- Heating capacity
-
15.6 - 19.1 MBH (4.5 - 5.6 kW) for AP1T-027020
23.4 - 28.9 MBH (6.8 - 8.4 kW) for AP1T-040029
28.9 - 37.6 MBH (8.5 - 11.0 kW) for AP1T-052038
37.8 - 48.1 MBH (11.0 - 14.0 kW) for AP1T-066049
46.2 - 54.8 MBH (13.5 - 16.0 kW) for AP1T-077056 - Cooling capacity
-
20.2 - 26.4 MBH (5.9 - 9.0 kW) for AP1T-027020
30.3 - 39.2 MBH (8.9 - 11.5 kW) for AP1T-040029
38.1 - 51.9 MBH (11.2 - 15.2 kW) for AP1T-052038
49.9 - 65.7 MBH (14.6 - 19.3 kW) for AP1T-066049
59.8 - 75.9 MBH (17.5 - 22.2 kW) for AP1T-077056 - Energy efficiency ratio (EER)
-
22.2 - 30.8 for AP1T-027020
21.2 - 29.0 for AP1T-040029
22.1 - 28.7 for AP1T-052038
20.7 - 28.0 for AP1T-066049
18.7 - 24.5 for AP1T-077056 - Coefficient of performance (COP)
-
4.2 - 4.6 for AP1T-027020
4.2 - 4.5 for AP1T-040029
4.2 - 4.4 for AP1T-052038
4.3 - 4.7 for AP1T-066049
4.0 - 4.4 for AP1T-077056 - Refrigerant type
-
R-454B
- Power supply
-
208/230 VAC
1 Phase
60 Hertz - Minimum circuit ampacity (MCA)
-
23.4 / 22.7 Amps for AP1T-027020
31.1 / 30.6 Amps for AP1T-040029
35.7 / 35.2 Amps for AP1T-052038
44.4 / 43.9 Amps for AP1T-066049
50.0 / 49.7 Amps for AP1T-077056 - Air flow / static pressure
-
800 CFM / 0.5 w.c. for AP1T-027020
1200 CFM / 0.5 w.c. for AP1T-040029
1600 CFM / 0.5 w.c. for AP1T-052038
2000 CFM / 0.5 w.c. for AP1T-066049
2400 CFM / 0.5 w.c. for AP1T-077056 - DHW flow rate
-
0.5 - 4.4 GPM (1.9 - 16.7 L/m) for all models
- Dimensions
-
Height
46 in. (1168 mm) for AP1T-027020
50 in. (1270 mm) for AP1T-040029
54 in. (1372 mm) for AP1T-052038
58 in. (1473 mm) for AP1T-066049
60 in. (1524 mm) for AP1T-077056Width
27¼ in. (694 mm) for AP1T-027020
32¼ in. (821 mm) for AP1T-040029
32¼ in. (821 mm) for AP1T-052038
32¼ in. (821 mm) for AP1T-066049
32¼ in. (821 mm) for AP1T-077056Depth
26½ in. (673 mm) for AP1T-027020
28½ in. (724 mm) for AP1T-040029
28½ in. (724 mm) for AP1T-052038
28½ in. (724 mm) for AP1T-066049
28½ in. (724 mm) for AP1T-077056 - Supply air connection
-
16 x 14 in. (406 x 356 mm) for AP1T-027020
20 x 18 in. (508 x 457 mm) for AP1T-040029
20 x 18 in. (508 x 457 mm) for AP1T-052038
20 x 18 in. (508 x 457 mm) for AP1T-066049
20 x 18 in. (508 x 457 mm) for AP1T-077056 - Return air connection
-
22¼ x 22¾ in. (565 x 578 mm) for AP1T-027020
26¼ x 27¾ in. (667 x 705 mm) for AP1T-040029
30¼ x 27¾ in. (768 x 705 mm) for AP1T-052038
34¼ x 27¾ in. (870 x 705 mm) for AP1T-066049
34¼ x 27¾ in. (870 x 705 mm) for AP1T-077056 - Filter size
-
24 x 24 x 2 inches for AP1T-027020
30 x 28 x 2 inches for AP1T-040029
30 x 32 x 2 inches for AP1T-052038
30 x 36 x 2 inches for AP1T-066049
30 x 36 x 2 inches for AP1T-077056 - Weight
-
265 lbs (120 kg) for AP1T-027020
334 lbs (152 kg) for AP1T-040029
371 lbs (168 kg) for AP1T-052038
388 lbs (176 kg) for AP1T-066049
440 lbs (220 kg) for AP1T-077056 - Warranty
-
Limited 10-year warranty for the heat pump unit and compressor, and 5-year warranty for parts and accessories, in residential applications. See warranty sheet for details.

Efficient geothermal heating and cooling that keeps comfort affordable
Geothermal heat pump system that provides high efficiency heating and cooling at an attractive value. Ideal for residential and commercial applications. Five sizes available. Heating capacity: 15.6 to 54.8 MBH / cooling capacity: 20.2 to 75.9 MBH. * Available in select regions
Flexible configurations
Left, right, or rear return all in one unit
Highly efficient
Lower utility bills with efficiencies up to 4.6 COP and 30.8 EER
Environmentally friendly
Low GWP R-454B refrigerant
Domestic hot water production
Integrated desuperheater with pump included
Built to last
Robust and reliable design for a longer system lifespan
Ultra-quiet operation
Fully insulated indoor unit and no outdoor unit required for minimal noise and vibration

Designed to fit your needs
Viessmann’s newest ground source heat pump (GSHP) system, the Vitocal 100-WA, delivers exceptional value and performance as one of the most comprehensive heating and cooling systems on the market. This clean and sustainable full system option reduces reliance on fossil fuels and minimizes environmental impact by using the energy stored in the earth to heat and cool your home.
The Vitocal 100-WA is also capable of producing domestic hot water consistently and efficiently as a standard feature. Engineered with user convenience in mind, GSHP systems are known for their durability and longevity, with the reliability to provide highly efficient comfort for decades.
The Vitocal 100-WA is the ideal amenity for new builds and retrofits alike, offering premium heating and cooling while significantly reducing environmental emissions. Viessmann’s GSHP is available in five sizes, all designed for maximum efficiency and application flexibility with field-reversible controls, and included factory-installed desuperheater for highly efficient domestic hot water production.
Compatible with any loop system and requiring minimal maintenance, this quiet, sustainable solution ensures year-round comfort with a streamlined installation process—making it the ideal fit for your commercial or residential needs.

1. Vertical loop: Pipes are inserted vertically where space is limited or where soil conditions prohibit horizontal loops.
2. Horizontal loop: Typical install requires a half-acre of available space where pipes are laid horizontally in trenches and backfilled.
3. Pond loop: A series of coiled, closed loops are placed at the bottom of an adequately sized body of water.
4. Open loop: Best for homes with an abundant supply of quality well water. Water is drawn into the geothermal system, used by the system, and then discharged into an adjacent drainage ditch or pond.
Renewable energy from the earth for the highest performance
Geothermal systems can be installed with a variety of loop system configurations. “Closed loops” use recirculated fluid in a series of pipes installed vertically, horizontally, or in a pond. “Open loops” utilize abundant water sources such as wells, lakes, or ponds, and the water is then returned to the environment rather than recirculated in a closed loop.
Highly efficient, highly sustainable
Viessmann's geothermal systems harness the earth's natural, consistent underground temperature to provide efficient and eco-friendly heating and cooling.
Solar energy warms the ground, and approximately 47% of that heat is stored beneath the surface. Just a few feet below the frost line, the temperature remains consistently between 55°F (13°C) and 70°F (21°C) in many climates year-round, creating an ideal and reliable source for sustainable comfort. Making use of this stable, renewable energy source, the Vitocal 100-WA delivers consistent warmth in winter and cooling in summer—all while significantly reducing your carbon footprint and energy bills.
The factory-installed desuperheater for enhanced domestic hot water production uses water heated with waste heat from air conditioning at no cost in the summer and at substantial savings in the winter. This “free preheat” technology boasts efficiencies up to 3x higher than conventional systems. Ideal for residential, commercial, and large-scale property alike, Viessmann combines cutting-edge technology with sustainability to provide year-round comfort and a faster return on investment.
The difference of design
Viessmann innovation is changing the game when it comes to the installation and maintenance of geothermal systems. Field-reversible controls paired with a reversible cabinet design allows for left, right, or rear return configurations without the need for multiple SKUs for unmatched convenience and ease of installation and service. An integrated LED display makes it easy to know system status and operation at a glance.

Look inside the Vitocal 100-WA
- Integrated desuperheater with pump
- Flexible mounting of the junction box
- Compatible with closed and open loop systems
- Information display panel
- 2-stage compressor