I'm just curious, Justin.  What to you do with the rain water that you 
collect?


----- Original Message ----- 
From: "Justin Richards" <justin.richards@gmail.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, June 17, 2008 9:21 PM
Subject: [OT]: How to keep a water cooler filled from a rainwater tank


> Hi Folks,
>
> I have finally installed a rain water tank.  I now fill my 19 litre
> water cooler bottle from a small tap that I have piped into the house
> at floor level.
>
> Its a pain to fill as it is slow and the tap under the sink is awkward
> to get to.
>
> What I would like to do is sense the level in the cooler resevoir and
> use a pump to top it up as it is used.
>
> The tank and cooler hieghts require that I pump and shut off the flow
> as the level in the water tank can be above or below the level of the
> cooler.
>
> I want to minimise on standby current, minimise on price and come up
> with an elegant solution.  Naturally.
>
> I have come up with 3 solutions.
>
> 1. Using a small easily available cheap windscreen washer pump, pump
> the water up thru a loop of water pipe that extends above the top of
> the water tank and then flows down thru pipe to the water cooler.  At
> the apex of the water pipe loop at a point above the water tank
> install something like a shephards crook so there is an opening to
> air.
>
> This will allow the water to be pumped up under pump pressure then
> flow down to the cooler under gravity.  Once the pump is shut off the
> water remaining on the tank side of the loop will return to the tank
> and on the water cooler side will empty into the water cooler.  ie
> there will be no syphon action as there will be an opening at the apex
> of the loop.
>
> I like this solution but is a little untidy plumbing wise and results
> in more pipe exposed to the sun and I dont think it is good to have
> rainwater at raised temperatures.
>
> 2. Use a sqeeze pump (do they use another name for these) like the
> ones used to deliver accurate doses for medical purposes.  For me this
> is difficult to build or aquire.  I like this as it provides a method
> that combines pumping and shutting of the flow in one device.
>
> 3. Use a windscreen washer pump and a solenoid.  This is not a bad
> idea but I cant seem to find small solenoid valves and havent
> experimented (as I have none) to see if they significantly restrict
> flow.  Most of these that I can source are desgned for irrigation and
> as such the pressure they control would be quite high compared with
> what a windscreen pump can deliver and not sure if they would work at
> all.
>
> Anyone have any clever solutions or know a good source of low pressure
> smallish solenoid valves (in Perth Western Australia).
>
> I think I have the control side of things sorted.  I considered reed
> switch with floating magnet but I have decided to just use a probe
> that detects the level of water by the drop in resistance.
>
> Thanks for your time.  Any help greatly appreciated.
>
> Cheers Justin
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