Gravity toilet not emptying via macerator

[Houdsie73]

I have a 9 gallon gravity feed toilet in my new to us Mainship 34 MKII. We have a stark rule of liquids only in the toilet. On our recent journey, I tried emptying the toilet with the macerator but it is not emptying. I hear the macerator running but it is a high pitch which sounds like there is no liquid passing through. The seascock is open and the tank is maybe 1/3 full. I had a similar problem a few weeks ago when i tried emtpying it for the first time and the tank was full. It took quite a few tries for it to work and when it did work, the pitch of the motor was lower. Are there prepatory steps needed to empty the tank and I'm missing something?

 

[Comodave]

Sounds like the macerator isn’t primed. Hopefully it isn’t a blockage in the discharge hose. As to how to fix it, maybe just keep running it until it primes. Don’t run it continuously but rather in spurts. Good luck.

 

[O C Diver]

Sounds like it's air locked. Follow the sanitation hose from the tank to the macerator. If the hose rises and then drops coming to the pump, that part of the hose may be air bound and not feeding liquid to the pump. Raising the liquid level in the tank may resolve the problem. Making the hose from the tank to the pump, flow down hill is the solution. The impeller or housing in the pump may be worn, keeping the pump from creating a vacuum to pull the fluid over the hose rise.

Ted

 

[FF]

Yes macerator pumps are very poor at pumping air.

Depending on the layout the simple solution is to use a hose to fill the tank and prime the pump.

A far better solution would be to mount the pump to feed from the tank bottom, where it would not have to prime.

To be able to repair the pump a simple cheap RV tank valve should be installed between the tank and pump.

This would solve almost all pump problems , but since its not common , its not done that way. Boat assemblers need an education.

 

[PM]

Air locked. try a plunger to get it primed.

pete