On Fri, 27 Nov 2020 15:28:48 +0000, Caecilius
wrote:

snip

Or have both functions (clock / stat) combined?

Yes, no reason not to combine the two functions. But that's not
essential.

It just stopped there being a 'tree' of plugin things. ;-)


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.

https://www.timeguard.com/products/c...r-time-control

I'm not sure the actual switch is silent though but it is very quiet.

It's probably an improvement on the WW2 era bimetalic strip that my
convection heater uses,

Quite, the overtemp stats in the little (600W) oil filled rads are
particularly noisy (in an otherwise quiet bedroom).

but I suspect it's still a relay inside and it
probably has a fairly high hysterisis to preserve contact life.

Yes, that sounds right (from the discrete 'Click' you can just hear
now and again).

Unfortunately the data sheet doesn't give much information about the
switching method or the operating parameters.

No, it is a pretty basic piece of kit but it's what's right in front
of me now and in it's second season of use.

The problem you might have is getting the heater itself to stay on
without it's overtemp or main stat cycling, even though the remote
timer / stat is calling for heat?

I don't think that will be a problem. If I set the thermostat on the
convection heater to, say, 25C then it shouldn't activate unless the
room is unpleasantly hot.

No, it *shouldn't* and being a convector, might not.

And if the internal overtemp operates then
there's something badly wrong.

Well, that's how I treated the functionality of the (several) oil
filled rads I have here but it's how they work nonetheless.

Even the 600W ones can generate more heat than they can dissipate and
so do 'overheat' and then cycle on their overtemp stats, way before
they may have reached the temp set by the main thermostat. I even
considered (and may well try this year) or rigging up two sockets on
an extension lead and wiring two of the 600W heaters in series so they
become two x 300W heaters. Set one stat on Max and then use the other
to manage the actual room temp.

I did buy some mains level PWM power controllers with the intention of
mating them with an Arduino and remote thermostats (one on the heater
and one in the room) so that I could manage the power to a small oil
filled rad (that couldn't dissipate it's heat energy fast enough so
would modulate on it's overtemp stat) and manage the room temp both
silently and more accurately (no temperature overshoot etc).

Not gotrountuit yet of course ... ;-(

We've all been there with arduino/pi things I think.

I just had a look on eBay and there are quite a few choices of 2kW
opto coupled module that should be very easy to interface. An Arduino
Nano, a Dallas I2C external temperature probe and a few lines of code
and you should be able to do what you need.

Mount it all in a plastic double box (like a trailing lead) with a
double pole switch on one side and 13A socket on the other and with
the stat coming out though a rubber grommet to somewhere suitable in
the room and you should be good to go (if you are ok with the coding).
;-)

I know I have.

I was sorting though some electronicy stuff earlier and came across an
ESP32 with external SIM card reader that was part of a project I was
playing with previously. That has built in BT and WiFi so you might
even be able to use one of those and set / adjust the required temp
with an App! ;-)

Cheers, T i m