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Discussion Starter · #1 ·
Just installed an ITT Jabsco solid vane driven pump as a washdown pump, but am having trouble and hope this group can isolate the problem. I teed into the raw water intake on the head. The intake runs from the thru hull then tees off for the pump about 16" up. The water intake continues to an anti siphon valve and onto the toilet. The pump seems not to want to prime, but when I pump the toilet to fill the bowl, the pump reaches pressure. If a sea water intake must have an anti siphon, does that negate using it for a pump intake for the deck? Shopuld I have teed in after the anti siphon valve?
 

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Jim, If I understand your post correctly, there should not be an anti-syphon valve in your washdown system. Tee off the intake, run through a filter, straight to the pump and to the deck fitting. Anything else is going to allow air to enter and the pump will not prime. Chuck
I read from the OP that the anti-syphon vavle is after the tee to the washdown pump. The valve does appear to be the problem as he is getting air to the pump and the only place that can be is from the anti-syphon valve. It would appear that he needs to find a different through-hull to connect his pump.
 

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I don't quite understand what you have done BUT

My wash-down pump intakes water from the sink drain seacock and i use the sink stopper to close off the sink as and air source

The pump is at least 24" above the waterline and primes in seconds AND for good measure if i close the seacock and fill the sink with freshwater i also have a freshwater rinse
 

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Discussion Starter · #5 ·
Hi everyone,
I appreciate the help. I am surprised that teeing off the toilet intake is a problem because I often hear that others do the same thing.
As I think about it though, teeing closer to the intake should eliminate the problem as the siphon break assures the water on the intake never rises above the waterline and where I am currently teed in is above the waterline so I am sucking air. Closer to the intake should solve the problem. Thanks for everyone's input.
 

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I don't quite understand what you have done BUT

My wash-down pump intakes water from the sink drain seacock and i use the sink stopper to close off the sink as and air source

The pump is at least 24" above the waterline and primes in seconds AND for good measure if i close the seacock and fill the sink with freshwater i also have a freshwater rinse
I like that idea, making mental note, though I will likely forget it soon!:eek:
 

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Discussion Starter · #10 ·
Everyone, thanks for the replies. Pump works now-its a Groco c-80 that was given to me after I worked on a refit for a larger vessel. The issue seems to be that it needed help priming and it needed to be plumbed into the toilet intake closer to the waterline.

On another note, the pressure is not that impressive. I get a solid stream, but not a super strong blast by any stretch. Its a vane pump. Is this a good design for the application?
 

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The C-80's got plenty of oomf on paper but how long is the run to the thru-hull? What's the tubing ID? What kind of nozzle are you using? Are you sure it insn't still pulling a bit of air despite the fact that it's now priming? It doesn't take much to compromise its efficiency...
 

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The C-80 should give you a good volume of water at medium pressure range, 20-40 psi. If you want more pressure look at the ShurFlo Blaster and Jabsco Wash Down pumps.

I'm wondering if the vented loop is still causing a problem. It's easy to test, just cover the air inlet with a piece of tape and run the pump.

Assuming your toilet is a typical manual toilet with the pump connected to the bowl by a short hose, it will work better if you put the loop in the hose between the pump and the bowl rather than in the intake line. It will still prevent water from siphoning into the bowl but the pump won't be sucking air.

In toilets where you can't put the vent between the pump and the bowl, as on most electric toilets, you should use a vent with a solenoid that closes the vent when the pump runs.
 

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Johnson Aqua Jet 3.5 Washdown Pump Kit

I went with this as I did not want the AMP draw of the 5 GPM units and the nozzle they supply gives excellent velocity compare to a household item
 
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