The Kartell K-Rad Kompact P411K is a Type 21 double panel, single convector radiator, 400 × 1100 mm, giving 1134 W (3871 BTU/h) at ΔT50. Two water-carrying panels with a single bank of convector fins sit in a 70 mm case: 1134 W against 742 W for a Type 11 the same size, for 14 mm more depth. Nett weight is 21.67 kg and it holds 4.51 litres of system water.
Type 21 double panel400 × 1100 × 70 mm1134 W at ΔT50EN 442 testedWhite enamel RAL 901610-year guarantee
3871 BTU/h
Output at ΔT50 — 1134 W
21.67 kg
Nett weight — holds 4.51 l
EN 442
Tested and certified
10 years
Manufacturer guarantee
Applications & suitability
Where it goes
Wall-hung on a sealed or open-vented wet heating system, fixed no lower than 100 mm off the finished floor. At 400 mm high it suits a wall where vertical space is tight.
Typical job
A room needing roughly 1134 W on a 70 °C mean water temperature, or 1453 W where the system runs at 80 °C. Straight swap for a tired 400 × 1100 panel of the same size.
Works with / replaces
Pipe centres are 345 mm with a wall-to-centre of 65 mm or 80 mm, so it lines up with most existing 400 mm-high panels. Case depth is 70 mm against 56 mm for a Type 11 and 105 mm for a Type 22.
When not to choose this
The 1134 W figure is at ΔT50. Run a heat pump at low flow temperatures and it falls hard — Kartell’s own correction factor at ΔT30 is 0.515, so you would get about 584 W from this radiator. Size at the ΔT you will actually run, and step up to a Type 22 or 33 if the load needs it.
Key specifications
| Brand |
Kartell |
| Model |
K-Rad Kompact P411K |
| Radiator type |
Type 21 — double panel, single convector |
| Heat output |
| Output at ΔT50 |
1134 W (3871 BTU/h) |
| Output at ΔT60 |
1453 W (4959 BTU/h) |
| Size and weight |
| Dimensions (H × W × D) |
400 × 1100 × 70 mm |
| Centre distance |
345 mm |
| Wall to centre |
65 or 80 mm |
| Weight |
21.67 kg |
| Water content |
4.51 l |
| Build and rating |
| Max working pressure |
10 bar |
| Max working temperature |
120 °C |
| Finish |
White enamel, RAL 9016 |
| Standard |
EN 442 |
| Warranty |
10 years |
Installation & compatibility
Fix no lower than 100 mm from the finished floor. Allow 35 mm from the wall to pipe centre for a manual valve, or 45 mm for a TRV. Kartell requires the system to be cleansed and dosed with inhibitor to BS 7593:2019 — skipping it invalidates the guarantee, which covers product replacement only. Leave the protective packaging on until the radiator is fixed and the tappings are cut.
Related & next steps
Need more output?
The Type 22 at the same 400 × 1100 mm gives 1466 W at ΔT50, in a 105 mm case.
View Type 22
Tight on space?
The Type 11 is 56 mm deep and gives 742 W at ΔT50 — slimmer, but less heat.
View Type 11
Other sizes
Type 21 runs 400–900 mm high and 400–2200 mm wide, from 413 W to 3114 W at ΔT50.
Browse radiators
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