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Old 05-17-2015, 11:20 AM   #58
Northern Spy
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City: Powell River, BC
Country: Canada
Vessel Name: Northern Spy
Vessel Model: Nordic Tug 26
Join Date: Feb 2012
Posts: 2,746
Quote:
Originally Posted by markpierce View Post
Here are the two approaches suggested by the builder:

"It looks like the pump can't compress the air column in the outlet enough to force the water out near the thruhull. An easy fix is a "T" at the top of the loop to let the air out as the pump water goes up the hose and as it flows down to the thruhull the remaining air will escape. The vent hose has to go high enough to not allow the pressure to push water up and out. About 2 feet if possible. Or "T" the vent in the sink drain with a loop."
Yes. Venting the loop is important as it prevents the loop to reverse syphon SF Bay back into your shower.

If the loop is merely hose, than placing a tee would work as long as the tee is vented to an appropriate place at a higher elevation. Teeing the vent to the sink drain can work as long as you don't inadvertantly drain the sink into the shower sump. Ensure something like a sanitary tee or a wye is used. You can also purchase a vented loop, which will have a duckbill valve on the extrados at the top of the loop. Sometimes these may not work so well as they can get plugged with debris. If one is installed make sure you can access the duckbill valve easily enough for periodic cleaning.
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