HVAC Switchboards - Auto Off Manual

What is an Auto-Off-Manual Switch?

Auto-Off-Manual (AOM) switches are 3 position switches used to control the operating mode of HVAC equipment. They are found on the mechanical switchboards of HVAC equipment and are typically controlled by service technicians, on-site maintenance teams and security personnel.

The three modes of an AOM switch include:

  • Auto: equipment operation handed over to the control logic of the Building Management System (BMS). Default operation of equipment;

  • Off: equipment operation is disabled and BMS will no longer control the unit. Typically used during repair and maintenance, decommissioning or temporary isolation during tenant vacancies or fit-outs; and

  • Manual: equipment operation is manually overridden to run continuously. Typically used during testing of that specific equipment or others linked to it.

auto off manual switch

How do Auto-Off-Manual Switches Impact by Building?

Leaving equipment in Off or Manual modes can cause hidden risks to your building operations including:

  • Equipment not operating when being commanded by the BMS (cause tenant complaints and significant time wasted in troubleshooting related problems);

  • Reduced equipment lifecycle when being left to run continuously; and

  • Excess energy usage and utility costs when left in manual as well as causing costly central plant equipment operation.

Here are 4 simple steps you can follow to make sure human operator error does not prevent you from achieving your building’s sustainability goals.

Step 1 - Locate Your Auto-Off-Manual Switch

AOM switches are often located in service corridors or plant rooms near the equipment they are connected to. An abbreviation of the equipment can be seen above the AOM switch so you can be confident you have found the right switch (e.g. FCU-101).

Note the equipment names that have been left in either Off (OFF) or Manual (MAN) mode. Do not touch any switchboards that have Lockout Tagout tags left on them, speak to your electrical service contractors for an update on any service repair work being conducted on switchboards.

Step 2 - Identify the Tenancy

Login to your BMS to identify the tenancy that the equipment that has been left in either Off or Manual serves. On most BMS pages there will be a reference or note as to the location that equipment services under a common field “Area Served” (e.g. Lower Ground North Tenancies).

If you have a PEAK Account, you can easily identify the zone or tenancy that your equipment services by simply searching for your equipment using PEAK Charts and finding the exact level and zone/ tenancy that equipment services. You can also modify this.

Once you have identified the zone/ tenancy your equipment serves, identify if there have been any critical developments that would justify having the equipment overridden. For example: major construction works, vacated tenants or special events.

Step 3 - Switch Back to Auto Mode

Once you are confident that the override was only supposed to be temporary now is when you can set the AOM switch back into AUTO. The BMS control will now be able to resume its control.

BMS time schedules will always have special event considerations to accommodate required changes and are the preferred method for making overrides vs leaving turning AOM switches to Off or Manual position.

Step 4 - Communicate the Change in PEAK

Add a comment and upload a photo to PEAK Actions to notify everyone of the change and maintain a complete digital record for future reference.