Hello dear friend, I recently had a used boiler for nothing. I showed the disassembly earlier. Today I decided to disassemble a specific GRUNDFOS pump for our region. Show his device to you and clean it at the same time.
And so what we have:
A pump that was installed inside a two-room boiler (heats hot water supply and heating) for circulating the coolant (water or antifreeze).
Its peculiarity is that the impeller chamber is separated from the drive. The rotation is transmitted remotely. The oil seal is missing. I will show how it works below.
Typically a wet rotor pump is used. That is, the rotor is in the liquid that it is pumping. And around the rotor, in a dry casing, there is a stator that creates a magnetic field and makes the stator rotate with the impeller.
Our pump has a different system. I disassemble and show. Scroll through the gallery:
Removing the top cover reveals a thin stainless steel dividing plate. The black part of the pump is a magnet. Something like the speakers from the music speakers.
Having removed it, we find ourselves in a wet chamber with an impeller:
It also contains magnet.
All pump parts were disassembled, I decided to clean them from salts with citric acid.
Dissolving it in boiling water, dipped the parts to soak.
While the pump parts were taking a water bath, I decided to check the operation of the engine itself. I connected it to the boiler and started it up. The engine started to turn, but the rpm began to float. Looked closely at the stator winding ...
Unfortunately, a spark slipped, apparently during the operation of the boiler, water dripped onto it, from the connections, or condensate.
What led to the failure of the stator winding. A spark breaks into adjacent wires. This leads to the "floating" of revolutions.
After this news, I decided to stop water treatment for the pump and put it back together. Preparing for disposal.
And so that the solution does not disappear. I decided to atone for the secondary heat exchanger in it.
In the end, what we have. In fact, the efficiency of a centrifugal pump with a dry rotor is higher compared to a pump with a wet rotor. But such pumps are noisier due to the cooling impeller; open stator wiring is not friendly with random moisture (as in our case). Therefore, almost all boilers, at the moment, use "wet" type pumps.
How do you like the material? Appreciate it. Respectfully yours Timofey Mikhailov, Plumber.
"This is a gift!" I told the client. He gave me a wall-mounted gas boiler for nothing. I disassemble it and enjoy the parts as a child.