How To Add Air Compressor Auto Shut Off, Timer, And Remote Shut Off Using Smart Home Z-Wave Switch

The shop air compressor would benefit from a smart switch that could do the following.

1. A timer that shuts off the air compressor after hours and starts it up again in the morning. This is simple enough, except that there are times when we want the air compressor to stay on after hours, like if we have resin items that are curing in the pressure pot. A simple timer won't account for these anomalies, and we would need to add a bypass switch and remember to enable the bypass switch. With a smart switch, it would be possible to add a switch or pressure sensor at the pressure pot line that gets turned on when the pots are on. This prevents the smart switch from turning off the air compressor.

2. A remote shut-off that allows us to turn it on/off remotely from the smart home (SmartThings) app.

3. An auto shut-off that will stop the compressor from running if there is a leak or burst air hose. It has happened a few times that an air line breaks or some large leak occurs and the air compressor runs nonstop. There are switches designed for pumps and air compressors that have timers that shut them down if they run for too long due to a leak. A smart switch could also be used for this but may require some basic programming. Using a smartwatch that can measure current/load, a timer could be set to shut down the air compressor if it is running for too long.

Each of these requirements could be solved individually with individual components. However, a single smart switch could also solve all the problems at once. Watch the video to see how I did it, and continue reading for links to parts.

UPDATE: Watch the PART 2 video for the electric unloader valve that is required to release pressure on the compressor motor if the power is cut mid-cycle.

The 120V air compressors I use are already on the edge of tripping 15 to 20-amp circuits. The oil air compressor will often trip the circuit breaker, usually on start-up, while the oil-less air compressor rarely trips the circuit breaker, even when running continuously. Therefore the ~2 HP motors on these air compressors won't work with 15A-rated smart home switches. There are basically no 20A 120V plug-in smart home switches because 20A outlets are less common.

This is the Kobalt Quite Tech oil-less air compressor that the switch will be used with. It has a 1.8HP motor. It's similar to the California Air Tools Ultra Quite air compressors, but the quality is a little lower. See the post where I replaced the prematurely worn piston rings with ones that I sourced myself because Kobalt doesn't offer replacement parts.

The solution to controlling the air compressor power is to use a 40A 220V (but also works with 110V) smart switch. There are a few options available for this.

Aeotec Heavy Duty Smart Switch, Z-Wave Plus Home Security ON/OFF controller, 40 amps

The Aeotec Heavy Duty 40A smart switch works for 240V and 120V and fits the above requirements (Up to 5 HP AC Motor), but it doesn't have an onboard switch to turn it on and off manually. The integral switch is important because it can be overridden remotely. If a physical switch was added before or after the Aeotec, it would not be possible to override it remotely.

WHERE TO BUY:

Aeotec Heavy Duty Smart Switch

Power Ratings:

2 phase (Split phase - US)

240VAC, 50/60Hz;

Maximum:

• 9600 Watts 40A Resistive;

• 2400 Watts 10A Capacitive;

• 3840 Watts 16A Inductive;

240VAC 5HP AC Motor;

1 phase only (Split phase - US)

120VAC, 50/60Hz;

Maximum:

• 4800 Watts 40A Resistive ;

• 1200 Watts 10A Capacitive;

• 1920 Watts 16A Inductive;

120VAC 5HP AC Motor;

Enbrighten Z-Wave Plus 40-Amp Indoor/Outdoor Metal Box Smart Switch, Direct Wire, 120-277VAC, for Pools, Pumps, Patio Lights, AC Units, Electric Water Heaters

The ENBRIGHTEN (GE) Z-Wave Plus 40A smart switch works for 240V and 120V and fits the above requirements, and it has a switch on the front to manually turn it on and off (Up to 5 HP AC Motor). This is the switch that I bought to control the air compressor.

WHERE TO BUY:

Enbrighten Z-Wave Plus 40-Amp Indoor/Outdoor Metal Box Smart Switch

LINK TO SPEC SHEET

The load can be wired in several different ways. The air compressor will be wired in 120VAC Single Load Energy Monitored.

ISSUES TO CONSIDER

Under normal operating conditions, a mechanical unloader valve opens at the end of the cycle to release the pressure between the compressor motor and the check valve at the tank. Cutting off the power to the compressor motor mid-cycle doesn't relieve the pressure built up in the line between the compressor motor and the tank. If the pressure is still there when electricity is re-applied to the motor, the motor won't be able to start again due to the excessive startup load caused by the pressure. An electric unloader valve must be used to release the air pressure each time the power is cut to the motor mid-compression cycle.

The electric unloader valve can be tied into the copper tube that goes between the check valve and the mechanical unloader valve. The electric unloader valve should be normally open, such that it releases air when not powered. It should be connected in parallel with the compressor motor, such that it closes during the compression cycle and opens to release air when the cycle is complete and the motor stops.

1/4" Compression x 1/4" Bottom NPT Male Tee

1/4 Inch NPT 110V Brass Electric Solenoid Valve

The products shown here were purchased by me with the intent to use them. I did not receive any free items, and I am not being paid or compensated for this review. The video, description, and comments may contain affiliate links. If you click on a link, I may receive a commission. Money earned helps to support my channel and bring you more informative videos about engineering, crafting, and DIY.