FAQs Pool Contractors

Recotherm has been designing and manufacturing ventilation systems for indoor pools for over 35 years, refining our technology to offer highly efficient solutions that minimize running costs. Our systems are specifically engineered to handle the unique demands of indoor swimming pools, providing both effective dehumidification and temperature control. 

While it might seem that a couple of fans and a heater battery could manage the air quality, they cannot provide the long-term energy efficiency or reliability of a Recotherm system. Off-the-shelf ventilation units typically lack the energy-saving features we’ve built into our systems. They also often struggle to withstand the corrosive effects of the swimming pool environment, where high humidity and chlorine levels can quickly deteriorate less specialized equipment. 

Our systems are built with high-quality materials and components designed to endure the pool’s harsh atmosphere, ensuring a longer lifespan and consistent performance. In fact, many of our Recotherm units have been operating reliably for over 30 years. This durability, combined with low running costs, makes our ventilation systems a much more cost-effective and sustainable solution in the long run. 

By investing in a Recotherm ventilation system, you’re choosing a solution that has been optimized for both energy efficiency and the specific needs of a swimming pool environment. This provides better air quality, lower maintenance costs, and more effective protection of your building’s structure. 

No, a heat pump dehumidifier is not the only option for controlling condensation in a pool hall, and in many cases, it may not be the most effective or cost-efficient solution. A heat pump dehumidifier operates by recirculating the air within the space, removing moisture through a direct expansion evaporator. The heat generated during this process is then used to warm the air and, in some cases, the pool water. 

While this approach can reduce humidity, it has significant drawbacks. First, the dehumidification process relies heavily on electricity, which is expensive to operate. This can lead to higher energy costs, especially in comparison to systems that incorporate advanced energy-saving technologies like heat recovery. 

Second, because a heat pump dehumidifier primarily recirculates the air within the pool hall, it does not address the removal of contaminants such as chloramines (produced by the interaction of chlorine with organic materials) or unpleasant body odor smells. This can result in a poor-quality atmosphere that is less enjoyable for pool users and potentially damaging to the building structure over time. 

Recotherm ventilation systems offer a superior alternative. They prioritize the use of fresh air to manage humidity, remove odors, and maintain a healthier and more pleasant environment. Recotherm units also incorporate highly efficient heat recovery technology, which captures and reuses heat from the outgoing air to preheat the incoming fresh air. This reduces the reliance on electricity and significantly lowers operating costs compared to heat pump dehumidifiers. 

Additionally, Recotherm systems are specifically designed to withstand the corrosive environment of swimming pools, ensuring long-term durability and reliability. By focusing on both air quality and energy efficiency, Recotherm units provide a more comprehensive solution that protects the building, enhances user comfort, and minimizes running costs. 

The idea that maintaining the air temperature 1°C above the pool water temperature prevents condensation is a common myth, but it oversimplifies the science of humidity control and condensation. Condensation occurs when moist air comes into contact with a surface that is cooler than the air’s dew point. The dew point is determined by the temperature and humidity level of the air, not simply by the relationship between the air and pool water temperatures. 

For example, you can safely have the air temperature 5°C below the pool water temperature without causing condensation, provided the dew point of the air is below the temperature of the internal surfaces, such as walls, windows, and ceilings. This is why managing humidity is just as critical as controlling temperature. Without proper control, high humidity levels can increase the dew point, causing condensation to form on cooler surfaces. 

Recotherm ventilation systems are specifically designed to regulate both temperature and humidity within indoor pool environments. By controlling these variables, the system ensures that the dew point is kept below the surface temperatures of the room, preventing condensation. For instance, in a scenario where the external temperature is -1°C and the room temperature is 30°C, maintaining a humidity level of 50% would effectively prevent condensation on a double-glazed panel. Similarly, if the air temperature were lowered to 25°C, increasing the relative humidity to 55% would still prevent condensation on the same surface. 

This precise control is what sets Recotherm systems apart. They are engineered to account for the complex interplay of temperature, humidity, and surface conditions, ensuring a comfortable and safe environment while protecting the structural integrity of the pool area. By debunking myths like the need for air temperature to exceed water temperature by 1°C, Recotherm systems demonstrate a more nuanced and effective approach to condensation prevention and indoor climate management 

No, a three-phase electrical supply is not always necessary. Recotherm offers single-phase units capable of handling airflows of up to 1m³/s, which is sufficient for a domestic pool with an area of up to 100m². This makes our single-phase units an excellent choice for most residential applications, as they are designed to provide efficient performance without requiring a more complex or costly three-phase electrical setup.

However, for larger commercial pools or pool halls with higher demands, a three-phase supply may be necessary due to the increased capacity requirements of larger ventilation units. If your pool exceeds the size or operational needs of a typical domestic pool, we can advise you on the most suitable system to ensure energy efficiency and reliable performance.

Our range of units is designed to cater to both single-phase and three-phase installations, ensuring we can provide a solution that aligns with your electrical setup and pool requirements. Whether your pool is small or large, we’ll work with you to select a unit that fits your specific needs.

Yes, Recotherm ventilation units can be designed for external installation by incorporating weatherproofing features to ensure they operate reliably in outdoor conditions. These weatherproof units are built to withstand exposure to the elements, including rain, wind, and temperature fluctuations, making them a practical option when indoor space is limited or when external installation is more convenient for your pool hall design.

However, there are a few considerations to keep in mind. While the unit itself can be weatherproofed, the display panel, which provides access to controls and system information, must be protected. To address this, the display panel can either be installed inside the building where it is easily accessible or housed in a dedicated weatherproof enclosure if it needs to be located outside. This ensures that the controls remain functional and protected from moisture, dust, and temperature extremes.

By offering the option for external installation, Recotherm systems provide flexibility to accommodate various building layouts and space constraints, all while maintaining the performance and durability that Recotherm is known for. Whether installed indoors or outdoors, the unit will deliver the same high level of efficiency, air quality, and humidity control for your swimming pool environment.

Yes, the display panel can be installed remotely, up to 800 meters away from the ventilation unit, providing flexibility in its placement. The panel is connected to the unit via a multi-core cable, which ensures reliable communication between the two components regardless of the distance. This feature allows the display panel to be conveniently located in an area that is easily accessible to operators, such as a plant room, maintenance area, or office, even if the unit itself is installed in a less accessible location like an outdoor space or a separate building. By separating the panel from the unit, you can ensure that system monitoring and adjustments are simple and hassle-free, without needing to access the physical unit directly.

Recotherm’s design flexibility in allowing remote placement of the display panel ensures that their systems can be seamlessly integrated into a variety of layouts and configurations, offering convenience and functionality tailored to your specific needs.

Yes, a pool cover can significantly reduce evaporation and is highly recommended for domestic pools, particularly when the pool is only in use for 1 to 2 hours a day. Covering the pool during non-use hours minimizes the amount of water that evaporates into the air, which in turn reduces humidity levels in the pool hall. This not only decreases the load on your ventilation system but also lowers heating costs by retaining the water’s warmth and reducing energy consumption. For domestic applications, a pool cover is an excellent investment that enhances energy efficiency and helps to maintain a comfortable pool environment. 

For commercial pools, however, the benefits of a pool cover may not be as clear-cut. In many commercial settings, the pool remains uncovered for aesthetic purposes, allowing the water to be a central feature of the space. Additionally, commercial pools often have extended operating hours, meaning the pool may only be covered for a short period each day, limiting the potential savings on evaporation and heating. In such cases, the cost of a high-quality cover might not be recovered within its lifespan, making it a less practical option. 

Ultimately, the decision to use a pool cover depends on your specific needs and circumstances. For domestic pools with limited daily use, a cover offers clear advantages in terms of energy savings and reduced wear on ventilation systems. For commercial pools, the decision may hinge on factors like operational hours, aesthetics, and the overall cost-benefit analysis. Consulting with a ventilation and pool management expert can help determine the best approach for your pool environment. 

Yes, you can reduce the air temperature when the pool cover is on because the evaporation rate is significantly lower when the pool is covered. With minimal evaporation occurring, a slight reduction in air temperature will have only a minor impact on the rate of moisture entering the air. This adjustment can help save energy and reduce heating costs during periods when the pool is not in use. 

Recotherm ventilation systems are designed to accommodate this functionality seamlessly. The system can be programmed to automatically lower the air temperature whenever the pool cover is deployed. This automation is achieved through a connection between the pool cover mechanism and the Recotherm unit, typically using a simple telephone-style cable. Once connected, the system can detect when the cover is on and adjust the air temperature settings accordingly, ensuring optimal energy efficiency without the need for manual intervention. 

By integrating this feature, Recotherm systems not only enhance convenience but also maximize cost savings while maintaining a stable and efficient pool environment. This makes them an excellent choice for those seeking to optimize energy use without compromising the overall comfort and condition of the pool hall. 

The amount of evaporation from the surface of a swimming pool is influenced by several factors, most importantly the difference in the vapour pressures between the air and the water. Vapour pressure is a measure of how much water vapour is in the air. When the vapour pressure of the air is lower than that of the water in the pool, evaporation occurs, as the water moves into the air to balance the pressures. 

Several other factors also impact the rate of evaporation: 

Air Temperature and Humidity: The warmer the air and the lower the humidity, the greater the evaporation. Warmer air can hold more moisture, so the difference in vapour pressures increases, leading to more evaporation. Conversely, cooler, more humid air reduces the evaporation rate. 

Air Movement: Wind or ventilation plays a significant role in evaporation. Increased air movement over the pool’s surface helps carry away the water vapour, allowing more water to evaporate. In a poorly ventilated pool room, the air near the surface becomes saturated with moisture, slowing down evaporation. 

Pool Activity: A pool with high occupancy or activity will experience more evaporation. This is because as people swim, more heat and moisture are transferred to the air. The energy released by the bodies of the swimmers raises the temperature of the water and the surrounding air, accelerating evaporation. 

Water Temperature: The higher the water temperature, the faster the evaporation. Hot water will cause the air to become saturated with moisture more quickly, leading to higher humidity levels and increased evaporation. 

Surface Area of the Pool: The larger the pool, the more surface area there is for evaporation to occur. A bigger pool exposed to air will naturally experience more evaporation than a smaller pool. 

By understanding and managing these factors, you can control evaporation rates, reduce humidity, and minimize energy costs associated with heating and dehumidifying your pool space. Proper ventilation and temperature control systems, like those offered by Recotherm, help maintain a balanced environment to optimize comfort and energy efficiency. 

Yes, using a heat pump as your heating source does affect the selection of the ventilation unit and its design. Heat pumps operate differently from traditional heating systems like gas or oil boilers, which means certain adjustments and compromises need to be made to ensure efficient operation while keeping costs manageable.

When heating is supplied by a standard boiler, the system is typically designed for a worst-case scenario: full fresh air intake and maximum heating demand for an uncovered pool during mid-winter. This design assumes high flow and return water temperatures (65°C/45°C), which are easily achievable with gas or oil boilers. With heat pumps, however, the situation is different due to their lower flow and return temperatures and their limited capacity to handle peak heating loads.

To accommodate this, the system design needs to adjust in the following ways:

Limited Fresh Air Operation in Winter In winter, fresh air has a much lower moisture content, meaning that less fresh
air is needed to achieve the same dehumidification. With a heat pump system, the unit may lose the ability to operate on full fresh air during cold months to avoid overloading the heat pump. This compromise reduces the overall heating
demand while still maintaining effective dehumidification.

Larger Unit Size and Heat Exchanger Adjustments Because heat pumps operate at lower water temperatures, achieving the required air temperatures can be more challenging. Often, a larger ventilation unit is necessary to handle these limitations. Even with a larger heat exchanger inside the unit, other factors such as airflow resistance and fan capacity may restrict performance. The design must strike a balance between increasing the unit size and maintaining feasible energy use.

Extended Heat-Up Times and Reduced Peak Performance Heat pump systems often require longer periods to heat the pool hall and may struggle to maintain the desired room temperature in the depths of winter. This is due to closer design margins necessitated by the heat pump’s lower temperature capabilities. While the pool hall may remain comfortable, achieving and maintaining very high temperatures consistently might not always be
possible.

All these considerations are aimed at optimizing the heat pump’s duty and reducing the overall equipment and operating costs. Heat pump systems can still be effective and energy-efficient for pool environments, but
the design must account for their unique limitations.

If clients or heat pump providers expect guarantees for performance in high-temperature environments, they may need to prepare for higher duties and increased costs. Recotherm works to strike a practical balance, designing systems that meet the needs of both customers and energy providers without excessive capital costs. Maintaining a room at 30°C with a 45°C coil temperature is a challenge, but Recotherm strives to deliver solutions that are both effective and cost-efficient.

While Recotherm specializes in designing and manufacturing high-end swimming pool ventilation units, we do not supply pool water heat exchangers. However, through our extensive work with pool contractors, we’ve observed that homes heated by air or ground source heat pumps are becoming increasingly common. This trend will only grow as new regulations after 2025 prohibit the installation of fossil-fueled boilers in new homes.

When sizing a pool water heat exchanger for a system using a heat pump, there are critical considerations that differ significantly from those of traditional boilers. The primary challenge arises from the way heat exchangers are sized based on supplier catalogues.

Most catalogues provide charts that list the required kW rating for the heat exchanger based on specific water volumes and three primary flow temperatures. However, these charts often overlook a vital question:
How quickly does the pool water need to be heated?

The heat required to maintain a pool’s operating temperature is minimal compared to the energy needed to heat the pool water from a cold fill to its target temperature. Heat exchangers are typically sized based on the initial heat-up load, which can lead to oversizing, especially when dealing with heat pumps. Pool contractors generally aim for a heating rate of no more than 0.5°C per hour, meaning a 20°C increase (from 10°C to 30°C) would take approximately 40 hours. Some manufacturer charts assume a heat-up period of around 46 hours.

With a standard boiler, oversizing a heat exchanger has minimal financial impact since the cost difference for a slightly larger boiler is relatively small. However, for heat pump systems, oversizing the heat exchanger can lead to significantly higher upfront costs because the heat pump itself must also be oversized to meet the increased demand. The cost difference for a larger heat pump can be substantial, running into thousands of pounds.

To optimize efficiency and cost, it’s essential to consider longer heat-up periods. For example, increasing the heat-up time from 46 hours to 96 hours (4 days) could reduce the required heat exchanger size to 48% of the original, allowing the heat pump to be sized much closer to its actual operating load. This adjustment significantly reduces capital costs without compromising long-term efficiency.

We raise this issue because pool contractors often size heat exchangers directly from manufacturers’ charts without fully accounting for the heat-up time or the actual operating conditions of the heat pump. While these charts are designed for convenience, they don’t address the specific needs of systems using heat pumps. The first step in correctly sizing a heat exchanger should always be to calculate the actual heat demand, followed by selecting an appropriate heat exchanger based on the heat pump’s flow temperature and the desired heating time frame.

By carefully considering these factors, you can avoid unnecessary expenses while ensuring your heat pump system operates efficiently and effectively for your pool.

Yes, the Recotherm unit has the capability to monitor and control the temperature of your pool water. This functionality is integrated into the system’s internal controller, making it a convenient and efficient solution for maintaining your desired pool water temperature.

To enable this feature, you will need a temperature sensor and a control valve. Both components are available from Recotherm and can be seamlessly integrated into your ventilation unit. The temperature sensor measures the current water temperature, while the control valve adjusts the heating system to ensure the pool water remains at your preferred setting.

By using the Recotherm system to manage your pool water temperature, you gain precise control, reducing the need for separate systems and ensuring that the pool environment remains comfortable and energy-efficient. This integrated approach simplifies operation and ensures that both air and water temperatures are balanced for optimal performance.

Yes, every Recotherm unit is supplied with a comprehensive control system, designed to manage all aspects of its operation effectively. The controls are fully integrated into the unit, providing seamless functionality for maintaining the ideal temperature, humidity, and air quality in your pool hall.

These controls are pre-programmed and ready to use, ensuring the unit operates efficiently right from installation. They include advanced features to monitor and adjust settings automatically, optimizing energy usage while protecting the pool environment and building structure.

Additionally, if you require customization, such as remote access or integration with existing building management systems (BMS), Recotherm can accommodate these needs to provide a tailored solution. Our controls are designed to make operating your unit as easy and intuitive as possible, delivering both reliability and convenience.

No, in most cases, the ventilation unit can be served by the same boiler that heats the pool water. Pool boilers are typically sized to handle the significant heating load required to bring the pool water from cold to a comfortable temperature of 30 °C within a specified time frame, such as 48 or 72 hours. Once the pool water reaches and maintains this temperature, the boiler generally has spare capacity that can be utilized to supply the ventilation unit.

For domestic installations, this shared arrangement is usually sufficient, as the boiler can efficiently handle both the pool water and the ventilation unit’s heating needs without additional equipment. However, for commercial projects, where larger pools or higher operational demands are common, additional considerations may be required. For instance, if the system must account for frequent backwashing or high rates of water turnover, extra boiler capacity may be necessary to ensure adequate performance.

Recotherm units are designed to work efficiently with your existing heating infrastructure, but during the design phase, it is essential to assess the total heating requirements to determine whether the existing boiler capacity is sufficient or if supplementary equipment may be needed.

The supply air in a pool hall should be distributed through either metal ductwork or builder’s work ductwork. It is essential to direct the air over the coldest surfaces in the room, which typically means the windows. Properly distributing the air in this way prevents condensation from forming on these surfaces. If there are other surfaces colder than the windows, this indicates a structural or insulation issue that should be addressed to maintain optimal conditions.

The return air, on the other hand, can be extracted from a single point on one of the walls. It is important to note that the location of the return air grille does not influence the distribution of the supply air, as supply and return operate independently in this context.

Additionally, care should be taken to avoid directing the supply air stream directly at the surface of the pool water. Blowing air across the water can significantly increase evaporation rates, leading to higher humidity levels and increased heating demands. Moreover, this can create an uncomfortable environment for pool users by making them feel colder due to the accelerated evaporation of water from their skin.

Proper design and placement of air distribution systems are critical for maintaining a comfortable and energy-efficient pool hall environment while ensuring the building structure is protected from moisture-related damage.

Yes, having a spa pool will impact the selection of the ventilation unit. Spa pools typically operate at higher water temperatures than standard swimming pools and are more active when in use, generating significantly more evaporation and humidity.
This higher level of evaporation increases the demand on the ventilation system to manage the additional moisture in the air effectively.

To ensure the correct unit is chosen, it is crucial to inform the supplier or installer that you have a spa pool and provide details about its size. The unit’s capacity must be calculated to accommodate both the swimming pool and the spa pool,
factoring in the higher evaporation rates and specific conditions associated with spa usage.

A properly selected Recotherm ventilation unit will handle the combined needs of your pool and spa, maintaining a comfortable and safe environment while minimizing the risk of condensation and protecting the building structure from potential moisture-related damage.

Yes, it is possible to avoid condensation even if you cannot run ductwork directly to your windows. In such cases, specialist air distribution grilles can be used to ensure the air is effectively circulated throughout the pool hall and directed towards all corners of the room, including the windows. These grilles are designed to create a sufficient air throw, ensuring the movement of warm, dry air reaches critical areas where condensation is most likely to occur.

However, since the windows will not be directly covered by warm, dry air, you may need to operate the ventilation system at a lower indoor humidity level. Reducing the humidity ensures that the dew point of the air remains below the surface temperature of the windows, minimizing the risk of condensation forming.

Recotherm ventilation systems can be tailored to suit these conditions, offering precise control of temperature and humidity to maintain a comfortable and condensation-free environment, even in challenging situations where ductwork cannot be installed as traditionally recommended.

Yes, some of our smaller units, including the Aeris range up to 100, can operate from a standard 13-amp supply, making them suitable for domestic installations where only a single-phase power source is available.

However, larger units typically require a higher electrical capacity and will need a larger supply to accommodate their power requirements. This is especially true for commercial or larger residential pools where the unit’s airflow and heating demands are greater.

Recotherm units are designed to work efficiently within the specified power requirements, and our team can advise you on the best unit for your pool and electrical setup. If a larger unit is necessary, you may need to consult an electrician to ensure your supply is adequate.

Yes, it is important to have the unit running 24 hours a day to ensure the building’s structure is protected from the high humidity levels that naturally occur in indoor pool environments. The continuous operation of the unit helps maintain proper ventilation, preventing condensation, mold growth, and potential damage caused by moisture build-up, which could deteriorate the building’s structure over time.

However, if your pool hall is well-insulated and you use a pool cover when the pool is not in use, the system can adjust its operation to become more energy-efficient. In these conditions, the unit will reduce its speed and power usage to the minimum necessary to maintain adequate airflow and prevent excess humidity. This means that while the system will still be running, it will consume significantly less energy, using only a small amount of electricity to power the return fan.

So, while the unit needs to operate continuously, you won’t need to worry about excessive energy consumption if the pool hall is properly insulated and covered. The system is designed to automatically adjust to the conditions, ensuring effective humidity control without unnecessary energy use.

Yes, to maintain the pool water temperature and prevent excessive heat loss, it is essential to keep the pool at the desired temperature 24 hours a day. The consistent warmth helps to reduce the risk of condensation, which can damage both the pool area and the building structure due to high humidity levels. Maintaining a stable temperature also ensures that the pool is always ready for use, avoiding fluctuations in comfort and water quality.

In order to do this, it is necessary for the hot water from the boiler to be available on demand at all times. The boiler must be capable of maintaining the pool’s temperature around the clock, especially during colder months when heat loss tends to be higher. While the boiler doesn’t need to be running at full capacity continuously, it must be able to respond quickly to maintain the required temperature whenever needed.

By keeping the system running consistently, the temperature of the pool remains stable, reducing the likelihood of energy inefficiencies and preserving the integrity of both the pool environment and the surrounding structure. This ensures that your pool stays in optimal condition while avoiding costly repairs or damage caused by moisture build-up.