Ozito 12V Pressure Pump - Relay Tip

nathan173

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Dec 22, 2018
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Hello all.

I live in a rural area, the first things I did when I started my off grid journeywas convert my lights to DC and change my water pump to an Ozito 36W 12VDC 600L/hr pump.

The pump runs off my spare car battery collection (probably just 1 would be necessary), seperate to the rest of the house because it made my lights flicker, its better that way because having water is a higher priority than lights etc.

At 600 l/hr it is underpowered, but with a bit of adjustment to the gas hot water temperature it works perfectly. Using less water is a definite plus and we have gotused to it. Ozito do make a bigger one, but it isn't available in bunnings.

I initially had issues with the sensitivity it just clicked and clacked (rather than put put put)and I thought that's just what it was supposed to do, I don't recall anything in the manual about it, but all it needed was an adjustment.

Eventually it started misbehaving again and would intermittently not turn on or off, took me a while to figure out.

The sensitivity adjustment changes the pressure it cuts off at(in a relaxed state the pump is on), if its too loose (won't turn on)it might prevent the plastic nubbeing pushed away from the microswitch button, too tight it won't turn off. If its not playing ball that is because the microswitch is faulty.

The pressure switch isa microswitchlike the ones in your microwave oven door, but rated at 20A, I couldn't find a switch with the same rating (not even from RS components), although you can buy the whole unit on ebay for $19. Better than that, I've replaced it with an ordinary microswitch and a relay, now the relay carries the load and the microswitch will last a lot longer and behaves better than it did when new. Adding a capacitor for a buffer will further improve its longevity.

Personally I believe the pump should have come with a relay, running the entire current through a microswitch is a design flaw. If you buy one, put a 12V relay on it at the beginning, you can wire it up without physicallymodifying the pump using spade connectors and just run another negative wire for the relay.

One final issue and another design flaw, it has these quick release type connectors, if the pump flexes they drip a bit of water, a probable good fix for this would be permanently gluing them in.

Hope this is of help to someone. :)
 
Thanks for the tip! :D

I've considered going DC on a well pump. It won't be here at this location, but where I put my new dwellings. So I have time to consider them.
But if I have a similar issue like this, I'll have to try to keep this in mind.
 
Interesting post, good job finding & fixing :)
If the relay doesn't cope after a while, maybe look at using a mosfet instead of the relay.
If the capacitor is a larger storage one, you might find the relay contacts don't last as well due to a higher current spike.
A small suppression type cap or reverse spike diode (like used on relay coils) might help the contacts last longer.
 
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