The system operates in five modes (controlled by four motorised valves, and one solenoid valve).
- Shed cooling only.
- High Volume: to run for up to 30 mins when the fire front is close to arriving or has arrived (say when temperature sensor indicates > 65 deg C)
- Low Volume: for cinder attack prevention, capable of running for at least 3 hours.
- Intermittent low volume: spray mode by means of a 3-way motorised valve switching between flow and recirculation to the tank, or, when battery voltage > 12.25 V and cycle length ≥ 5 min, by starting and stopping the pump.
- Low Volume – gel injection (still under development): capable on remote command or autonomously on near exhaustion of water to apply a coating of Barricade gel to the house.
A pressure gauge and flow meter allow manual observation of the flow characteristics.
The 30.3 k litre tank is fed from house main controlled by a float valve. A ¾” Floating Ball Automatic stainless steel valve ($10.17 on Aliexpress) was used for automatic refill, given the max working pressure is 1MPa which is greater than residential tap pressure (0.3-0.5 MPa).
Whilst in order to keep options open, the tank was ordered with a 65mm outlet in the end it was decided that the DN50 outlet to DN50 pipes would be sufficient. They are plumbed in DN50 copper pipe into the pump shed and then connected to the pump inlet via a silicon wire reinforced inlet hose with appropriately sized inlet and outlet sleeves which was available on Aliexpress..