York YAWS018 - 075 Installation Manual

York YAWS018 - 075 Installation Manual Manual pdf 12 page image

12Hydronic SectionGeneral guidelines are shown below for componentselection and design/installation criteria for the pipingsystem. Local codes supersede any recommendations inthis manual.Shut Off/Flow Regulation ValvesUse full port ball valves or gate valves for componentisolation. If valves are going to be used frequently, ballvalves are recommended. Globe valves are designed for flowregulation. Always install globe valves in the correct direction(fluid should enter through the lower body chamber).Check valvesSwing check valves must be installed in the horizontalposition with the bonnet of the valve upright. Spring checkvalves can be mounted in any position. A flow check valveis required to prevent thermo-siphoning (or gravity flow)when the circulator pump is off or when there are twocirculators on the same system.Storage (Buffer) TankA buffer tank is required for all hydronic heating systemsusing Water-Water heat pumps. The tank should be sizedto provide 2 gallons of storage capacity for every onethousand Btuh’s of nominal heat pump capacity.Pressure Relief ValveMost codes require the use of a pressure relief valve if aclosed loop heat source can be isolated by valves. Even iflocal code does not require this device, The manufacturerrecommends its installation. If the pressure relief valve inthe buffer tank is not already rated at 30 psi (207 kPa)maximum pressure, one must be installed. The pressurerelief valve should be tested at start up for operation. Notethat the waste pipe must be at least the same diameteras the valve outlet (never reduce), and valves may not beadded to this pipe. The bottom of the pipe must terminateat least 6” (15 cm) above the floor. If the piping is connectedto a drain, there must be an air gap.Backflow Prevention Check ValvesMost codes require backflow prevention check valves.Note that a single check valve is not equal to a backflowprevention check valve. Even if local code does not requirethis device, The manufacturer recommends its installation.This is particularly important if the system will useantifreeze.Pressure Reducing Valves or Feed Water ValvesThis valve lowers the pressure from the make-up water lineto the system. Most are adjustable and directional. A “fastfill” valve is required for initial filling of the system. Somehave screens, which must be cleaned after the initial filling.If there is a restriction in the screen, the system could go to0 psi (0 kPa), potentially causing pumps(s) failure. A valveshould be installed on each side of the pressure reducingvalve for servicing. Both valves should have tags reading“Do not shut this valve under normal operation – servicevalve only.”Expansion TanksExpansion tanks are required on hydronic systems to helpabsorb the pressure swings as the temperature in thesystem fluctuates.Elbows/TeesLong radius elbows or two 45° elbows will lower pressuredrop. Standard tees have a greater restriction on the “T”portion than tees designed with angled outlet ports.AntifreezeAntifreeze is required if any of the piping system is locatedin areas subject to freezing.Dielectric UnionsDielectric unions are recommended whenever connectingtwo dissimilar metals to one and other to prevent electro-galvanic corrosion.When using the various types of hydronic heat distributionsystems, the temperature limits of the geothermal systemmust be a major consideration. In new construction, thedistribution system can easily be designed with thetemperature limits in mind. In retrofits, care must betaken to address the operating temperature limits of theexisting distribution system. The maximum storage tanktemperature for the hydronic heat pump is 130°F (54.4°C).Typical in floor radiant systems require much lowertemperatures, typically 100°-115°F, which is ideal for thehydronic heat pump.AFFINITY SINGLE STAGE HYDRONIC INSTALLATION MANUAL