So, I've finally started to document our system. The trouble with bushfire EWSS (External Water Spray Systems) is that there is very little hard research so there are many 'opinions'. I've only found one paper on EWSS but I will blog on that another time.
Given the nature of an ember attack, if we are not home the only proper home defense would be a full deluge system that would need to run for hours as detecting spot fires is not practical as the amount of water required would be huge (town water may not be available). Also, the CFA tells us that fires start from inside a house. How can we detect a broken window and deluge a room?
So the objectives of the initial system are:
- Protect the dogs from a surface fire during an ember attack. We can keep this area wet for about 6 hours with available water so this is 'possible'.
- Run fire hoses to make home defense easier.
- Independent water supply (25,000L) as town water may not be available.
- Run without mains electricity as history shows that the power goes early in a bushfire.
- Remote start from work.
The attached diagram is my first attempt at documenting our system. We chose a Davey Firefighter 5 pump as the Honda engine is very reliable and this version provides a flat pressure curve over a wide flow rate (up to about 500L/m) which means that we can use it drive hoses and sprinklers at the same time. We got the electric start model as we want to remote start it and in any case we do not want to fighting a recoil start when stressed out.
The remote start system is bases around a low power 12VDC computer system and our home internet connection is also powered off the battery backed 12V supply which is real convenient as we often loose power in this are. More about that later.
More photos of the system here.