I realize that this forum mainly deals with toilets but since I have a sink in the head, I thought I'd throw this to the "head mistress".. Last year I replaced the water heater in my boat but I did not plumb it in. I just hooked the cold water "in" line directly to the hot water "out" line and bypassed the water heater. Yesterday, I hooked in the water heater and filled the fresh water tank but the system won't pressurize enough for the fresh water pump to shut off. Water gets to all sinks on the hot and cold sides but it never really develops a steady stream. It sort of comes out in spurts. Any ideas?
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Air entrapment ......
You probably have a large 'bubble of air' trapped somewhere in your system .... a hose that is higher than the tank or heater etc. Look for such 'high-spot' and relocate them so that when filling the system you dont trap air and the system can be 'totally filled' with water. If these 'high' areas are hard piped or such a pain in the butt to relocate them to a lower position, apply a small bleed valve to bleed off the air when initially filling the system .... but be advised that you will accumulate bubbles continually at these high spots and will need to occasionally bleed the system. Dont even THINK of putting a air bleed float valve in such places.
You probably have a large 'bubble of air' trapped somewhere in your system .... a hose that is higher than the tank or heater etc. Look for such 'high-spot' and relocate them so that when filling the system you dont trap air and the system can be 'totally filled' with water. If these 'high' areas are hard piped or such a pain in the butt to relocate them to a lower position, apply a small bleed valve to bleed off the air when initially filling the system .... but be advised that you will accumulate bubbles continually at these high spots and will need to occasionally bleed the system. Dont even THINK of putting a air bleed float valve in such places.
I emailed my water heater guru...here's his reply:
Rich is correct....the air needs to be bled out of all the lines. But there's no need to modify any plumbing. Turn on the fresh water pump, then open the taps--both cold and hot that are FARTHEST from the pump and leave them open until the water flows smoothly and evenly at that tap. Then you go to the tap next farthest from the pump and do the same thing...working your way back to the tap closest to the pump. When all the air has been bled out of the lines, and water flows evenly out of all taps, the water heater will begin to fill. Could take 10 or 15 minutes but eventually the system will come up to pressure and the pump will shut off. As long as there's air remaining in the lines, the pump may not shut off. But once all the air has been purged from the lines, it'll come up to pressure and shut off - as long as there aren't any leaks in the system. Note: the cold water "in" is at the bottom (of the water heater) and the hot water "out" is at the top - be sure you haven't plumbed it backwards. Also note that the electric breaker must be kept OFF until all the air is out of the system and the tank has filled, the system has come up to pressure and the pump has shut off... then and only the do you turn on the electric power....'cuz turning it on before the heating element is completely under water will burn out the element.
Rich is correct....the air needs to be bled out of all the lines. But there's no need to modify any plumbing. Turn on the fresh water pump, then open the taps--both cold and hot that are FARTHEST from the pump and leave them open until the water flows smoothly and evenly at that tap. Then you go to the tap next farthest from the pump and do the same thing...working your way back to the tap closest to the pump. When all the air has been bled out of the lines, and water flows evenly out of all taps, the water heater will begin to fill. Could take 10 or 15 minutes but eventually the system will come up to pressure and the pump will shut off. As long as there's air remaining in the lines, the pump may not shut off. But once all the air has been purged from the lines, it'll come up to pressure and shut off - as long as there aren't any leaks in the system. Note: the cold water "in" is at the bottom (of the water heater) and the hot water "out" is at the top - be sure you haven't plumbed it backwards. Also note that the electric breaker must be kept OFF until all the air is out of the system and the tank has filled, the system has come up to pressure and the pump has shut off... then and only the do you turn on the electric power....'cuz turning it on before the heating element is completely under water will burn out the element.
Happy ending
The air entrapment was between the fresh water tank and the pump. I was afraid that the hose between the two was leaking (pulling in air. It is not very accesible or visible. I finally decided to test it by injecting air from the pump end back to the tank. I figured if there was a split in the hose, the air would take the path of least resistance and go through the split rather than fighting the head pressure on a full water tank. The result was free flow of air (bubbles) in the tank. I hooked the line back onto the pump and everything started working. I'm not exactly sure how but it is fixed now. Thanks again for the advice.
The air entrapment was between the fresh water tank and the pump. I was afraid that the hose between the two was leaking (pulling in air. It is not very accesible or visible. I finally decided to test it by injecting air from the pump end back to the tank. I figured if there was a split in the hose, the air would take the path of least resistance and go through the split rather than fighting the head pressure on a full water tank. The result was free flow of air (bubbles) in the tank. I hooked the line back onto the pump and everything started working. I'm not exactly sure how but it is fixed now. Thanks again for the advice.
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