NATATORIUM ENVIRONMENTAL CONTROL SYSTEM
Description of Design and Operation of the Dual Fan PoolPak System
In order to control a natatorium environment and structurally maintain a building, the following functions must be provided: · Ventilation to satisfy health and safety code requirements. · Space heating to maintain a comfortable environment for the occupants and minimize evaporation. · Dehumidification to prevent condensation from destroying the building. · Pool water heating to make the pool enjoyable to swimmers. The PoolPak unit provides these functions and does so at the lowest operating cost. This manual includes a step-by-step narrative of the PoolPak's control functions and features. Automatic Control of Air and Water Temperatures and Humidity
An integral part of the PoolPak system is a proven microprocessor control which automatically senses and maintains comfort conditions. Sensors detect changes in natatorium air temperature and humidity, quickly regulating supply air conditions to meet set point comfort levels even during periods of unusually heavy pool use. PoolPak also continuously monitors pool water temperature and adds heat as necessary. To prevent condensation on walls and windows, PoolPak automatically adjusts humidity in response to changes in wall or window surface temperature. As seasons or weather conditions change, PoolPak alters its method of operation accordingly. Throughout the year, PoolPak thinks "efficiency" and automatically selects the least expensive energy source for pool air and water heating needs. Reduction in Energy Costs
PoolPak dramatically reduces energy costs in two important ways: · By recovering exhaust air heat and returning it to the indoor pool environment. · Closely controls indoor air conditions so minimum outside air is necessary to heat it. PoolPak offers significant advantages compared to either conventional heat and ventilation natatorium systems, which waste energy and money by exhausting large volumes of indoor air, or to improperly applied dehumidifiers that may provide inadequate control. Application of Heat Pump Technology
Through the use of heat pump technology, PoolPak automatically performs the following seven functions: · Dehumidification/Humidity Control · Natatorium Space Heating · Pool Water Heating · Proper Ventilation Control · Recovery of Reusable Heat · Natatorium Space Cooling · Wall Condensate Prevention Prevention of Building Damage
Effective control of humidity and temperature conditions in the indoor pool environment eliminates condensation on interior surfaces. Laden with pool chemicals, this condensation encourages mold, mildew, paint blistering/peeling and rust. Steel supports, lockers, light fixtures and hardware along with heating and air conditioning systems can quickly corrode beyond repair. In many cases, reinforcement steel embedded in concrete can be seriously damaged or weakened by the percolating effects of pool chlorine and moisture condensation. The installation of PoolPak equipment significantly reduces routine maintenance costs while preventing structural damage. Off-Evaporator Temperature and Relative Humidity Sensor Pool Air Entry (Return Air Top, Side or Bottom) Outside Air Temperature and Relative Humidity Sensor Fresh Air Outside Air Damper Recirculated Air Damper Supply Air Space Temperature and Relative Humidity Sensor Pool Water Supply and Return Connectors Optional Gas Heat Supply Fan and Drive Assembly Auxiliary Heat and Cool Coils (Optional) Condenser/Reheat Coil (Air Heating Coil) Exhaust Air Exhaust Air Damper Air Filter Return Fan and Drive Assembly Aquastat Pool Water Heating Condenser PoolPak Isometric View Figure 1. Receiver Scroll Compressor(s) Control Panel Air Filter Condensate Drain Outlet Evaporator (Heat Recovery Coil) Optional Air-Cooled Condenser Figure 1. PoolPak Isometric Component Drawing Functional Description of System
Primary Function The primary function of the PoolPak system is to provide environmental control of the space through the use of heat pump technology. Heat from the warm, humid pool air is recovered for reuse while the air is dehumidified and cooled. The recovered heat is then used to heat the supply air and, if necessary, the pool water. System Description (see Figures 1 and 2) Warm, humid air from the pool enclosure is received in the return air section of the PoolPak. The return air is cooled and dehumidified as it passes over the evaporator coil. The sensible (dry) and latent (moist) heat is extracted from the return air and absorbed by the refrigerant in the evaporator coil, causing the refrigerant to flash to a vapor. As refrigerant gas leaves the evaporator coil it is supplied to the suction of the compressor where it is compressed to a higher pressure and temperature. The high pressure hot gas from the compressor can be supplied as required to the condenser/ reheat coil, the pool water condenser or the optional auxiliary condenser (either air or water cooled) by automatically controlled solenoid valves. 2 The return fan discharges the cool/dry air into the smart economizer where automatically controlled dampers exhaust a calculated portion of the air. The dampers mix re-circulated air from the evaporator with outside air. This air mixture is then drawn over the condenser/reheat coil by the supply fan. Hot gas supplied to the condenser/ reheat coil releases the recovered sensible and latent heat along with the added heat from the compressor to the supply air as it passes over the coil, causing refrigerant to condense into a liquid. This hot liquid refrigerant is then stored in the receiver. If an optional auxiliary heating system is installed, the air is heated further by the system as required. The supply fan then supplies the warm, dry air to the pool enclosure. Hot gas supplied to the pool water condenser gives up the recovered heat to the incoming cool pool water, causing the refrigerant to condense. Optionally, hot gas supplied to the auxiliary condenser removes the heat from the refrigerant gas. The hot liquid refrigerant is then stored in the receiver. Liquid refrigerant stored in the receiver passes through the expansion valve where it is expanded to the operating evaporator pressure and temperature. An auxiliary pool water heater is installed in the pool water return line. The auxiliary pool water heater is automatically controlled by the PoolPak and is turned on only when the heat available from the PoolPak is insufficient to heat the pool water. Figure 2. PoolPak Natatorium Environmental Control System Schematic S
Outside Air Compressor To Air Cooled Condenser, Water Cooled Condenser or Cooling Tower Condenser (optional) Solenoid Valves Auxiliary Heating Coil (optional hot water, natural gas, steam or electric) T H S Dampers T
Warm Return Air from Pool T
H Economizer
Supply Air
Supply Fan H
Evaporator Coil Expansion Valve Return Fan S Dampers Exhaust Air Receiver Condenser/ Reheat Coil T
H Temperature Sensor Relative Humidity Sensor Hot Liquid Refrigerant Hot Gas Refrigerant Cold Liquid Refrigerant Cold Gas Refrigerant Pool Water Condenser From Air Cooled Condenser, Water Cooled Condenser or Cooling Tower Condenser (optional) Cool Pool Water Warm Pool Water Auxiliary Pool Water Heater (required) 3 Recommended Pool Water Temperatures
Application Competitive Swimming Diving Pools Residential Pools Recreation Pools Therapy Pools Whirlpools
4 Recommended Temperature Settings 77°F to 80°F 82°F to 86°F 82°F to 84°F 80°F to 85°F 86°F to 92°F 99°F to 104°F Economizer Psychrometrics
The first stage of environmental control for the PoolPak is the economizer with the compressors off. The PoolPak control function to be discussed on each figure is highlighted on the left side of the page. The PoolPak components that pertain to that PoolPak control function are highlighted in the schematic. Ventilation and economizing is provided and controlled via: · Return Air Temperature and Humidity Sensor · Return and Supply Fans · Exhaust Air, Outside Air and Recirculation Air Dampers · Outside Air Temperature and Relative Humidity Sensor Anywhere from 0% to 100% of the return air can be exhausted from the natatorium depending on indoor and outdoor conditions. The PoolPak supply fan provides approximately 5% - 10% less airflow than the return fan to maintain negative pressure in the natatorium. Ventilation and Economizer
In the lower right hand corner of the figure below is the natatorium. To its left is the pool filter, circulation pump and auxiliary pool water heater. Above it is a PoolPak dual fan air handling system. To emphasize that the PoolPak is a totally factory packaged environmental control system including all the refrigeration components and control hardware and software, everything in the dark black outlined rectangular box is factory mounted/supplied with the PoolPak dual fan unit. 5 Economizer Psychrometrics
In the PoolPak control system, the psychrometric chart is stored in the memory. The set-points are entered into the PoolPak control system by the building operator. On the psychrometric chart, the set-points (82°F and 60% RH) are indicated by the point where the 82°F dry bulb line and 60% relative humidity line intersect. The PoolPak controls use these two set-points to divide the psychrometric chart into quadrants along the vertical 82° dry bulb line and the horizontal absolute humidity point or dew point line. Below is a description of how the PoolPak's economizer responds to every indoor and outdoor temperature and humidity condition. A. Air coming back from the natatorium (point "A") is too hot and too humid. The control system looks to see if the outside air is cooler and dryer than the air coming back from the pool. In this case, the PoolPak controls will look for outside air that is anywhere to the left of the vertical dry bulb line and below the dew point line because this air is cooler and dryer than the return air. When these indoor/outdoor air conditions occur, the PoolPak controls will bring up to 100% outside air into the space to bring area conditions back to the set-point. B. Return air at point "B" is too hot but the humidity is OK. The PoolPak controls will look to see if the outside air is cooler than the return air. Humidity is not a concern in this situation. When condition "B" occurs, the PoolPak controls bring in up to 100% outside air that is anywhere to the left of the 82° dry bulb line. The air is going to be cooler and will once again give free economizer cooling. C. Return air too cold and too humid, point "C". In this case, the PoolPak control system will look to see if outside air is warmer and dryer than the return air. Outside air in the bottom right quadrant of the psychrometric chart will satisfy this condition. When the outside air is in this quadrant, the PoolPak controls bring in up to 100% of the warmer/dryer air to bring space conditions to the set-point. D. The return air at point "D" is too cold but humidity is OK. The PoolPak controls bring in outside air that is warmer than the return air. That means the PoolPak controls brings in outside air that is anywhere to the right of the 82° dry bulb line. Space Setpoint Conditions 60%
Dewpoint Line Return Air (Too Hot, Too Humid) Space Setpoint Conditions 60% Absolute Humidity A Absolute Humidity B
Outside Air Cooler and Drier Than Return Air
Outside Air Cooler Than Return Air Return Air (Too Hot, Humidity OK) 82 82 Return Air (Too Cold, Too Humid) Space Setpoint Conditions Space Setpoint Conditions 60% 60% C
Outside Air Warmer and Drier Than Return Air Absolute Humidity D
Return Air (Too Cold, Humidity OK) Outside Air Warmer Than Return Air Absolute Humidity 82 82 The PoolPak heating, cooling and dehumidifying economizer logic will always first try to maintain space temperature and humidity while keeping the compressor de-energized. This mode of operation is the most energy efficient. 6 Heating Via Heat Recovery
To accomplish heating via heat recovery, a multi-stage refrigeration loop is included with the PoolPak consisting of: · Evaporator Coil · Compressor(s) · Condenser/Reheat Coil · Receiver As the return air (space) temperature drops below set-point, the first stage of refrigeration is activated. The PoolPak will remove the latent and sensible heat in the return air as it passes through the evaporator. A portion of the cold air off the evaporator is exhausted from the mixing box to satisfy the ventilation requirement. The recovered latent, sensible and compressor heat are absorbed by the refrigeration system. This heat is put back into the supply air stream at the condenser/reheat coil which is down-stream of the outside air intake. As the space temperature continues to drop, the subsequent stages of the refrigeration system are activated and continue to heat the natatorium space. 7 Heating/Auxiliary
When the refrigeration system cannot maintain the natatorium space temperature, such as on a heating design day, the last stage of heat is activated. The last stage of heat, an auxiliary heater (which can be low pressure hot water, steam, electric resistance or gas furnace) is turned on via the PoolPak's control system. This last stage should be sized to have enough heating capacity to do the entire job of heating the natatorium. The last stage does not necessarily need to be located in the PoolPak. If the pool's existing space heating system is in good condition, the PoolPak can bring it on as the last stage of heat. 8 Smart Economizing
The smart economizer operation is the simultaneous operation of the heat recovery and the economizer cycle in the space heating mode, allowing the PoolPak to take advantage of the outside air for space heating. When the refrigeration loop is running and the space is calling for heat, the air passing over the evaporator is being cooled to saturation. The PoolPak control system measures the condition of air leaving the evaporator with temperature and humidity sensors in the off-evaporator air stream. Remember there is also a temperature and humidity sensor located in the outside air stream. The PoolPak control system is constantly comparing the leaving-evaporator air and outside air conditions (see psychrometric diagram below). If the outside air is warmer and dryer than the leaving-evaporator air, the control system will automatically close the recirculation damper, open the exhaust and outside air dampers 100%, exhaust 100% of the cool, saturated air coming off the evaporator coil, bring in 100% of the dryer, warmer outside air and then pass it over the condenser coil, heating this outside air with heat recovered in the evaporator and compressor. This air is then sent to the pool. Using the smart economizing cycle, a significant amount of heat energy is saved which can be used for pool water heating. The smart economizer may save an owner $2,000-$4,000 per year in energy that standard economizer-mixing boxes cannot. This smart economizing is only possible if (A) the dehumidifier has a mixing box, (B) it is located downstream of the evaporator and upstream of the condenser as we have shown here, and (C) contains control software that knows what action to take when the proper energy saving conditions occur. 9 Dehumidification
For dehumidification, the following items are included in the PoolPak: · Humidity Sensor in the Return Air Plenum Section · Drain Pan Covering the Entire Length of the PoolPak · Multi-Stage, Multi-Directional Refrigeration System When space humidity rises above the set-point, the PoolPak activates the first stage of the refrigeration system. The humidity is removed from the return air via the evaporator coil. The sensible and latent heat along with the compressor heat are recovered and made available for space or pool water heating. As the humidity continues to rise, additional stages of the refrigeration system are activated. The second stage is usually required when the pool is being moderately used. When the pool is being heavily used and the evaporation rate is extremely high, the PoolPak's final stage is activated. This final stage always has enough moisture removing capacity to keep the relative humidity below the desired set point. Moisture collected during the dehumidification process can be returned to the pool via the filter system (if allowed by code) or drained to the sewer. 10 Pool Water Heating
To perform pool water heating, the following items are included in the PoolPak: · · · · Cupro-Nickel Tube-in-Tube Pool Water Condenser Aquastat Isolation Valves Flow Switch Pool water heating is controlled via the "B" refrigerant solenoid valve. Control of the main pool water heater is taken over by the PoolPak. As can be seen in the schematic, the thermostat for the auxiliary pool water heater is wired into the PoolPak's aquastat. The dashed line on the diagram below is a control wire (not a pipe). The PoolPak will keep the auxiliary pool water heater "locked out" until the PoolPak cannot supply all the pool water heating requirements. Typically the PoolPak will provide 70% to 80% of the pool's water heating needs. A secondary pool water circulation loop and pump, supplied by others, are required. The pool water circulation loop brings pool water from the filter system, past the PoolPak mounted aquastat into the pool water condenser where the water is heated. The heated pool water is then returned to the pool via the return leg of the secondary circulation loop. 11 Wall Condensate Prevention
One of the more significant control features of the PoolPak is its ability to prevent condensate from forming on the walls of the natatorium. This benefit is accomplished by mounting a temperature sensor in the natatorium on the inside of an exterior wall that will encounter the lowest natatorium temperatures. The best location for this sensor is on the inside of a window frame or door frame of a north-facing wall. As the outdoor temperature drops, this condition is monitored by the wall sensor. When the wall temperature drops and approaches the condensing temperature (or dewpoint) of the air in the natatorium, the PoolPak automatically resets the humidity set-point downward in order to lower the dewpoint of the air. By lowering the air's dewpoint, condensate is prevented from forming on the natatorium walls. 12 Flywheel Air Conditioning
Flywheel air conditioning uses the enormous thermal mass of the swimming pool as a heat sink during the day. Flywheel air conditioning does not require any remote condensers and is typically used in locations that have warm days and cool nights. During the day while the natatorium is occupied and space cooling is required, the outside temperature is cooler than the inside temperature and the PoolPak will cool the space with its 100% outside-air economizer. This condition usually occurs from the time the pool opens in the morning, about 6 am, until the outside temperature rises above the inside temperature in the early afternoon, about 12:30 p.m. The graph below illustrates this point. When the outside temperature is higher than the inside temperature the PoolPak reduces the outside air to the minimum quantity and cools the space mechanically. The PoolPak will only activate the number of mechanical cooling stages needed to meet the cooling load. The heat removed from the air is stored in the pool water. The space is mechanically cooled for a total of about 7 hours. During this air conditioning mode the water temperature can rise about one degree above the set-point. The PoolPak controls limit this rise to a maximum of two degrees. This pool water temperature rise is offset by the evaporative cooling effect occurring throughout the entire occupied period. Water agitation by the swimmers will accelerate this evaporative cooling effect. When the outside air temperature drops back below the inside temperature in the early evening, about 7:30 p.m., the PoolPak resumes space cooling with its economizer. The economizer cooling continues until the pool closes, about 11:00 p.m. If the pool temperature is below set-point at closing, the PoolPak controls close the outside air dampers until the pool opens the next morning. Should the water temperature exceed the set-point at closing time and additional pool water evaporative cooling is required to return the water temperature to set-point, the economizer operation continues circulating the cooler and dryer night air over the water until the pool water reaches set-point. In this night mode the pool water evaporation rate increases dramatically because the pool water is warmer than the air above it. Weather Data, Grand Rapids, MI Economizer Air Conditioning Night Purge Economizer Air Conditioning Mechanical Air Conditioning Pool Closes Night Purge Legend Pool Room - Dry Bulb Outdoor Conditions 13 Chilled Water Air Conditioning
If chilled water is available at the natatorium, then a chilled water coil and control valve can be installed in the PoolPak down-stream of the auxiliary air heating coil. When cooling is needed for a space, the PoolPak controls open the chilled water valve. The coil cools and dries the air which is delivered to the natatorium. If there is a simultaneous call for space cooling and pool water heating, the PoolPak controls will shut the chilled water valve and activate the refrigeration system. Heat recovered from the evaporator coil is used to heat the pool water. 14 Remote Air-Cooled Condenser Air Conditioning
For this cooling mode, a third refrigerant solenoid valve ("C") and refrigerant stubouts are provided with the PoolPak. These stubouts are connected to a remote air-cooled condenser via field-supplied and field-installed piping. When cooling is called for in the space, the PoolPak controls open the "C" solenoid valve and close valves "A" and "B." The PoolPak's refrigeration system removes heat from the natatorium and rejects the heat to the outside air through the external air-cooled condenser. The evaporator coil cools and dries the air which is delivered to the natatorium. If there is a simultaneous call for space cooling and pool water heating, the PoolPak controls will close the "C" solenoid valve and open the "B" valve. The heat recovered from the evaporator coil is used to heat the pool water. 15 Cooling Tower Condenser or Chilled Water Condenser Air Conditioning
In this mode a cooling tower water-cooled condenser module or chilled water condenser module are provided. The refrigerant side of this water condenser is attached to the "C" solenoid valve. When cooling is called for in the space, the PoolPak controls open the "C" solenoid valve and close valves "A" and "B." The PoolPak's refrigeration system removes heat from the natatorium and rejects the heat through the cooling tower water condenser or chilled water condenser. The evaporator coil cools and dries the air which is delivered to the natatorium. If there is a simultaneous call for space cooling and pool water heating, the PoolPak controls will close the "C" solenoid valve and open the "B" valve. The heat recovered from the evaporator coil is used to heat the pool water. 16 Summary of Control Strategies
This page summarizes all the control strategies described previously. In addition, another control feature can be provided as follows: · Domestic hot water or spa water heating which is accomplished by installing a desuperheater in the refrigerant discharge line of the compressor. In summary, the PoolPak can provide: · Ventilation and Economizing · Heating via Heat-Recovery and an Auxiliary Heating Coil · Smart Economizer · Dehumidification · Pool Water Heating · Wall Condensate Prevention · Air Conditioning via Flywheel, Chilled Water Coil, Remote Air-Cooled Condenser, Chilled Water Condenser and Cooling Tower Water Condenser · Domestic and Spa Water Heating 17 Off-Evaporator Temperature and Relative Humidity Sensor Pool Air Entry (Return Air Top, Side or Bottom) Outside Air Temperature and Relative Humidity Sensor Fresh Air Outside Air Damper Recirculated Air Damper Supply Air Space Temperature and Relative Humidity Sensor Pool Water Supply and Return Connectors Optional Gas Heat Supply Fan and Drive Assembly Auxiliary Heat and Cool Coils (Optional) Condenser/Reheat Coil (Air Heating Coil) Exhaust Air Exhaust Air Damper Air Filter Return Fan and Drive Assembly Aquastat Pool Water Heating Condenser Figure 1. PoolPak Isometric View Receiver Scroll Compressor(s) Control Panel Air Filter Condensate Drain Outlet Evaporator (Heat Recovery Coil) Optional Air-Cooled Condenser 18 Selection and Specifications
ENGINEERED FOR RELIABILITY Designed for continuous exposure to corrosive pool moisture and outdoor weather, PoolPak eliminates the high maintenance and service requirements typical of conventional pool environmental control equipment. All-copper coil construction and multi-stage, special-duty compressors add to the long-term durability built into every PoolPak system. INSTALLATION FLEXIBILITY The PoolPak system easily adapts to new construction, retrofit or replacement applications. It can be roof-mounted, installed at ground level outdoors or installed indoors, providing flexibility to meet virtually any architectural requirement. SELECTION ASSISTANCE Swimming pools and their enclosures vary greatly in size, design and use. As a result, selecting the right size for your application depends on a range of factors, and should not be based solely on moisture evaporation rates. A local PoolPak representative can select the right system for all your needs. General PoolPak Selection Criteria:
· Building size and construction · Typical design conditions (water temp. range: 78°F - 82°F, air temperature, 2°F above water temperature, relative humidity, 50% - 60%) · Total pool surface area · Building design heat loss · Moisture evaporation rates (max/min) · Average hours of pool area use · Air flow volume rate · Method of air distribution · Additional areas served by system (changing rooms, halls, etc.) · Ventilation for odor control 19 PoolPak Selection Chart
The following chart is provided for general reference only. A PoolPak International, Inc. representative will gladly help you determine the optimum PoolPak system for your specific requirements. PoolPak System Total Pool Surface Area in Square Feet
1000 Model Size (Ft.) Wt.lbs (Approx.) Input Power Max. Heat Recovery (MBH) COP Air Flow Range (CFM) SWHP80 2000 SWHP100 3000 SWHP120 4000 SWHP140 20' x 8' x 6' 5000 SWHP190 6000 SWHP220 7000 SWHP260 24-1/2' x 8' x 8-1/2' 8000 9000 SWHP300 15-3/4' x 4-1/2' x 5' 5,000 5,500 8,000 9,000 10,000 12,500 12,500 14,000 208/230/460/575 VOLT/3 PHASE/60HZ 226 5.4 5,5008,000 280 5.1 6,50012,000 350 5.1 8,00015,000 415 5.4 10,00018,000 482 5.1 11,00020,000 560 4.8 15,00024,000 719 4.6 18,00028,000 849 4.5 21,00028,000 No other dehumidification system works like a PoolPak because no other system is built like one. info@poolpak.com . www.poolpak.com M52MK-NATAT0502 3491 Industrial Drive . York, PA 17402 . USA 800-959-7725 . Fax 717-757-5085