Things that go buzz in the night

[DavidJ]

My shower drain pump will switch on for a couple of seconds every now and again during the night.
There is no water or condensation going in from the shower unit.
There is no switch to switch it off (unlike other boats I've had which have been switched from the 'water' switch).
It does it in calm conditions. ie not caused by 'slop'
I've cleaned the drain pump unit.
Any suggestions before I consider rewiring it into the 'water' switch so I can switch the damn thing off.
David

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[Guest]

Is it a self contained tray type with a float switch?

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[tcm]

praps the water is running back to the float switch, i think. So the float switch goes off, pumping it up the line. Then the level lowers, so it switches off. Then a bit of water comes back the line having not quite made it out, so the switch goes off again. perhaps. I think that slightly changing the route of the exhaust pipe would stop it, yerknow with cable ties, or adjusting the level at which the float switch works. or rewire it.

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[DavidJ]

Yes, it's a self contained plastic box with filter and float switch (although I've not taken the unit apart to see how the float switch works)
David

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[hlb]

Think tcm might be right. Try one of his sugestions or pack float switch a bit higher or lower.

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Haydn

 

[DavidJ]

Yes, I'll try that. The space is very accessible so quite easy to play around with pipe runs etc and certainly a million times easier than re-routing electric wiring.
ta
David

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[DavidJ]

Haydn
With what you have in mind with packing the float switch, would mounting the 'box' higher have a similar effect.
David

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[tcm]

mebbe try...
a) the exhaust pipe diameter is too big, so the amount of runback water floats the switch. So could use smaller pipe.

and/or

b) the exhaust run is too long, so capacity that fails to make it outside, runs back and again floating the switch

and 'or

c) the box thinghy is a small one, so small runback floats the switch, whereas if it was a bigger box, then ok.

or

d) the pipe run could be changed to avoid having all that runback.
not enough pipe on the exhaust side: a longer section of level pipe might act as a reservoir for the runback in the sloping length. not sure bouthis.


e) a slight downward bit before teh upward run to skin fiting might give a reservoir to the water that fails to make it to the skin fitting

anyway i9reckon it would be quite hard to set it as you have got it!


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[Guest]

You will need to investigate the tray to see if anything else is running to it. And also check if your expansion valve hose on your calorifier runs to it as is often the case. If it does then your pressure valve may need replacing.because that will continue to flow while your hot water heater is on.

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[tcm]

you should open the box once a year praps to get all the greeby hairs out of the coarse filter. Your float switch is working fab, praps when it gets a bit mankiy it may be a little les sensitive. Its a floaty lever usually, the lever floats and turns on the circuit.

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[DavidJ]

Yea
Good suggestions. I can't remember if the pipes are plain or those ribbed ones which would certainly hold back quite a bit of water. All the suggestions are in the right direction I think because I've noticed that after cleaning the 'box' and leaving it empty it doesn't do it until someone has had a shower and returned the water levels back to 'normal'.
David

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[jfm]

David we have the same thing. It's a bought-in shower sump unit - ours is on a fairline but praps the very same compoent as yours. Anyway, we had the same buzz in night prob. We re routed the outlet as others on this thread have suggested so it has a "hump" above the level of the skin fitting, and therefore only about 10" of pipe to drain back into the sump and re-trigger the float switch. It worked a bit, but it still buzzes occasionally, like once every 2 hours for 5 seconds. I think there is maybe a cheapo plastic non return valve that leaks slowly, which is why there is a 2 hour delay between buzzes

The manufacturers are supposed to fit a float switch that has enough "dead" travel ie if the float switch opens the circuit at height X it sould only re-close the circuit when the level rises to X + 10mm say. But they dont, hence this problem. But you might find that rerouting the outlet pipe to put a hump in it will reduce the flow back volume to less than the float switch retrigger point, the 10mm say, and that will cure it. So would making the sump bigger (ie more area on the horizontal plane), but that's a big job probly

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[tcm]

Re: slight mod

I bet there's no non-return valve - far too spensive an idea for a boat maker.

The rerouting as jfm has dunnit reduces the amount of drips in the exhaust pipe that flow back. But praps a beter way would be to have a longer level bit (or even a bigger dia bit of pipe) immediately on exit from the box, and then rise up quickly to the skin fitting. This way, the effective horizontal area of the reservoir is bigger, and the bit of water that floods back affects the reservoir height much less. Also, the pipe wd drain more quickly thereby thwarting the harmonic nature of this effect.



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[jfm]

Re: slight mod

All agreed. If you can increase horizontal surface area of sump then the flowback doesn't raise water level so much. But usually these things are in forward bilge, so ability to run pipe horizontally to the skin fitting is limited by hull Vee. Also, you might think you could coil up a couple of metres of pipe in a horizontal plane right near the sump, but that doesn't work as you need a space into which the water level can rise. Like a pipe laid out horizonatally and only 1/2 full, so the top half of the pipe diameter takes up the flow back. That's too hard. So you actually need a bigger sump box, or an expansipon tank alongside it or suchlike, eek. We gave up and just tolerate the buzz

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[Guest]

Re: slight mod

you wait till the bearing goes then u certainly won`t tollerate it. What a rackett.

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[DavidJ]

Re: slight mod

Yes it is in the forward bilge although a good 8ft back from the bow but I can raise the height of the box relatively easily to give me some horizontal area in which to coil the outlet pipe around thus as you say giving me more virtual sump area.
As tcm suggests you don't get non return valves in my sort of boat and it would probably either stick open or worst stick shut anyway.
David

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[Guest]

I know someone who has a boat that used to be very noisy at night. His partner was convinced that it was haunted and had the boat exorcised. As far as I know that cured the problem.

Just a suggestion...

Nigel

<hr width=100% size=1>Medway Motor Yacht Club
<A target="_blank" HREF=http://www.mmyc.co.uk>http://www.mmyc.co.uk</A>

 

[DavidJ]

hmmmm....maybe, when all else fails

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[tcm]

That sounds the most likely solution to me, actually.

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