Does anybody know if the drinking water tank on the 2002 H260 is vented?
On my buddy's H260, the galley and head sink pumps (Whale Flipper Galley Pump GP0418, non-pressurized) lose their prime and the water drains from the lines back to the tank. This doesn't happen when the tank is full, but starts when it's about half full.
The "suction" felt if you put a finger over the faucet hole is quite strong. It will even pull the pump handle from one end to the other depending on where you leave it positioned. Within seconds it drains enough that you have to pump many times to get the water back to flowing again.
It doesn't seem to me that gravity / hydrostatic pressure would be enough to do this. The only thing that I've thought of so far is the the tank is not vented, completely airtight at the filler on the deck, and the vacuum in the tank increases the more water that's pumped out.
I've ordered a couple of non-return check valves from Whale (FV1227). I thought they should go close to the pumps but a fellow at Whale in the UK said to put one close to the tank between the tank and the Y-piece that splits the tube to go to the two sinks. Or if not enough space there, put one on each line just past the Y-piece.
The boat is about 90 minutes away but we'll be going up to work on it next week (preparing for 2 weeks in the US San Juan Islands (WA state) a couple of weeks from now).
Any ideas about any of this?
On my buddy's H260, the galley and head sink pumps (Whale Flipper Galley Pump GP0418, non-pressurized) lose their prime and the water drains from the lines back to the tank. This doesn't happen when the tank is full, but starts when it's about half full.
The "suction" felt if you put a finger over the faucet hole is quite strong. It will even pull the pump handle from one end to the other depending on where you leave it positioned. Within seconds it drains enough that you have to pump many times to get the water back to flowing again.
It doesn't seem to me that gravity / hydrostatic pressure would be enough to do this. The only thing that I've thought of so far is the the tank is not vented, completely airtight at the filler on the deck, and the vacuum in the tank increases the more water that's pumped out.
I've ordered a couple of non-return check valves from Whale (FV1227). I thought they should go close to the pumps but a fellow at Whale in the UK said to put one close to the tank between the tank and the Y-piece that splits the tube to go to the two sinks. Or if not enough space there, put one on each line just past the Y-piece.
The boat is about 90 minutes away but we'll be going up to work on it next week (preparing for 2 weeks in the US San Juan Islands (WA state) a couple of weeks from now).
Any ideas about any of this?