Have a Hitachi 400GX Invertor water pump which I use to pump water out of  a pond for plant watering over the last month it has started to do a lot of recycling after the water lines are closed, at first it was just a few times a day and now it is every 15 seconds. When watering it seems to have enough pressure for watering. Opened the unit up, drained the tank cleaned the check valve. Everything seemed ok. Checked all of the valves an they are all closed, with as often as it recycles if I had a leak I would have a very wet spot somewhere. The only thing that I can think of is the pressure tank which has nitrogen in it. Any suggestions. The pump was purchased in September of 2016 and it says five year warranty on it but I would guess this would only be the motor

As a suggestion, check to see if the settings have changed from "Normal" to "Constant Pressure"

If you sure you don't have a leak, check the check valve at suction side

9 hours ago, JAFO said:

As a suggestion, check to see if the settings have changed from "Normal" to "Constant Pressure"

on this pump I always have operated it on constant pressure with no issue, I also have another one on the other side of my property which works fine on constant pressure

9 hours ago, Susco said:

If you sure you don't have a leak, check the check valve at suction side

cleaned the check valve a couple of times, did not help

Had a similar problem in the house recently and as the water bills were going through the roof had it checked out by water dept. Turns out we had a leak under the floor somewhere and the easiest solution was to cut out the feed to the whole bottom floor and run new piping above ground throughout. It did the trick and was all done in a day for around 8000 Baht.

 

Obviously your situation is different but the symptoms seem the same so maybe a closer inspection of the pipework may reveal something.