Rainwater Pump Controller

[Paulh_Boats]

I've just started a rainwater pump controller project based on the Arduino and I'll post pictures and code here. I'm teaching my daughter about the project at the sane time, she has picked up enough of the C language to change the timing of a flashing LED program to do a morse code character, dash dot dot dot.

The next step is to mock up the system using 3 switches and an LED.... to represent 2 float switches on the loft header tank and a float by the pump to show the main tank is empty. The LED will show when the pump is on.

-Paul

[Ivan]

Will you be building in fail-safe? eg if pump comes on for more than x minutes it registers a fault and turns off pump.

[Paulh_Boats]

Ivan,

The primary fail safe will be an overflow pipe, like all header tanks and toilet cisterns. A secondary fail safe like a 30 second pump timer is easily done.

I'm searching for a supply of float switches that bolt through a tank wall, any help will be appreciated.
There are lots of push fittings like this, but I prefer a good old belt and braces nut and bolt fitting.
http://www.reuk.co.uk/buy-FLOAT-SWITCH.htm

-Paul

[Ivan]

How about capacitive induction switches - no need for contact with the water - simply attach to outside of cistern (assuming it's plastic). We used them a lot in the medical industry, and they work perfectly - but probably not cheap.

[stephend]

Speaking of fail safes, how can one determine whether an electrical device is switched on or not?  E.g. Arduino senses water level and turns pump on, then waits 20 seconds and checks whether the pump is in fact turned on.

[Iain]

Hi
Been using this type for a couple of years. From RS.  317-932
I had an initial problem on installation, a bit of plastic swarf floated and stopped the pivot working. Since clearing the swarf there has been no problems(2 years). I use it to keep a rainwater header tank topped up. Only small current capacity so via a relay. For my larger pump that tops up my storage tanks I use a pump float switch(from Machine mart)Plastic float on the end of a cable. It has a larger "span" so is better for this.
Hope this is of some use.


Iain

[PEMTEK]

The only problem I have had with float sensors in the past is floaty bits in the water. They are magnificent at jamming up the mechanism. 

fit overflow protection!

[Iain]

Hi
In fact the float switch I used was RS 845-976(very similar)
Iain

[Paulh_Boats]

List,

I have ordered 2 nylon level switches from here:
http://www.floparts.co.uk/level_switches_miniature.htm

One at bottom of header tank to switch on pump, one at top to switch if off. The Arduino software will do the timing plus check a pump float switch down in the storage tank (3 waterbutts at the moment, 600L). One trick I learned from the net is not to use the pump at least 1 hour after the pump float goes from empty to full to allow enough rainwater to collect - that avoids on-off cycling when there is not enough water to fill the header. In the meantime the mains ball cock will supply water one inch below the lowest float switch, with rainwater pumped in the ball cock will close.

Regarding overflow safety the header tank will be in the loft and a big-boys-toys 25mm masonry drill will soon be bashing a hole for a 22mm overflow pipe. If that cannot drain the full pump output I'll parallel it up with another overflow pipe.

Pictures soon!

Paul