In the past, active chilled beams needing to perform both cooling and heating in a space were installed in a 4-pipe system. This meant that, due to the construction of the chilled beam coil, approximately 75% of the tubes used will be circuited for cooling only and the remaining 25% of the tubes will be circuited for heating only. By creating these two circuits the coil is unable to produce the same capacity as a coil using all of the tubes for heating or cooling. To combat this, a 6-way valve can be used allowing all of the tubes in the coil to be used for heating and cooling. This allows for the flexibility of a true 4-pipe system with the performance of a 2-pipe system, at a lower first cost than a 4-pipe system.
A 6-way valve is essentially two three way valves in a single valve body with a common actuator that controls the water is being delivered to the beams. Supply and return pipes from the chilled and hot water systems are connected to four of the six ports on the valve while the other two ports are for the supply and return to a zone of beams. During the summer the valve is signaled by the Building Automation System (BAS) to open the chilled water sequence. When the season changes to winter the valve is signaled to flip shutting off the chilled water sequence and opening the hot water sequence. The valves change over between hot and chilled water and modulate flow rates to control temperature, rather than using mixing for control. However, because of the common zone piping, water in the two loops does mix together over time, so both loops must have the same chemical treatments, such as glycol percentages.
As mentioned earlier, by using a 6-way valve the chilled beam is now able to utilize all of the tubes of its coil and produce a higher capacity. This opens up the potential to use less primary air, less secondary water, and even less or smaller beams. The valve also saves money on the cost of installation. Since two pipes are used to supply water to a zone of beams the extra pipes from the 4-pipe system are no longer needed saving on the cost of copper and the labor to install them.