foot valve vs check valve

[ThePioneer]

I have 2 automatic mitsubishi pumps, which have both there own feed and a foot valve mounted at the bottom of the pipe.

 

Now 1 of the pumps is running empty, and i suspect the foot valve is fallen off or stuck, but I don't want to go into the water tank.

 

Can I just add a check valve at the pump inlet and have the same effect?

[sometimewoodworker]

28 minutes ago, ThePioneer said:

Can I just add a check valve at the pump inlet and have the same effect?

Almost certainly no. The valve at the pump inlet is unlikely to be able to keep the pipe full for a prolonged period. 

 

But you could be lucky and it's not much work or expense to give it a try. 

[Artisi]

Having a CV at the inlet is sometimes OK, sometimes not - it depends. A foot valve keeps the inlet pipe full up to the pump whereas as a check valve doesn't guarantee it will - the inlet pipe from the CV to the tank could drain back, although in theory it shouldn't as there will be a vacuum to hold the pipe full. 

As the previous poster said - give it a try. 

 

 

[sherwood]

No a non-return valve at the pump will not fix your problem. If your foot valve is broken ie.. non return flap incorperated in the foot valve is stuck open then you need to replace the foot valve or repair same.

 

 

 

 

 

 

 

 

 

 

 

 

[Artisi]

2 hours ago, sherwood said:

No a non-return valve at the pump will not fix your problem. If your foot valve is broken ie.. non return flap incorperated in the foot valve is stuck open then you need to replace the foot valve or repair same.

 

 

 

 

 

 

 

 

 

 

 

 

maybe - maybe not.

When you are drinking your milk-shake, coke , beer or whatever via a straw and you stick you tongue over the end - does the straw drain or does it hold the column of drink in the straw?

Physics 101.

[ThePioneer]

Completely lost now.

 

Changed footvalve - changed pressure switch - all outgoing water is blocked off at the pump.

 

Pump keeps starting up every 15 seconds

[Artisi]

7 minutes ago, ThePioneer said:

Completely lost now.

 

Changed footvalve - changed pressure switch - all outgoing water is blocked off at the pump.

 

Pump keeps starting up every 15 seconds

What type of foot valve, does it open and close ok, is it installed in the correct direction. 

Or is discharge blocked for some reason? 

[ThePioneer]

18 minutes ago, Artisi said:

What type of foot valve, does it open and close ok, is it installed in the correct direction. 

Or is discharge blocked for some reason? 

 

Brandnew foot valve identical to the one previously installed for 10 years, and it works because when i unscrew the feed pipe it is topped up with water.

 

When the pump runs I hear air in the pump. But after 15 seconds it stops, and 15 seconds later it start again

Edited August 23, 2019 by ThePioneer

[Artisi]

7 minutes ago, ThePioneer said:

 

Brandnew foot valve identical to the one previously installed for 10 years, and it works because when i unscrew the feed pipe it is topped up with water.

 

When the pump runs I hear air in the pump. But after 15 seconds it stops, and 15 seconds later it start again

Is the pump completely free of air? 

[grollies]

Prime your pump properly.

 

PS, these pumps already have a check valve on the inlet suction side.

[Artisi]

6 minutes ago, grollies said:

Prime your pump properly.

 

PS, these pumps already have a check valve on the inlet suction side.

Provided they are functional... 

[ThePioneer]

After a full day wasting time found the cause.

 

There is 1 pipe that goes to the garden taps and the pool, which is not on a zone that can closed off.

 

After walking around for half an hour noticed a small puddle in the middle of the lawn and a sinkhole nearby.

 

So started digging there and found a blue pipe that had imploded and subsequent crack.

 

The hole is open now, but too much water in the ground to repair, so will be job for tomorrow.

 

Strange that a pipe that is in the ground for 10 years can implode at one point.

 

From the location I suspect it is the pipe that goes to the pool, but all pipes in the ground are 8.5 pressure rating.

[grollies]

1 minute ago, Artisi said:

Provided they are functional... 

Weeeeelllllll, yes but the OP doesn't seem to realise there is already a NRV in the pump manifold.

 

OP: unscrew the black cap on the suction side. There'll be a spring and check valve plunger. Make sure it's clean. Top up water with the plunger removed until it is full, replace plunger, spring and screw cap back on. Should work.

[grollies]

2 minutes ago, ThePioneer said:

After a full day wasting time found the cause.

 

There is 1 pipe that goes to the garden taps and the pool, which is not on a zone that can closed off.

 

After walking around for half an hour noticed a small puddle in the middle of the lawn and a sinkhole nearby.

 

So started digging there and found a blue pipe that had imploded and subsequent crack.

 

The hole is open now, but too much water in the ground to repair, so will be job for tomorrow.

 

Strange that a pipe that is in the ground for 10 years can implode at one point.

 

From the location I suspect it is the pipe that goes to the pool, but all pipes in the ground are 8.5 pressure rating.

Way hey, glad you got it sorted. Pump running OK?

[ThePioneer]

Just now, grollies said:

Pump running OK?

 

 

That we will know tomorrow after i have fixed the pipe, but since the pump has always been running ok until today, I expect there is no problem with the pump.

[Artisi]

The foibles of pump trouble shooting, from failed footvalve to split pipe, but certainly not the most intriguing I've come across - - wouldn't a crystal ball be great ????

Edited August 23, 2019 by Artisi

[ThePioneer]

More advice appreciated.

 

I have opened about 3 meter in the lawn, which is the maximum.

 

I will have to replace about 50 cm of 3/4 13.5 tube, but I can't move the pipe to left or right, and I'm also limited in lifting as there are other pipes running above.

 

What would be the way to replace that 50 cm of pipe?

[chickenslegs]

9 minutes ago, ThePioneer said:

More advice appreciated.

 

I have opened about 3 meter in the lawn, which is the maximum.

 

I will have to replace about 50 cm of 3/4 13.5 tube, but I can't move the pipe to left or right, and I'm also limited in lifting as there are other pipes running above.

 

What would be the way to replace that 50 cm of pipe?

You could use two union fittings

[grollies]

Or cut a gap 50cm and install 2 x 90deg elbows to make a 'U' shape on the same plane. That'll give you enough play to join the pipe back up.

[ThePioneer]

This guy seems to have the perfect solution.

 

Watch the video and get me point why I hate those youtubers with a vengeance.

 

 

[ThePioneer]

10 minutes ago, chickenslegs said:

You could use two union fittings

Been thinking about that, but consider a coupling like that underground a bit risky

[VocalNeal]

2 minutes ago, ThePioneer said:

Been thinking about that, but consider a coupling like that underground a bit risky

Risky in what sense?

[ThePioneer]

Just now, VocalNeal said:

Risky in what sense?

That it may leak of course

[sometimewoodworker]

2 hours ago, ThePioneer said:

That it may leak of course

Little chance of that, as long as you don't damage the 'O' ring and use a little silicone grease or Vaseline when putting it together.

[VocalNeal]

Why would it leak if glued and tightened properly? It cannot loosen when underground as there is nothing to encourage rotation.

[ThePioneer]

Well problem solved for now.I know I better had applied it sideways, but was too lazy to dig for more space

 

 

Still wonder how this can happen with a 13.5 tube about 50 cm under the ground, and no pressure applied there ever.

 

[bankruatsteve]

That appears to be the result of vacuum in the pipe.  (?)  Only in the one section?

[Artisi]

58 minutes ago, bankruatsteve said:

That appears to be the result of vacuum in the pipe.  (?)  Only in the one section?

Not vacuum on a sound pipe, damaged during installation or before - maybe. 

But of course, why would a pipe on the discharge side of the pump be under vacuum. 

As said previously the foibles of pump /ancillary trouble shooting, an area I have spent a lot of time with in my 40+ years in the pump industry. 

But a good fix-up which would have been better rotated 90 degree's. Ensure the pipe is well supported on the underside. 

Edited August 24, 2019 by Artisi

[ThePioneer]

11 minutes ago, Artisi said:

Not vacuum on a sound pipe, damaged during installation or before - maybe. 

Pipe was installed 10 years ago, so that would be a long time for a damaged pipe to start leaking.

 

Only thing I can think about is that since that pipe is to top up the pool, maybe the suction of a running pool pump, combined with a empty pipe for whatever reason.

 

I only can hope it's just 1 section that's damaged, because from there it goes under a tiled concrete floor.

[Artisi]

does the Mitsubishi pump feed the inlet side of your pool pump?