Zone Priority Breakdown
Zone priorities are settings that you can apply to each zone under a CCU no matter the schedule type. The purpose for a zones priority is to make it so all zones can properly heat or cool to their desired temps. It is also a way to prioritize specific zones as "more important" in order to make sure the RTU/AHU prioritizes the zones under higher priorities than others. Sometimes this could be a certain persons office, or many times it can be zones that have large windows or get large amounts of sunlight. Priorities can make it so these zones do not get too warm from the sun, or too cool either.
How It Works
Each zone under a CCU can get their own priority, the levels are none, low, normal, and high priorities. Each CCU has its own separate pairings of zones that do not affect or communicate with other zones connected to other CCU's so setting a high priority on one CCU will not affect the conditioning of a zone under another CCU.
When we think about priorities and how they work think of them as a voting system. When all zones under a CCU are on normal priority they will each have 1 vote for every time they need conditioning. This system is dynamic and depending on how far off its desired set point the 1 vote even under a normal priority could be worth more than just 1 vote, but under normal priorities if we have a zone in your building that gets plenty of sunlight during the summer and tends to be slightly warmer than normal, its vote will not always be enough to sway the system its direction enough to cool it. This is when high priorities come into hand. If this zone that tends to be warmer than other zones is set to a high priority suddenly its 1 vote weighs a lot more on the system than the others under the same CCU. To prevent over-cooling or overheating the zones around this one will close its dampers and allow the airflow to only flow to the zone where the air is needed. Its important to keep in mind that if you put to many zones under 1 CCU into high priority they will end up fighting one another since they now all have the same weight to their voting once again. For zones that are less important or wide open areas that need less attention this is where we can set a "Low" priority. A low priority will do the opposite of a high priority, we will lower the vote of that zone and let its temperatures drift slightly more before it starts to ask for heating or cooling. Again this system is dynamic so it will not allow these low zones to get too cold or too hot as it will call for needed conditioning to prevent this. If we have an empty room, or a storage room that is used as a zone we can apply a "none" priority to these zones. What none does is it completely strips the zone of its voting and it will run the zone in setback during its schedules time.