Application Note: Using a Belimo Zip Economizer Controller with 75F

Use Case:

In light commercial applications with small RTUs, the HyperStat is an ideal option.  However, it does not have the ability to natively perform economizer control.  In many applications, standalone economizer controllers, such as the Belimo Zip, are used to control the economizer as a supplement to the HyperStat.

Problem:

When standalone economizer controls are used, the BMS has no visibility into the state of the economizer unless the BACnet version of these devices are purchased and tied into the BMS.  This solution does not allow monitoring of the system, and more importantly, does not allow remote monitoring and alerting if the economizer controller fails.  Installing a traditional BMS in this application is a costly solution and may push the solution outside the budget of Facility Managers.  Zips also rely on CO2 sensors that are placed in the return duct, which only will accurately measure CO2 levels when the RTU fan is running.

Solution:

With a HyperStat, a Belimo Zip Economizer may be installed or left in place as the economizer controller.  The HyperStat will directly control the RTU with it's configurable relays with the native 75F sequences.  The HyperStat can also monitor the fault state of the Zip, while providing historical data and remote alerting through Facilisight.  If desired, the HyperStat may also be used for Demand Control Ventilation with it's onboard CO2 sensor and 0-10 VDC Analog Outputs.

Result:

• Lower cost implementation while exceeding benefits of a traditional BMS.
• Faults from the economizer controller can be remotely monitored, data historized, and generate remote alerts via email, text, and mobile or desktop push notifications.
• DCV is no longer reliant on a fan running, providing more accurate demand control ventilation and reducing cost during periods of low occupancy.
• Existing economizer controller can be reused, reducing overall job cost.
• Reduced overall install cost by using 75F.
• All of the benefits of 75F Facilisight and the data from the 8 onboard sensors from the HyperStat.

Notes:

• Requires a ECON-ZIP-BASE and a ECON-ZIP-EM.
• Custom alerts for alarm relay to be programmed by 75F Support
• See diagram below for terminations:

Belimo ZIP Configuration:

• Power RTU and enter Settings Menu.
  • Note: When the CO2 sensor is powered and DC 0...10 V is available at CO2+ and CO2, the ZIP Economizer will recognize the CO2 presence and the prompt to set up CO2 settings.
• Setting DCV settings.
  • With single speed indoor fan, only 2 DCV settings are required.
    • DCV Min Pos – This is the minimum occupied or zero occupancy ventilation rate expressed in damper percent open (Title 24 2013 section 120.1(b)2; ASHRAE 62.1 Section 6.2.7

• • • CO2 PPM Set Pnt – This is the CO2 concentration that is desired in the space (Title 24 2013 section 120.1(c)4. prescribed as 600 ppm plus outdoor air CO2 concentration assumed to be 400 ppm = a set point of 1000ppm).

HyperStat Configuration:

DCV Damper

Configure Analog-out2 as 'DCV damper' as shown below:

Configure the following additional options as follows:

Analog-out2 at Min DCV Damper will be set to 0V

Analog-out at Max DCV Damper will be set to 10V

CO2 Damper OpeningRate will be set to 10%

CO2 Threshold will be set to 3000 ppm

CO2 Target will be set to 1000 ppm