A question for the plumbers

bingefeller

When we got our shower installed the plumber hooked the outlet of shower into the same outlet pipe as the sink uses.

I would always be first in the shower and I noticed that the water would drain out very slowly.  If I run a sink full of water, and let it out while there is water sitting in the bottom of the shower tray, the shower immediately starts draining a lot quicker once the sink has emptied. 

Anyone know why this happens?

FX_Munkee

Venturi Effect?

bingefeller

FX_Munkee said:

Venturi Effect?

I looked that up and I still don't understand it. What does it mean in simple terms?

FX_Munkee

The water from the sink going down the waste pipe creates a loss of pressure in the adjoining pipe from the shower, in effect "sucking" the water out with it.

ESBlonde

Google 'Venturi Pump' to have text and piccygraphs.

boogieman

At a guess it's working like a syphon. The water from the sink is at a higher level, so the water has more weight and wants to flow through the pipe quicker than the pipe from the shower. This increases the suction in the other pipe and sucks out the water from the shower tray with it. 

bingefeller

I get it now.  I only have to do this once and the shower drains out fine the rest of the time, until the next day.  Would that still be the Venturi effect?

boogieman

bingefeller said:

I get it now.  I only have to do this once and the shower drains out fine the rest of the time, until the next day.  Would that still be the Venturi effect?

Yup. Same as syphoning something. You just have to start it off and then it runs by itself. 

bingefeller

boogieman said:

bingefeller said:

I get it now.  I only have to do this once and the shower drains out fine the rest of the time, until the next day.  Would that still be the Venturi effect?

Yup. Same as syphoning something. You just have to start it off and then it runs by itself. 

Oh cool.  Thanks.