GB2463990A

GB2463990A - Intelligent rainwater management system

Info

Publication number: GB2463990A
Application number: GB0917265A
Authority: GB
Inventors: Marcus Bicknell; Adrian Lester
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-10-05
Filing date: 2009-10-02
Publication date: 2010-04-07
Anticipated expiration: 2029-10-02
Also published as: GB0818131D0; GB2463955A; GB2463990B; GB0917265D0; GB0907159D0; GB2463955A9

Abstract

The invention relates to apparatus for the collection and storage of rain water falling onto a building and the management and supply of the rainwater for use around the building. The apparatus comprises a header tank 6 in the roof space with upper and lower level sensors (U, L figure 2a), a Controller 5 at ground level and an electric pump 4 to provide water to the header tank. All the water in the header tank is used before refilling, which reduces the cost of electricity, pump strain and wear due to pumping water every time a small amount is used. The level sensors in the tank inform the Controller which opens valves (D, E, F figure 2a) as required by its programmed logic, pre-calibrated fill timings and user modes. The pre-calibrated fill timings are used to protect against failure of the upper level sensor and flooding of the building and to establish that the lower sensor "water out" signal indicates that the rainwater is not available.

Description

Apparatus for optimising the collection and storage of rain falling onto a building by managing the supply of this rainwater for use around the building.

The present invention relates to apparatus for the collection and storage of rain water which falls onto a building, generally onto a roof from which it is collected via guttering, although such systems can also collect rainwater from other large free surfaces. Such apparatus collects the rainwater which can then be reused either in the home or for external horticultural or similar purposes, rather than being wasted.

Various prior art systems are known for collection of rainwater, in particular: GB2437527 discloses a rainwater supply system where a receiver chamber 21 pumps water to an elevated storage tank. The storage tank is provided with an upper level detector 12 and a first level detector 18.

JP2004107907 discloses an arrangement for supplying "natural water", which may include rainwater, to a water storage tank 10, provided with level detectors 16a, 16b, 16c. A control circuit 17 is operable to supply mains water through activation of a solenoid valve in the event of shortage of ground water.

DE202004005418U1 discloses a gravity fed water tank 14 provided with water level measuring means 7. An underground cistern is provided with a submersible pump. SA control unit 5 is operable to refill from the mains supply if the level in the underground cistern is too low.

AU20031 00692A4 shows a water storage system for collecting rainwater, whereby a mains supply line 5 is provided to top up a rainwater storage tank, in the event that the water held in the tank drops below a certain level.

However each of these systems suffers from problems which the present invention seeks to overcome. In particular, where water is pumped to an upper level tank, such as a gravity system header tank, level detectors may be used for control of pumped water flow. In such cases if the upper level detector fails, there is a serious risk of flooding. The present invention overcomes this problem.

Accordingly the present invention provides apparatus for the collection and storage of rain water which falls onto a building and is collected in a rain water storage means, comprising a header tank arranged to receive water pumped from said rain water storage means and to feed water by gravity to end use locations, upper and lower level sensing means for sensing upper and lower water levels in said header tank and for provision of tank empty and tank full signals, water control valves and a controller for controlling the feed of water to and from said header tank, said controller being arranged to control pumping of water into said header tank in dependence on said tank empty and tank full signals in a manner where all the water in the tank is used before re-filling, and pumping is stopped when the water level reaches said upper level sensor, said controller further comprising a timer, a memory for storing a calibration time value for filling the header tank from the lower to the upper sensor levels, and circuitry for determining whether the time of filling said header tank exceeds said stored calibration time value, thereby providing a safeguard against upper sensor failure. In addition to protecting the system against upper sensor failure and hence risk of flooding, the arrangement has the merit that pumping only takes place when filling the tank from the lower to the upper sensor positions so wasting excessive hunting or usage of a pump motor as would happen if topping up every time any water was drawn from the system. In that sense it is different from a domestic mains header tank which is filled continuously in dependence on demand via a ball cock valve.

Conveniently the rainwater supply means may be an underground storage tank incorporating a pump which is cycled on and off as the controller receives the tank empty and tank full signals.

A preferred feature of the invention is directed to providing a back up supply of mains water to allow for the situation where the rainwater supply is curtailed, such as through drought or equipment failure. The present invention allows for a particularly convenient solution since the controller already includes a timer and memory.

According to this aspect of the invention the controller is arranged to detect that a tank full signal has not been received within a pre-determined time interval from activation of rain water supply to the header tank, so establishing an absence of water in the header tank, and then to activate supply of mains water to said header tank. Either the lower or the upper sensor may be arranged to detect the absence of water in the header tank for this purpose.

After the header tank has been filled and then through water usage the level falls again to the tank empty condition, the time interval feature automatically allows the system to revert to rain water supply if by then rainwater has become available since the time delay for activation of mains water supply In the event of the system including a mains water back up feature, it is preferred that there are separate stored calibration values for both rain water supply and mains water supply since the average filling times are likely to be different. In each case, therefore, top sensor failure is safeguarded.

Preferably a return pipe will be provided allowing water to be returned from the header tank to the rain water supply means. This allows for recycling of water for a number of reasons. During commissioning the filling times will need to be calibrated so the water will need to be filled and emptied several times, and during use, it may be necessary to flush out and refill the system at times to avoid contamination. This can be for the purpose of preventing bacterial activity making the rainwater yellow and unattractive or dangerous for domestic use in the header tank typically in the roof space where temperatures can be 10 to 20 degree warmer than the principal rainwater storage tank which is underground.

The invention will be described by way of example with reference to the accompanying diagrams in which Diagram 1 is a schematic overall view of a rainwater storage system; Diagram 2 shows a part broken away view of a Controller; and Diagram 2a is a wiring diagram showing how the units are connected together 1) Diagram 1: schematic overview of building Rain is collected off the roof and fed by gravity through normal gutters (Diagram 1, 1) and downpipes (2) to the underground storage tank (3). A submersible electric pump (4) supplies rainwater via a multi-function Controller (with buttons, mode indicator lights, a microprocessor-board and solenoid valves) (5) (see below) to a specially-equipped Header Tank (6) (see below) in the roof space. Water flows by gravity as required through a dedicated network of pipes (7) to those appliances round the building which do not require potable water (notably, in the UK, toilets, washing machine (8) and garden taps).

One of the Invention's functions is as an automatic electronically controlled mains water backup. Mains water (9) is available at the Controller to replenish the Header Tank, if no rainwater is available.

The rainwater feed pipe (10) and the flush pipe (11) (which enables the Header Tank to be emptied as required) are also commanded by the Controller.

2) Diagrams 2 and 2a: Controller The Controller with its water valves can be located on a wall in a visible place on the ground floor (in a utility room or kitchen) or where convenient. The references here can be read in conjunction with both Diagrams 2 (controller) and 2a (wiring diagram). The microprocessor (CPU -central processing unit), incorporates a timer, a memory unit and a logic unit for processing the various functions of the system and with associated components is mounted on a printed circuit board and housed in the watertight control unit (A). The memory is arranged to hold a calibration time value for filling the header tank from the lower to the upper sensor levels, and the logic unit circuitry is arranged to determine whether the time of filling the header tank exceeds the stored calibration time value, thereby providing a safeguard against upper sensor failure. Generally two calibration times will be stored, one for rainwater and the other for mains water filling, and these will be established during setting up of the system, as will be described later.

The on-off switch, other buttons and indicator lights are mounted on this control unit and are accessible by the user. The Controller is powered by a 12 volt electric supply (B) fed from a wall-socket-mounted mains converter. Wires (C) to the control unit bring signals from the sensors in the Header Tank (Upper sensor (U) and lower sensor (L)). These signals are then processed in the CPU so that further wires can send commands to cause the opening and closing of the three solenoid valves (D, E, and F). Solenoids, water pipes and control unit are mounted on a back panel and protected by a moulded cover (H) with an aperture for viewing the indicator lights and manipulating the control unit buttons (A). A manual valve (G) permits the user to turn on mains water feed to the Header Tank even in the case of a power cut.

The two level sensors in the Header Tank (upper and lower) (see below) provide a "tank full" or "tank empty" signals to the CPU built in to the control unit of the Controller, which then controls three electrically operated water valves alongside: 1. The electric solenoid valve for rainwater (E) controls the inflow of pumped water from a 240 volt pressure-sensitive pump in the underground rain water storage tank. When the valve opens, the pump registers the drop in pressure and is thereby activated to supply water to the Header Tank until a "tank full" signal from the sensor then causes the valve to close.

Rainwater flow is upwards, from the underground storage to the Header Tank.

2. The electric solenoid valve for mains water (F) is connected to the mains water supply. This is used mainly as a back up water supply if the rainwater should run out. Mains water flow is upwards, from the mains water supply to the Header Tank.

3. The electric flush valve (D) can be opened by the system to let water out at any time. Water flow is downwards, from the Header Tank back to the underground storage tank.

In the event of a power supply failure the manual mains water bypass (G) can be opened by hand and the tank will fill with mains water until the conventional ball cock in the Header Tank closes.

3) Diagram 3: Header Tank The Header Tank is normally situated in the roof space or anywhere in the building above the highest appliance to which water is to be fed by gravity.

The rainwater supply pipe (Diagram 3, A) enters near the top of the tank and is routed to the bottom of the tank, to reduce turbulence or splash. The mains water supply pipe (B) enters near the top of the tank through its ball cock valve (C) which stops the flow of mains water when the tank is full and which therefore prevents overflow of the mains water even when there is no electrical power. To provide the air gap required by U.K. building regulations, for the purpose of eliminating the risk of contamination of mains water by rainwater, the mains water flows into the tank from above the surface of the water.

There are no user controls in the Header Tank. Two float sensors (D) as previously mentioned register the upper and lower water levels within the tank and inform the programme logic in the control unit.

The overflow tower (E) in the Header Tank is a large, open-topped, watertight cylinder whose top is below the top of the tank. If all other systems were to fail, and rain or mains water is flowing unchecked into the Header Tank, the excess water flows over the top of the cylinder and out of the 40mm overflow pipe (F) to the outside of the building. The large diameter overflow tower provides the head and impulsion to ensure high volume flow through the overflow pipe. Despite this provision, UK Building Regulations require an A-B Gap (G), a rectangular opening which is situated in the back of the Header Tank to further prevent contamination of mains water by rainwater; the water level in the tank could not reach the level of the mains water inlet pipe because it would have flowed out of the A-B gap. The overflow tower in the Header Tank of the invention prevents water flowing out of the A-B gap or over the top edges of the tank itself into the roof space by allowing excess water to flow down the overflow tower.

Water flows from the Header Tank through the outlet pipe (H) near the bottom of the tank.

4) Normal Running During normal use the Controller monitors and maintains the availability of rainwater in the tank. When the lower sensor shows an absence of water, the pump is switched on and the Power On indicator light comes on. The Rain filling light flashes when rain water is being pumped into the Header Tank and this continues until the water level reaches the top sensor at which point the pump is switched off by the controller circuitry.

Should the rainwater run out or become otherwise unavailable, the system automatically switches to mains water and the Mains filling light begins flashing. In exceptional circumstances, the functioning mode of the invention is changed automatically using the control unit buttons, as follows.

The means by which the absence of rainwater is detected is a unique feature of this invention and solves a significant problem. When the low sensor in existing systems on the market detects the absence of water, it can only establish that the rainwater storage tank is empty by a float switch in the rainwater tank. Such systems are subject to vagaries of the level at which the float switch detects an absence of rainwater compared to the level from which the submerged pump intakes rainwater, and the relative unreliability of the switch.

In the present apparatus, no float switch is needed. The controller logs the time it takes from the lower sensor indicating absence of water in the header tank and the lower sensor again showing water present. If a greater time has elapsed than the factory pre-set time without the sensor showing water present, then the controller know there is no rainwater left and therefore switches in the mains water to fill the header to the top sensor.

Furthermore, because a rainfall may have occurred in the meantime, every time the lower sensor shows an absence of water, (generally due to normal water usage), during this mains water provision mode, the controller waits again for rainwater to be pumped up from the storage tank. After the preset time, if no water appears, the system again reverts to mains water filling. As an alternative to the system described above, the time delay can be arranged to operate in conjunction with absence of a water present signal from the upper of the two sensors in which case a greater time delay will need to be set.

5) Set-up Mode The set-up (or "commissioning" mode) is used once after installing when the user or installing engineer press both the flush and holiday buttons at the same time. This process last several hours and automatically calibrates the flow timers and stores in memory the time it takes for the rain water to fill the tank and for the mains water to fill the tank. At any time in normal use thereafter, if the top sensor fails, the tank fills with rain water (if available) or mains water according to the time intervals memorised.

The reason why the time intervals have to be calibrated for each installation of the invention is because different sized Header Tanks, different water pressures and other variables make it impossible to establish the fill times as a factory setting. Calibration of the flow timers by set-up mode only needs to be completed once in the system's lifetime unless a new Header Tank or pump is fitted.

During the set-up process the Power On light flashes. The tank fills with rainwater, flushes, fills with mains water and flushes... then repeats the process two more times. The computer takes the average of the fill time for rainwater and for mains water and stores these two values. During these cycles, the Rain Filling, Mains filling and Flush indicator lights come on and off. The set-up may therefore take several hours. The user can interrupt the process if absolutely necessary but would have to run it again to complete the installation.

6) Auto Tank Refresh If the water in the Header Tank is not used in a 3-day period, the refresh program automatically flushes out the system, emptying the Header Tank back into the underground tank. The header then refills with fresh rainwater.

This feature is disabled when the holiday mode is running (see (8) below). If the building is left empty, and the holiday button is not pressed, the Controller automatically refreshes the system every 3 days. The purpose of refresh is to prevent bacterial action making the rainwater in the Header Tank (which in a roof space in summer could be at 20°C or higher) from getting stale and discoloured; cool clear water from the underground tank (at about 5°C or less) is pumped into the header and bacterial action prevented.

7) Flush Mode The flush mode allows the rainwater in the Header Tank to be changed by pressing the flush button on the panel. When the valve is opened the water will flush out and is directed back into the rainwater-harvesting tank. This might be triggered if little water has been used and the ambient temperature is high; this gives the user the choice to avoid staleness and discolouration by replacing the water in the Header Tank. This is the same as Auto Tank Refresh but triggered manually.

8) Holiday Mode The holiday mode empties the Header Tank and then refills with mains water.

The holiday button needs to be pressed a few hours in advance of leaving.

Providing the Header Tank has had time to fill with mains water and providing the user flushes the toilets twice after pressing the holiday button, the toilet cisterns and bowls are filled with chlorinated water that stays fresh for however long the duration of the holiday. On return from holiday all toilets and washing machines will be available as normal and the system will then automatically revert to normal mode.

9) Mains Water Only Mode Once the mains water only button is pressed, the system selects mains water to fill the Header Tank. The existing water in the Header Tank is used as usual but is replenished with mains water. This method of operation continues until the normal button is selected. This mains water only feature is provided to enable the rain water to be conserved for garden use during a drought. The same pump submerged in the rain storage tank can still be used at that time provided that its output is equipped with a T joint feeding a tap or other garden outlet. Alternatively a second pump for garden use only can be installed in the rain storage tank.

10) In the event of power cut In the event of a mains electricity power cut, firstly, water in the Header Tank flows by gravity as required until it runs out. Secondly, thereafter, the mains water supply valve can be manually opened and the tank will fill with mains water until the conventional ball cock closes; see Manual mains water bypass below. This valve will require closing after the power is restored.

11) Time Limit Flow Mode -upper sensor failure In the unlikely event of a failure of the UPPER float sensor in the Header Tank, the Controller tries to fill the Header Tank, establishes that the upper sensor has not given a "full" signal, and "times out". The Mains water not working light illuminates. The invention then switches to its back up program which fills the tank according to the flow time stored in memory. Please also read the note on Set-Up mode above. The warning light indicates that the sensor most likely needs changing (unless both rain and mains water had run out).

12) Manual mains water bypass -lower sensor failure In the unlikely event of a failure of the LOWER float sensor in the Header Tank, the Invention would not know that the tank is empty. No indicator light would show but the user would become aware that water is not available at the appliances fed with rainwater.

To reinstate water supply, the user removes the Controller cover, selects the left hand manual (non electric) valve and turns it 90 degrees to open the mains flow. Electric power to the other valves is 12 volt only so there is no risk of electric shock. Mains water flows into the Header Tank until the ball cock valve turns the flow off. This safety feature works even if there is no electric power to the system.

13) Safety Features The invention has several inbuilt safety features: 1. Float Sensor: The upper float switch in the Header Tank is the first barrier to flooding. It turns off the rain or mains water supply when the Header Tank is full.

2. Time Limit Flow control: Should the upper sensor fail, the Controller uses time limit flow control. The timing values used are those calibrated for this particular system during set-up. See (5) and (11) above.

3. Ball Cock Valve: This valve limits the mains water level in the Header Tank even if there is a power cut.

4. Overflow Tower: A 4" (100 mm) diameter drain is designed to absorb the combined flow of both the rain and mains water feeds if they were left on by the unlikely event of significant equipment failure. The large diameter overflow tower provides the head and the impulsion to ensure high volume flow through the overflow pipe, thus reducing to a minimum the risk of any overflow over the top edges of the tank itself into the roof space. With this feature in place, all the water delivered to the Header Tank harmlessly flows out of the building, into the guttering and back in to the rainwater tank.

14) Options Electrically-switched pump. The description above refers to a pressure sensitive pump in the rainwater storage tank which maintains rainwater pressure to the Controller. As an option, the invention can be equipped with a submersible pump in the rainwater storage tank which is electrically switched by the Controller. This permits a cheaper pump and uses even less electricity (as pressure is not maintained in the pipe to the Controller); the option pump only switches on when water is needed.

Solar powered pump and Controller. The description above refers to 220 Volt AC power for the pump and for the controller (converted to 12 Volt DC for the Controller). As an option, the invention can be equipped with a 12 volt or 24 volt electrically switched pump run by photovoltaic cells on the roof of the building and accumulator batteries. The Controller would also run directly off the 12 Volt DC supply. In this way the entire system and circulation of rainwater around the building can be assured without any use of mains electricity and costs can be further cut. Claim

Claims

What I claim is:- 1) Apparatus for the collection and storage of rain water which falls onto a building and is collected in a rain water storage means, comprising a header tank arranged to receive water pumped from said rain water storage means and to feed water by gravity to end use locations, upper and lower level sensing means for sensing upper and lower water levels in said header tank and for provision of tank empty and tank full signals, water control valves and a controller for controlling the feed of water to and from said header tank, said controller being arranged to control pumping of water into said header tank in dependence on said tank empty and tank full signals in a manner where all the water in the tank is used before re-filling, and pumping is stopped when the water level reaches said upper level sensor, said controller further comprising a timer, a memory for storing a calibration time value for filling the header tank from the lower to the upper sensor levels, and circuitry for determining whether the time of filling said header tank exceeds said stored calibration time value, thereby providing a safeguard against upper sensor failure.
2) Apparatus according to claim 1 in which the controller is arranged to activate supply of mains water if the water level has fallen to below the level of the lower sensor and a pre-determined time interval has elapsed without water being supplied from said rainwater storage means.
3) Apparatus according to claim 2 in which said memory is arranged to store a rain water calibration time for filling the header tank from the lower to the upper sensor levels from the rain water storage means and a mains water calibration time for filling the header tank from the lower to the upper sensor levels from a mains water supply.
4) Apparatus as claimed in any preceding claim in which said rain water storage means is an underground rainwater storage tank and includes a pump for pumping water to the header tank, said pump being arranged to be controlled by the controller.
5) Apparatus according to any preceding claim comprising a return pipe allowing stored water to be returned from said header tank to said rain water storage means to allow re-cycling of water stored in the header tank.