Grundfos Macerator Problems

Grundfos Macerator Problems Troubleshooting FAQ

For models D-3, PWC-3 Sololift+, CWC-3, C-3 Sololift+, WC, WC-1, WC-3 Sololift+

Although this is a website for Saniflo problems the motor used in the models above are the same as a Saniflo so the same symptoms will apply.

We have compiled a list of common Grundfos problems and the most probable cause. A well maintained Grundfos Macerator Pump will give years of service if it is used as per the manufactures instructions.

WARNING – Do not remove the motor dielectric oil from any Grundfos macerator motor as it needs it to run. All the electrical repairs to the Grundfos are carried out in the box connected to the motor, there is nothing to actually fix inside the motor itself.

Grundfos Macerator Pumps

If you found are information useful please bookmark our website or share it with others or leave a review here. All answers below are based on our years of experience repairing Grundfos macerators on site.

1, Can I Descale My Grundfos With Bleach

The answer is no, heavy and continuous over use of bleach or other toilet cleaners can shrink and harden the rubber membrane which covers the pressure switch. When the rubber membrane shrinks it stops the pressure switch from turning on and off properly.

The symptoms would be that the macerator pump after use runs on for too long, is very sensitive meaning if you have a wooden floor just walking past the Grundfos macerator would set it off, or the machine should stay on for what seems like forever until it eventually switches of itself or it overheats and the thermal cut out kicks in and switches the machine off which is not good overall for the macerator motor. Bleach will clean it to some extent and just make it smell nice for a while.

Bleach or other toilet cleaners can be used lightly and in small doses but will not descale a macerator pump thoroughly, only macerator descaler will totally descale the machine. If you have the above symptoms it’s best to change the membrane and the microswitch whilst the machine has been dismantled because if you change just the membrane, install the machine and it is still not activating properly you will have to go through the whole process all over again.

2, My Grundfos Macerator Keeps Running And Wont Switch Off

There are a few reasons for this, a running tap, a blockage in the Grundfos macerator, a blockage in the Grundfos waste pipe leading outside, the membrane is damaged or the microswitch is stuck on.

3, My Grundfos Macerator is Vibrating It Looks And Sounds Like It Will Take Off

There will be a foreign object inside the Grundfos macerator caught on the macerator blade like Tampax/sanitary towels, toilet cleaning wipes or baby wipes. A Grundfos macerators cannot chop these items up and throw the motor off balance when it is running, you will need to remove these objects immediately to avoid damaging the motor.

4, My Grundfos Macerator Keeps Starting On Its Own Sometimes At Night

There are a few reasons for this type of problem, you could have a faulty microswitch, a faulty membrane or water is getting in to the Grundfos macerator from a dripping tap, overflowing toilet, a condensing boiler may be connected to it or some other water source.

More Grundfos Problems Troubleshooting FAQ Solutions

5, My Grundfos Macerator Macerator Keeps Fusing Tripping The Electrics

Normally this is bad news, the reason for this type of problem is a worn or faulty motor as water is getting in to the electrics and fusing the circuit. Sometimes but in rare cases you may have loose wiring where the Grundfos macerator is connected but is very rare its normally a dead Grundfos macerator, you will have to buy a new unit as the motor is unrepairable try connecting to another power source to make sure its not a faulty socket.

5, My Grundfos Macerator Is Leaking When It Is Running

If your Grundfos macerator is leaking from the air vent on the top when running could be caused by a dirty Grundfos, it will need to be removed and cleaned out by hand as there could be too much waste inside, the switch or the membrane is defective and the machine is not turning on quick enough to pump out the water or the motor is on its way out and cannot turn fast enough to pump out the water, this will be accompanied by a knocking noise. Other reasons for air vent leaks are jammed motors.

6, My Grundfos Macerator Is Blocked And Backing Up In The Bath Shower Basin

First thing you should try is make sure the Grundfos macerator is switched on and has power going to it. Your Grundfos motor could be jammed and unable to pump out, this will be accompanied by a humming or buzzing noise and the box will be quite hot and the motor will need to be freed up. Another reason is for this problem the membrane or microswitch is defective and is not allowing the motor to turn on or worst case scenario the motor is not working at all and you will have to buy a new Grundfos.

6, My Grundfos Macerator keeps foaming up out of the air vent

If your Grundfos macerator is foaming out of the air vent or inside the toilet bowl it is because the Grundfos either has too much toilet cleaner inside the machine, bleach, or bubble bath if connected to a bath or shower. If foam is coaming out of the machine it will not pump out the water properly and will pump constantly and will eventually overheat and cut out if left on for too long. You must try and dilute the water or switch it on for short bursts until all the foam has gone. Never use excessive amounts of cleaners, bleach, bubble bath or leave bleach blocks in the cistern.

8, Grundfos Macerator Running On, Not Pumping Out (Winter Time)

If your Grundfos macerator is running on or not pumping out and the temperature outside is below Zero it is most likely the Grundfos macerator waste outlet pipe has frozen solid or your Grundfos macerator is located in and outside building which is not insulated and the machine itself has frozen. Turn the machine off to avoid burning it out. All external waste pipes must be lagged with foam insulation and machine must be protected against frost, the Grundfos macerator installation booklet will tell you this. If it is not possible to lag the pipes or machine due to lack of access or pipework fitted at height you will have to wait until the temperature goes above freezing before using the machine, possibly around midday. Turn the machine back on when the temperature is above freezing and if it pumps out and switches off it was a frost problem, if not you have a normal blockage in the machine or pipework which needs to be removed.

If you cannot find a solution to a problem, just email us.

Thanks for visiting Doctor Saniflo

Get Grundfos Macerator Problems Troubleshooting FAQ Solutions


Please leave a review if you found our information useful.

No registration is needed and takes less than a minute to do – Reviews

Shopping Cart
Scroll to Top