Digi-RTU For Packaged Rooftop Units
The Digi-RTU® is a control kit for HVAC Direct Expansion (DX) unit (package rooftop unit, water-source heat pump, split system). It optimizes the HVAC DX unit operation by modulating the speed of both compressor(s) and indoor fan, the number of compressors in operation to match the space load.
Cooling Control
Cooling call is initiated by the existing T-stat or BAS system. The controller will turn on optimal number of compressors and modulate the cooling capacity output to match the space load and modulate the supply fan speed to maximize the coil performance.
Heating Control
Heating call is initiated by the existing T-stat or BAS system. The controller modulates the fan speed to maintain the supply air temperature at the optimal set point.
Demand Control Ventilation
The controller measures the return air CO2 concentration and modulates the outside air damper and fan speed to maintain the return air CO2 concentration set point. Digi-RTU DCV control complies ASHRAE Standard 62.1 and California Title 24.
Ventilation Control
When there is no cooling or heating call, the fan speed is set at the minimum ventilation speed. If the return air CO2 level is higher than the required level, outside air damper starts to modulate open. When the outdoor air damper position is at the high limit and the CO2 concentration is still higher than the set point, the fan speed is modulated to maintain the return air CO2 set point.
Economizer Control
During the economizer cycle the controller controls the room temperature at or below the room set point by modulating the supply fan speed. The controller modulates the outside air damper to maintain supply air temperature at the optimal set point.
Integrated Economizer Control
When the outdoor air temperature is lower than the economizer high limit or the outdoor air temperature is lower than the return air temperature, the Digi-RTU optimizes the fan and compressor speed and outside air damper position to maximize outside air intake and ensure safe compressor operation.
Remote Monitoring and Control
Cloud-based energy management feature
- Excellent room temperature and humidity control.
- Reduces peak electricity demand by up to 50%.
- Reduces electricity consumption by 40% to 80%.
- Reduces compressor cycling and extends its service life.
- Reduces maintenance costs.
- Reduces noise at the conditioned space.
The Digi-SBM® provides Building Owners and Service Contractors digital ‘eyes’ for improved comfort, energy performance and reduced O&M costs.
Installing Digi-SFT® provides exceptionally modernized tools for large corporations and Facility Service Providers.
- Plug and play; easy installation and set-up with minimal cost.
- Clear and easy graphic view of operational performance.
- Fault detection & diagnostic functions
Prevents excessive HVAC run hours. - Verifies energy savings automatically and remotely
Simple cost payback within one year. - Reduces O&M costs by generating specific repair lists prior to dispatching a technician.
Case Studies – HVAC Rooftop
Distribution Center ASHRAE Climate ZONE 5
Water – Sourced Heat Pumps
Public School
ASHRAE Climate ZONE 5
- What is a Digi-RTU®? A Digi-RTU® is an aftermarket control kit designed to improve the energy efficiency of a rooftop air conditioning unit.
- What is the typical payback period for a Digi-RTU®? The simple payback period varies from 1 to 4 years depending on factors, such as the local utility rate, the area climate zone, the rooftop unit capacity, and available incentives and rebates provided. by utility companies.
- How does the Digi-RTU® work? The Digi-RTU® modulates the capacity of a roooftop air conditioning unit to match the cooling or heating loads by regulating both the supply air fan (VAF) and compressor speed (VRF).
- Can a Digi-RTU® be installed in any rooftop unit? The Digi-RTU® can be installed on in any rooftop unit.
- Is a Digi-RTU® sized according to the rooftop unit? Yes, the Digi-RTU® is sized based on the rooftop unit.
- How long does it take to install a Digi-RTU®? It takes about 3-6 hours to install and test a Digi-RTU®.
- What is the communication protocol that comes with a Digi-RTU®? It comes with a native Modbus-RTU communication protocol. A Gateway can be used for the BacNet and Lon Work communication protocols. It is suitable for direct t-stat connections and can communicated with any BAS system.
