On Thu, 6 May 2021 05:50:51 -0700 (PDT), polygonum_on_google
wrote:

snip

But how much of the time does that efficiency matter? I suspect a large proportion of radiators are throttled by a TRV.

Yes, *once* the room is up to temperature?

Further, if the radiator can cope on the coldest days, it probably has plenty of capacity in hand for most of the rest of the year.

Agreed, once it has brought the room up to temperature. ;-)

Dropping efficiency to, I suggest, 90% would only really affect that small period during which the absolute maximum output is required.

And how long it takes to get the room up to temperature. ;-)

My first experience of the reliance on 'central heating' was as a kid
and when going back to my mates house after playing in the snow.

At our house we had pretty crude coal fired free standing boiler,
gravity fed rad system and so also had electric fan heaters to 'top
up' as / when / where required.

If you came in cold you could flick one on and sit right in front of
it and be warmed up pretty quickly.

So, mate turns the central heating on and we have to stand next to the
radiators waiting for some heat to get in them to be able to thaw our
fingers out again. ;-(

Cheers, T i m