Central heating radiators come down to three checks: output, size and how the unit sits on the wall. More panels or convector surface usually give you more heat from the same footprint, while single-panel options suit tighter spaces and lighter loads. If the pipework and wall space are fixed, dimensions matter as much as output - the wrong size is the one that causes the call-back.
Stelrad Compact P+ Double Panel Plus Radiator - 600mm x 800mm
Compact Type 21 radiator, white, 600x800mm, BS EN 442 compliant, 10yr warranty
Halcyon TPl Convector Radiator Type 33/K3 - 600mm x 700mm
Type 33/K3 convector radiator 600mm x 700mm for homes and commercial use.
Stelrad Halcyon Compact P+ Double Panel Radiator - 600mm x 800mm
White 600mm x 800mm Type 21 double panel steel radiator, 1.09kW, 15-year guarant…
Halcyon TPL Convector Radiator - Type 33/K3 700mm x 1200mm
White Type 33 convector radiator, 700x1200mm, 3346W (11417 BTU)
Stelrad Halcyon Compact K2 Double Panel Double Convector Radiator - 700mm x 1100…
Compact white type 22 radiator, 700 x 1100mm, 2.159kW output
Stelrad Elite K2 Double Panel Double Convector Radiator - 700mm x 1200mm
Stelrad Elite K2 double panel radiator 700 x 1200 millimetres white
Stelrad Compact P+ Radiator - 450mm x 2200mm
Stelrad Compact P+ radiator 450mm x 2200mm, conforms to BS EN 442, space-saving.
Center Type 11 75SC60 Single Panel Single Convector Radiator - 750mm x 600mm
Type 11 white steel radiator, 750 x 600mm, 2518 BTU/h
Type 11 Single Radiator - 600 x 1000mm 3182 BTU
600 x 1000mm Type 11 single radiator with 3182 BTU output
Stelrad Halcyon K2 Compact Radiator - 400mm x 1800mm
Stelrad Halcyon K2 compact radiator, 400 x 1800mm, white RAL9016
For central heating radiators, start with the system and the job spec, not the finish. A standard wet system usually keeps you in the same family of product, but the real checks are output, depth, and whether the pipework and wall space will take the size you want. On a tight swap, a slimmer panel can be easier to land. If the room needs more heat, you may need a deeper unit or a larger footprint. The install package matters too. Flue route, filter requirement, fuel type, and who’s signing it off all change what you should be buying.
Flat panel central heating radiators are the usual pick when you want a straightforward swap and do not need much depth off the wall.
If you need more output from the same footprint, a double panel or double convector version gives you that. The trade-off is depth. It sits further out and can be tighter on pipe centres and clearance.
Single panel units are slimmer and easier to place where space is awkward, but you give up output. Once you have fixed the room layout, Radiators is where you step back and compare the wider range against the job.
The first check is output against space. A deeper unit gives you more capacity, but it also stands further off the wall and takes more room around pipework, skirting and furniture.
On a straight swap, that often matters more than the finish. For tighter spaces or lighter loads, a slimmer panel is usually the cleaner fit. Column Radiators suit jobs where the look is part of the brief and you can live with the extra depth. Designer Radiators come in when appearance is driving the choice, but you usually give up some simplicity and sometimes some output for that.
Once you’ve picked the unit, the next call is what sits around it. If the room needs a cleaner finish, radiator covers are the usual add-on, but they do reduce output a bit and make access tighter when you’re back for a valve change.
Radiator foil is worth considering on older external walls where you want heat back into the room rather than into the masonry. For a neater install, radiator valves and the right parts and accessories matter more than people think - it’s usually the small mismatches that slow you down on site.







