Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 07-08-2008, 10:07   #1
Registered User

Join Date: Aug 2008
Posts: 4
Bleeding Fresh Water System

Just recently changed out my fresh water pump. Loud knocking occurs when the faucet is turned. Is there a recommended procedure for bleeding the system? (I am assuming the noise is from trapped air)

rjarrell is offline   Reply With Quote
Old 07-08-2008, 10:44   #2

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,077
If you have an accumulator tank, there may be a pressure or bleed screw on it. The knocking sounds like "water hammer". In systems without an accumulator, there may be a vertical pipe stub (a dead end vertical pipe, capped at the top) that is designed to prevent water hammer, too. Normally that's got no provision for bleeding, but if it leaked or was removed, could cause the same problem. If the new pump is stronger than the old one, and there was no accumulator tank before? Adding an accumulator tank would solve the problem, and make the pump work less, too.

hellosailor is offline   Reply With Quote
Old 07-08-2008, 10:54   #3
Marine Service Provider
AnchorageGuy's Avatar

Join Date: Mar 2003
Location: Wherever the boat is!
Boat: Marine Trader 34DC
Posts: 4,617
Air in the system will result in spurts out of the faucet and if the tank or lines are emptied you need to run the pump with all faucets open including hot water until water flows without air. The hot water tank needs to be full of water and not partially filled with air. The knocking may be your pump not fastened down. If you have rigid water lines then some may be hitting the hull as the water pulses until the air is gone.
Chesapeake Bay, ICW Hampton Roads To Key West, The Gulf Coast, The Bahamas

The Trawler Beach House
Voyages Of Sea Trek
AnchorageGuy is offline   Reply With Quote
Old 08-08-2008, 20:38   #4
Eternal Member
Chief Engineer's Avatar

Join Date: Aug 2006
Location: North of Baltimore
Boat: Ericson 27 & 18' Herrmann Catboat
Posts: 3,798
Start with the faucet furthest away from the pump.

What type of freshwater pump are you using?

Some have a hard time priming.

Remove hose from outlet side of pump and turn on till you get water.

Are the tanks full?.... (seriously...this happens frequently)
Chief Engineer is offline   Reply With Quote
Old 09-08-2008, 01:13   #5
Moderator Emeritus
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 29,375
Images: 240
You are all right, this knocking is "air hammer".

I installed a bleeder valve on Southbound. This was just a “tee” fitting with a valve on the open end, inserted in line just after the pressure water pump. To bleed the water lines, you open the bleeder valve, and let the pump run until you get “airless” water.

Without a bleed valve, open up your plumbing pipe/hose at the lowest practicable point, or the nearest faucet.

Then open faucets one at a time, starting at next nearest, and run till airless.
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

GordMay is offline   Reply With Quote
Old 09-08-2008, 04:24   #6
Moderator Emeritus
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Without a bleed valve, open up your plumbing pipe/hose at the lowest practicable point, or the nearest faucet.
I find I need to open more than one faucet. I open all 4 galley and the head faucets since they are closest to the pump. The pump can't push air against water that well so it does relieve the resistance in front of the pump until the pump has water to it. I only have to do this if the tank sucks air. The T fitting after the pump would work much better. I use one before the pump for winterizing.

Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Raw-water to fresh-water cooling conversion Catamount Engines and Propulsion Systems 31 06-05-2012 07:29
Blue Water or Fresh Water? John-in-Hamilton General Sailing Forum 13 26-08-2009 01:11
Greetings from a fresh Water Sailor! Catania Meets & Greets 2 04-03-2008 09:50
fresh water pump teamivey Construction, Maintenance & Refit 7 11-02-2006 19:37
Fresh water tank leak lannen Construction, Maintenance & Refit 4 09-10-2003 17:55

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 14:43.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.