"dennis@home" wrote:


"Matt" wrote in message
.. .
"dennis@home" wrote:


Like I said that's how TRV based systems work.
The room stat has to be in the warmest room and switch the system on even
if
only that room wants heat.

No they don't. There is nothing to stop a thermostat being located
*anywhere* where it will receive the appropriate amount of output from
the heating system. Lots of thermostats are located in hallways with
no TRV's on the rads and controlling to a much *lower* temp than the
main living areas. As long as the rads are sized correctly, the
thermal losses through the structure are not wildly different, the
outer doors are not opened on a too regular basis and doors from an
area with a higher desired temperature are usually kept closed then
they function well.

No they don't.
Say you put the stat in the hall and set it to 15C as the temperature you
want in the hall.
Then the system will not provide any heat until the outside temp drops well
below 15C and the hall catches up.
I.e. no room set to a higher temp will get any heat until the temperature
has dropped well below what the owner actually wants.
In fact if the outside sits at 16C the rest of the house will also sit at
16C and the heating will not turn on.

Now go and think about where the correct place to put a room stat is.

A huge number of systems have the thermostat in the hallway, Its not
the ideal place by a long way but if you site a thermostat in say the
main living area and this has a separate heat source like a gas fire
you can severely depress the temperature in the rest of the house.

One of the key factors in hallway siting is to get the radiator sized
correctly. If that is done then the boiler will run until the
thermostat is satisfied, if the radiator sizes are correct elsewhere
in the house then their requirements will be met. Make the hallway
super insulated, fit it with a radiator sized at 250% of the
requirements, fit the thermostat 2 inches above the radiator and it
will be a dogs dinner.

No one except you was ever advocating a 15 deg C thermostat setting, a
more practical 18 or 20 deg C - just below the main occupancy rooms
is required. The main rooms will still stick at 18 deg C forever and a
day with no boiler firing because of the lack of thermostat call, BUT
a thermostat sited in a main living area set to 23 deg C with
additional heat sources present could conversely in extreme conditions
leave a bedroom at 18 deg C below zero.


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