This Trane HVAC chiller serves four different apartments. Chilled water systems offer a great way for multi-zone air conditioning. From small apartment buildings to large commercial buildings chilled water systems can serve multi-zone air conditioning systems. From one air conditioning zone to hundred the only limitation is the size of the chiller. If the air conditioning zoning system (the load) is matched up with the right sized chiller (in tons) the system will serve all air conditioning zones and keep all the occupants comfortably cool. Chilled water systems can also be integrated with the boiler system so that the same system can be used for heating and cooling. A good control system will add efficiency and more comfort to the system.The big difference between a chilled water system and the standard DX split system units are that only one outside unit are necessary where with the DX split systems you need multiple condensers for each zone. The are a few exceptions for this but the alternatives are limited. This Trane chilled water system has a single chiller that serves four different air handlers with chilled water coils in the air handlers. The chilled water system and the air handlers are connected to each other via a chilled water piping system. The chilled water system provides excellent mutli-zone air conditioning systems. Air conditioning systems come in different varieties from chilled water air conditioning systems to DX cooling air conditioning systems. The chiller in this photo serves an apartment building with approximately 6 one to two bedroom apartments. The chilled water is piped to individual air handlers that serve each apartment so each apartment has its own air handling unit with a chilled water coil inside the air handler. A single chiller can handle multiple zones which makes a chilled water system ideal as compared to several different DX condensing units to handle each zone. In this case one chiller replaces six different DX condensing units to provide cooling for the apartments. The downside to a system like this is if the chiller breaks down then everyone loses cooling until the chiller is repaired. A complete DX cooling system would not have that problem as each air handler would have its own condenser. For zoning systems and having a smaller foot print with a single machine the chilled water system is ideal and can be more cost effective for serving multiple zones versus having separate DX condensing unit systems. In the winter the system is switched over to a boiler with the same set up as the chilled water system. The boiler produces hot water and piping is run to a hot water coil inside the air handler. The air handler distributes hot air throughout the zone it serves while the boiler keeps the water hot for the hot water loop just as the chiller keeps the water cold for use in the chilled water coils inside the air handler. The system was not set up to heat and cool at the same time so a little sacrifice has to be made by the tenants as different people have different comfort levels so usually a date is set by the maintenance staff for the changeover from heating to cooling and then another date to changeover from cooling to heating again in the Spring. There are some exceptions made in extreme circumstances but most maintenance departments stick to the dates so if there is a really cold day in late September and the switchover is not set to be changed over until October then some one will be cold. There are alternative systems for heating and cooling using chilled water systems and boiler hot water systems. It truly depends on the control and the piping set up where the above type of system is the cheaper alternative for heating and cooling in several different zones. The above described system is a four pipe system where the supply and return for the chilled water system enter and leave the coil and are pipe directly to the chiller or a chilled water manifold as is the hot water coil. The hot water coil is piped to the hot water loop or a hot water loop manifold. So each coil has it’s own return and supply that is piped directly to its own piping system that is dedicated to chilled water or hot water. A two pipe system would be piped so in the winter the chilled water piping is isolated and shut down and hot water is piped through a single coil in the air handler. Usually in a situation like this when the chilled water piping is isolated for winter operation the procedure is done manually. In the Spring the maintenance department manually switches the system for delivering chilled water. There are systems that offer automatic control of heating and cooling with absolutely no manual operation required.