On a standard domestic water tank, does the suction pipe have a Non Return Valve (Float valve) on the bottom?

My pump is running for far too long and when I line up direct feed from outside i.e. bypass the tank, all is well, pump cuts out after a few seconds.

So it appears that I have a suction problem when lined up on the tank.

The answer should be no. Non return valves are usually installed on water lines on the discharge side of the pump if there is potential for water to flow back through the pump casing if the head of the discharge exceeds the suction head.

 

Float valves are installed on in-coming water supply into a tank and the ball float tilts up (floats) as the tank fills, slowly closing the water inlet valve.

On all the underground water tanks I have seen there is a "foot valve" at the lower end of the outlet pipe - preventing water from flowing back into the tank when the pump is off.

 

 

So I guess there is potential for this foot valve to fail, after time, reckon mine is 9 years old. Will be a nightmare to change out? Unless the pipe can be unscrewed.

Check the air vent is not blocked and the tank under vacuum.


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I'd go with Aussieroaming as a standard water tank purchased in Thailand would normally not be mounted underground and comes with no valves. Or that's how it used to be.

Is yours above ground or underground?

If it's above ground look for a simple solution first like an air leak and bad joint.

 

It depends on what style of pump you have, if the normal Mitsubishi / Hitachi or their clones, no valve needed on the inlet, if a conventional pump fitted with an air tank, pressure switch etc - yes. 

I have a Grundfos house pump, it needs a NRV on the inlet side as the whole system from pump inlet to supply side is under pressure. 

Sorted. Managed to unscrew the suction pipe, inside the tank, to dissever the foot valve was indeed broken. Fitted new foot valve and all's good now. The pipe came out easy enough, just a tad awkward when leaning into tank.

Big thanks to all who helped, especially Mt chickenlegs for informative drawing.

 

Looking at the piping arrangement at the pump, I may have a separate issue. The piping is fitted so that, in the event of a electric power cut, the tank can be bypassed. So the suction line valve from the tank can be closed and the water supply valve opened. The bypass line enters the system on the suction side of the pump. But this then pressures up the suction side of the pump, this cannot be any good for the pump.

So I am thinking that I have to redo the pipe work, so that the water supply (in the event of a power cut or pump failure) enters the system, on the discharge end of the pump, with a valve that can be closed to prevent water going back into the pump.

2 hours ago, hackjam said:

just a tad awkward when leaning into tank.

Very curious hackjam - what kind of tank? I have both an old underground and a newer stand alone vertical shape and the base of both are about 5/6ft from the hatch opening so impossible to get to without getting in it?

6 hours ago, hackjam said:

Sorted. Managed to unscrew the suction pipe, inside the tank, to dissever the foot valve was indeed broken. Fitted new foot valve and all's good now. The pipe came out easy enough, just a tad awkward when leaning into tank.

Big thanks to all who helped, especially Mt chickenlegs for informative drawing.

 

Looking at the piping arrangement at the pump, I may have a separate issue. The piping is fitted so that, in the event of a electric power cut, the tank can be bypassed. So the suction line valve from the tank can be closed and the water supply valve opened. The bypass line enters the system on the suction side of the pump. But this then pressures up the suction side of the pump, this cannot be any good for the pump.

So I am thinking that I have to redo the pipe work, so that the water supply (in the event of a power cut or pump failure) enters the system, on the discharge end of the pump, with a valve that can be closed to prevent water going back into the pump.

The small illustration on the top-left of this diagram may help.

8 hours ago, topt said:

Very curious hackjam - what kind of tank? I have both an old underground and a newer stand alone vertical shape and the base of both are about 5/6ft from the hatch opening so impossible to get to without getting in it?

Its an underground tank. I just put my hand inside and with a wrench, was able to undo the long ( about 5 feet long) suction pipe, take it out and changeout foot valve.

15 hours ago, hackjam said:

Its an underground tank. I just put my hand inside and with a wrench, was able to undo the long ( about 5 feet long) suction pipe, take it out and changeout foot valve.

From experience I always (now) tie a lanyard onto any tools being used inside our tank 

 

6 minutes ago, Crossy said:

From experience I always (now) tie a lanyard onto any tools being used inside our tank 

 

Or have access to a large magnet, on a lanyard of course. 

1 minute ago, Artisi said:

Or have access to a large magnet, on a lanyard of course. 

I think I invented magnet-fishing before it was popular ?

 

The tank in question was (of course) our irrigation water tank which pumps from the river, the water isn't exactly, er, clear. It's even less so when the mud on the bottom has been disturbed by the unscheduled arrival of a large pair of Stilsons.

 

From experience I always (now) tie a lanyard onto any tools being used inside our tank 
 

Spectacles too !

13 minutes ago, johng said:

46 minutes ago, Crossy said:

From experience I always (now) tie a lanyard onto any tools being used inside our tank 
 

Spectacles too !

Voice of experience??

Voice of experience??

An expensive pair of mine are at the bottom of "the Welsh Harp"
(Brent reservoir) after a 360 degree canoeing escapade.

1 hour ago, johng said:

"the Welsh Harp"

Wow!...….…. That evoked some ancient memories. 

 

Welsh Harp - North Circular - Ace Café...…………….

 

I feel quite nostalgic.   

22 hours ago, Daffy D said:

Welsh Harp - North Circular - Ace Café

All still there  just where you left them ?

On 9/15/2018 at 11:14 AM, hackjam said:

Looking at the piping arrangement at the pump, I may have a separate issue. The piping is fitted so that, in the event of a electric power cut, the tank can be bypassed. So the suction line valve from the tank can be closed and the water supply valve opened. The bypass line enters the system on the suction side of the pump. But this then pressures up the suction side of the pump, this cannot be any good for the pump.

So I am thinking that I have to redo the pipe work, so that the water supply (in the event of a power cut or pump failure) enters the system, on the discharge end of the pump, with a valve that can be closed to prevent water going back into the pump.

Well the water that is flowing into the house through the unpowered pump is not likely to damage the pump. But your pressure and flow rate will be quite a bit lower than it could be so it would be good practice to reroute the flow. Non return valves are often better as then you have less chance of forgetting which valve needs to be in which position.

For years, I have buying water filters from a lady who had a stall under Big C, Pattaya Klang, she was set up opposite the food court, beside the door to the car park. She was reasonably priced for the filters but, alas, she is no more. Was wondering if anyone knows where she relocated to or of a similar place to buy the water filters, as the like of Homepro are a rip off.

1 hour ago, hackjam said:

For years, I have buying water filters from a lady who had a stall under Big C, Pattaya Klang, she was set up opposite the food court, beside the door to the car park. She was reasonably priced for the filters but, alas, she is no more. Was wondering if anyone knows where she relocated to or of a similar place to buy the water filters, as the like of Homepro are a rip off.

Try www.duan-daw.com. Big selection of filters, prices to me seem ok, quick delivery. 

Only drawback is to pay up front by bank transfer or similar and then forward payment receipt.