1 SINQ 1SINQ ONE-21 vs CTA AH CL 21a
SCOP (35 °C): 1 SINQ 1SINQ ONE-21 4.95, CTA AH CL 21a 4.66. Both models win equally often (5 of 13 points).
Who wins where
- 1 SINQ 1SINQ ONE-21
- CTA AH CL 21a
Biggest differences
| Fact | 1SINQ ONE-21 | AH CL 21a |
|---|---|---|
| Refrigerant charge | 2.6 kg | 2.3 kg |
| Indoor unit sound power | 36 dB(A) | 40 dB(A) |
| COP A-7/W35 | 2.74 | 2.95 |
| Rated output 55 °C | 22 kW | 20.65 kW |
| COP A2/W35 | 4.6 | 4.32 |
| SCOP (35 °C) | 4.95 | 4.66 |
Score per area = position (0–100) relative to all 1000 models in this category; higher is better.
| Technical specifications | 1 SINQ1SINQ ONE-21 | CTAAH CL 21a |
|---|---|---|
| Grants & market | ||
| Boiler Upgrade Scheme | £7,500 – £9,000 | £7,500 – £9,000 |
| Performance | ||
| Rated output 35 °C | 21 kW 1 | 21 kW 1 |
| Rated output 55 °C | 22 kW ✓ 1 | 20.65 kW 1 |
| Efficiency | ||
| SCOP (35 °C) | 4.95 ✓ 1 | 4.66 1 |
| SCOP (55 °C) | 3.62 1 | 3.83 ✓ 1 |
| Seasonal efficiency ηs 35 °C | 195 % ✓ 1 | 184 % 1 |
| Seasonal efficiency ηs 55 °C | 142 % 1 | 150 % ✓ 1 |
| COP A7/W35 | 5.15 1 | 5.31 ✓ 1 |
| COP A2/W35 | 4.6 ✓ 1 | 4.32 1 |
| COP A-7/W35 | 2.74 1 | 2.95 ✓ 1 |
| Noise | ||
| Outdoor unit sound power | 53 dB(A) 1 | 53 dB(A) 1 |
| Indoor unit sound power | 36 dB(A) ✓ 1 | 40 dB(A) 1 |
| Refrigerant | ||
| Refrigerant | R290 1 | R290 1 |
| Refrigerant charge | 2.6 kg 1 | 2.3 kg ✓ 1 |
| Electrical | ||
| Max. power input | 14 kW 1 | 11.5 kW 1 |
| Connectivity & smart | ||
| SG Ready | Yes 1 | Yes 1 |
Sources
- List of eligible heat pumps (BEG) — Bundesamt für Wirtschaft und Ausfuhrkontrolle (BAFA) · accessed 27 Sept 2026