SELECTION GUIDE DEHUMIDIFICATION OF SWIMMING POOLS Copyright © Dantherm 2016 CONTENTS Why Should You Dehumidify an Indoor Swimming Pool? 5 Understand the Air 6 Ensure the Chemistry of the Water Is Correct 10 Choose the Correct Materials 11 Two Ways to Control Humidity 12 Which Type of Dehumidifier Should You Choose? 15 Temperature Management 16 How to Determine the Operating Conditions 18 How to Calculate the Humidity Load 20 Selecting the Type of Dehumidifier 25 How to Dimension the Dehumidifier 36 Air Circulation 38 Air Distribution 40 Regulating The Volumes of Air 42 Step by Step – How to Dimension Correctly 43 December 2016 Copyright © Dantherm 2016 Copyright © Dantherm 2016 1 WHY SHOULD YOU DEHUMIDIFY AN INDOOR SWIMMING POOL? Large volumes of water constantly evaporate from the surface of a pool, and from the damp tiles around the pool. Several thousand litres of water can evaporate from a swimming pool in a single day. Far too many private and public indoor swimming pools have been destroyed because the inventory, walls and building structures were destroyed by mould, rot and corrosion – because an adequate dehumidifying system was never installed. Humidity in itself is critical, and at the same time chlorine is an aggressive substance, which severely attacks building materials when it is present in condensation. In addition to protecting the building, dehumidification is also about people’s comfort. Excessive humidity will lead to visitors and staff having a bad experience in the swimming pool. A tool for choosing the correct solution To deal with these problems, Dantherm has written this Selection Guide for the dehumidification of swimming pools. The aim of the guide is to provide engineers and pool fitters with a tool for choosing the correct pool dehumidifier – regardless of whether it is for smaller pools, hotel swimming pools or public swimming pools. The dimensioning of a pool dehumidifier is not an exact science, and there are many mutually dependent factors which have an impact. Making a change in one area, often affects other areas. Dehumidification requires careful thought and above all, good dialogue between the architect and consulting engineer. A good dehumidification solution is an overall solution, and therefore this guide relates to both dehumidification, temperature regulation and ventilation. This Selection Guide is based on Dantherm’s extensive expertise and many years of experience in dehumidifying thousands of indoor swimming pools. This is why we can say with confidence that you are on safe ground if you follow the directions in this guide. 5 Copyright © Dantherm 2016 2 UNDERSTAND THE AIR To understand the processes that happen in the The highest relative humidity that can be al- air, you need to think of the air as a mixture of lowed with a given room temperature is de- dry air and water vapour. fined by the insulation grade of the building, the water content of the air, the outdoor air We call this mixture, humid air. Air expands temperature and the air circulation in the room. when it is warmed and contracts when it is cooled. When air is warmed up, it can hold For example, if the air inside a swimming pool more water vapour and when it cools down, it is at 28 °C and it has a relative humidity of 60 %, can hold less water vapour. When the air cools the air will condense on the wall if the wall’s down a lot, it reaches the dew point, which temperature is less than 19.5 °C. means the air is saturated, and the water vapour condenses as water. To be able to explain and understand the physical interplay in the air, we use a Mollier diagram. The dew point is a crucial term in relation to the dehumidification of indoor swimming pools. The terms used in a Mollier diagram are speci- Humid air will condense on a cold surface when fied below. the temperature of the cold surface is below the dew point. The air’s density (ρ) The vertical orange axis all the way out on the left. The air’s density changes in line with changes to temperature/relative humidity. In general, the air weighs less the higher the relative humidity is. We use ρ = 1.175 kg/m3 air as the average value of the air’s density indoors and outdoors. Air temperature (t) Dry bulb (t) The vertical pink axis on the left with corresponding lightly sloping lines. The temperature we measure in the air using an standard thermometer. The temperature is given in °C. Enthalpy (h) The purple diagonal lines. Enthalpy is the air’s heat content and is stated as kJ/kg air. Starts at 0 °C = 0 kJ/kg. Relative humidity (RH) The green curves. The relative humidity is stated as a percentage (%) and is an expression of the air's actual water vapour pressure compared to the water vapour pressure when the air is saturated. Water content (x) The horizontal light blue bottom axis. The water content describes the amount of water that is actually present in the air, and is given as g water per kg air. Water vapour pressure The vertical blue axis on the right. (p) The water vapour pressure is measured in mbar and is read to determine the partial water vapour pressure. The brown diagonal line in the bottom half of the diagram is an aid to use to determine the partial water vapour pressure. 6 Copyright © Dantherm 2016 Luftens densitet kg/m3 Air density kg/m3 MOLLIER HX-DIAGRAM 1.100 Relative humidity % Air temperatureoC 0% Lufttemperatur oC 60 % 20 Relativ fugtighed % 1 30% 55 50 40% 45 50% 60% 40 1.150 70% 80% 90% % 100 35 30 90 g /k kJ g /k kJ 70 60 20 g /k kJ 1.200 80 25 g /k kJ 50 40 g /k kJ 15 kJ 35 g /k 30 20 5 g /k kJ 0 25 10 g /k 20 -5 15 1.350 -10 10 -15 -20 5 0 5 10 15 20 25 Vanddamptryk (mbar) kJ 1.300 Water vapour pressure (mbar) 10 30 1.250 g /k kJ 40 0 Vandindhold (x) i g vand/kg luft Water content (x) in g water/kg air 7 Copyright © Dantherm 2016 EXAMPLE: HOW TO USE THE MOLLIER DIAGRAM The Mollier diagram allows you to read the dew point temperature and water content in the air, if you know the relative humidity of the air and the air’s temperature. The point is plotted in the diagram and the water content of the air is found on the X-axis. The dew point temperature is found by moving vertically, until you intersect the 100 %RH curve, after which you read the dew point temperature on the Y-axis. At 28 °C; 60 %RH, the water content is approx. 14 g water per kg air, and the dew point temperature is approx. 19.5 °C. This means that if there are surfaces in the room that have a temperature that is less than 19.5 °C, condensation will form on these surfaces. If the building is poorly insulated, it may be necessary to lower the relative humidity to 50 %RH, the water content will change to 12 g water/kg air and the dew point temperature will change to 16.5 °C. Luftens densitet kg/m3 Air density kg/m3 MOLLIER HX-DIAGRAM 1.100 Relative humidity % Air temperatureoC % 60 % 20 Relativ fugtighed % 10 Lufttemperatur oC 30% 55 50 40% 45 1.150 50% 40 60% 35 80% 90% % 100 70% 30 90 g /k kJ g J/k 70 60 20 g /k kJ 1.200 k 80 25 g /k kJ 50 kJ 15 g /k 40 40 g /k kJ g /k kJ 35 30 20 g /k kJ 0 25 k 10 1.300 g J/k 20 -5 15 1.350 -10 10 -15 -20 5 0 5 10 15 Vandindhold (x) i g vand/kg luft Water content (x) in g water/kg air 8 Copyright © Dantherm 2016 20 25 0 Vanddamptryk (mbar) 5 Water vapour pressure (mbar) 10 30 1.250 Copyright © Dantherm 2016 3 ENSURE THE CHEMISTRY OF THE WATER IS CORRECT The correct combination of chemicals in an At the same time, the incorrect composition of indoor swimming pool is crucial, both for the chemical ingredients in the water can destroy health of users and for the inventory inside the all of the inventory in a very short space of time, pool room and the swimming pool’s technical including the dehumidifier and other equip- room. ment that have been installed to process the air. Insufficiently treated water results in poor hy- Shown below are the threshold values, which giene, while water that has been excessively apply to products for indoor swimming pools treated results in gases in the air that contain in accordance with EN/ISO 12944-2, protection chlorine, which can irritate the eyes and cause class C4. These threshold values must be com- breathing difficulties. plied with for the warranty to be valid. WHEN ADDING CHEMICALS Ingredients PPM Free chlorine 1.0 - 2.0 Combined chlorine Max 1/3 of the free chlorine content pH 7.2 - 7.6 Total alkalinity 80 - 150 Calcium hardness 250 - 450 Total dissolved solids < 2,000 Sulphates < 360 WITH OWN PRODUCTION OF CHLORINE 10 Copyright © Dantherm 2016 Ingredients PPM Salt (NaCl) < 30,000 Total dissolved solids < 5,500 pH 7.2 - 7.6 Total alkalinity 80 - 150 Calcium hardness 250 - 450 Sulphates < 360 4 CHOOSE THE CORRECT MATERIALS The environment in an indoor swimming pool vanised steel that has been powder coated. The is aggressive, which means it is very important heat exchangers should be made of aluminium that the materials that are used in a dehumidifi- that is epoxy-protected and coated. er are corrosion-protected, because the lifetime of the products will otherwise be very short. The evaporators and condensers in particular need to have good protection, first with a Components in comfort ventilation units are primer using epoxy coating and then with top not protected in relation to an aggressive envi- coating. In general, galvanised steel or alumini- ronment like a swimming pool. This means that um that is powder coated are the only materials comfort ventilation cannot be mixed with the that are suitable for swimming pool environ- swimming pool ventilation. ments. Standard stainless steel should not be used. The basic material that is used in the dehumidifier for heat exchangers, fans and surfaces, can Dantherm’s swimming pool dehumidifiers have different corrosion classes, depending on are as standard, protected in accordance with the required lifetime. It is recommended that EN/ISO 12944-2, protection class C4. the basic material is aluminium or hot-dip gal- 11 Copyright © Dantherm 2016 5 TWO WAYS TO CONTROL HUMIDITY door air is good for comfort but warming the DEHUMIDIFICATION USING CONDENSE DEHUMIDIFIERS new air is expensive in terms of energy con- For small pools in private homes, in hotels or in sumption. spa centres, often a dehumidifier is used, which In the past, the standard practice was to replace the air in a swimming pool with new air. Out- recirculates the air and condenses the water by Increasing energy prices and increased aware- using an evaporator coil. This type of dehumidi- ness of energy consumption has led to great- fier is called a condense dehumidifier. er focus on saving energy – and this includes dehumidification. Therefore today there is focus What does a condense dehumidifier consist on recirculating as much air as possible or re- of? covering heat in heat exchangers. A condense dehumidifier consists of a fan, a cooling unit and if required, an outdoor air in- Basically, an indoor swimming pool can be de- take. humidified in two ways: by using condense dehumidifiers or by using ventilation dehumidifiers. TERMINOLOGY Outdoor air: Air that is drawn in from outside the building and used as replacement air. supply air Exhaust air: The air that is blown outside the building. Supply air: The dry, dehumidified air, which is blown into the pool room. Extract air: The humid air from the extract air pool room that is drawn into the dehumidifier. 12 Copyright © Dantherm 2016 outdoor air exhaust air The cooling unit consists of an evaporator, a condenser and a compressor. How does a condense dehumidifier work? In a condense dehumidifier, the humid air is led What does a ventilation dehumidifier consist of? A ventilation dehumidifier consists of a fan, a heat recovery section, a mixing section. and if required, a heat pump. over a cold coil (evaporator in the cooling unit), and the water vapour in the air condenses into water. The cooling unit functions by letting a refrigerant evaporate at low pressure and low temperature in the evaporator and then condensing it at high pressure and high temperature in the condenser on the other side of the compressor. In some types of condense dehumidifiers, there is also the option of taking some of the dry outdoor air in – up to 30 % – if there is a need to take air quality and comfort into consideration or if there is a requirement in consideration of In a ventilation solution, the air is completely the dehumidification needs. or partially replaced. It may be preferable to let some of the airflow recirculate, so that anything A condense dehumidifier generates energy between 0 % to 100 % of the air is circulated, because of the condensation process and the depending on the requirements. The airflows compressor and fan power input. The thermal are mixed in the dehumidifier’s mixing section. contribution from a condense dehumidifier is significant and should be included in the overall How does a ventilation dehumidifier work? thermal loss calculation. In a ventilation solution, the humid warm air is extracted from the pool room and replaced If desired, the surplus energy or some of it can with dry outdoor air. The energy from the warm periodically be removed via a water-cooled humid air in the swimming pool room is recov- condenser or an external air-cooled condenser. ered in the heat recovery section, normally in a plate heat exchanger. DEHUMIDIFICATION USING VENTILATION In a ventilation dehumidifier with a heat pump, In small swimming pools with high comfort and a dedicated heat pump. This solution pro- standards or large public pools, it will often be vides better heat recovery and minimises the necessary to replace a large part of the air for necessary outdoor air intake. The heat pump comfort and for hygiene considerations, and a will warm the air during winter and can also ventilation solution is the best solution. dehumidify the air during the night, if there is the heat pump functions both as a dehumidifier a need for this. 13 Copyright © Dantherm 2016 Copyright © Dantherm 2016 6 WHICH TYPE OF DEHUMIDIFIER SHOULD YOU CHOOSE? Shown below is a list of simple characteristics, which can help you to decide which type of dehumidifier is the right choice. CONDENSE DEHUMIDIFIER Advantages Disadvantages Easy to install and use Generates heat Low investment Can only take a limited volume of outdoor air VENTILATION DEHUMIDIFIER Advantages Disadvantages Optimal regulation of humidity and Cannot be used when the outdoor air is more temperature humid than the indoor air. Up to 100 % outdoor air Higher investment than the condense dehumidifier Free cooling Requires more space than the condense Active cooling option dehumidifier In small pools and spas there is rarely a desire for large volumes of outdoor air. In these cases, people will often choose a condense dehumidifier, since the investment is small and it is simple to use. In medium large pools, private pools or hotels, the choice will be between a condense dehumidifier and a ventilation dehumidifier, depending on several factors: requirements for the volume of outdoor air, level of comfort and the size of the budget. If there is a strong requirement for the volume of outdoor air and comfort, and the budget is large enough, the choice will tend to favour a ventilation dehumidifier. In large public swimming pools, because of the number of users, the requirement for the volume of outdoor air will often mean that ventilation dehumidifiers are the correct solution. But if the outdoor air is more humid than the indoor air for long periods of time, the choice will of course be a condense dehumidifier. 15 Copyright © Dantherm 2016 7 TEMPERATURE MANAGEMENT In addition to dehumidification, the dehumidifier Free cooling (only with dehumidification can also be used to regulate temperature of the using ventilation) air and pool water. However, the pool water can When the summer sunlight shines through the only be warmed by a unit that has a built-in cool- windows, the swimming pool often warms to ing circuit. a temperature that exceeds the desired room temperature. If the actual room temperature HEATING/COOLING THE AIR The thermal requirements for a swimming pool is higher than the desired setpoint and higher than the outdoor air temperature, then you have the possibility of utilising free cooling. are determined by several factors: With free cooling, the cooler outdoor air can be »» Ventilation loss, both mechanical and through drawn past an exchanger through a by-pass, so infiltration loss from leaks in the building. that the outdoor air is not further warmed. In »» The building’s transmission loss, i.e. the ther- this way, the outdoor air can help to lower the mal loss through walls, ceilings, windows, etc. room temperature. The control of the free cool- »» Solar gains eg sunlight entering through ing is fully-automatic, done through the unit’s windows. own control unit. Depending on which dehumidifier has been Cooling with reversible heat pump (only chosen, there are different options available for with dehumidification using ventilation) temperature regulation. In some countries, free cooling is not sufficient, Heating coil A heating coil is the most popular way to con- and in those cases it is possible to build a heat pump in a reversible cooling unit using a 4-way valve. trol the temperature. Depending on the unit, the heating coil is run by an ON/OFF (small unit) Reversible means that the heat pump reverses or 0–10 V signal (large unit). the flow of the refrigerant, so that the section that was originally an evaporator in relation to the ex- There are two different types of heating coil: A hot haust air now becomes a condenser, and the sec- water coil for connecting the central heating sys- tion that was originally the condenser in relation tem and an electrical heating coil. Both types can to the outdoor air, now becomes an evaporator. normally be supplied in different sizes, depending on water temperature and heating requirements. Thus it is now possible to activate the further cooling of the warm outdoor air. The outdoor A unit that dehumidifies using outdoor air, must air is drawn across a cold coil and cooled down. always have a heating coil. A condense dehu- The control of the 4-way valve and subsequent- midifier only needs a heating coil if it operates ly the cooling, is fully-automatic, done through with a certain portion of outdoor air or in con- the unit’s actual control unit. nection with recirculation, where there is no further heating in the pool room. 16 Copyright © Dantherm 2016 Cooling using a cooling coil for active cooling of the pool room without hav- If the cooling capacity of a reversible heat pump ing an extra built-in cooling coil. is insufficient, or a condense dehumidifier installed in a country with a hot and humid cli- External air cooled condensers are not normally mate, a cooling coil is often necessary. Depend- supplied by Dantherm, but Dantherm makes ing on the unit, the cooling coil is run by an ON/ all of the necessary data available for the cal- OFF (small unit) or 0–10 V signal (large unit). culation of these. Condense dehumidifiers are supplied ready to be connected to the external There are two different types of cooling coil: A condenser. The control of the external condens- water cooling coil for a central cooling unit or er is fully-automatic, done through the unit’s a DX cooling coil for direct expansion to a sep- control unit. arate compressor unit. Both types can normally be supplied in different sizes, depending on cooling requirements. POOL WATER HEATING The heating requirements of the pool are mainly In countries with very hot summers, the abso- determined by two factors: lute humidity of the outdoor air can be too high to use outdoor air to dehumidify with. In those »» Evaporation from the pool water. situations, a cooling coil can be used for dehu- »» The pool’s transmission loss, i.e. the thermal midification of the outdoor air. loss through the pool’s bottom and sides. Since the outdoor air in this case must be With dehumidifiers with built-in cooling units or cooled down by a great deal to be dehumidi- heat pumps, it is possible to have the dehumidifi- fied, the cooling coil must be positioned before er delivered with a built-in water-cooled condens- the built-in heating coil. In this way, it is possible er as a supplement to the air-cooled condenser. to warm up the air again to avoid too cold air being blown into the pool room. In a condense dehumidifier, warm air is always added when the compressor is operating, and in Cooling using an external condenser (con- some cases – especially when the temperature dense dehumidifier only) outside increases and the heating requirement in A condense dehumidifier will always produce the pool room falls – the excess heat is undesira- some excess heat. This is due to the electrical ble. In such situations, a water-cooled condenser energy that is used in the compressor, and that can be used and the excess heat utilised to warm every single litre of condensed water produces the pool water or utility water. a thermal output of around 0.7 kW. In other words, with a water-cooled condenser Often a water-cooled condenser is built into this more comfort is achieved than with a condense unit. This makes it possible to transfer the excess dehumidifier. Furthermore the running costs will heat to the pool water or to the utility water. decrease. However, in countries with a hot climate during A ventilation dehumidifier does not pose the the summer, the excess heat from the unit is of- same problem with excess heat that arises with a ten greater than the water’s thermal loss, so the condense dehumidifier. If the temperature in the excess heat must be dealt with in some other way. room is too high, if required, the compressor can simply be switched off, since dehumidification is In this situation, it is possible to use an external carried out using outdoor air. In other words, a wa- air-cooled condenser. This means the excess ter-cooled condenser in this type of dehumidifier heat can be transferred fully to the outdoor air, does not provide more comfort, but it will be able and it is even possible to transfer more than to extend the operating time of the compressor that. Thus, an external condenser can be used and thus utilise the excess heat more efficiently. 17 Copyright © Dantherm 2016 8 HOW TO DETERMINE THE OPERATING CONDITIONS VDI 2089 Based on the physical laws there are exact for- THE ROOM’S RELATIVE HUMIDITY (RH VALUE) mulas to calculate the humidity load from an The setpoint should be an RH value of 50–60%. indoor swimming pool. These formulas are You can also choose to operate with a differ- however complicated to use in practice. This entiated setpoint, so that it is low during win- has lead the German institure VDI to make a ter (50 %RH) to avoid condensation problems guideline which comprises recommendations on cold surfaces, and high during summer for which values to set for internal condition, (60 %RH) to reduce the operating costs. When outside condition and amount of outdoor air. the temperature is high during the summer, VDI has also made a simplified formula where condensation problems do not occur. you can use data from a project and calculate humidity load. This guideline is called VDI 2089 Above 60 %RH, the higher the RH value the poor- and it is normal standard in Europe and it is the er the comfort level, and there is an an increasing guideline which we use at Dantherm. risk of condensation problems and fungal attack. An RH value that is lower than 50 %RH is not THE ROOM TEMPERATURE In consideration of both comfort and budget, appropriate, because evaporation will increase and this means greater dehumidification requirements and increased operating costs. the air temperature inside a swimming pool should be higher than the water temperature. midification requirement. However, it should be WATER CONTENT IN THE OUTDOOR AIR noted that all else equal, increased room tem- The water content in the outdoor air (X outdoor perature also means a higher heating bill. air) varies a lot over the year, more or less all This minimises evaporation and thus the dehu- over the world. From more than 12 g water/kg In general, it is recommended that the room air during the summer an down to 2 g water/kg temperature is set to 2 ºC higher than the water air during the winter. temperature. Only in therapy baths and spas should the air temperature be allowed to be VDI has chosen 9 g water/kg air as the value that lower than the water temperature. characterises outdoor air in Northern Europe and we use this figure in DanCalcTool. This is be- THE WATER TEMPERATURE Copyright © Dantherm 2016 ed approx. 20 % of the year. (learn more about When setting the water temperature, the fol- DanCalcTool in section 11 "How to Dimension lowing is often the case: the Dehumidifier" on page 36.) Private pools and hotels: 26–30 ºC However, other values can be used for outdoor Public swimming pools: 26-28 ºC air in the calculation program DanCalcTool, if Competition swimming: 24-27 ºC the values deviate significantly from the North- Therapy baths: 30-36 ºC ern European standard. Spa: 36-40 ºC 18 cause the value 9 g water/kg air is only exceed- In addition, VDI 2089 recommends that the ab- Day and night solute water content does not exceed 14.3 g In general, a dehumidifier should be installed water/kg air (54 %RH with an air temperature of according to daytime operations since the 30 C), if the water content of the outdoor air is evaporation is greatest during the day, when less than 9 g water/kg air, which will be the situ- the pool is used the most. It is during daytime ation during winter. operations that you must assess the level of activity that best describes the way the pool is During the summer a higher water content in the being used. indoor air can be permitted, since the temperature in the air that enters from outside is high and Winter and summer thus does not contribute to condensation. When outdoor air is incorporated in the installation, you must use the summer load as the OUTDOOR AIR’S SIGNIFICANCE Outdoor air temperature point of departure for the determining the humidity load. The water content in the outdoor air is highest during the summer. You must ensure that the dehumidifier is sufficiently large to deal with the humidity load with 100 % outdoor The outdoor air temperature and the water air volume during the summer. During the win- content in the outdoor air affect the choice of ter, the outdoor air is very dry and thus will in- dehumidifier type. For example, low outdoor air crease the dehumidification, so in that situation temperature will favour a ventilation solution the dehumidification capacity will be more than with a heat pump. enough. Outdoor air RH value Volume of outdoor air The RH value of outdoor air is related to the wa- VDI 2089 states that the volume of outdoor air ter content in the outdoor air. The water content must be at least 15 % of the circulating air. This in the outdoor air influences the overall humid- applies for public and commercial pools. ity load and if the water content in the outdoor There are no specific requirements in VDI 2089 air is higher than the water content in the pool for the addition of outdoor air in private pools. room, the condense dehumidifier must have a larger capacity. Copyright © Dantherm 2016 9 HOW TO CALCULATE THE HUMIDITY LOAD There are three factors that must be taken into However, we have elected to adjust the con- consideration when calculating the humidity stants for the level of activity that VDI 2089 has load from a swimming pool. The evaporation set for private pools and hotel pools, since we from the pool, together with the bystanders believe, that VDI 2089 uses inappropriately high and users, contributes positively to the humid- values for the level of activity in these two areas. ity load, while it is normally the opposite with the outdoor air. In addition, in small private pools it will often be the air circulation that defines the need for »» Evaporation from the pool (+) dehumidification, and not how much activity »» Users and bystanders (+) there is in the pool. »» Outdoor air (-) The following factors are used to calculate the THE EVAPORATION FROM THE POOL evaporation from the pool: »» Water temperature The calculation of the evaporation from the »» Air temperature pool can be carried out in accordance with »» Air humidity different formulas. At Dantherm, we use the »» Pool area German guideline VDI 2089, which is the normal »» Level of activity in the pool standard in Europe. Set the values in the formula below. W = e/(RD × T) × (Pb - Pl) × A = Evaporated water (l/h) W e =Level of activity in the pool RD = Gas constant = 461.5 (J/kg K) T = Average between air temperature and water temperature (K) Pb = Saturated vapour pressure, water (Pa) Pl = Partial vapour pressure, air (Pa) A = Pool area (m2) 20 Copyright © Dantherm 2016 Level of activity, e If a more precise calculation of the humidity The level of activity in different types of pools is load is desired, then a weighted level of activity listed below. can be chosen, where both daytime load and The values are generated automatically when nighttime load is calculated, and then a weight- the pool type is selected in DanCalcTool. For ed average activity load is calculated. example, if you enter private pool it will automatically calculate with e = 9.5. However in this case, it is important to note that there can be periods with peak load, where the e = 9.5 for private pools general setpoint cannot hold, and so there is a e = 11 for hotel pools, normal activity need to assess whether the consequences with e = 18 for hotel pools, high activity operating with a lighter under-dimensioned de- e = 14 for therapy pools humidifier during a period of time is acceptable. e = 20 spa/Jacuzzi* However in general, Dantherm recommends e = 2 8 for public swimming pools, water depth that dimensioning is carried out in accordance more than 1.35 m with peak load situations. e = 4 0 for public swimming pools, water depth less than 1.35 m e = 50 for wave pools * assumes 30 minutes operation and 30 minutes stop. When the sensitivity of the calculation must be assessed, it should be noted that the evaporation from the pool increases when: »» The water temperature increases »» The room temperature decreases VDI 2089 includes wet areas around the pool »» The RH value decreases (tiles, etc.) and overflow gutters in the epsilon »» The activity in the water increases factors. There is a large difference in the values for pri- USERS AND BYSTANDERS vate and public facilities, which results in dispro- When a public swimming pool is used for com- portionately large differences in the calculated petitive swimming, the temperature of both the humidity loads. In some cases, it is therefore air and water is usually reduced. This means that advisable to carry out an individual assessment the humidity load decreases, so that the extra of the level of activity and to set "e" accordingly. humidity contribution from the users and bystanders is counteracted by reduced humidity This can be done by selecting “manual water from the actual pool. transfer coefficient” in DanCalcTool, e.g. should an indoor pool at a university be assessed indi- It is thus not necessary to add separate humidi- vidually. It is not a public pool, but it should be ty contributions from users and bystanders. considered more as a hotel pool with a high level of activity. In that case, e = 18 can be chosen. 21 Copyright © Dantherm 2016 OUTDOOR AIR The air quality in a pool room is crucial for com- OTHER FACTORS fort, and poor air quality is often associated with The size of the room a high RH value and high levels of chlorine or The air circulation is just as important as the CO₂. capacity of the dehumidifier. If insufficient air moves around the room, there will be areas In other words, the addition of outdoor air is a where the dry air does not pass through and crucial factor in ensuring good comfort. At the thus those areas will not be dehumidified. The same time, the outdoor air is a crucial part of the room’s size is therefore crucial to how much basis for the choice of the type of dehumidifier volume of air the dehumidifier must be able to and the size of the dehumidifier. The outdoor air deal with. To learn more see "Air Circulation" on is often crucial for the dehumidification of the page 38. room, since the water content in the outdoor air normally is less than the water content in the Covering the pool room air. If the pool is covered over at night when it is not used, evaporation from the pool will be mini- During the summer, the outdoor air in some geo- mised. Doing this can save a lot of energy. graphical areas, primarily the Middle East and Asia, can for longer periods of time be so humid Room insulation that it is necessary to dehumidify the outdoor The worse the insulation, the lower the set- air before it is added to the room. For example, point for the RH value has to be. In some cases, this can be done using a cooling coil. 50 %RH may be required to avoid condensation problems. For examples of condensation prob- If the pool is used for competition swimming, lems, see: “Understand the air” on page 6. where there are greater numbers of users and bystanders, then a separate calculation for the Height (level) necessary volume of outdoor air must be made, In general, the formulas apply at atmospheric This calculation shall be made on the basis of pressure of 1,013 mbar (sea level), but they can local regulations. easily be applied to heights of up to 1,500 m. At higher heights, individual assessments should be carried out. 22 Copyright © Dantherm 2016 Copyright © Dantherm 2016 24 Copyright © Dantherm 2016 10 SELECTING THE TYPE OF DEHUMIDIFIER In the section "Which Type of Dehumidifier Should You Choose?" on page 15, some of the advantages and disadvantages of the two types of dehumidifier are stated, and where the two types are normally used. In this section, we will look in more detail at the different types of dehumidifier that Dantherm supplies – from small private pools, to major public swimming pools. Ventilation dehumidifiers DanX XD/HP DanX XKS/XWPRS/XWPS Condense dehumidifiers CDP/CDP-T 40, 50, 70 CDP 75, 125, 165 DanX AF 0 20 40 60 80 100 120 140 160 180 200 220 240 260 pool area in m2 25 Copyright © Dantherm 2016 CDP 40, 50 AND 70 CDP 40, 50 and 70 are condense dehumidifiers for smaller, private swimming pools and spa pools. They are positioned in the pool room. The three different sizes cover a dehumidification capacity of 34 l/day to 68 l/day. pool area in m2 0 26 Copyright © Dantherm 2016 20 40 60 80 100 120 140 160 180 200 220 240 260 CDP 40T, 50T AND 70T CDP 40T, 50T and 70T are condense dehumidifiers for smaller, private swimming pools and spa pools. They are positioned in the adjoining technical room. The three different sizes cover a dehumidification capacity of 34 l/day to 68 l/day. pool area in m2 0 20 40 60 80 100 120 140 160 180 200 220 240 260 27 Copyright © Dantherm 2016 CDP 75, 125 AND 165 CDP 75, 125 and 165 are condense dehumidifiers for larger private swimming pools, fitness centres, hotel pools and smaller public swimming pools. The dehumidifier is positioned in the technical room and the air is transported through ducts to and from the pool room. The control panel can be positioned on both sides of the dehumidifier, and the supply air can be blown in horizontally or vertically. Up to 15% of the outdoor air can be added by the dehumidifier via a separate outdoor air duct. The dehumidifiers are available in a version with a water-cooled condenser, so the excess heat can be used to heat the pool water or the utility water. The three dehumidifiers for connection to a duct system are available with a dehumidification capacity of 65 l/day to 162 l/day. pool area in m2 0 28 Copyright © Dantherm 2016 20 40 60 80 100 120 140 160 180 200 220 240 260 DANX AF DanX AF is a condense dehumidifier, i.e. the humidity condenses on a cold evaporator coil. This means that the cold part of the heat pump is used for dehumidification. DanX AF is a good solution for swimming pools with less activity, e.g. hotel pools and swimming pools where there is limited space, so the unit can be installed under the ceiling. It is perfect for controlling the air humidity and temperature, and at the same time, it has very low operating costs. It is possible to add up to 30% outdoor air. DanX AF is ideal when the requirements for the volume of outdoor air are less stringent, and in geographical areas where the outdoor air is so wet, that dehumidification is not possible with 100 % outdoor air. In such cases, the air can be recirculated and only a smaller volume of air will be replaced with outdoor air. pool area in m2 0 20 40 60 80 100 120 140 160 180 200 220 240 260 29 Copyright © Dantherm 2016 DANX XD DanX XD is a ventilation dehumidifier with a double cross-flow heat exchanger (2-step heat exchanger). DanX XD is a compact unit with high efficiency and has a built-in mixing, which ensures that only the necessary volume of air is replaced. Thus it ensures high comfort and very energy economic operation. pool area in m2 0 30 Copyright © Dantherm 2016 20 40 60 80 100 120 140 160 180 200 220 240 260 DANX HP DanX HP is a compact ventilation dehumidifier with a double cross-flow heat exchanger and heat pump (2-step heat exchanger). The combination of heat pump and highly efficient double cross-flow heat exchanger ensures very low operating costs and the optimal solution for low outdoor air temperatures. The integrated mixing ensures that no more outdoor air than necessary is taken in to achieve a good indoor climate. pool area in m2 0 20 40 60 80 100 120 140 160 180 200 220 240 260 31 Copyright © Dantherm 2016 DANX XKS DanX XKS is a ventilation dehumidifier with a very efficient cross-flow heat exchanger. DanX XKS is perfect for controlling the air humidity and temperature in a swimming pool, and with a temperature efficiency of up to 80 %, it reduces operating costs and energy consumption. The built in mixing function ensures that only the precise volume of outdoor air needed to maintain a pleasant climate is added. pool area in m2 0 32 Copyright © Dantherm 2016 20 40 60 80 100 120 140 160 180 200 220 240 260 DANX XWPS DanX XWPS is a ventilation dehumidifier with a cross-flow heat exchanger with a built-in heat pump. A temperature efficiency of up to 100 % reduces operating costs and energy consumption. The built-in mixing ensures that only the precise volume of outdoor air that is necessary for maintaining a pleasant indoor climate is added. To achieve even greater energy savings, a water-cooled condenser can be integrated in the heat pump. In this way, the excess heat can be utilised efficiently to warm the pool water or the utility water. pool area in m2 0 20 40 60 80 100 120 140 160 180 200 220 240 260 33 Copyright © Dantherm 2016 DANX XWPRS DanX XWPRS is a ventilation dehumidifier with a cross-flow heat exchanger with a reversible heat pump. This means it delivers the same functions and benefits as the XWPS. In addition, the reversible heat pump means the unit can operate with active cooling during the summer period. It is especially suitable for therapy baths with a high heat load from the hot pool water or buildings with large glass facades. pool area in m2 0 34 Copyright © Dantherm 2016 20 40 60 80 100 120 140 160 180 200 220 240 260 Copyright © Dantherm 2016 11 HOW TO DIMENSION THE DEHUMIDIFIER Once we have calculated the humidity load, When entering data into DanCalcTool, you do and we have determined the type of dehumid- not need to consider this. Based on the entered ifier we will use, we are ready to dimension the data, the program will automatically take into dehumidifier’s size and accessories. consideration the difference and give proposals with both condense dehumidifiers and ventila- A certain amount of safety is included in the cal- tion dehumidifiers, which can meet the require- culation. There is therefore no need for a safety ments. factor on the calculated humidity load when determining the size of the dehumidifier. If you do not use the DanCalcTool, but read the data on a capacity diagram, it is important that The dehumidifier’s necessary capacity is calcu- you choose the dehumidifier’s size on the basis lated a little differently, depending on whether of the actual operational data. it is a condense dehumidifier or a ventilation dehumidifier. THE DEHUMIDIFIER’S NECESSARY CAPACITY DEHUMIDIFICATION USING CONDENSE DEHUMIDIFICATION In a condense dehumidifier, both the dehumidifier and the outdoor air contribute to the dehumidification, so the dehumidifier’s necessary capacity, W capacity dehumidifier, is found by using the formula stated below. W states the humidity load calculated in accordance with VDI 2089. W capacity dehumidifier = W – W outdoor air W capacity dehumidifier can be read in the capacity diagrams in the catalogue material. If you use DanCalcTool, the capacity is read automatically and the program devises proposals for solutions. W capacity dehumidifier = necessary capacity dehumidifer (l/h) W outdoor air = minimum 15 % of the recirculated volume of air, K (m3/h), must be outdoor air in accordance with VDI 2089 W= humidity load according to VDI 2089 (l/h) W outdoor air = 0.15 × K ρ × (X indoor air – X outdoor air) (l/h) 1000 X outdoor air = water content outdoor air (g water/kg air) = 9 g water/kg air in accordance with VDI 2089 X indoor air = water content at setpoint in the swimming pool (g water/kg air) ρ = the air density = 1.175 kg/m3 36 Copyright © Dantherm 2016 DanCalcTool DEHUMIDIFICATION USING VENTILATION In a ventilation dehumidifier, the dehumidifier must be able to supply the necessary capacity with a summer load, because the outdoor air in those circumstances is the most humid. In this situation with 100 % outdoor air, the dehumidifier must have a minimum capacity that corresponds to the humidity load, i.e. W = W capacity dehumidifier, calculated in accordance with VDI 2089. For a ventilation unit, the dehumidifier must be installed in accordance with the volume of air, Q, which is replaced in the room. It is determined by the following formula: Q = 1000 × W capacity dehumidifier/(ρ × (X indoor air-X outdoor air) The volume of air, Q, can be found in the catalogue. If you use DanCalcTool, you will automatically be shown dehumidifier solution proposals in the program. Q = necessary air volume (m3/h) W capacity dehumidifier = necessary capacity dehumidifer (l/h) X outdoor air = water content outdoor air (g water/kg air) = 9 g water/kg air in accordance with VDI 2089 X indoor air = water content at setpoint in the swimming pool (g water/kg air) ρ = the air density = 1.175 kg/m3 37 Copyright © Dantherm 2016 12 AIR CIRCULATION The air circulation is defined as the total num- The air circulation, Z, is defined as the volume ber of times which the volume of air circulates of air in the dehumidifier divided by the pool in the room in an hour. room’s size. The air circulation must normally be Z = 3–10 Air circulation in a pool room is important, because air that moves does not condense as easily as air that is stationary. In other words, the air times every hour. 3 ≤ Z ≤ 10 circulation must not be too small, since this will give insufficient flow across surfaces. Very cold With small pools, the humidity load from the surfaces can cause condensation problems. pool is often so small, that the air circulation on Poorly insulated buildings lead to cold surfaces its own determines the size of the dehumidifier. and thus have a lot of influence on how much air circulation is required. In special cases, with a very small pool area in a large room, you can alternatively plan with On the other hand, excessively high air cir- zone division or with decentralised circulation culation is irritating in the form of noise and systems. draughts, so you cannot just circulate endless large volumes of air. Copyright © Dantherm 2016 Copyright © Dantherm 2016 13 AIR DISTRIBUTION Distributing the air in the pool room also plays If the room’s relative humidity is used as an in- an important role. It is important that critical put signal for the dehumidifier, it is important areas and surfaces are supplied with sufficient that the sensor is positioned in the extract volumes of dry air. duct or appropriately in the room. If it is placed in sunlight or in a position where it is hit by If you add outdoor air to the room, then exhaust splashed water, there will be a risk of erroneous air must also be extracted from the room. It is measurements. important because otherwise overpressure will occur in the room, which can lead to condensa- Avoid air being blown on the water surface, as tion in the walls and chlorine odour in the adja- this will increase the evaporation. The air above cent areas. It can be done by dehumidifying the the pool should be as still as possible and with a pool room with one system, while the adjacent maximal airspeed across the water of 0.15 m/s, areas are dehumidified using a separate venti- Of course due regard must be shown for swim- lation system. mers, so that they receive sufficient outdoor air. To ensure negative pressure the volume of ex- The return air, which is led back to the dehu- haust air + extract air should be approx. 10 % midifier, should be extracted from the opposite higher than the volume of supply air. A solution end of the pool room, so that “dead zones” are with a condense dehumidifier and addition of avoided where the air is not replaced sufficient- outdoor air, must therefore have an exhaust fan ly. installed. It is normally sufficient to position a return air To ensure negative pressure in the pool room, fan, which should be positioned high up in the control of the exhaust air should relate to the room, 3–5 m above the floor. In this way, the control of the outdoor air. short-circuiting of the supply air and the extract air is avoided. The control of outdoor air and exhaust air can among other things, be based on the following signals: »» Sensor for relative humidity »» Manual switch, e.g. cover. When the pool cover is rolled back, the dehumidifier starts automatically. »» CO₂ sensor, alternatively CO₂ equivalent sensor »» Time setting in relation to daytime and nighttime operation 40 Copyright © Dantherm 2016 There are two different ways to do this: Below grade ducting The warm dry air is sent up towards the window panes. This is the optimal way to distribute air, because it utilises the fact that warm air naturally rises up. In line with the dry air rising up, it draws in the humidity, and the humid air is extracted back to the dehumidifier via a return grate. The grate’s positioning is ideally 3–5 m high on the wall. Ceiling ducting Ceiling ducting can be used if the supply duct extends to the ceiling, because if required, dry air shall be blown on a skylight. Approx. 80 % of the air shall be blown on the windows, while the rest of the air is blown to the ceiling to avoid still areas with cold humid air. A skylight should add 10–20 % extra air because of the risk of condensation. 41 Copyright © Dantherm 2016 14 REGULATING THE VOLUMES OF AIR Condense dehumidifiers of air falls. If necessary, this can be solved us- Regulating the volumes of air in condense ing a de-icing kit (accessories). In this way the dehumidifiers must be done as precisely as dehumidifier can have an active de-icer, which possible to achieve the dehumidification ca- means that warm refrigerant is drawn through pacity, which is stated in the documentation. the evaporator, when this is about to ice up. The capacity in the documentation is stated at the nominal volumes of air and will change in If the volume of air is too high, e.g. because the line with changes in the volume of air passing dehumidifier works against a small duct pres- through the dehumidifier. sure loss, this leads to problems with lower capacity. Nominal volumes of air are stated on the ba- 42 Copyright © Dantherm 2016 sis of an external pressure loss. If the external Ventilation dehumidifiers pressure loss is exceeded, the result will be a In a ventilation dehumidifier, it is the volume of reduced volume of air, which will increase the air at 100 % outdoor air, which is the basis for risk of ice forming on the evaporator coil. The regulating the volume of air and dimensioning evaporation temperature falls when the volume of the ducts. 15 STEP BY STEP – HOW TO DIMENSION CORRECTLY There are many factors that play a part in deter- 1 mining how you shall dimension a dehumidifier Data for pool unit selection Project: Address: for an indoor swimming pool. Indoor temperature Indoor humidity Air volume Pool type: Date: Ref.: Air Summer: °C Air Winter: °C Summer: % RH Winter: % RH Summer: m³/h Winter: m³/h Private Summer: °C Winter: °C Summer: % RH Winter: % RH Supply: Pa Pressure drop Exhaust: Pa Public > 1,35 m Public < 1,35 m Wave deep deep °C Pool hall volume m³ Pool covered in the night time Outdoor temperature Outdoor humidity Hotel A manageable way to tackle the process is to Pool size: m² Water temp: Pool hall open in the summertime use “Dantherm Selection Software” and go Control system Included: Type of fans Heating coil Plug fans Water temp.: Supply air temp.: Capacity Separate cooling coil Supply temp.: Solution: through the following three steps. Yes Cables: Yes No No Requested meters: 2 speed belt driven 1 speed belt driven / °C Electrical: kW °C kW CW: °C Lacquering Dehumidifier (AF type) Internal Yes Fresh air damper: 1. First, you must determine the operational Ventilation with heat recovery (XKS type) data for the project. Here it is advantageous if No Ventilation with recovery and heat pump (XWPS type) are certain that you have included everything. Ventilation with recovery and reversible heat pump (XWP type) 2. The operational data is entered into the soft- R 407c External: °C R 134a Yes Water cooled condenser: Remarks: Yes Supply filter : °C R 717 No Yes Remarks: Extract filter: you use a checklist (see illustration), so that you °C / DX: Evaporation temp.: R 404c Supply filter : Water cooled condenser: Extract filter: Remarks: Supply filter : Water cooled condenser: Extract filter: Remarks: Yes Yes Dantherm Air Handling A/S . Marienlystvej 65 DK-7800 Skive Tel.: +45 96143700 www.dantherm-air-handling.com dantherm.dk @dantherm.com Fax: +45 96143800 . VAT No. 20864591 ISO 9001 & 14001 Certified Company ware’s calculation section, DanCalcTool, where it is used to calculate the possible solutions for the project. 2 3. We then select one or several solutions and have them modelled and verified in the configuration section, DanConfTool, which can then make a specific tender, for DanX. For CDP final selection is done according to datasheets. POOL DEHUMIDIFIERS CDP 3 IFIERS CDP POOL DEHUMID 3 DIMENSIONS CDP 35 DEHUMIDIFIER 800 Function 680 The CDP 35 is an energy-efficient and quiet pool dehumidifier. ItPOOL works in ac cordance with the condensation 800 680 DEHUMIDI principle. A fan draws the humid 800 680 dehumidifier and through air into the FIERS CDP 800 680 an evaporator coil. When passing TECHNIC through the evap orator the air ALdown is cooled DATAto below its dew point temperature, and its con tent of water vapour is condensed into315water, which falls into the Model drip tray and then is led from the drip tray to a drain. The cold, Operating dry air is then passed B condenser coil – humidity CDPover where itrange 35 the is re-heated, before leaving the unit at a Operating A range – temperatu temperature, which is approx. 40 – 100 %RH 5°C higher than at the315inlet. re 315 Air volume 315 10 – 36 °C Power supply 890 Applications: 250 m3/h 890 B Max. ampere 950 950 1x230/50 V/Hz A • Indoor swimming pools consumption Max. power consumpt • Therapy pools 2,8 A ion Refrigerant • Spas 0,72 kW position Drain outlet • Gymnasia Compressor R407C Quantity of refrigeran Rotary t Sound level (at 1 metre) 0,600 kg FEATURESWeight 47 dB(A) Colour • The CDP 35 is built into a strong 60 kg and robust powder-coated hot-galvanized Protection sheet metal cabinetclass RAL 7044 / 9016 • Evaporator and condenser coils are epoxy-coated for higher IPX4 corrosion resistance • All external and internal parts of the cabinet are powder-coated CAPACITY • The CDP 35 is fixedCURVES to the wall by means of a wall mounting strip supplied with the unit Min. 225 placing of 40 *400 40% • The condensate Recommended * outlet is locatedRH at the bottom of the60% RH35. The CDP stub can outlet 80% RH the CDP 35 35 be connected to a 1⁄2” water hose • Air intake through a filter that is placed behind the front panel Min. 225 • Radial 30 fan **400 • The CDP 25 35 can be floor mounted by means of a floor mounting kit (accessory) **800 20 • Optionally the CDP pool dehumidifier can be fitted with a water heating coil (accessory) 15 Min. 225 10 g kit Electronic Floor mountin 5 **800 controldimensions indicate the placing *The 1 in this series: Also available CDP 45 CDP 65 CDP 35T CDP 45T CDP 65T CDP 75 CDP 125 CDP 165 data sheets) (see separate 2 3 4 of the wall mounting strip The CDP 35 has a built-in hygrostat and is fully automatic with electronic trol. The hygrostat 0 con is factory set to approx. 60% 645 RH. * An easy to read display 0 current indicates the panel status 0,5 of operation. Min. 225 1 Accessories Room hygrostat kit Floor mounting kit Ext. failure monitoring coil Water heating data sheets) (see separate 1,5 1. Power on 2. Dehumidification – the compressor * is on 3. Cooling INSTALLA circuit failure TION – the dehumidifier is switched ffo 2 l/h 2,5 * Defrosting Passive, demand-controlled defrosting is incorporated in the electronic control. A sensor on the evaporator coil ensures that the evaporator is only defrosted when required. The compressor * is switched blows room air through the Warmer Dry Air ffo during defrosting and the fan evaporator, thereby melting 645 rator. the ice on the evapo - If the relative humidity has to Warm Wet Air the wall be adjusted to the flooraorremote frequently, *To be fixed room hygrostat can be connected to the CDP 35. s are in mm. All dimension Pool Area dantherm.com CDP 35/45/65 CDP 35/45/65 units hall or area to be are designed for installation directly in the pool dehumidified. dantherm.com 43 Copyright © Dantherm 2016 dantherm.com ELECTRONICS COOLING DEHUMIDIFICATION VENTILATION MOBILE HEATING & COOLING Dantherm The parent company is located in Denmark, and together with companies located in Norway, Sweden, Germany and England, and a sales office in Russia, Dantherm employs a total of 240 people. We operate in the following business areas: Dantherm Air Handling A/S Marienlystvej 65, 7800 Skive, Denmark www.dantherm.com Electronics cooling Climate control of electronics and batteries in radio base stations and other telecommunication infrastructure. Telecoms customers include network suppliers and network operators. Dehumidification Mobile and stationary dehumidifiers, for e.g. drying buildings and damage control, and for use in private pools and wellness centres. Ventilation Major ventilation units, which are used in swimming pools and for buildings that require large volumes of air replaced, e.g. in shopping centres and cinemas. The product programme covers residential ventilation units with high-performance, in-house manufactured heat exchangers and smart controllers. 01.17.XXX Thorvig Tryk, Skive Mobile heating and cooling Products for heating or cooling tents and equipment, which can be used by the defence sector and aid agencies. Customers include primarily the defence sectors in NATO countries and tent and container manufacturers.