the heating gets extra time if we stay up late. We're usually
in the living room in that case. A minor point - if the controls
stayed in the kitchen it would hardly be a problem, especially with
'boost' functions rather than just on/off.
or more importantly while you're on holiday. The ACL has 3 settings
each day. By default it comes on in the morning and tries to get the
house to 20C, lets it cool to 16 during the day, back to 21 in the
evening and then down to 7 overnight (from what i remember). If you're
ill or feeling the cold for some reason it's simple to turn it up a
degree or two and it reverts to the normal settings at the next junction.
That's the plan. the claim is that it can save 10% of fuel bills and
with a solid walled, single glazed house you need all the savings you
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