hello

The pump is new , is an HITACHI WT-P200GX2 ,blue and white, 200W

here is the problem: when I open a tap the pump persistently starts and stops, please see the video:

http://www.youtube.com/watch?v=SRiu47OG48o&feature=youtu.be

If I open 3 or more taps the pump works well.

In this image the pump is the red one, and it gives water to the 3 green houses, all the taps are far from the pump 5 to 10 meters. The pump , the tanks and the taps are all on the floor level.

What's wrong?

Thank you :-)

I will start by saying, what an excellent presentation of your query......

But my first question which you are not clear about.

The intermittent pumping to the single swelling, does it actually deliver the water.? Or not.

We have a pump that makes an awful noise sometimes as it pumps to an upper floor, and also when water is evaporating from any of the tanks.

I don't know the answer but if the pump is designed to work in relation to the "draw" of water then a quick pump every 5 seconds is all it needs, where as three dwellings drawing tells the pump to pump every second.

Sure others will know the mechanics,just my educated suggestion.

Often no water in the pipe maybe broken somewhere?

Try to open the pump

To see the machanics!

If it's cycling every 4 or 5 seconds, nothing is wrong, it's simply hitting the upper pressure limit of the switch.

You could try adjusting the pressure switch slightly higher which would slow down or eliminate the small load cycling. But take care there are live parts accessible with the lid off the switch and only 1/2 a turn at a time.

You could install a blader tank after the pump.

@gimatli: what do your really mean the pump works well with 3 taps on? Does that mean it's running continuously, or cycling at a different rate, etc?

Based on the video where the pump is cycling about every second with only one tap on, your pump's pressure tank could very very be waterlogged (no air cushion/spring inside). With only one tap on it should cycle on for about 5 seconds, then off approx 5 seconds, on approx 5 seconds, etc...etc...etc.