Photo: CTC
Ground sourceR407C
CTC GS / GSi 600
Ground-source (brine/water) · 5 models
Brine-to-water units with built-in control and hot water tank. The GSi 600 is speed-controlled (608, 612, 616; 7.7 to 15.6 kW at B0/W35 from the sheet), the GS 600 is the fixed-speed version. The GSi 600 manual describes a Modbus TCP setting (port 502) and SmartGrid inputs.
Grant lists
Grants depend on the exact model being on the official list. The counts below are the entries of this series we found in each list.
BAFA WEP (Germany)
No model on the list
No model of this series is in the BAFA Wärmeerzeuger-Portal, so it cannot be funded under the German BEG grant.
checked November 4, 2026
ZUM (Poland)
5 models listed
5 models of this series are on the Lista ZUM, which the Polish Czyste Powietrze grant requires.
checked November 4, 2026 · See the entries
Specifications
| Type | Ground-source (brine/water) |
|---|---|
| Heating output (datasheet) | 7.7–15.6 kW |
| SCOP at 35 °C | – |
| SCOP at 55 °C | – |
| Refrigerant | R407C (GWP 1774) |
| Outdoor sound power | – |
| Max. flow temperature | – |
Heating output is the figure in the manufacturer's datasheet; the basis (nominal output at A7/W35 or B0/W35, or design heat load) differs between brands, so check the datasheet before comparing. * = design heat load Pdesignh at 35 °C from the BAFA portal.
Control and connectivity
| SG Ready | Yes |
|---|---|
| Modbus | Yes (TCP, RTU) |
| EEBUS | Not documented |
| Cloud API | open API (myUplink) |
| §14a EnWG control | not confirmed |
| Local interfaces | Modbus TCP, Modbus RTU, SG Ready, relay input |
Source: ctc-heating.com/file-download-product/5613 · ctc-heating.com/file-download-product/7572 · ctc.se/file-download/8d8da8b1da79dae7a2f41a08c712f910.pdf
Zerofy
NativeZerofy controls CTC heat pumps natively, through the manufacturer's cloud, and moves heating and hot water into hours with surplus solar power or low prices.
Models in this series
Model codes as the manufacturer documents them. The official list entries, with their own naming, follow below.
Models on the ZUM list 5
On the Lista ZUM on November 4, 2026, with the list's own device number.
| Model | ZUM id |
|---|---|
| GS 606 | PG-601302 |
| GS 608 | PG-801301 |
| GSI 608 | PG-901292 |
| GSI 612 | PG-901305 |
| GSI 616 | PG-701306 |
Entries as published in the official lists on the date shown; names and numbers are copied verbatim. Check the list for your exact model before you order.
More CTC heat pumps
Sources
- Datasheet: ctc-heating.com/file-download-product/7817
- Product page: ctc-heating.com/products/ground-source-heating/ctc-gsi-600
- Control and connectivity: ctc-heating.com/file-download-product/5613
- Control and connectivity: ctc-heating.com/file-download-product/7572
- Control and connectivity: ctc.se/file-download/8d8da8b1da79dae7a2f41a08c712f910.pdf
- BAFA Wärmeerzeuger-Portal – Wärmepumpen – checked November 4, 2026
- Lista ZUM (Instytut Ochrony Środowiska) – checked November 4, 2026
- EEBUS certified devices – checked November 2, 2026
All figures are taken from the manufacturers' datasheets and the official BAFA and ZUM lists on the date shown and may have changed since. This is not grant advice – check the list and your grant conditions before you order. Zerofy is not affiliated with any of the manufacturers listed.
SG Ready is a label of the Bundesverband Wärmepumpe (BWP) e.V.; “Yes” means the manufacturer documents the two-input interface or declares it on the BAFA portal, not that the series carries the BWP label – the label list is at waermepumpe.de. EEBUS is a standard of the EEBus Initiative e.V.; Modbus is a registered trademark of Schneider Electric, licensed to the Modbus Organization. Product names, logos and photos belong to their manufacturers and are shown to identify the products. Grant data: BAFA Wärmeerzeuger-Portal and Lista ZUM (IOŚ-PIB) as of the dates shown; the SCOP at 55 °C in the BAFA tables is calculated by Zerofy from the portal's ηs value.
Heat with your own solar power
Zerofy moves your heat pump's runtime into the hours with surplus solar power or low prices – automatically.
Get Zerofy