Learning the HARD way...
Join Date: Jan 2007
Location: Boston Area
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Re: How to blow out fresh water tanks
There are un-pressurized, usually 5/8", hoses that run from the water tank(s) to the pressure pump. Frequently, there is also a "Y" valve to select the draw from either pump.
To drain, and purge the system;
- run a cold water faucet to empty the tank(s) as much as possible. You'll hear the pump running continuously, and the sound it makes will change to a higher pitch. When one tank is dry, switch to the other.
- disconnect the hose at the tank that you drew from last.
- connect the compressor hose to this hose.
- open the drain valve on the hot water heater, and let it drain. Close the drain valve when the hot water heater is empty.
- set the pressure to NO MORE than 20PSI
- open a cold water faucet
- blow compressed air into the line, until air comes out of the faucet
- open the adjacent hot water faucet
- blow compressed air into the line, until air comes out of the hot water faucet.
- repeat steps 6 - 9 at every fixture (head, galley, etc.) until you have blown all the lines clear. Don't forget freshwater toilets (if you have them) and transom showers.
Be careful using ANY form of alcohol, as it will eat rubber seals in the system. If you have a "Y" valve, it will be among the first things that you have to replace (DAMHIK).
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USCG Licensed OUPV Captain, ASA 101/103/104/105 Certified Instructor - Also certified in Recreational Marine Electrical Systems
Last edited by eherlihy; 10-10-2013 at 04:38 PM.