Carrier AquaSnap 30RAP010-150 Installation Instructions Manual

Also see for AQUASNAP 30RAP010-150: Start up & operation manual Installation instructions Controls, start-up, operation, service, and troubleshooting Controls, start-up, operation, service, and troubleshooting

Carrier AquaSnap 30RAP010-150 Installation Instructions Manual Manual pdf 24 page image

24For example, assuming a system containing a 20% concen-tration of ethylene glycol and 50 feet (15.2 m) in height fromthe top of the system to the expansion tank, the minimum tankpre-charge pressure would be:Tank Pressure = 4 + (50 / 2.38) = 25.0 psig= 27.6 + (15.2 x 22.6 / 2.38) = 171.9 kPaTable 2 — “X” Factor for Setting Tank PressureNOTE: If expansion tanks are placed elsewhere in the system thismethod cannot be used since extra pressure drop between the tankand the pump must be accounted for.NOTE: If the system requires a pre-charge greater than40 psig (276 kPa), increase pressure as described below.Expansion Tank Pre-Charge — To pre-charge the expansiontank, do the following steps:1. Check the tank air pressure at the pre-charge connectionwith an accurate pressure gage. Adjust as needed.2. If additional pressure is required, charge the tank with oil-free compressed air or nitrogen gas. Occasionally checkthe pressure as when filling a tire.3. Check the air valve for leakage. If it leaks, relieve thepressure and replace the core with a Schrader type tirecore. DO NOT depend on the valve cap to seal the leak.Once the system is pressurized, the pressure at the connec-tion point of the expansion tank to water piping will not changeunless the water loop volume changes (either due to addition/subtraction of water or temperature expansion/contraction).The pressure at this point remains the same regardless ofwhether or not the pump is running.Since the expansion tank acts as a reference point for thepump, there cannot be two reference points (two expansiontanks) in a system (unless manifolded together). If systemvolume or other design considerations warrant the placementof another expansion tank somewhere in the system, the expan-sion tank in the 30RAP hydronic package MUST be discon-nected from its hose and the end of the hose securely plugged.This is also true for applications where two or more 30RAPchillers are placed in parallel. There should not be more thanone expansion tank in the system (as seen in Fig. 20) unlessmanifolded together. When multiple 30RAP chillers are ap-plied in parallel, and the chillers include the optional hydronicpackage which contain expansion tanks (sizes 010-060), theexpansion tanks must be disconnected from the 30RAP hy-dronic package. It is permissible to install the expansion tank(s)in a portion of the return water line that is common to allpumps, providing that the tank is properly sized for combinedsystem volume.If the application involves two or more chillers in a primary/secondary system, a common place for mounting theexpansion tank is in the chilled water return line, just before thedecoupler. See Fig. 21 for placement of expansion tank inprimary/secondary systems.The expansion tank included in the 30RAP hydronic pack-age is a diaphragm tank, meaning that a flexible diaphragmphysically separates the water/air interface. With this type ofexpansion tank, it is undesirable to have any air in the waterloop. See the section on air separation below for instructions onproviding air separation equipment.AIR SEPARATION — For proper system operation, it isessential that water loops be installed with proper means tomanage air in the system. Free air in the system can causenoise, reduce terminal output, stop flow, or even cause pumpfailure due to pump cavitation. For closed systems, equipmentshould be provided to eliminate all air from the system.The amount of air that water can hold in solution dependson the pressure and temperature of the water/air mixture. Air isless soluble at higher temperatures and at lower pressures.Therefore, separation can best be done at the point of highestwater temperature and lowest pressure. Typically, this pointwould be on the suction side of the pump as the water is return-ing from the system or terminals. Generally speaking, this isthe best place to install an air separator, if possible.1. Install automatic air vents at all high points in the system.(If the 30RAP unit is located at the high point of thesystem, a vent can be installed on the piping entering theheat exchanger on the ¼-in. NPT female port.)2. Install an air separator in the water loop, at the placewhere the water is at higher temperatures and lowerpressures — usually in the chilled water return piping.On a primary-secondary system, the highest temperaturewater is normally in the secondary loop, close to thedecoupler. Preference should be given to that point on thesystem (see Fig. 18). In-line or centrifugal air separatorsare readily available in the field.It may not be possible to install air separators at the place oflowest pressure and highest temperature. In such cases, prefer-ence should be given to the points of highest temperature. It isimportant that pipe be sized correctly so that free air can bemoved to the point of separation. Generally, a water velocity ofat least 2 feet per second will keep free air entrained andprevent it from forming air pockets.Automatic vents should be installed at all physically elevat-ed points in the system so that air can be eliminated duringsystem operation. Provision should also be made for manualventing during the water loop fill. It is important that theautomatic vents be located in accessible locations formaintenance purposes, and that they be located where they canbe prevented from freezing.% GLYCOL ETHYLENEGLYCOL PROPYLENEGLYCOL0 (pure water) 2.31 2.3110 2.36 2.3320 2.38 2.3630 2.40 2.3840 2.43 2.3850 2.47 2.403432176 5LEGEND1 — Strainer2 — Blow-Down Valve3 — Service Valves4 — Discharge Check Valve(Dual Pumps Only)5 — Expansion Tank6 — Balancing Valve withDrain Plug7 — Field ConnectionsFig. 20 — Typical Dual Pump Package(010-030 sizes only)a30-5380