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serioladumerili

Same hose for manual and electric bilge pump?

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Maybe this is dumb question...

My boat has just a manual bilge pump. I don't want to make new hole (if not really necessary) for new drain, so is it possible to connect new pump to existing drain hose? Do I have to connect after the manual Jabsco pump or it is possible with valves on the suction side?

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The manual pump outlet is often higher than the auto outlet.   The auto has to work harder to pump up to a elevation, so is that a concern?

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How do you prevent backflow of one pump through the other? Do both have check/flapper valves built in? Most centrifugal "Rule" type ones do not.

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35 minutes ago, Zonker said:

How do you prevent backflow of one pump through the other? Do both have check/flapper valves built in? Most centrifugal "Rule" type ones do not.

I can install an "inline" valve to prevent backflow. I don't know if the manual pump will permit flow started by electric pump.

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Inline valves i.e. check valves are a bad idea on bilge pump outlets even if both pumps have a good strainer. They get clogged with shit, and the bronze ones stick in place. 

Swing checks must be mounted horizontally, lift checks use a spring. Both impose extra head on the pump, reducing performance. 

It's far better practice to just run another hose to it's own outlet

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Or have the two hoses join at the thru hull. If both are sloping down (which they should be) they can't backflow.

 

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My boat has had this setup since new and it works ok. The electric pump connects after the manual pump and is connected in such a way that the pipe from the electric pump is about 6 inches above the manual pump which seems to prevent backflow when activating the manual pump.

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We have a Y valve just before the transom outlet.

works automatically, not sure of he make, I assume it is just a flap valve.

I check the pumps now and then, so it works ...

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I'm looking at doing the same but was going to put a 3 way valve on the intake side of both pumps.  That way I can choose and there is no worries about backflow and/or check valves.

If the small capacity electric (that I want to install to keep nuisance water (like from the mast)) fails, I can revert to the manual if need be.  There is a large capacity manual in the cockpit.

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Using a common outlet fitting is not unreasonable.

Using a common hose might not be a good idea, as a hose or pump or valve failure on the lift side takes out both pumps. 

Think about putting teeing the two hoses at the outlet fitting's seacock and putting a vacuum breaker on the automatic one unless it's above water  at all heel angles

 

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My concern about joining two pumps at any point for water egress is compromising either/both pump(s) when both are running in an emergency situation.  

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13 hours ago, sail69 said:

My concern about joining two pumps at any point for water egress is compromising either/both pump(s) when both are running in an emergency situation.  

Agree,  piping needs to sized accordingly.  Remember also that where two say 1" discharges meet the combined size is not a 2"equivalent. 

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run two hoses. its the only intelligent solution. I've tried making this work because it seems so much easier to have less holes and hoses in the boat. I now have more hoses and holes. 

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You can run the 2 pumps into the 1 outlet. There are a few things that you will need to do help The pumps work at better and increase the out put. 

 

1 - make the outlet the maximum size for the biggest pump e.g if you are running a 1” hose and the pump can take a 1 1/2” hose you need to change it to the bigger size skin fitting and hose. When fitting a new pump you should always fit the biggest skin fitting and hose as possible.

2 - fit a Y fitting as close to the outlet as possible. Fit a non return valve next to the Y fitting. Note if you fit the non return valve next to the pump and a few feet from the outlet the pump will not be able to push the water in the hose and open the valve. 

3 - always fit a loop in the hose above the outlet wear possible as it stops the water following back into the boat. 

 

Pulpit 

 

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On 11/29/2017 at 8:10 AM, sail69 said:

My concern about joining two pumps at any point for water egress is compromising either/both pump(s) when both are running in an emergency situation.  

Can you pump out more water with a manual bilge pump or a bucket?

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