Well water

We have two options at our residents: buy city water for $16/kgal, or use well water. City inspector estimates a consumption of 40-45kgal for irrigation per month (hot TX sun). The well yields 5 GPM, the zones measure 15-30 GPM.

One solution would be to pump into a buffer 500 gal tank, and then run a single zone, then wait until the tank is full again, and run the next. There are 24 zones.

Options:

• A sensor input that tells the controller to wait until the tank is full before to start the next zone. Only run one zone, then check for “full”.
• A timer, that has a hold-down of one hour in-between zone calls.
• A sensor that reports fill-level to the controller and calculates zones calls appropriately.
• Keeping track of fill-level via flow sensor. Not as precise, needs an error margin.

We can theoretically water 24/7. However, it is advisable to leave the hottest portion out of the day. Hence, we may water a few zones one day and another the next. The complexity is of course also the weather. If it is raining, we skip that zone, or future zones, and how much watering do we make up for.

Which options sound feasible with Rachio?

Post by sbrunner on Jan 24, 2018

These are options:

Which options sound feasible with Rachio?

Post by DLane on Jan 24, 2018

• The largest controller is currently 16 stations, so at least two controllers would be needed.
• Each controller would need to be scheduled separately (e.g. one for M, W, F and the other one for S,T,Th or one from 3 AM to 9 AM and the other from 6 PM to Midnight - every day) as one currently can’t schedule across or combine controllers.
• There is no well delay in the current software - this has been/is a very frequent request. So right now the solution is to add a phantom zone that is not hooked up to anything between actual zones to act as a well delay. This would require three Rachios to enable the every other zone is a real zone configuration.
• I would hook the low water/tank empty sensor up to the Rachios sensor port as a Rain Sensor so that the Rachios won’t continue to think they’re watering when the pump from the tank isn’t providing water. If one is using a Flex schedule (probably won’t matter for the Fixed time schedule) this should help keep the available water level correct.

Or as Brody might say - You’re going to need a bigger tank.

Post by sbrunner on Jan 24, 2018

I thought about the rain sensor port. But I am not sure how this port has been implemented. I would think, typically, the rain sensor does not delay the execution of the next current and next zones, but instead interrupts the current watering cycle.

Post by DLane on Jan 24, 2018

The rain sensor won’t delay the execution of the zone, but it will keep the available water balance correct, so the Rachio would fire again on the next schedule opportunity.

Post by robertokc on Jan 25, 2018

No matter what controller you install, a well with an output of only 5 gallons per minute is really low. If this system is already installed and the zones at 15-30 gallons per minute, the heads will not even pop up.

With just the well, the system will not work. But for a rotor zone with a 30 gallon per minute demand, it becomes more difficult. If you were to operate at 30 gallons per 30 minutes that is 900 gallons. It would take three hours to fill a 900 gallon tank. This is a situation of mathematics.

The utility forbids a cross connection between the well water and the city water.

Post by sbrunner on Jan 25, 2018

Yes, 5 GPM is really low. We are probably doing a 500 gallon buffer tank and run one zone at a time, and wait an hour and a half for the tank to fill up again. Cross connections are permissible. Regardless whether you cross connect or not, you need an RPZ backflow preventer, which is a more fail prove version of a double check valve normally used for sprinkler systems.

Post by robertokc on Jan 26, 2018

The RPZ is installed on the city’s potable water side, right? Do they ask for one from the well too?

Post by sbrunner on Jan 26, 2018

The link about auxiliary water sources is about cross connection contamination, not about that you cannot have the systems connected.

Post by Lars on Jan 27, 2018

With the number of delays you need between zones, you may have to put zones on separate schedules starting an hour apart each. Using dead zones in the schedule won’t supply enough zones and may throw off calculated water use.