The Marco pump has a built in check valve, you do not need to add another one.
Check valves are required on the centrifugal AC pumps. If there is no check valve when another pump (engine, genset, toilet) pulls water from the sea chest is is possible for water, and then air, to back flow through the AC pump and then with air in the system, everything goes wrong.
This is the downside of having a common seachest supplier multiple raw water users.
Key West, FL.
---In amelyachtowners@..., <sailor63109@...> wrote :
Merry Christmas all!
I'm replacing some of the engine room pumps, and I'm wondering if I need a backflow preventer?
I've installed a Marco gear pump (UP3/E) for the fresh water system. It doesn't run unless a faucet is opened so it doesn't seem to need one. (By the way, this is a noisy pump, you don't need a red light on the panel to know it's running).
I also have installed a March AC-5C-MD pump to replace the airconditioning pump. What's the reason Amel put a backflow preventer on the orginal centrifugal pump? Would backflow damage a centrifugal pump?
By the way, this pump has a lot of openings around the rotor so I'm making a cover for it for when there is anything wet happening in the engine room. They make a sealed version of this pump but it's twice the cost.