Connecting Vaillant Air Conditioners with Heat Pumps or Boilers
Why this topic is even discussed
Almost with every major heating renovation today, we come across the question of whether the new wall-mounted air conditioner Vaillant climaVAIR pro can somehow be "connected" to a heat pump or gas boiler that the customer already has, or plans to install at the same time. The answer is not a simple yes or no - it depends on what exactly we imagine under the term "connection". In this article, we will go through it thoroughly and technically, without marketing phrases, exactly as it looks in real installation practice.
Right at the beginning, it is important to clarify one thing that is often mixed up in customer discussions: the wall-mounted air conditioner Vaillant climaVAIR pro is an air-to-air split system that works with refrigerant (R32) and transfers heat or cooling directly into the air in the room. The heat pump Vaillant aroTHERM plus or the gas condensing boiler ecoTEC, on the other hand, are water-based heat sources of type air-to-water or gas-to-water - they heat water, which then circulates in radiators, underfloor heating or a hot water storage tank. So we are dealing with two different technological principles that cannot be connected hydraulically (via water pipes), because no water circulates in the air conditioner. Therefore, the connection always takes place at a different level - electrical, control, spatial and operational. This is exactly the subject of this article.
Difference between air conditioning and heat pump/boiler - technical basis
In order to be able to talk about a meaningful combination, it is necessary to understand the principle of both systems. The air conditioner Vaillant climaVAIR pro works on the principle of a compressor cooling cycle - the outdoor unit contains a compressor that compresses refrigerant R32, which passes through the heat exchanger in the indoor unit and transfers or removes heat directly from the air in the room. The system is able to work in both directions - in summer it cools (removes heat from the interior and expels it outside), in winter it functions as an air heat pump and conversely delivers heat to the room. The power range available at atria.sk covers standard apartments and family houses - from the smallest model VAIB1-025WN with a power of about 2.5 kW through VAIB1-035WN and VAIB1-050WN up to the most powerful VAIB1-065WN with a power of about 6.5 kW.
An air-to-water heat pump (e.g. Vaillant aroTHERM plus) works on a similar physical principle - a refrigerant compressor cycle - but the output is not air, but heated water, which is sent to the heating system and hot water storage tank. The gas condensing boiler ecoTEC heats water by burning natural gas or propane. Both of these sources therefore "serve" the whole house via a water circuit, while the air conditioner serves only the room where its indoor unit is installed.
Why combine air conditioning with a heat pump or boiler at all
We see this combination increasingly often in practice and the reasons are very specific. It is not about duplication, but about dividing tasks between devices so that each does what it is best suited for.
Cooling in summer, which a heat pump for heating cannot solve efficiently
A heat pump connected to underfloor heating can theoretically work in cooling mode (so-called passive or active cooling), but the real effect is usually mild - a temperature drop in the room of 2 to 3 °C, slow response, risk of condensation on the pipes and floor at high air humidity. A wall-mounted air conditioner can cool the space quickly and significantly, by 8 to 10 °C within tens of minutes, and at the same time dehumidify it. Therefore, the combination of "heat pump for heating and DHW + air conditioner for cooling in summer" has become one of the most common solutions in new builds and renovations.
Supplemental heating of rooms where the heating system is underdimensioned
A common scenario from practice: an attic room added later, where it is no longer worth pulling a new underfloor heating circuit or adding a radiator connected to the boiler. A wall-mounted air conditioner in heating mode (heat pump) can heat such a room independently, while the main source (boiler or heat pump) continues to handle the rest of the house. This is typical especially for lower power models, such as VAIB1-025WN or VAIB1-035WN, which are just enough for one room up to about 35-40 m².
Bivalent operation when the main source is underdimensioned
In older houses, where only the boiler or only the heat pump was replaced without any changes to the distribution system, it sometimes happens that the main source reliably covers most of the house, but one or two rooms (e.g. a living room with large glazed areas) have a heat loss that the main system cannot handle at the lowest outside temperatures. In such a case, the air conditioner functions as an additional heat source precisely in this room, similarly to how an electric heater would work, but with much better efficiency (the COP of the air conditioner in heating mode is around 3.5-4 at mild temperatures, so from 1 kW of electricity you get 3.5-4 kW of heat).
How the "connection" really takes place - what is and what is not possible
This is probably the most important part of the article, because it is precisely here that the biggest misunderstandings arise. Let's divide it into four levels.
1. Hydraulic connection - does not exist
The air conditioner climaVAIR pro does not have a water circuit, so it cannot be connected to the heating distribution, DHW storage or expansion vessel. If someone promises "connecting the air conditioner to the heating system", it is a misunderstanding or a completely different type of equipment (e.g. a ventilation unit with a water heat exchanger, which is not the case with climaVAIR pro).
2. Control/communication level - limited connection
Heat pumps and Vaillant boilers communicate via the eBUS bus with controllers such as multiMATIC or sensoCOMFORT. Wall-mounted air conditioners climaVAIR pro are controlled by their own remote control, or via a separate WiFi module and mobile app. These two worlds do not communicate directly - the air conditioner "does not see" what the boiler is doing, and vice versa. In practice, this means you cannot set up a single interface where you could say "if the outside temperature drops below -5 °C, the air conditioner turns off and the heat pump takes over" - such switching must be handled either manually by the user or by an external smart home system (e.g., Loxone, KNX gateway, or a universal smart home hub), which controls both systems in parallel via their own interfaces and synchronizes their schedules using scenes and time plans.
3. Electrical level - real and common connection
This is the level where the systems are always connected. Both the air conditioner and the heat pump have separate electrical circuits, separate circuit breakers, and in many cases, even separate consumption meters (especially if the customer has a lower tariff for the heat pump). When designing the electrical installation, both devices must be considered simultaneously to ensure that the main circuit breaker in the distribution board can handle their combined startup (compressors draw the highest current surge at startup).
4. Spatial and operational level - the most common real-world issue
Outdoor units of air conditioners and air-to-water heat pumps are essentially similar devices - both have a fan, a heat exchanger, and exhaust air at a different temperature than the surrounding environment. If placed close to each other, they can interfere with each other by "stealing" the intake air or disrupting airflow, which reduces the efficiency of both. Noise is also an important factor - two outdoor units running simultaneously in summer (air conditioner cooling, heat pump heating DHW) can together exceed noise limits, especially near a property boundary.
Typical connection diagram in a single-family house
To make the idea more concrete, let's take a typical example of a 140 m² house, where the main heat source is the aroTHERM plus heat pump connected to floor heating and a DHW storage tank, and at the same time, wall-mounted air conditioners climaVAIR pro are installed in two rooms (living room and attic bedroom). Below is a simplified diagram showing how it looks in terms of energy flow and control.
In this specific case, the heat pump during the heating season ensures basic thermal comfort throughout the house via floor heating and is set to a low output temperature (e.g., 35 °C), achieving a high COP. The air conditioner in the living room is activated only during sudden drops in outside temperature, when large glazed areas cause rapid heat loss and the floor heating cannot compensate for the losses. In summer, the air conditioners take over the cooling function, while the heat pump continues to heat only the DHW, thus running at a significantly lower capacity and for a shorter time.
When the combination is worth it and when it is unnecessary
Not every house needs both technologies simultaneously. The decision should be based on the specific characteristics of the building, not on an automatic "it's a trend, so I want it" mindset.
- It is worth it in houses with large glazed areas facing south/west, where overheating is a risk in summer and floor cooling from the heat pump is insufficient.
- It is worth it in newly insulated attics or additions, where it is not cost-effective to extend the heating distribution system.
- It is worth it if the customer wants to be able to quickly and locally regulate the temperature in one or two rooms (e.g., a home office, a child's room) without affecting the rest of the house.
- It has little sense in a small, well-insulated apartment, where the air conditioner alone can cover both heating and cooling, and a separate boiler/heat pump would be unnecessarily oversized.
- It has little sense where the budget is limited and the main source has sufficient capacity without the air conditioner - in such cases, it is better to invest in better window shading or to improve the control of the main system.
Practical examples from customer projects
Example 1 - new build with a heat pump and two air conditioners
A single-family house of 160 m², low-energy standard, with the main source aroTHERM plus 7 kW connected to floor heating. The customer additionally ordered two wall-mounted air conditioners for the living room with a glazed wall (model VAIB1-050WN) and for the attic bedroom (VAIB1-025WN). The outdoor units were placed on a shared concrete base next to the heat pump's outdoor unit, with a distance of 1.8 m and exhaust redirected so that they do not blow into each other's intake. The electrician added a separate sub-circuit with a 16 A circuit breaker for each air conditioner outdoor unit in the distribution board, separate from the heat pump circuit.
Example 2 - renovation with a gas boiler and attic cooling
An older house after partial renovation, where the gas boiler ecoTEC remained as the main heating source for radiators. During roof insulation and attic conversion, the customer wanted to solve cooling in summer, as the roof heated up significantly during the day. Instead of extending the radiator circuit to the attic (which would require new risers), we proposed a wall-mounted air conditioner VAIB1-035WN, which provides cooling in summer and also heats the room during transitional periods (spring/autumn), so the boiler does not need to start at all for just one room during that period.
Example 3 - Office space with bivalent heating
A smaller business with an existing gas boiler connected to radiators, where insufficient thermal comfort was experienced in one larger room (45 m²) due to heat gains from lighting and computing equipment in the summer. The solution was an air conditioning unit VAIB1-065WN, which provided cooling even with a higher occupancy of the room, while the boiler continued to supply heating outside this room and hot water heating in the kitchenette.
Example 4 - Apartment with an air-to-water heat pump and air conditioning in the bedroom
An apartment in a multi-storey building with a compact heat pump for heating and domestic hot water. The owner wanted a lower temperature in the bedroom for sleeping in the summer than could be achieved with cooling via radiators (which were not even dimensioned for cooling mode). The air conditioning unit VAIB1-025WN with a quiet night mode (around 19-21 dB(A) in the indoor unit) solved the problem without interfering with the apartment building's shared heating system.
What to pay attention to in a combined installation
Electrical capacity and circuit breakers
When designing the system, you need to account for the total power consumption - a heat pump typically has a power consumption of 1.5 to 3 kW depending on the model and capacity, and an air conditioning unit in cooling or heating mode has approximately 0.7 to 2.3 kW depending on the model (from VAIB1-025WN to VAIB1-065WN). When multiple devices are running simultaneously, it is necessary to verify the main circuit breaker of the apartment or house and possibly request an increase in reserved capacity from the utility provider.
Condensate drainage
A wall-mounted air conditioning unit in cooling mode produces condensate, which must be drained via a separate hose outside the building or into the rainwater drainage system - never into the condensate drain of a condensing boiler or heat pump, as these have a different chemical character of condensate (slightly acidic in the case of a boiler) and different requirements for slope.
Noise and placement of outdoor units
If the outdoor units of both systems are on a shared wall or terrace, the total noise level may approach the hygienic limits for nighttime (typically 40 dB(A) at the façade of a living room at night). We recommend having the total noise level calculated by the installation company, especially in densely built areas.
Refrigerant circuits and safety clearances
Climaviar pro uses refrigerant R32 (mildly flammable, category A2L), while aroTHERM plus heat pumps use R290 (propane, category A3, higher flammability). When planning a mechanical room or placing outdoor units close to each other, it is necessary to maintain minimum distances from openings, shafts and ignition sources according to current standards and the manufacturer's installation instructions - this is always handled by a certified installation technician, not by DIY installation.
Control and operation scheduling
We recommend setting a simple operational rule, for example: the air conditioning unit handles cooling from May to September and heating of peripheral rooms only when the outside temperature drops below a certain threshold, while the main source operates primarily for the rest of the year. This rule is set manually or via a time schedule in the air conditioning app, as direct communication between the heat pump/boiler controller and the air conditioning unit (as mentioned) does not exist.
Selecting the right model of climaVAIR pro for a combined system
When selecting the capacity of an air conditioning unit that will operate alongside an existing main source, it is not necessary to dimension it for the entire heat loss of the room, as part of the load is taken over by the main system (floor heating, radiators). In such cases, the air conditioning unit is usually designed more for cooling capacity and the ability to respond quickly, rather than for maximum heating capacity in the cold. Roughly:
| Model | Cooling capacity | Recommended area (as a supplement to the main source) |
|---|---|---|
| VAIB1-025WN | ~2.5 kW | up to 25-30 m² (bedroom, smaller room) |
| VAIB1-035WN | ~3.5 kW | up to 35-40 m² (attic, smaller living room) |
| VAIB1-050WN | ~5.0 kW | up to 50-60 m² (large living room, glazed walls) |
| VAIB1-065WN | ~6.5 kW | open space, meeting rooms, large living kitchens |
For a more precise calculation, we recommend reading a separate article "What air conditioning capacity do I need for a given room size" and "Comparison of models VAIB1-025WN, 035WN, 050WN and 065WN", where the differences are also discussed in terms of noise, air flow and energy classes. If you want to separate only the outdoor unit (e.g. when replacing a damaged part or expanding the system), a standalone outdoor unit Vaillant climaVAIR pro VAIB1-025WNO is also available.
Frequently asked questions
Can the Vaillant air conditioning unit be connected to the same controller as the heat pump?
Not directly. Controllers such as multiMATIC or sensoCOMFORT communicate with the heat pump and boiler via the eBUS bus, while climaVAIR pro is controlled by its own remote control or via a separate app with a WiFi module. If you want to control both systems from one place, the solution is an external smart home system that controls both devices in parallel using scenes and schedules.
Can I completely replace the heat pump or boiler with an air conditioning unit?
Yes, in one or two well-insulated rooms, an air conditioning unit can function as the main source of heating and cooling. However, for an entire house with multiple rooms, hallways and a need for domestic hot water heating, this is not a practical solution - in that case, an air-to-water heat pump or a boiler connected to the heating distribution is more suitable, with the air conditioning unit used as a supplement.
Will the simultaneous operation of the air conditioning unit and the heat pump affect my electrical connection?
Yes, you need to account for the total power consumption of both devices when designing the circuit breakers and possibly also the main circuit breaker of the apartment or house. We recommend having the existing electrical installation assessed by an electrician before installing the air conditioning unit, especially if the house already has a heat pump with a higher power consumption.
Do the outdoor units of the air conditioning unit and the heat pump need to be far apart?
Not necessarily far away, but they should have sufficient clearance (approximately at least 1.5-2 m) and should not blow air into each other's air intake. The optimal placement and orientation are always assessed by the installation company on-site, according to the building's facade layout and the direction of the prevailing wind. You can find more on this topic in the article How to correctly place the outdoor and indoor unit of an air conditioner.
Is it worth combining an air conditioner and a heat pump in an apartment in a panel building?
Yes, provided the apartment has its own heating system connected to the building's central source (e.g., a heat exchanger unit) and the owner wants to cool and possibly heat a specific room locally, without interfering with the shared system. In such a case, a smaller model such as VAIB1-025WN is most commonly selected.
Is a special permit required for the simultaneous operation of two outdoor units?
The combination itself does not require a permit, but when applying for a building permit or notifying the local authority of the construction, it may be necessary to provide a noise study if both units are located close to the property boundary adjacent to a neighbor. This is a matter that should be verified according to local conditions and the recommendations of the installation company.
Summary
The Vaillant climaVAIR pro air conditioner and the Vaillant heat pump or boiler are not physically connected by piping or shared control, but operate as two separate, well-designed systems that complement each other - one provides basic heating and hot water for the entire house, while the other provides fast and localized cooling or supplementary heating of selected rooms. The key to a successful combination is a properly designed electrical installation, well-planned placement of the outdoor units, and a clearly defined operating mode specifying when each system should run. When selecting a specific air conditioning model for such a combination, we recommend considering the actual thermal load of the room and consulting with a technician during an on-site inspection - at atria.sk, we are happy to assist you with the design and selection of a suitable model from our current range of wall-mounted air conditioners from Vaillant.
Do you have a question about this topic?
Are you unsure or dealing with a specific situation in your home? Feel free to write to us - we are happy to help.