Cause of damage to combi boiler pump

[ADarkDividedGem]

Hi,

I recently had the water pump in my combi boiler replaced. Once the pump was removed and I saw that there appeared be a layer of rust like crust covering some of the surface I was curious what it was and how it formed.


My current theory is that it had formed a slow leak and and over time it had left a sediment of copper from the pipes. Before the pump broke entirely I had been getting drops in pressure and was wondering if that was the cause.

Does my theory make sense and is this a common issue with a pump after 8 years of use?

 

[gas112]

your auto air vent on it has been leaking

 

[nwgs]

As above and I hope the expansion vessel has been checked/charged by the person who for the new pump

 

[MeldrewsMate]

The staining will be from rust, which forms in the iron parts of the system, like radiators. The magnetic field around the pump will temd to attract this, and it would have worn the pump bearings before causing it to slow down, then seize. The stalled rotor then gets causes the induction coil to get hotter than normal and burns out.
Consider installing a magnetic filter just before the boiler, and treating your system water to a cleaning flush and corrosion inhibitor.

 

[ianmcd]

As you have been already advised the auto air vent has been letting by and the water has got into the pump