Metasys UNT Series, Technical Manual

Page: 79 / 96

UNT Controller—Unitary Controller (UNT) 79
Appendix A: Precautions for
Rooftop Installations
Mount the UNT within the rooftop unit or some other enclosure to protect
it from rain, snow, etc. We recommend venting for small enclosures in
environments that regularly exceed 32°C (90°F). The installation site of
the UNT must meet the following environmental standards:
•
The atmosphere must be free of explosive gases, or corrosive
chemical or salt vapors.
•
The relative humidity (noncondensing) must be between 10 and 90%.
•
The temperature for the UNT110/111 series controllers must be
between 0 and 52°C (32 and 125°F).
•
The temperature for the UNT120/121 series controllers must be
between -40 and 52°C (-40 and 125°F).
Use the UNT120/121 series controllers in extremely cold environments or
where some condensation is possible. The UNT120/121 series controllers
have built-in heaters and conformally coated circuit assemblies. You must
mount the UNT120/121 series controller within a relatively small
enclosure, such as a BZ-1000-7, or within the confined area of the rooftop
unit’s wiring cabinet for optimal heater efficiency.
Instructions for installing a UNT in a rooftop unit are detailed in this
section:
1. Mount the UNT inside the rooftop unit or some other enclosure to
protect it from outside elements, such as rain, snow, etc.
2. Install a separate transformer (not the rooftop unit’s power
transformer) to provide 24 VAC power to the UNT. You may use a
line voltage to 24 VAC transformer or a 24 VAC to 24 VAC isolation
transformer. We recommend using one of the following transformer
types:
Note: Unless the UNT has a separate transformer, the UNT is prone
to resetting due to electrical noise within the rooftop unit.
Environmental
Information
Installation
Requirements