Mitsubishi wp-255: air entering into pump

[alviks]

Hi all

 

My 3 year old Water pump, a Mitsubishi wp-255 has, less often when it was new, developed an air lock. Now it runs 24 hours at best before I need to let air out. The air inside prevents the pump to reach cut-off pressure, so it runs non-stop and get pretty hot. I have replaced all rubber seals bar the membrane in a gizmo that I think regulate how much air should be in the pressure tank. The pump is fed from an above ground tank and the flow into the pump is not restricted. Has anyone had the same symptoms and if so, what was the problem?

 

 

[Artisi]

If it's been a problem since new, although a lesser problem than now, it would indicate air-entrainment from somewhere. 

 

Where is the inlet to the pipe leading to the pump in relation to the low water level in your overhead tank?

Where is the water for the overhead tank coming from?

[alviks]

1 hour ago, Artisi said:

If it's been a problem since new, although a lesser problem than now, it would indicate air-entrainment from somewhere. 

 

Where is the inlet to the pipe leading to the pump in relation to the low water level in your overhead tank?

Where is the water for the overhead tank coming from?

Both the pump and the storage tank are standing on the ground next to each other. Pump inlet is about 15 cm above ground. I have two Storage tanks, which both are topped up by a secondary pump. The top-up pump is taking it's water from the municipality feed. I'm pretty sure that the water level in the storage tank that is feeding the pump is at all times well above the pump inlet. If there are any leaks between pump and tank, wouldn't that show? I mean there would be water leaks or at least some moist? Everything is bone dry however...