Water Pump Question

[JetsetBkk]

The government water pressure is so low that when I open a tap my water pump switches on to pump water out of the emergency tank.

But I think it is switching on and off too frequently:

It is a Hitachi model WT-P200GX2 and fairly new, maybe less than a year.

My landlord reckons it's OK, but I was wondering if it needed more air in the Pressure tank.

I downloaded the manual and lack of air in the tank could explain the problem:

Just want a second opinion from the members here before I go any further.

Any suggestions welcomed.

.

[transam]

What tank..?..

If there is no water available the pump is stuffed. My pump is similar to yours but has a 1000ltr tank to provide gravity fed water to the pump. The tank will fill under very low pressure during the day..

Edited November 21, 2014 by transam

[Pib]

You sure your underground tank has any water in it?

If the pump is pumping water/pushing water to your taps (can't tell from the video) but just cycling frequently like in the video then you most likely have a "waterlogged" pressure tank...that is, the little tank the motor/manifold is setting on. Lots of threads/posts on ThaiVisa about waterlogged pressure tanks.

Edited November 21, 2014 by Pib

[wayned]

If the tank is water logged it can be easily fixed. Turn off the electric and water supply to the pump. Open one of the taps to release the pressure in the tank, the water stops flowing. There should be a drain valve or plug on the tank. Open the valve or remove the plug and allow the tank to drain. Reverse the process. If the problem is a water logged tank it should fix the problem.

[JetsetBkk]

What tank..?..

If there is no water available the pump is stuffed. My pump is similar to yours but has a 1000ltr tank to provide gravity fed water to the pump. The tank will fill under very low pressure during the day..

In the video above, the underground emergency tank is the blue thing top left of the picture.

It is fitted with a float that will turn off the electricity if the water level gets too low, to stop the pump running while dry.

[JetsetBkk]

You sure your underground tank has any water in it?

If the pump is pumping water/pushing water to your taps (can't tell from the video) but just cycling frequently like in the video then you most likely have a "waterlogged" pressure tank...that is, the little tank the motor/manifold is setting on. Lots of threads/posts on ThaiVisa about waterlogged pressure tanks.

Yes, the underground tank is absolutely full of water. As it is underground, it will fill with water however low the pressure is from the government supply.

Yes, the pump was supplying water when I took the video, else it would have been off. But it wasn't supplying much water. If I turn on two of the garden taps, there is enough water flowing out to stop the pump ever switching off because it can't get the pressure up enough - it can't keep up with the demand.

I think you're right - the pressure tank doesn't have enough air in it, so as soon as the pump switches on, the pressure gets to the cut-off pressure too quickly

[JetsetBkk]

If the tank is water logged it can be easily fixed. Turn off the electric and water supply to the pump. Open one of the taps to release the pressure in the tank, the water stops flowing. There should be a drain valve or plug on the tank. Open the valve or remove the plug and allow the tank to drain. Reverse the process. If the problem is a water logged tank it should fix the problem.

Thanks wayned, for the detailed procedure! I'll give that a go later and post what happened. I'll also search for other posts about "waterlogged" pressure tanks as Pib suggested.

Today, the government water was back up to pressure - above the cut-off pressure of my pump - so I'll have to turn off that supply to test the pump after I've drained the pressure tank.

[Pib]

And if a waterlogged tank turns out to be your problem, then you need to figure out what caused it to get waterlogged (i.e., air loss); otherwise, the problem will probably come back...sometimes very soon.

These type of pumps do not use a bladder or diaphragm in the tank to keep the water and air separated so the air is naturally absorbed into the water and this absorbed air requires replenishment. This replenishment is done by an air control/balance value, which on your pump is that value on the side of the manifold assembly with a small black hose coming out of it and going back to the water inlet side of the manifold. On each pump cycle the valve injects a very small amount of air back into the incoming water flow which goes into the pressure tank where a little bit if air is always being absorbed into the water...the valve is suppose to keep the tank air balance at the correct level...that is, offset that little bit of air that is naturally absorbed in the pressure tank since there is no barrier between the water and air in the tank. If the rubber diaphragm in the air control/balance value is ruptured...even a pin hole size rupture....the value will not operate properly causing the pressure tank to get waterlogged overtime. Even with a completely defective air control/balance value and after completely draining the tank to allow an air recharge/reentry, it could take a couple of weeks before the tank becomes waterlogged again. Good luck

[JetsetBkk]

And if a waterlogged tank turns out to be your problem, then you need to figure out what caused it to get waterlogged (i.e., air loss); otherwise, the problem will probably come back...sometimes very soon.

These type of pumps do not use a bladder or diaphragm in the tank to keep the water and air separated so the air is naturally absorbed into the water and this absorbed air requires replenishment. This replenishment is done by an air control/balance value, which on your pump is that value on the side of the manifold assembly with a small black hose coming out of it and going back to the water inlet side of the manifold. On each pump cycle the valve injects a very small amount of air back into the incoming water flow which goes into the pressure tank where a little bit if air is always being absorbed into the water...the valve is suppose to keep the tank air balance at the correct level...that is, offset that little bit of air that is naturally absorbed in the pressure tank since there is no barrier between the water and air in the tank. If the rubber diaphragm in the air control/balance value is ruptured...even a pin hole size rupture....the value will not operate properly causing the pressure tank to get waterlogged overtime. Even with a completely defective air control/balance value and after completely draining the tank to allow an air recharge/reentry, it could take a couple of weeks before the tank becomes waterlogged again. Good luck

Thanks, Pib, for your detailed explanation of how these pumps work.

This pump hasn't been used for quite a few weeks because the city water pressure has been high enough to prevent it coming on. So maybe the air in the pressure tank got absorbed over that time and the pump's "air charger" hasn't operated enough to recharge the tank with air.

I'll probably have a go at it - draining the tank - on Monday and post what happens.

[bankruatsteve]

Are you all sure there is something wrong? I have a Hitachi pressure pump (2.8KW - the rectangular kind) and that's how it has operated for 4 years now when, for whatever reason, the tap just doesn't open enough for a constant pump. So, if you open multiple taps does it still on/off like that? Mine will stay on for things like the shower, toilet, and multiple taps but always surges like that when only one tap that is probably clogged with calcium. IE: sounds normal to me.

[Pib]

Are you all sure there is something wrong? I have a Hitachi pressure pump (2.8KW - the rectangular kind) and that's how it has operated for 4 years now when, for whatever reason, the tap just doesn't open enough for a constant pump. So, if you open multiple taps does it still on/off like that? Mine will stay on for things like the shower, toilet, and multiple taps but always surges like that when only one tap that is probably clogged with calcium. IE: sounds normal to me.

Since you say "rectangular kind" that sounds like the shape of a constant pressure pump...completely different design than the OPs. A constant pressure pump will run close to 100% of the time even with a small constant draw of water. They usually do have a small pressure tank "bottle" of one or two liters that keeps them from kicking on for small leaks and very small, short term draws of water like getting a half glass of water or so.

[IMHO]

That sounds like the pump isn't primed to me.. If you undo the dark gray "radiator cap" on the top-most reservoir, do you see any water?

Note: be careful - it could be under pressure, and disconnect the mains first too

Edited November 22, 2014 by IMHO

[JetsetBkk]

Are you all sure there is something wrong? I have a Hitachi pressure pump (2.8KW - the rectangular kind) and that's how it has operated for 4 years now when, for whatever reason, the tap just doesn't open enough for a constant pump. So, if you open multiple taps does it still on/off like that? Mine will stay on for things like the shower, toilet, and multiple taps but always surges like that when only one tap that is probably clogged with calcium. IE: sounds normal to me.

Since you say "rectangular kind" that sounds like the shape of a constant pressure pump...completely different design than the OPs. A constant pressure pump will run close to 100% of the time even with a small constant draw of water. They usually do have a small pressure tank "bottle" of one or two liters that keeps them from kicking on for small leaks and very small, short term draws of water like getting a half glass of water or so.

That sounds like the pump isn't primed to me.. If you undo the dark gray "radiator cap" on the top-most reservoir, do you see any water?

Note: be careful - it could be under pressure, and disconnect the mains first too

Pib was right .

I just drained the tank after turning off the power and isolating it from the house.

There are three outlets at the bottom of the pressure tank - one is fitted with a pipe that connects to the house, one is a blanking plug and the other is a blanking plug with a removable plug in the centre.

So I removed the plug in the centre of the third outlet and let most of the water drain out.

The pump now switches on for about 1.5 seconds and then off for 3.5 seconds. Before today, it was switching on for one second and off for one second.

The shower in the bathroom now has a much steadier flow of water coming out, whereas before it was very jerky and quite annoying!

Thanks to all for replying!

[Pib]

I hope you let enough water out to where the water level got below the drain outlet, otherwise, air can't get into the tank since water is still blocking (flowing out of) the outlet. But based on your on-off cycling period you now have you must have let enough water drain out. Now you need to recheck your on-off cycle over come the coming days and weeks to see if it starts significantly shifting back to be on most of the time/rapid cycling...be sure to do the comparison with the same water flow (i.e, one tap fully on, etc). If the cycle starts degrading significantly, then you have an air leak which would really make itself visible by leaking water somewhere on the upper pressure tank and/or manifold assembly. If no leak, then the air charge/balance value could be defective. Good luck.

[JetsetBkk]

I hope you let enough water out to where the water level got below the drain outlet, otherwise, air can't get into the tank since water is still blocking (flowing out of) the outlet. But based on your on-off cycling period you now have you must have let enough water drain out. Now you need to recheck your on-off cycle over come the coming days and weeks to see if it starts significantly shifting back to be on most of the time/rapid cycling...be sure to do the comparison with the same water flow (i.e, one tap fully on, etc). If the cycle starts degrading significantly, then you have an air leak which would really make itself visible by leaking water somewhere on the upper pressure tank and/or manifold assembly. If no leak, then the air charge/balance value could be defective. Good luck.

Thanks, Pib, I will check each week for leaks and keep monitoring the on/off cycle times.

[Naam]

Are you all sure there is something wrong? I have a Hitachi pressure pump (2.8KW - the rectangular kind) and that's how it has operated for 4 years now when, for whatever reason, the tap just doesn't open enough for a constant pump. So, if you open multiple taps does it still on/off like that? Mine will stay on for things like the shower, toilet, and multiple taps but always surges like that when only one tap that is probably clogged with calcium. IE: sounds normal to me.

2.8KW

??? ???

[JetsetBkk]

Are you all sure there is something wrong? I have a Hitachi pressure pump (2.8KW - the rectangular kind) and that's how it has operated for 4 years now when, for whatever reason, the tap just doesn't open enough for a constant pump. So, if you open multiple taps does it still on/off like that? Mine will stay on for things like the shower, toilet, and multiple taps but always surges like that when only one tap that is probably clogged with calcium. IE: sounds normal to me.

2.8KW

??? ???

It's a bit bigger than mine ...

.

[Sophon]

Are you all sure there is something wrong? I have a Hitachi pressure pump (2.8KW - the rectangular kind) and that's how it has operated for 4 years now when, for whatever reason, the tap just doesn't open enough for a constant pump. So, if you open multiple taps does it still on/off like that? Mine will stay on for things like the shower, toilet, and multiple taps but always surges like that when only one tap that is probably clogged with calcium. IE: sounds normal to me.

2.8KW

??? ???

I bet he has pretty good water pressure

Sophon

[bankruatsteve]

OK. OK. My pump is 280 W or .280 KW. Sorry about the mistake.

[Naam]

OK. OK. My pump is 280 W or .280 KW. Sorry about the mistake.