Controlling a Sprinkler Valve with APEX Jr.

Fresh water for the aquarium automatic water change system is supplied by a sprinkler valve tied into the landscaping watering system. When I first set it up I used the landscaping timer to control the timing of the water changes. I wanted the entire process to be controlled by the APEX, so I bought the APEX Fluid Monitoring Module (FMM) and added the 24 volt power adapter and connected the 24 volt output line to the sprinkler valve. They were both 24 volts, so I thought it would work. It did work, but only for a few days, and then stopped working. The whole FMM froze, so I reconnected the water valve to the landscaping timer until I could resolve the issue.

I researched it further and found that the problem was that the FMM power adapter provides 24 volts DC power. Sprinkler valves use 24 volts AC, I knew they both used 24 volts, but I didn’t pay attention to whether it was DC or AC – I just assumed they were the same. I found a blog post that provided a very good explanation on the differences. 24 volts DC works, but it draws way too much power and caused the FMM to overload and freeze, it also causes the valve solenoid to get hot reducing its lifespan. To fix this I bought a 24 volt AC power adapter online. I was able to find one pretty cheap since I didn’t care about the cable end. I cut the end off the output cable and wired it to sprinkler valve. Then I plugged it into an APEX controlled outlet that was not in use and copied the programming for the water changes over to the new outlet. Then it worked without any issues. I measured the amount of power it was drawing and it was 0.1 amps, which is well within the limitations of the adapter and the valve. I didn’t measure it with the DC adapter, I just know it didn’t work for long.