Thermia heat pumps

Air/water monoblocGround source 8 series

Thermia is a Swedish heat pump manufacturer based in Arvika; the company dates its history back to 1923 and launched its first ground-source heat pump in 1973. Its residential range consists of inverter ground-source units (Atlas, Calibra E, Calibra RXT, Sigrin, Legend) and air-to-water units (iTec E, iTec XTR, Elve), plus large heat pumps for commercial buildings. The heat pumps can be monitored through the MyThermia app. Thermia has belonged to the Stiebel Eltron group since 2018, when Danfoss sold its heat pump business.

Checked November 2, 2026 · Arvika, Sweden, founded 1923 · Manufacturer website

Photo: Thermia

Grant lists

BAFA WEP (Germany)

8 / 8 checked November 4, 2026

ZUM (Poland)

5 / 8 checked November 4, 2026

Thermia in Zerofy

Zerofy has no integration for Thermia 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.

Thermia heat pump types

Air-to-water monoblock3 Ground-source (brine/water)5

Thermia 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 monoblocR32

Thermia iTec E

4 models

Output: 5–16 kW
SCOP 35 °C: 4.48–4.69
Max. flow: 65 °C
BAFA WEP: 3 models listed
ZUM: No model on the list
Zerofy: Via SG Ready

Details and listed models

Air/water monoblocR290

Thermia iTec XTR

4 models

Output: 5–16 kW
SCOP 35 °C: 4.7–5.1
Max. flow: 75 °C
BAFA WEP: 6 models listed
ZUM: No model on the list
Zerofy: Via SG Ready

Details and listed models

Air/water monoblocR290

Thermia Elve

2 models

Output: 12–15.3 kW
SCOP 35 °C: 4.89–4.96
Max. flow: 75 °C
BAFA WEP: 2 models listed
ZUM: No model on the list
Zerofy: Via SG Ready

Details and listed models

Thermia Ground-source (brine/water)

Draws heat from a borehole or ground loop, so the source stays at a steady temperature all winter. Higher efficiency and no outdoor noise, but boreholes cost money and need a permit.

Ground sourceR410A

Thermia Atlas

4 models

Output: 12–18 kW
SCOP 35 °C: 5.75–5.9
Max. flow: 65 °C
BAFA WEP: 4 models listed
ZUM: 6 models listed
Zerofy: Via SG Ready

Details and listed models

Ground sourceR452B

Thermia Calibra E

6 models

Output: 8–16 kW
SCOP 35 °C: 5.57–5.76
Max. flow: 65 °C
BAFA WEP: 10 models listed
ZUM: 22 models listed
Zerofy: Via SG Ready

Details and listed models

Ground sourceR290

Thermia Calibra RXT

4 models

Output: 7–12 kW
SCOP 35 °C: 5.21–5.4
Max. flow: 70 °C
BAFA WEP: 6 models listed
ZUM: 4 models listed
Zerofy: Via SG Ready

Details and listed models

Ground sourceR454C

Thermia Sigrin

6 models

Output: 9–19 kW
SCOP 35 °C: 5.14–5.28
Max. flow: 65 °C
BAFA WEP: 10 models listed
ZUM: 3 models listed
Zerofy: Via SG Ready

Details and listed models

Ground sourceR452B

Thermia Legend

8 models

Output: 4–17 kW
SCOP 35 °C: 4.79–5.09
Max. flow: 60 °C
BAFA WEP: 6 models listed
ZUM: 10 models listed
Zerofy: Via SG Ready

Details and listed models

Thermia series at a glance

Series	Type	Output	SCOP 35 °C	SCOP 55 °C	Refrigerant	Max. flow	BAFA WEP	ZUM	SG Ready	Modbus	EEBUS
iTec E	Air/water monobloc	5–16 kW	4.48–4.69	3.53	R32	65 °C	3 models listed	No model on the list	Yes	–Not documented	–Not documented
iTec XTR	Air/water monobloc	5–16 kW	4.7–5.1	3.55–3.65	R290	75 °C	6 models listed	No model on the list	Yes	–Not documented	–Not documented
Elve	Air/water monobloc	12–15.3 kW	4.89–4.96	4	R290	75 °C	2 models listed	No model on the list	Yes	–Not documented	–Not documented
Atlas	Ground source	12–18 kW	5.75–5.9	4.25–4.4	R410A	65 °C	4 models listed	6 models listed	Yes	Yes	–Not documented
Calibra E	Ground source	8–16 kW	5.57–5.76	4.1–4.4	R452B	65 °C	10 models listed	22 models listed	Yes	Yes	–Not documented
Calibra RXT	Ground source	7–12 kW	5.21–5.4	4.05–4.2	R290	70 °C	6 models listed	4 models listed	Yes	Yes	–Not documented
Sigrin	Ground source	9–19 kW	5.14–5.28	4.03–4.2	R454C	65 °C	10 models listed	3 models listed	Yes	–Not documented	–Not documented
Legend	Ground source	4–17 kW	4.79–5.09	3.7–3.83	R452B	60 °C	6 models listed	10 models listed	Yes	–Not documented	–Not documented

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 2, 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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