ᐅ Checking the circulation pump... What needs to be shut off?

Hello everyone,

It seems that the circulation pump in our house has stopped working. It has been idle for a long time, and I’ve read that these pumps often seize up but can usually be freed again after disassembly.

So far, so good. However, I’m not sure which parts I need to shut off before removing the pump. Basically, apart from the main shut-off valve, there are only two shut-offs in the entire system: one on the cold water supply to the tank and one on the tank side going to the hot water. None of the other pipes have any valves.

Now the question is how I can isolate the pump to keep it “dry.” There is actually a small brass screw right above the pump that usually allows you to shut off that side. In my case, the screw is hollow and appears to have threads inside. However, I cannot turn it with a screwdriver.

If I simply close the two valves I still have, won’t all the water in the circulation loop drain out as soon as I remove the pump?

I’m a bit puzzled here. Does anyone have any ideas?

Thank you very much and best regards,
GarMir23

I’m not sure what kind of circulation pump you have installed. But usually, there is a screw on the pump that you can unscrew, and then you can use a screwdriver to manually turn the pump impeller or check if it is rotating, which helps determine if there is a mechanical issue. The pump only needs to be turned off for this.

The pump does not need to be removed for this procedure. Since this is a common situation, pump manufacturers generally design their products accordingly.

This is a "Star-Z NOVA (DE)" from Wilo. Unfortunately, this version does not have a shut-off valve or check valve. When I unscrew the motor head here, the pipe is open. Therefore, my question is how I can prevent all the water from draining out of the circuit when I dismantle it. I am not referring to removing the entire pump, but to disassembling the motor head so that I can free up the rotor.