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How to Buy an HVAC Controller in 2021

By Andrew Erickson

July 30, 2021

There was perhaps a time when you could shrug off moderate inefficiencies in your HVAC setup. Perhaps you'd use a simple thermostat that offered "good enough" performance. Maybe you would run your lead HVAC into the ground without rotating the lag unit into the lead role. You can't do that in 2021...

Heating, Ventilation, and Air Conditioning (HVAC) control systems are tremendously important for your network management. As long as your telecom equipment runs on electricity, it's going to be generating heat. You might also live and work in a warm climate.

You need your HVAC units to optimally cool your site. The idea of your telecom hut, server room, or other facility triggering a thermal shutdown is totally unacceptable. You can even damage equipment if things get too hot.

Of course, efficiency is also a concern. Energy costs are going up. That's a trend that probably won't be reversing any time soon.

You can't afford to use "best guess" HVAC management

There was perhaps a time when you could shrug off moderate inefficiencies in your HVAC setup. Perhaps you'd use a simple thermostat that offered "good enough" performance. Maybe you would run your lead HVAC into the ground without rotating the lag unit into the lead role.

You can't do that in 2021. There are too many expenses. There are too many environmental concerns related to energy consumption.

The 7 key things you need in a modern HVAC control module:

Fortunately, for you, it's 2021. There are a wide range of building automation systems that will help you perfect your HVAC management.

What you need is a compact box (wall-mount, or sometimes rack-mount) that provides:

  1. Digital controls - functioning as a "Direct Digital (DDC) Controller" - for your existing HVAC units (either traditional sets of 4 contact closures or modern protocols like MODBUS)
  2. Smart cooling (and heating, if necessary in your climate) based on customizable start/stop temperature ranges. You want the system to support advanced logic if you need it, but also simple "on/off windows" so you can get up and running quickly.
  3. A complete web-based user interface for configuration and monitoring. You don't want to install required software, as this creates security headaches with your IT department.
  4. Smart connectivity to your central management system, whether it's a T/Mon or an SNMP manager or something else.
  5. Measurement of energy savings with simple split-core current transducers.
  6. Intelligent toggling of lead-lag roles. This should happen during individual cycles (lag activates if lead is struggling with heat load) and across longer periods (lead/lag roles swap to balance lifespans of your HVAC units).
  7. (Optional) A local display screen that can be used to check system status and even change settings.
The LCD touchscreen from an HVAC BMS device.
This LCD touchscreen allows on-site technicians to both view the current state of each cooling/heating zone and take manual actions, including activating the "Comfort Mode" that automatically expires.

Choose an HVAC control system with a proven track record

Perhaps one downside of our modern world in 2021 is that it's easier than ever for companies to bring a tech product to market. You end up with many products released by companies that have no business putting out a DDC system, HVAC module, or whatever they decide to call it.

When it comes to controlling your air conditioners for mission-critical remote telecom sites/huts, you need to find a manufacturer who has been doing this for a while.

The PCB of a wall-mounted monitoring & control box, an early prototype build
An HVAC control system should involve a complex device that create powerful energy efficiency. Look for durable hardware, a clean web interface, and a proven design.

Consider the long path that DPS took to end up with its modern HVAC Controller devices:

  1. In the early 90s, our first product was a central alarm master called "T/Mon".
  2. Later in the 90s, the first "NetGuardian" RTU was released to collect alarm data from telecom equipment, generators, rectifiers, temperature sensors, and HVACs.
  3. The NetGuardian RTU line grew into many different I/O capacities and mounting styles, including several wall-mount units.
  4. Internal testing of remote boxes focuses on wide temperature range, overvoltage, undervoltage, EMI, and repeated power on/off cycling.
  5. Designs are modified to replace sensitive components with rugged variations. Mechanically unnecessary standoffs are added to PCBs to increase grounding.
  6. In the 2010s, the HVAC Controller is released. It's essentially a NetGuardian RTU in a wall-mount configuration with highly specialized firmware for managing HVAC units in addition to general I/O. The national telco who was "client zero" for the project dictated no-laptop-required setup via the front-panel LCD screen.
  7. In 2021, the HVAC Controller G4 is produced and sold for the first time. Before shipment, its name changes to the "G6 HVAC Controller" to unify with the rest of the G6-platform DPS remote monitoring boxes.

Can you see how this type of evolutionary development over nearly 30 years pays off, even for new products? With a seasoned manufacturer, you get an entire pedigree of bedrock advantages that form the base of any new product released.

The G6 HVAC Controller will increase your network uptime and reduce energy consumption

Based on the full history of the NetGuardian RTU line, and the G3 HVAC Controller deployments across several years, the new G6 HVAC Controller is prepared to deliver a range of benefits for you:

  1. First and foremost, you can control your HVAC units with smart lead-lag roles. You can choose which units (up to 4 or 6, depending on Controller model) will be "lead" and which will be "lag". You can choose when they will swap roles (default = 24 hours).
  2. The G6 HVAC Controller is also a general-purpose monitoring device. You can monitor the current temperature, humidity, and run state of your HVAC system. You can also monitor a variety of discrete (general purpose contact-closure inputs) and analog (voltage or current) values from connected devices and sensors. Multiple RS485 ports are available for connecting to MODBUS HVAC systems and other MODBUS-compatible devices. Alarms may be reported to T/Mon or any SNMP manager (SNMP protocol v1-v3).
  3. Your technicians arriving at the site can use the "Comfort button" function to tighten the cooling window to something more comfortable for humans. This function times out after 1 hour (and can be renewed with repeated presses for long site visits). This means that you can set your cooling window to a higher temperature for normal operation, which reduces energy consumption. Visiting staff can be comfortable, and it's impossible to forget to change the temperature setting when departing.
The web interface of a device for monitoring HVAC status in several zones, including temperatures and run states for each.
This web interface tells you what's currently happening at your sites, both in terms of climate control and general remote site monitoring.

This device will give you better reliability at your sites, reduce energy costs and environmental impact (your PR team will love the "green" angle), and make your job easier.

Tell me what you need from HVAC BMS

Building management systems (BMS) must always take temperature control into account. Your gear is sensitive and expensive, and you have to control it.

That's the part I already know about you, whether you work at a telco or a power utility or a railroad or a government agency.

What I don't know is "the last 10%" that will make this device perfect for you. What do you need from an HVAC control box? Keep in mind, the only reason the G6 device exists is because someone needed it. The only reason the earlier G3 model exists is because someone needed it.

Now it's your turn. What do you need from an HVAC Controller? Maybe it's as simple as a firmware tweak to meet a specific environmental initiative. Maybe you have HVAC systems that communicate with a protocol other than MODBUS. Maybe you want to mount on a DIN rail.

Whatever it will take to make the G6 HVAC Controller the right device for you, I want to know about it.

Give me a call (559-454-1600) or send me an email (sales@dpstele.com) and let's talk.

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and opt...