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Heat pumps · UK

CTCGSi 616

CTC GSi 616
Image: CTCrequest removal

The CTC GSi 616 is a heat pump with SCOP (35 °C) 5.23 and refrigerant R407C.1

Last updated: Technical specifications Rules in the UK ⇄ Compare this model
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SCOP (35 °C)
5.231

Seasonal efficiency: how much heat you get per kWh of electricity across a heating season.

Refrigerant
R407C1
Official source
Type (source)
Ground source1
Official source
Rated output 35 °C
16kW1
Official source
Rated output 55 °C
16kW1
Official source
UK

Rules in the UK

Boiler Upgrade Scheme

Check conditions

£7,500 – £9,0002Fixed grant (England & Wales)

Fixed grant in England and Wales, deducted from your installer’s quote. £9,000 when replacing oil or LPG off the gas grid (until March 2027). Scotland: Home Energy Scotland grant instead.3,4

  • Must be MCS-certified (product and installer). Check the Ofgem product eligibility list.
  • Rated output 16 kW; the scheme covers systems up to 45 kW.
  • SCOP at 55 °C: 4.04. The installed system needs a SCOP of at least 2.8 (MCS calculation).
Heat pump grants in the UK explained →

Technical specifications

General
Type (source) Ground source1
Performance
Rated output 35 °C 16 kW1
Rated output 55 °C 16 kW1
Efficiency
SCOP (35 °C) 5.231
SCOP (55 °C) 4.041
Seasonal efficiency ηs 35 °C 201 %1
Seasonal efficiency ηs 55 °C 154 %1
Energy label 35 °C A, , , 1
Energy label 55 °C A, , , 1
Noise
Indoor unit sound power 42 dB(A)1
Refrigerant
Refrigerant R407C1
Refrigerant GWP 1,7741
Refrigerant charge 2.2 kg1

Variants

This model is registered in 3 combinations (for example with a different indoor unit or cylinder) with exactly the same performance. All figures on this page apply to each of these types. The part of the type number that differs is in bold; small differences (e.g. cylinder volume or anode) are listed after it:

  • GSi 616
  • EcoPart 616M
  • EcoPart i616M

Manufacturer documentation

External links to CTC's official website. The manufacturer may change or move documents; where they differ, the manufacturer's latest version applies.

Frequently asked questions

What is the SCOP (35 °C) of the CTC GSi 616?

The SCOP (35 °C) of the CTC GSi 616 is 5.23.1

Which refrigerant does the CTC GSi 616 use?

The refrigerant of the CTC GSi 616 is R407C.1

How much Boiler Upgrade Scheme grant can you get for the CTC GSi 616?

£7,500 in England and Wales, provided the product and installer are MCS-certified (£9,000 when replacing oil or LPG off the gas grid, until March 2027). The installer applies and deducts the grant from your quote.1

Sources

  1. Heat Pump Keymark certificates — EHPA / DIN CERTCO (Heat Pump KEYMARK) · accessed 29 Sept 2026
  2. Boiler Upgrade Scheme: what you can get — GOV.UK · accessed 27 Sept 2026
  3. Boiler Upgrade Scheme: guidance for installers (V5) — Ofgem · accessed 27 Sept 2026
  4. Boiler Upgrade Scheme product eligibility — Ofgem · accessed 27 Sept 2026