Heiztechnik heat pumps

Air/water monoblocAir/water splitHot water 3 series

HT Heiztechnik is a Polish manufacturer of pellet, wood and biomass boilers based in Skarszewy (Pomeranian Voivodeship) and part of the Austrian Hargassner group. It built its first CALLA heat pump in 2011. Today's range is the CALLA VERDE inverter air-to-water heat pump with R452B in eight sizes from 5 to 20 kW, sold as a monoblock (Calla Verde M) or a split (Calla Verde S) with a Basic, Style, Comfort or Comfort II indoor module, plus the CALLA UNA ZG250 hot water heat pump.

Checked November 4, 2026 · Skarszewy, Poland, founded 2007 · Manufacturer website · Datasheet library

Photo: Heiztechnik

Grant lists

BAFA WEP (Germany)

0 / 3 checked November 4, 2026

ZUM (Poland)

2 / 3 checked November 4, 2026

Heiztechnik in Zerofy

Zerofy has no integration for Heiztechnik yet. Where a series below has an SG Ready input, Zerofy can still switch it through a Shelly relay. The heat pump comparison lists every brand Zerofy supports.

Heiztechnik heat pump types

Air-to-water monoblock1 Air-to-water split1 Hot water heat pumps1

Heiztechnik Air-to-water monoblock

The whole refrigerant circuit sits in one outdoor unit; only water pipes run into the house. The most common choice for retrofits, because no refrigerant lines need to be installed inside.

Air/water monoblocR452B

Heiztechnik Calla Verde M

8 models

Output: 5–20 kW
SCOP 35 °C: 4.09–4.76
Max. flow: 65 °C
BAFA WEP: No model on the list
ZUM: 16 models listed
Zerofy: Via SG Ready

Details and listed models

Heiztechnik Air-to-water split

An outdoor unit plus an indoor hydraulic station, joined by refrigerant lines. The pipework inside the house stays frost-free without glycol, and the indoor part is often quieter to place.

Air/water splitR452B

Heiztechnik Calla Verde S

8 models

Output: 5–20 kW
SCOP 35 °C: 4.09–4.76
Max. flow: 65 °C
BAFA WEP: No model on the list
ZUM: 8 models listed
Zerofy: Via SG Ready

Details and listed models

Heiztechnik Hot water heat pumps

A small heat pump built onto a hot water tank. It heats drinking water only and is a good way to turn surplus solar into stored heat – or to add hot water to a house that is otherwise heated differently.

Hot water

Heiztechnik Calla UNA ZG250

1 model

Output: –
SCOP 35 °C: –
Max. flow: 60 °C
BAFA WEP: No model on the list
ZUM: No model on the list
Zerofy: Not supported

Details and listed models

Heiztechnik series at a glance

Series	Type	Output	SCOP 35 °C	SCOP 55 °C	Refrigerant	Max. flow	BAFA WEP	ZUM	SG Ready	Modbus	EEBUS
Calla Verde M	Air/water monobloc	5–20 kW	4.09–4.76	3.23–3.68	R452B	65 °C	No model on the list	16 models listed	Yes	–Not documented	–Not documented
Calla Verde S	Air/water split	5–20 kW	4.09–4.76	3.23–3.68	R452B	65 °C	No model on the list	8 models listed	Yes	–Not documented	–Not documented
Calla UNA ZG250	Hot water	–	–	–	–	60 °C	No model on the list	No model on the list	?Not confirmed	?Not confirmed	?Not confirmed

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.

Sources

Specifications come from the manufacturer's datasheets linked above, grant status from the official lists below, checked November 4, 2026:

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.

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