Who do I call when something's wrong — IT, HVAC, or the controls contractor?

Updated 11 October 2026

Who owns what

On most buildings the network, the equipment and the control programming belong to different people. Calling the right one first saves a wasted site visit.

IT / network

Owns switches, VLANs, IP ranges, Wi-Fi and firewalls. Call them about reachability: you can't get a port on the controls VLAN, you're on the wrong subnet, or something is blocking UDP 47808 between you and the controllers. One catch: on a lot of older sites the controls contractor installed and still owns the BAS switches, and IT has never touched them. Ask before you assume.

HVAC / mechanical contractor

Owns the physical equipment: RTUs, AHUs, chillers, boilers, pumps, fans, VFDs, dampers, valves. Call them when the machine is the problem. A typical example: the BO for AHU-1 SF-C reads On, the VFD shows no fault on the network, but there's no airflow because a belt is gone.

Controls / BMS contractor

Also called the ATC or temperature controls contractor. They programmed and commissioned the controllers and the head-end (Niagara, Metasys, Desigo CC, EBO, WebCTRL and so on). Call them when the equipment is healthy and reachable but the logic is wrong: a point stuck in override, a schedule not running, a setpoint that won't hold, a duplicate Device ID, or MS/TP controllers that aren't routed onto IP. On some jobs the controls contractor works under the mechanical contractor, so your first call may still go to mechanical.

Symptom → who to call first

What to have ready

• Your phone's IP address. The app shows it on the scan screen, with a Copy button. That's the first thing a network person will ask for.
• The Device ID, name and IP of the controller in question.
• The point and what it's doing: Present Value, units, status, and the Commanded At priority from the point screen.
• What you expected versus what you saw. “RTU-3 SF-C reads On, commanded at priority 8, fan not turning” tells everyone whose problem it is.
• Where you're plugged in: which panel, switch and port.

For a controls call, an exported spreadsheet of the device's points is often the quickest thing to send. See what to send when a vendor asks for your BACnet information.

The grey areas

• “I can't find any devices.” Usually a network or which-port-am-I-in problem first. If you're definitely on the controls VLAN and the missing controllers are MS/TP, it becomes a controls question: are those trunks routed onto IP?
• “The value looks wrong.” Check the status flags. A FAULT on a sensor is usually wiring or a failed sensor (controls, sometimes mechanical). A sane value that nothing acts on is usually an override or sequence problem (controls).
• “It worked yesterday.” Ask what changed: a network change, a failed part, or someone editing the program.

Where Easy BACnet fits

The app shows what's on the BACnet IP network, what each point reads, and which priority is commanding it. That's enough to call the right people with evidence. It won't fix a VLAN, a motor or a sequence, and it is BACnet IP only.