On 28 Nov 2020 at 15:20:39 GMT, "Pamela" wrote:

On 20:58 27 Nov 2020, Caecilius said:

On Fri, 27 Nov 2020 19:49:06 GMT, Pamela
wrote:

On 13:55 27 Nov 2020, Caecilius said:

I've got a large house with gas central heating which I use
during the day. It gets cold overnight in the bedroom though,
so I use a 2KW electric convection heater with the thermostat
set to about 18 C on a timeclock which switches on between
midnight and six am (boiler comes on again at six).

This was a great improvement last winter, and it only uses one
or two KWh overnight which must be cheaper than heating the
whole house with gas.

This year I want to improve the solution to keep the temperature
more constant (there's a big hysteresis on the convection heater
thermostat) and remove the bimetallic thermostat clicking noise.

I think I want electronic switching to remove the clicking noise
and allow a lower hysteresis plus an external temperature
sensor. Maybe something that's closer to a temperature
controlled dimmer switch instead of a standard bimetallic
thermostat.

My plan is to put this temperature controller between the
timeclock and the heater, and set the heater thermostat to
something like 25C as a fail-safe.

Has anyone found or built something like this? I'm sure I can't
be the only person who want a constant overnight bedroom
temperature without running the main house heating.

If you can't find anything along those lines, then a low power
oil-filled electric heater might do the job. You could leave it
on all night or, alternatively, if you use the stat it wouldn't
trip as frquently as a convection heater.

I don't know if my arithmetic is out of date but I seem to recall
electricity is about 3 times the price of gas, watt for watt.

If so then heating one room overnight with electricity might cost
the same as heating 3 with gas. Someone is bound to correct me if
I've gone wrong.

Yep I'd agree, taking into account the relative efficiency.



The bedroom area is only about 6.5% of the house area, so the
difference would need to be much greater than 3:1.

I've measured the overnight consumption of the electric heater,
and it's just under 1KWh at the moment which seems quite
reasonable to me.

Are you sure because 1 kWh seems very little for heating a room
overnight. It equates to a "one bar" fire left on for an hour which
wouldn't heat my room much.

Perhaps that room needs only the slightest amount of additional
heating

Indeed

--
Cheers, Rob