How much water to flush a Jabsco manual toilet

[syvictoria]

Hello! Can anyone tell me how much water (on average) it takes to flush a standard Jabsco Par manual toilet (not one of the eco flush electric models)? Thanks!

 

[pvb]

Wouldn't it depend on the length of the outlet pipe? To minimise smells, blockages, etc, it's important to give marine toilets a good flush. Or are you considering holding tank capacity?

 

[syvictoria]

Thanks for your reply. I'm really thinking about holding tank capacity and the vertues of a Lavac which states 3 pints (or 1.7 litres) per flush. Our current pipe runs are very short. Thanks again.

 

[vyv_cox]

As pvb has said it depends on the length of the discharge hose. The piston and hose are roughly the same diameter, so divide the length of the hose from the toilet discharge to the top of the loop by the stroke of the piston. Add one stroke to this number for pump losses, and another two for flushing the bowl. That's the minimum to clear everything through.

 

[syvictoria]

Thanks for this! Sorry, I'm being a bit thick... assuming the discharge hose is 1m and the diameter/stroke is 5cm, that gives me a final figure of 35 (20/5 + 5 + 10), but what does this mean? 3.5 litres? Sorry, told you I was being thick :-(

 

[Tranona]

The great advantage of a Lavac over a Jabsco is simplicity. It is also much more predictable in practice in respect to volume of water used if you follow the instructions. Problem with Jabsco is that it is easy to pump too much.

If doing a new installation, go for a Lavac, but replacement of a Jabsco can be tricky because of the different layout of pipes and pumps.

 

[vyv_cox]

Thanks for this! Sorry, I'm being a bit thick... assuming the discharge hose is 1m and the diameter/stroke is 5cm, that gives me a final figure of 35 (20/5 + 5 + 10), but what does this mean? 3.5 litres? Sorry, told you I was being thick :-(

The diameters of the hose and the pump are almost the same. So if the stroke (the distance between piston down and piston up) is, say 15 cm, then the first figure is 100/15 = about 7, the full figure is then 7 +1 +2 = 10 strokes.

 

[Elemental]

The diameters of the hose and the pump are almost the same. So if the stroke (the distance between piston down and piston up) is, say 15 cm, then the first figure is 100/15 = about 7, the full figure is then 7 +1 +2 = 10 strokes.

If I understand the OP he's struggling to convert the stroke value to litres.

10 strokes = 1.5m. Diameter of pipe = 5cm

Cylinder volume = pi x r^2 x h

vol (cubic metres) = 3.14 x (0.025 x 0.025) x 1.5 = 0.00294375
vol (litres) = 2.9

 

[syvictoria]

Thank you all very much! My question is now answered! The Lavac definitely appears to be the winner on this one - especially since I unfortunately only have space for a small holding tank. Thanks again, much appreciated.

 

[JackFrobisher]

I recall that the handbook suggests seven strokes of the pump for every metre of outlet pipe run. This has more to do with ensuring that the outlet pipe is fully flushed to avoid blockages but it will however affect the rate at which your holding tank will fill.

 

[pvb]

I recall that the handbook suggests seven strokes of the pump for every metre of outlet pipe run. This has more to do with ensuring that the outlet pipe is fully flushed to avoid blockages but it will however affect the rate at which your holding tank will fill.

And if the object of flushing is to clear the outlet pipe, then surely it doesn't matter whether the actual toilet is a Jabsco or a Lavac??

 

[JackFrobisher]

I guess not really. A long analysis of volume per stroke in relation to the outlet pipe diameter and length and the number of strokes to ensure that all contents are clear of the pipe might be interesting and definitive but I can't be asked.
{|)

 

[dulcibella]

With fairly long pipe siphon-breakers, I reckon that 30 strokes for a wee and 50 for a poo is about right.