Vented Loop, head supply water line

Peter · Post by **Peter** » Sun Mar 11, 2007 11:38 pm

I have a question regarding the correct location for the vented loop in the head water supply line.
Does it go between the thru hull and the head pump,
or
does it go between the head pump and the head bowl?
(The head is below the water line.)

Yeah, I know, dumb question , but I'm just about pooped out on this head / holding tank installation :-)

Figment · Post by **Figment** » Mon Mar 12, 2007 9:10 am

I'm not sure that it matters, but my instinct would be to put it between the thruhull and the pump. This way, the vacuum break gives some protection in the event that the connections at the pump start to leak.

Ceasar Choppy · Post by **Ceasar Choppy** » Mon Mar 12, 2007 10:21 am

Figment wrote:I'm not sure that it matters, but my instinct would be to put it between the thruhull and the pump. This way, the vacuum break gives some protection in the event that the connections at the pump start to leak.

Ding ding ding!. The whole point of a VL is to prevent the boat from sinking from water siphoning in from a thru-hull. Another reason you don't want it on the draw side of the pump, is that the pump won't be able to generate the suction if the vent on the loop is working properly.

Hirilondë · Post by **Hirilondë** » Mon Mar 12, 2007 6:48 pm

The general rule for vented loops is that the run from the loop to the seacock is "sacred". Nothing but nothing should ever go in between, no fittings, no connections no nothing!!!!! Unfortunately, as Ceaser has pointed out, your suction pump won't work if you do this on the supply water side. Therefore you need to put the loop between the pump and the bowl. Do however in the process make sure you double clamp everything on the through hull side of the loop (you should do this to all connections really) and make sure these connections are well secured and the hose and pump in good condition. Any potential leak between the loop and through hull is not protected.