Water Pumps - Again.

[euca]

My domestic water supply pump, type: Hitachi WTS/P300GX hunts, instead of giving a continuous delivery, viz. it stops & starts at about 1-second intervals with quite a bonk. I would guess that if I knew what to adjust I would get a quiet, continuous water stream until equalization in the pipes. I suspect the auto pump trigger which seems to have an adj-screw but I would like to get the advice of the more knowledgeable on this forum first. Ideas welcome, thanks.

Edited June 16, 2015 by euca

[Crossy]

It's almost certain that the pressure tank is waterlogged.

Several threads in DIY that address this problem and it's an easy fix.

Let's move over there as it's not really farming.

[gerry123]

it is a simple fix generally the adjustment screw is a means of achieving smooth pump running as they are generally

topped with a lock tite fluid don't come loose so it might be an idea to take a general look around at the other components that may also cause hunting symptoms ie the diaphragm if that seems to be ok well go for the adjustment/solenoid screw i have adjusted mine when the pump was live but i think it would be recommended to isolate the power source

the picture shows the diaphragm housing in side is the component that quite often is at fault

i purchased a new complete one at a local aggri store foe 250 bht

[gerry123]

took a look at the picture but incomplete try this the actual inner component

[lopburi3]

We suspect you have a waterlogged pump meaning there is not enough space for air due to too much water - correct for this first by release of pressure and then removing drain plug from bottom of tank to allow it to empty. Then start again, It should work but if quickly becomes waterlogged again there are issues. Some pumps have a membrane between water/air and these should operate fine as long as there is no tear in it - if there is air will mix with the water and over time a new drain/start again will be required. Older pumps have no membrane and use what you see in post above to add air as needed - these can become defective over time and require repair or replacement (not expensive). Again problem can be solved in short term by drain/restart.

[billd766]

it is a simple fix generally the adjustment screw is a means of achieving smooth pump running as they are generally

topped with a lock tite fluid don't come loose so it might be an idea to take a general look around at the other components that may also cause hunting symptoms ie the diaphragm if that seems to be ok well go for the adjustment/solenoid screw i have adjusted mine when the pump was live but i think it would be recommended to isolate the power source

the picture shows the diaphragm housing in side is the component that quite often is at fault

i purchased a new complete one at a local aggri store foe 250 bht

Water, electricity and the human body are best kept apart.

Catching hold of a live wire whilst standing in a puddle is NOT a good idea.

It is not always fatal but it can certainly screw up your day and it hurts too.

Electricity in Thailand is dangerous enough on its own.

[Pib]

Yeap, sounds like a water logged pump....that, is the little pressure tank the motor/manifold assembly sets on is waterlogged...lost it's air charge. When a pump is waterlogged it will do exactly what yours is doing. You have probably lost the air that is suppose to be maintained in the tank like in lopburi3 picture which provides an energy spring of sorts since air can be compressed while water can't to assist the pump motor and smooth out the water pressure variations. Plenty of posts on ThaiVisa about dealing with waterlogged pumps.

Now if it is waterlogged just draining the pump pressure tank to get air back into the pressure tank (like talked in other threads) will only provide a temporary fix until the problem causing the tank to get waterlogged is fixed. Like gerry123 talks in his post above these type of tanks have a "air balance/charger value" that keeps the air in the tank at the proper level. If that valve is defective it will cause the pump to get waterlogged over time...like within a few weeks from failure. Your air balance valve is a little square value mounted on the side of the manifold, but for Mitsubishi pumps like I have and gerry123 has it's a six side valve that screws into the top of the tank. My air balance valve failed once with a small rupture of the rubber diaphragm in the valve just like shown in in gerry123's post. It's failure caused the same problem you are having...pump was turning off and one about every second with water was being drawn and it was a pulsating water flow.

As mentioned other things can cause a pump to become waterlogged like losing prime due to a defective back flow valve or footer valve. Good luck.