Daikin WRA Installation And Maintenance Data

Daikin WRA Installation And Maintenance Data Manual pdf 7 page image

IM 1072-1 Water to Water Source Heat Pumps Page 7 of 44Earth Coupled Application Closed LoopEarth coupled closed loop systems should follow the sameInternational Ground Source Heat Pump Association guidelinesused for closed loop heat pump applications. Once piping iscompleted between the loop pump kit and the earth loop, finalpurging and charging of the loop is required. A flush/purgeassembly capable of obtaining a velocity of 2 fps throughoutthe entire system is required. Usually a pump of at least 1.5 hpwill be adequate to purge air and dirt particles from the loopitself for most residential systems. Commercial systems mustbe sized carefully using pump manufacturer pump curves andsystem specific data. Flush the system adequately to remove asmuch air as possible then pressurize the loop to a static pressureof 20 to 30 psi. This is normally adequate for proper systemoperation. Check for proper flow through the unit by checkingpressure drop across the heat exchanger and compare it to thecooling and heating operating pressure tables on page 12. Inorder to achieve proper cooling capacity in a earth coupled closeloop application, a rate of 3 gpm per ton is required. Antifreezesolutions are required when low evaporating conditions areanticipated. Always use pressure/temperature ports to provideproper fluid flow rates.Typical Load Side ApplicationsThere are many load side applications for which the fluid tofluid liquid chiller heat pumps can be used. The most popularused would include: Hydronic baseboard heating, hydronic in-slab floor heating, forced air fan coil heating or cooling, ice andsnow removal, heating potable water, heating swimming poolsand spas, and process fluid heating and cooling. When specify-ing load side heat transfer surface it is important to consider theheat pump output capacities and fluid flow rates. Insufficientload side heat transfer surface may cause unstable heat pumpoperating. Pressure/temperature ports should always be usedto determine load side flow rates. Avoid contact of dissimilarmetals in the load side piping system.The units can provide heating or cooling for pools and spaswithout the use of a secondary heat exchanger. This applicationwould however require a cupronickel load side heat exchanger.Automatic chemical feeders must never be installed upstream ofthe heat pump. An external bypass should be installed to avoidover flowing the heat exchanger which could cause erosion.Proper pool PH levels and chemical balances must be maintainedto avoid possible heat exchanger damage.ApplicationsCooling Tower/ Boiler Application Closed LoopCooling Tower and Boiler Loop System temperature isusually maintained between 55°F and 90°F. In the coolingmode, heat is rejected from the unit into the source water loop.To reject excess heat from the water loop, the use of a closedcircuit evaporative cooler or an open type cooling tower witha secondary heat exchanger between the tower and the waterloop is recommended. When utilizing open cooling towerschemical water treatment is mandatory so that the water is freefrom corrosive minerals. It is imperative that all air be removedfrom the source closed loop side of the heat exchanger to protectagainst fouling.In the heating mode, heat is absorbed from the source waterloop. A boiler can be utilized to maintain the loop at the desiredtemperature. In milder climates a “flooded tower” concept isoften used. This concept involves adding makeup water to thecooling tower sump to maintain the desired loop temperature.When making water connections to unit sizes 036 thru 072,a Teflon taped thread sealant is recommended to minimize foul-ing of the pipes. Sweat connections are used for unit sizes 120thru 420. The water lines should be routed so as not to interferewith access to the unit. The use of short lengths on high pressurehose with a swivel type fitting may simplify the connections andprevent vibration transmission to the building.Before final connection to the unit, the supply and return hosekits must be connected together and the system flushed to removedirt, piping chips and foreign material. Ball valves should beinstalled in the supply and return lines for unit isolation and unitwater flow rate balancing. The return valve can be adjusted toobtain the proper flow rate whenever the unit heats or cools.CAUTIONWater piping exposed to outside may freeze.Pressure/temperature ports recommended both supply andreturn lines adjacent to the unit for system flow balancing. Flowcan be accurately set by measuring the refrigerant-to-water heatexchangers water side pressure drop.Well Water Application Open LoopWater pressure must be maintained in the heat exchanger byplacing water control valves at the outlet of the unit. A bladdertype expansion tank may be used to maintain pressure on thesystem. Pressure/temperature ports should be used to set flowrates by checking pressure drop across the heat exchanger. Avoidusing low voltage (24 volt) solenoids, using them may overloadthe unit transformer or interfere with the lockout impedancecircuit. Line voltage solenoids across the load side of compres-sor contactor are recommended. Normally residential systemsrequire about 2-gpm of flow rate per ton of cooling capacity isneeded in open loop systems.Discharge water from a heat pump is not contaminated inany manner and can be disposed of in various ways dependingon local building codes.Disposal methods may be by recharge well, storm sewer,drain field, adjacent stream or pond. Most local codes forbid theuse of sanitary sewer for disposal. Consult the local buildingand zoning department to determine compliance in your area.