Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.

Thanks,
Stephen.

"Stephen" wrote in message
...
Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.

Thanks,
Stephen.

You could fit the stat onto a backing plate or pattress.

On Sun, 22 Mar 2009 13:00:05 -0000, "John"
wrote:

You could fit the stat onto a backing plate or pattress.

Thanks but for some reason the manufacturers say that they should not
be fitted onto patress boxes. Why? Is it because it makes them stick
out more and are more likely to be knocked?

"Stephen" wrote in message
...
On Sun, 22 Mar 2009 13:00:05 -0000, "John"
wrote:

You could fit the stat onto a backing plate or pattress.

Thanks but for some reason the manufacturers say that they should not
be fitted onto patress boxes. Why? Is it because it makes them stick
out more and are more likely to be knocked?

It is because they do not fit. Try one.

Adam

On Mar 22, 7:52*am, Stephen wrote:
Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.

Thanks,
Stephen.

TRV valves are alot cheaper, and calculate the extra electricity
needed to power zone equipment 24x7

"ransley" wrote in message
...
On Mar 22, 7:52 am, Stephen wrote:
Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.

Thanks,
Stephen.

TRV valves are alot cheaper, and calculate the extra electricity
needed to power zone equipment 24x7

I think you still need a room stat to turn off the boiler.

I would think the intermittent power to operate valves and controls is
negligible.

On Sun, 22 Mar 2009 07:50:03 -0700 (PDT), ransley wrote:

calculate the extra electricity needed to power zone equipment 24x7

4/5ths of bugger all. A mechanical room stat only uses power when it's
calling for heat (for the internal compensation resistor) zone valves only
use power when they are open, mine are plated at 6W. A receiver for a
wireless stat or a wired programmable stat is probably less than a couple
of watts.

So lets say 5W for a the stat 24/7 = 43kWHr/year or about £4.30 or roughly
a quarter the cost of a decent TRV...

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.net...
On Sun, 22 Mar 2009 07:50:03 -0700 (PDT), ransley wrote:

calculate the extra electricity needed to power zone equipment 24x7

4/5ths of bugger all. A mechanical room stat only uses power when it's
calling for heat (for the internal compensation resistor) zone valves only
use power when they are open, mine are plated at 6W. A receiver for a
wireless stat or a wired programmable stat is probably less than a couple
of watts.

So lets say 5W for a the stat 24/7 = 43kWHr/year or about £4.30 or roughly
a quarter the cost of a decent TRV...


And the 6W electrical heating of the thermostat is not wasted. It just helps
heat the room.

Adam

On Sun, 22 Mar 2009 16:05:42 +0000 (GMT), "Dave Liquorice"
wrote:

calculate the extra electricity needed to power zone equipment 24x7

4/5ths of bugger all. A mechanical room stat only uses power when it's
calling for heat (for the internal compensation resistor) zone valves on=
ly
use power when they are open, mine are plated at 6W. A receiver for a
wireless stat or a wired programmable stat is probably less than a coupl=
e
of watts.


I have heard of compensation resistors but don't really know what they
do. Is it something to do with hysterisis by the resistor generating
heat when a current flows through it? Do you need a neutral connection
to the stat for the resistor or does the current flow through the
load? I haven't seen any stats with neutral connections.

Do all dial type thermostats have these resistors? If so, does this
mean that these thermostats can only ever be used to switch mains ac,
as I presume they need a minimum current to heat the resistor?

I upgraded my room thermostats to digital ones and they are battery
powered. So they add nothing to the electricity bill, though I will
incur a charge when I have to replace the batteries. I have wondered
whether it might be possible to power the thermostats from some sort
of DC supply, possibly using something like a burglar alarm supply
with lead-acid battery back-up?

These digital stats can switch any voltage so they could be used to
switch small DC voltages if you wanted to use some fancy home
automation system.

My controller draws a current, I don't know how much, but I doubt it
is much. That's a digital one too, but even a clockwork one would need
a power supply so there's no escaping that.

My valves are also rated 6W. You can get motorised ones that only take
power when switching between on and off but I didn't know that when I
bought mine.


Stephen.

Stephen posted

I have heard of compensation resistors but don't really know what they
do. Is it something to do with hysterisis by the resistor generating
heat when a current flows through it?

Also called the "accelerator resistor". What it does, it warms up when
the thermostat is in the ON state. This in turn heats up the bimetallic
sensor to well above room temperature, causing it to turn the thermostat
to the OFF state. Then the sensor cools down, and since it was much
warmer than the room it cools off quickly, and so it soon turns itself
on again.

Thus the resistor reduces the dead-band (or hysteresis) of the
thermostat. That's the theory. In practice their performance is rather
poor.

Do you need a neutral connection
to the stat for the resistor or does the current flow through the
load? I haven't seen any stats with neutral connections.

Yes you need a neutral for it to work properly.

Do all dial type thermostats have these resistors? If so, does this
mean that these thermostats can only ever be used to switch mains ac,
as I presume they need a minimum current to heat the resistor?

Yes.

--
Les

In an earlier contribution to this discussion,
Big Les Wade wrote:

Stephen posted


Do you need a neutral connection
to the stat for the resistor or does the current flow through the
load? I haven't seen any stats with neutral connections.

Yes you need a neutral for it to work properly.

You need a neutral connection for the accelerator resistor to work *at*
*all*.

Do all dial type thermostats have these resistors?

I think that all mechanical thermostats whose switching function is
performed by means of a bi-metallic strip will have accelerator resistors. I
have a feeling that some digital stats may have a knob to twiddle to set the
temperature - in which case these *wouldn't* have accelerator resistors.

If so, does this
mean that these thermostats can only ever be used to switch mains ac,
as I presume they need a minimum current to heat the resistor?

Yes.

Just for the avoidance of any possible confusion, the load switched by the
stat doesn't go through the resistor but is in parallel with it.
Nevertherless, the spec of the resistor is such that it will only get warm
if fed with mains voltage, so if - for example - the stat was used to switch
a 12v circuit, the accelerator resistor would be totally ineffective.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

"Stephen" wrote in message
...
Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.

Thanks,
Stephen.

The usual trick is to run trunking down to the thermostat and then chisel
into the plaster at the end of the trunking behind the thermostat so that
the damage is not seen.

Personally I would not allow trunking at all in my house. Add the cost of
the cable and trunking and wireless may be a viable option. You can use a
mixture of wired and wireless thermostats if you want to.

Adam

In article , ARWadsworth
writes

The usual trick is to run trunking down to the thermostat and then chisel
into the plaster at the end of the trunking behind the thermostat so that
the damage is not seen.

Personally I would not allow trunking at all in my house. Add the cost of
the cable and trunking and wireless may be a viable option. You can use a
mixture of wired and wireless thermostats if you want to.

Also, if using honeywell stats, you can only synchronise the wireless
ones which is good to limit boiler cycling if a small zone comes on out
of sync with larger ones.

I assume the same will be the same for other manufacturers unless they
use some kind of wired communications link.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs

On Sun, 22 Mar 2009 17:39:04 +0000, fred wrote:

Also, if using honeywell stats, you can only synchronise the wireless
ones which is good to limit boiler cycling if a small zone comes on out
of sync with larger ones.

I assume the same will be the same for other manufacturers unless they
use some kind of wired communications link.

Sorry, you have lost me. I have never used wireless ones before;
what's all this about synchronising them?

On Sun, 22 Mar 2009 16:11:28 GMT, "ARWadsworth"
wrote:

The usual trick is to run trunking down to the thermostat and then chisel
into the plaster at the end of the trunking behind the thermostat so that
the damage is not seen.

Personally I would not allow trunking at all in my house. Add the cost of
the cable and trunking and wireless may be a viable option. You can use a
mixture of wired and wireless thermostats if you want to.

Thanks for the tip. The trunking would only be temporary until I get
around to re-papering the room.

Stephen wrote:
Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.


MM. Thats the problem..stupid when a bloody radio mouse costs peanuts innit?

Thanks,
Stephen.

On Sun, 22 Mar 2009 12:52:47 +0000, Stephen
wrote:

Hello,

I've been looking at dividing my CH into zones. To do this I would
need to retrofit a thermostat into each zone (amongst other things).
All the thermostats I have seen so far require the cable to enter
directly from behind. The problem is that I don't really want to start
chasing walls and having to redecorate. I was hoping there might be a
model where I could run the cable down the wall in truncking until
such time as I want to redecorate but I cannot find any models like
this. Are there any?

I know I could go wireless but they are more expensive.

Thanks,
Stephen.