Glowworm CXi Leaking Hot Water Flow Sensor 2000801910

Was called to look at a Glow-worm CXi today because there was water leaking from the bottom of it. Looking at the boiler it was difficult to see where the leak was coming from. I could see water dripping from the bottom of the boiler near the right hand side of the plate heat exchanger. Looking from side I could see the connections to the plate heat exchanger and there was no sign of water there. It was not coming from the rear of the pump housing either. It looked to be coming from between the filling loop and the pump housing. Then I caught sight of a drip, it was coming from the hot water flow sensor's connection to the pump housing.

I stripped out the flow sensor by removing the filling loop connection and inlet filter, and disconnecting the cold inlet pipe. I suspected that the o-ring may have failed or that the pump housing had split. The o-ring looked good, but there was what looked like limescale coating the flow sensor and so assuming this problem began to clean it off. As I did so I noticed that the plastic had become soft and I was able to damage it quite easily with my nail and so decided to replace it with a new one.

The old one pictured above has been superseded by part number 2000801910 which is now made of black plastic and retails in Plumb Center for £106+VAT under part number 442716. A surprisingly costly part considering it's size and lack of complexity. Replacing the flow sensor solved the leak which was good, after a couple of days I noticed that there was actually a split in the old part as pictured below.

Disclaimer:

The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem.

Work should only be carried out by persons qualified and competent to do so.