Water Pump Problems

[Mobi]

I have a large water pump that feeds the water around one rai of land, house, annex etc. I also have two large storage tanks which are supplied by city water, and from which the pump extracts the house supply.

A few days ago, unbeknown to me, the city water was cut, and the tanks ran dry. We bought a truck load of water to fill the tanks, but the pump did not pump the water round. So we primed the pump with water, and after a while the water started running again, and everything seemd to be OK.

The next day the city water was back on.

The problem is that the water pressure drops after a tap (or hose or shower) is run for more than 2 - 3 minutes. When you turn it on, the pressure is fine, then it slowly reduces to a trickle. I then wait five minutes, and turn on again - the pressure has reurned but only for a couple of minutes and then gone again.

I have asked around, but no-one seems to know what is causing this. We have primed the pump twice more, but it makes no difference.

Any ideas out there?

Thanks.

[Mid]

sounds like a leak ......................

[Mobi]

sounds like a leak ......................

Where?

in the pump?

[Mid]

sounds like a leak ......................

Where?

in the pump?

good a place as any to start looking ,

i'm guessing you have a pressure reservoir at the pump ( air pressure over water is how the magic works ) .......

good luck

[billd766]

It depends on the type of pump you have.

There are 2 basic types which are

1 direct feed and running all the time, or

2 what is called a well pump or pressure on demand.

The direct feed pump is easy to check because you switch it on and either it runs or it doesn't.

The well pump has a storage tank built into it which holds 2 to 5 litres of water and when you turn the tap on, the holding tank pressure falls which opens a valve to allow more water in and also starts the pump running until the tap is turned off and the pressure builds up and shuts down the motor and stops the incoming water.

I had a similar problem a couple of years ago with a Mitsubishi WP205 well pump and it turned out to be a small valve on the side had failed. I took it to the repair shop in Bangkok and they fixed it for me free of charge. Meanwhile I bought another pump which wasn't as good but it did the job but the problem was the Mitsu pump had the inlet and outlet 180 degrees apart and the other pump has then at 90 degrees which resulted in a plumbing job for me.

Now of course I have a spare pump for the next time.

I hope that helps.

[Mobi]

Thanks Bild.

It's a type 2 Fujiko pump - looks like it holds at least 5 litres of water - maybe more. It's a bloody great thing, about 1 year old. The pump runs when you turn on a tap, and stops when the the tap is off (a few minutes later).

The problems all started when the tanks ran dry, so I can't help feeling it's connected, but maybe not.

Seems to be a bit better this morning, but it still loses pressure.

I know nothing about plumbing so wouldn't know where to start. I guess I'll have to get someone in to take a look

[lopburi3]

You probably pumped a bunch of mud into the pressure tank and air exchange valve, pressure sensor. I would remove the air exchange valve and make sure it is clean and at the same time drain the pressure tank. Not sure if the pressure sensor could get fouled but that may also be a possibility so maybe remove/clean that also. Be very sure to kill electric to the pump first (and test in case it shuts off neutral rather than hot).

[Mobi]

You probably pumped a bunch of mud into the pressure tank and air exchange valve, pressure sensor. I would remove the air exchange valve and make sure it is clean and at the same time drain the pressure tank. Not sure if the pressure sensor could get fouled but that may also be a possibility so maybe remove/clean that also. Be very sure to kill electric to the pump first (and test in case it shuts off neutral rather than hot).

Your knowledge knows no bounds, Lopbury - visas, now Plumbing

I had a guy round to take a look and I didn't know the Thai for air exchange valve, but with a series of phone calls I got your diagnosis through to him - and lo and behold - 30 minutes later - the pump is working fine. A blocked up valve was indeed the cause.

Many thanks

Next question: How do I clear out all the shit from the bottom of my storage tanks without blocking the pump again? Very difficult to get down to the bottom of the tanks which are buried in my front garden.

[lopburi3]

A reason to have above ground tanks and drain line. Do you pump from a pipe above the bottom with a foot valve on it? How high?

You could use a sump pump to pump down the last foot or two and have someone go into the tank and clean it out. We have had them clean out the old meter square galvanized tanks in years past and they were really small to work in. Should be no problem with larger tanks.

[tutsiwarrior]

look on the suction side of your pump...if there is a level/suction problem the developed head (TDH) across the pump will be reduced with a reduced discharge pressure. Any filters, dirty valves upsteam of the pump?...check it out...

[Tony Clifton]

To clean the tank, once a year, we use up most of the water in the tank, city water valve closed. I lower a small pump on a cable and move it around to clean out most of the sludge. When the pump can't suck up any more, down the ladder with a broom, hose and dustpail until it's all clean. Never leave the pump there with you in case of shock from leakage or a cut electric cable.

While you're down there, check for gaps and cracks. I could see daylight around the cover on mine. Hung a fan it it for a few hours and then applied silicone where needed. Also fixed a few cracks where stinky groundwater was seeping in

I add a bit of bleach and fill up. Bleach added every month.

[astral]

Stainless tanks have a drain hole in the bottom.

Once empty a small person can climb inside and give it a scrub.