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-   -   Plumbing a 2d Bilge Pump (http://www.sailnet.com/forums/gear-maintenance/44434-plumbing-2d-bilge-pump.html)

jjablonowski 06-25-2008 11:27 AM

Plumbing a 2d Bilge Pump
 
I'm adding an electric bilge pump that will sit above the intake hose for the existing manual bilge pump. To avoid cutting another through-hull hole, I'll run the new hose to a Y connection downstream of the outlet of the manual pump.

Q: Will bilgewater from the new electric pump flow backwards into the Y, through the manual pump, and into the bilge? The existing manual pump appears to be a Whale Gusher Urchin or similar.

I could install a non-return valve upstream of the Y connection, but advice that I've seen recommends against that, because it'd (1) restrict the outflow and (2) possibly jam.

negrini 06-25-2008 02:14 PM

You should have a valve on your actual pump, avoiding last drop (or bucket, depending the lenght of your hose) backing to the bildge. Think like water will flow mostly to where pose less resistance, so, with both pump valved, that should be enough to avoid closed re-circulating. Not sure about ABYC standards, but I'd open another dedicated exit ....

jr438234606 06-25-2008 02:32 PM

"Y" connection by itself will allow backflow and defeat both pumps. Check valves will create too much head pressure, unless you got a check valve with REALLY light cracking pressure. Even if the manual pump has a rubber check value (which it probably does), pumping the manual one will still cause back flow through the electric one. That is unless both hoses have a considerable "riser" section.

I advise that you install a dedicated thru-hull for each bilge pump.

sailingdog 06-25-2008 03:58 PM

If you're really against installing a new through hull for the second pump, you could always plumb it so that it drains into the cockpit, and out the cockpit drains. Of course, if your cockpit drains use hoses and they fail, this will tend to screw you royally... but you can't have everything.... :) It is just as much work to install a through hull as it is to have the bilge pump drain into the cockpit, so just do yourself a favor and install a through hull instead.

Sequitur 06-25-2008 04:17 PM

I don't like the idea of sharing bilge pump through hulls. First, because the non-return may jam or fail and then the pump dumps right back into the bilge. Second, if you ever have to use both pumps at the same time, the outlet won't take the volume you're asking it to, and neither pump will work to capacity.

I have three pumps in my bilge sump, a primary rated at 5800 lph, a high water pump with alarm rated 15,500 lph and a manual gusher capable of about 12,000 lph. Each is led to its own through hull.

jjablonowski 07-03-2008 09:26 PM

Thanks all.

New electric bilge pump (atop manual one, seldom used except when there's a problem) now dumps into my cockpit.

Lets me know (if I'm aboard) that bilge level is overly high. Also, no new through-hull.

jjablonowski 07-07-2008 08:32 PM

Post Script on 2d bilge pump
 
Weeks before I posted my original query, I e-mailed the tech desk at Whale pumps with the same question.

Now, after having turned my cockpit floor into an occasional foot bath, I got a reply:
"Our pumps have a non return valve inside the outlet port
so you should be fine without a backflow preventer valve."

So I could'a used the Y connector and the original transom bilgepump through-hull after all. :rolleyes:

sailingdog 07-07-2008 08:46 PM

one advantage of the foot bath is that you'll be more aware of that pump and how often it cycles. :)
Quote:

Originally Posted by jjablonowski (Post 338103)
Weeks before I posted my original query, I e-mailed the tech desk at Whale pumps with the same question.

Now, after having turned my cockpit floor into an occasional foot bath, I got a reply:
"Our pumps have a non return valve inside the outlet port
so you should be fine without a backflow preventer valve."

So I could'a used the Y connector and the original transom bilgepump through-hull after all. :rolleyes:



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