Syphoning problems

[bowlingo]

Hi all,

I have a main tank with a pump in it pumping into a smaller tank. When the pump in the main tank turns off it continues to syphon down into the smaller tank. I am using a float switch system that I would like to turn on the pump within the main tank when the second tanks level gets to low then turn off via another flat switch when it reaches its level. I am not sure how I can stop it from syphoning back on itself once the main tanks pump turns off..I have seen these

http://www.wickes.co.uk/invt/420182

I am using 1/4" hose of which I think is the same as a washing machine hose?

Thanks

 

[ChrisR]

Take the pipe from the outlet of the pump higher than the level of the water in the main tank.
Then put your anti-vac valve there, so it breaks the syphon. If it doesn't let enough air in , use an air admittance valve as used on waste pipe, or if that doesn't work, a tundish.

 

[bowlingo]

the outlet pipe from the main tank is about 1.5 foot above the inlet on the second tank and well above the pump in the main tank..do you have any links to some anti syphon vales?

Thanks

 

[ChrisR]

the outlet pipe from the main tank is about 1.5 foot above the inlet on the second tank and well above the pump in the main tank..

The outlet has to be above the inlet on the MAIN tank, with somewhere there to let air in.
Google should throw up parts, from the words I used.

 

[ChrisR]

 

[cantaloup63]

Spigot fitted onto an open ended vertical piece of 40mm pipe would do it

 

[bowlingo]

Here is an extremely rough sketch of the way I have it set up..

It keeps on pushing water into the second tank when the main tanks pump turns off..

Can anyone tell me an easy way of stopping it from syphoning i.e something I can put on the pipe within the main tank just before it comes out..there isnt any water at the very top of the main tank where it pumps out via a hosetail connector. The problem I have is ive cut a hole in the second tank.

thanks

 

[cantaloup63]

Are the bases of these tanks at the same level? If yes, then it's not a syphoning effect that is occurring, which means a different solution to the one's mentioned up to now

 

[bowlingo]

Are the bases of these tanks at the same level? If yes, then it's not a syphoning effect that is occurring, which means a different solution to the one's mentioned up to now

The bases are at the same level

 

[ChrisR]

That's why it siphons then, green is higher level than red. You need an air inlet at girlie purple:

it could go inside the main tank, at similar height.

Dunno why you need a pump, why not just use a ball/float valve in the smaller tank, like a loo costern fed from a loft tank?
Gravity is fairly reliable, on the whole

 

[cantaloup63]

Agree with the solution, but is the setup more akin to water finding it's own level via the pipe as the connector more than a syphonic effect? Must admit, it's got my head scratching

 

[bowlingo]

That's why it siphons then, green is higher level than red. You need an air inlet at girlie purple:

it could go inside the main tank, at similar height.

Dunno why you need a pump, why not just use a ball/float valve in the smaller tank, like a loo costern fed from a loft tank?
Gravity is fairly reliable, on the whole

its for a project im doing where I am not sure where the end user would position the tanks so I would rather use electronics..

So where you say an air inlet if I got a small piece of 1/4 plastic, pushed the 1/4 hose on both ends in the top of the main tank then drilled a couple of holes into it...this would make the water squirt through when the pump was on and loose pressure...is there not a proper valve for this so the water will flow through both ends when the pump is on without coming through the air hole?

Thanks

 

[Nige F]

Hi all,

I have a main tank with a pump in it pumping into a smaller tank.

No, you have 2 cisterns

 

[spraggo]

Install a spring loaded check valve in the pipe work just above the pump.

 

[doitall]

Just needs a ballvalve on the second tank.

If it was set up right, when the lower tank was low and the ballvalve opened the siphon may start again and top it back up without the pump.