I have a Rachio3 that replaced a Rainmachine. I also have a 3/4 hp pump and Rainbird PSR110220 pump start relay. When I first installed the Rachio, I do not recall having any “zone fault” issues. Then toward the end of last year, most of the time when I activated a zone, the pump would not come on and I would get the fault message. If I turned off the zone and back on again, sometimes a few times, the pump would come on. This year, I am getting this issue quite often. Again, if I turn the zone off and on, at some point, the pump will come on. Thought it could be a faulty relay so replaced with the same exact one, brand new and the issue still exists. I have no idea what the issue could be. I have tried contacting rachio for assistance but do not receive a response. I have stood at the control and activated and can hear the relay click, but pump does not come on. And when the pump does come on, it seems like the relay makes kind of a louder thump. Am going to try and determine if when the relay clicks and pump does not come on, if relay is sending the 110v to the pump. I have not opened the back of the pump to see if maybe a loose connection. Any input is greatly appreciated as we have very low water pressure and if the pump does not come on, the heads in the zone dont water much.
Sound like you are using an overly large relay, known as contactor, to run your 3/4 hp pump, it’s kind of like running a yard hose off of a fire hydrant. Zone faults occur when the device is drawing too much current (and contractors are designed to run much more than 3/4 HP pumps).
Take a photo of your pump relay.
It is likely you are using something like this (designed for up to 10 hp):
Note that these relays need 1.25+ amps to run (Rachio only comes with 1 amp power total).
If you replace it with more appropriately sized relay, such as this one from Orbit, your problems will go away.
https://www.homedepot.com/p/1-2-HP-Pump-Start-Relay-57009/100181554
I have done more diagnosis with a volt meter and found that when the pump does not turn on, there is no 24 volts coming out of the controller.
When the zone fault is detected, output is disabled to protect the controller. Power would be applied for a very short time, current load measured, and if the measurement exceeds safety limits, output is disabled.
Pump relay is a Rainbird PSR110220. Is rated for 2 hp motor as largest 120v.
That orbit PSR you referenced does not seem to be available. Not at Home Depot.
Also, you say if relay is drawing too much, the controller will diable the output to protect the controller and the power would only be applied for a very short time. With volt meter attached and a zone activated, the volts stay constant a 0 when the pump does not turn on. The volts do not go to 24 or higher and back to 0. They stay at 0. When the pump does turn on, the volt meter reads 24.5 volts.
While looking at the specs from my relay, the inrush amps is 950 mA, which is less than 1 amp. So it would not seem that the relay is drawing too much.
The relay has been designed for up to 5 hp applications. Do not forget that there’s other power consumption going on at the same time as the master relay. Wi-Fi, CPU, and at least one zone valve are all running at the same time as the master valve. In order to see the power being turned on, and turned back off after measurement, you will need to use an oscilloscope, the timing is simply too short to see with a multimeter.
Relay I linked to can be found at Lowe’s, amazon and google shopping. Using an appropriately size relay is the easiest way to solve your issue.
I am having the exact same issue as you with the same relay. I do have a 220V pump with a 3/4hp pump. You have done quite a bit of investigation, I haven’t yet but I have the exact same behavior.
One other thing which I do notice is that if I try to run all eight zones for more than 15 minutes each the relay clicks with a lower noise (meaning pump doesn’t work), anything 15 minutes or less each it seems to run more often but it still is a massive hit and miss.
Were you able to resolve the issue ?
Rachio support doesn’t seem to be responding!!