We run one rad, a Type 33 1400 X 600 in annexe loft room.
The rest of the property is underfloor heating.
We had a Type 22 in there at first.
Of course the MCS calcs said the Type 22 would be big enough🙄… Heat loss of the room Vs LWT of 50°C flow at -3!
They wouldn’t listen so we accepted it and did that rad ourselves.
Don’t underestimate the weight of Type 33 rads!
The Type 22 rad was getting the room to 18C or so at the LWTs we use.
Even at the coldest in Jan / Feb we don’t go above 33C or so LWT.
That’s a rad delta T of just 13C for 20C room.
It’s a sitting room so we wanted 21+ in there.
We did the calcs for room at a rad delta T of 10C.
Using a very helpful rad output table that showed rad sizes Vs output from delta T of 10C and upwards.
Going from type 22 to type 33 increased the performance perfectly.
The room is always around 21 now. No complaints.
Added: I’ve seen some using fans to assist heat distribution from rads. I tried a normal summer fan blowing from the side of the radiator behind it as a test.
It did raise the room temp a degree or so.
You can get or make bespoke low voltage fan arrays for the job that fit underneath and assist the convection.
Can be quiet enough apparently..