Rain Backup in a Box® - the plug-and-play mains water backup for rainwater harvesting systems.

Rainwater harvesting plays a large role in reducing the dependence of any building on expensive treated water from the mains. Toilet flushing, clothes washing and any outdoor use of water can be assured by rainwater. In most cases the total mains use of the building can be cut in half.

But what happens if rainwater runs out? Every system needs a mains water backup to keep the appliances going. The simplest way is a float switch and solenoid valve; the float switch detects when the rainwater storage tank is empty and opens the electrically-actuated solenoid valve so that mains water flows into the bottom of the tank. When the float switch floats off the bottom of the tank it turns the solenoid valve off. The bulk of the storage tank remains empty ready to admit the water from the next rain shower.

U.K. Building Regulations require that rainwater cannot possibly flow back into the mains water supply. For this reason all mains backup devices must have an air gap where the mains water flows into the rainwater tank. The simplest way to do this is for the mains water to flow through open air into a funnel shaped device called a tundish. It can be seen in the photo at the bottom right of the unit.

The Rain Backup in a Box® is fitted inside the building where the occupiers can see and hear it. When rainwater has run out, any mains water running from the solenoid valve into the tundish can be seen through the transparent cover and can be heard through the aperture at the side.The Rain Backup in a Box® replaces a higgle piggle of components with a single wall mounted unit, one electric plug to a wall socket, mains water input and a pipe to the underground storage tank.

Limitation on Use: Note that the Rain Backup in a Box® is intended for domestic and light garden use. If you run two garden taps with a high power pump (like the Enviro, Steel Pumps or Divertron 1100 watt pumps) then the outflow of water is higher than the inflow from the backup device. When the underground storage tank is empty the pump will have no water and its dry-run-protection will turn it off. Some pumps need resetting at the main in this case which is a bore. Most users get round this issue by having mains water taps available alongside the rainwater outlet so that they can switch to mains for garden use when the underground tank is empty. The Rain Backup in a Box® will continue to keep up with demand in the house for toilets and washing machine.

Dimensions:

The control unit is 170mm wide, 220mm high x 80mm deep

Installation instructions

These instructions assume the separate installation of a rainwater harvesting system in the building with rainwater flowing off the roofs through a filter into an underground storage tank and a pump to take the rainwater through a separate pipe network for toilets, washing machine and outdoor use.

a) Locate the best position for the Rain Backup in a Box® unit.
a. Inside the building where the occupiers can see and hear it and where it is protested from frost or freezing temperatures.

b. Within a metre of a 220v AC wall socket into which to connect the plug.

c. Accessible to a mains water pipe, and

d. Above the top of the underground storage tank so that the backup mains water flows by gravity into the tank.

b) Mount the unit securely to the wall and pipe the mains water supply using 15mm pipe to the inlet at the bottom left of the unit. Ensure that the pressure reducing valve, top right, is closed before you turn the mains water supply on.

c) Ensure the outlet of the tundish is fitted with a T piece, therefore providing 2 outlets. Pipe the first outlet of the tundish using 21.5mm waste pipe from the bottom right of the unit to the rainwater storage tank. In most installations this outlet can be channelled to the closest possible rainwater downpipe from the roof, but ensure that the pipe to the tank is protected from frost and freezing temperatures. The backup water supply does not have to be piped separately to the storage tank.

d) Connect the second outlet of the tundish T piece to an overflow pipe running directly out of the house at the closest place. If the pipe to the underground tank does get frozen up or otherwise blocked, mains water will flow to this overflow rather than flooding the building.

e) Channel the float switch to the underground storage tank. Typically this is through a service pipe made of 4 inch (110 mm) plastic which also carries (i) the mains electricity supply to the submerged pump (if so fitted) and (ii) the return pipe carrying rainwater from the storage tank back to the appliances in the house.

f) Attach the wire of the float switch, at a point about 1 inch (25 mm) away from the float switch, with a nylon tie wrap to a suitable point near the base of the storage tank. Typically, the 10 inch (255mm) downpipe from the filter to the calmed inlet on the floor of the tank is the best securing point, or the calmed inlet itself. Either can be drilled without risk for the tie wrap. When the tank is empty the float switch should hang from its wire a few millimetres above the floor of the tank, as shown in the picture.

g) Connect the unit's 12 volt DC adapter to a 220V AC mains socket. Power should be maintained to the unit at all times.

h) With the float valve in the down position, (A) in the picture, open the reducer valve, top right in the unit, slowly. When mains water starts splashing out of the tundish, close the reducer valve slightly. Adjust mains water flow according to the mains pressure available.

i) The installation is finished. Some mains water will continue to flow into the storage tank until the float switch rises.

Go here to download the installation instructions in pdf format

Go Here to download the product brochure for the Rain Back up in a Box®

Trade enquires are welcome For more information call 0800 074 7234