1. What material is required to zone a standard system?
In general you need:
- A control panel
- A thermostat per zone
- A pressure relief damper
- A motorized damper per zone
- A transformer
2. What should we know to select a pressure relief damper with an SMZ, RED series panel or a JTZ-HP?
This pressure surplus can be sent to the mechanical room, to a false ceiling, a basement, etc. However, it is essential that this excess pressure be dumped into an area covered by the zoning system to prevent the building or house from being in a negative pressure.
The by-passed air can also be ducted back to the return. The pressure relief damper is installed on the side of the supply duct before the first zone. Next you install a duct from the pressure relief damper to the return duct, as far away as possible from the equipment. This should be done far enough down the line to ensure that the dumped air is tempered to reduce any chance of damage to the compressor, the furnace fan or it's heat exchanger, etc. If the air is by-passed right at the unit, install sensor controls. It is always possible to install some probes or safety features if you consider it necessary.
Zoning a Retrofit System
Generally, in retrofit your duct sizing options are few. Plan on installing a by-pass damper in all retrofit applications.
3. When we zone an existing ventilation system, should we try to have about the same amount of CFM in each zone?
Yes. The best situation would be to obtain a balanced distribution of the total pressure of the system. An even distribution of the air will give better results and an easier installation. You should install a pressure relief damper.
Zoning a New System
4. Working in new construction, when a zoning system is going to be installed, should I consider it before I design the ventilation system?
Yes. The goal is to keep a constant velocity whether one zone or all zones are in demand.
Two or three zone systems:
Systems of four zones and more:
Questions on Zone Dampers
5. Is it possible to order some sizes of zone dampers, even if they are not in the DuroZone catalogue?
Yes, custom sizes of Multi-Blade dampers (PMB) and (MMB) are available.