Bosch-Worcester 35CDi Fan Failure

It was a cold start to 2021, outside temps well below freezing, I guess that was the final straw for the ~20yr old fan in my combi boiler. On New Year’s Day I’d noticed it was making more noise that usual as I was putting some rubbish in the wheelie bin, nothing more than a very faint screech…. but the next day the central heating came on at 7am and the poor old fan ran for about 5 mins then gave up…
(temperature graphs courtesy of my Grafana/Influx logging system 🙂 )

Bearing in mind that the fan in this design of combi boiler sits on top of the hot exhaust gasses (and blows them out of the flue) they’re also surrounded by the cold fresh air coming in to the combustion chamber so they must have a pretty tough life.

The plumber & I both tried to source a replacement part from the usual plumbers’ merchants and online stores but not with much luck as a 20yr old part is considered “very obsolete” 😀

I thought I’d found a source of re-furbished units via eBay but when it arrived they’d sent me the wrong part. The family and the house were getting colder by the day and even with a wood-burning stove and a handful of electric fan heaters they’re no substitute for the 25kW of the boiler. The plumber’s son (also a plumber!) remembered using a local business a few years ago that refurbished electric motors, worth a shot?

A phone call and a day later the old fan had had its motor refurbished and was working in the boiler again. The local business that did it was a one-man-band outfit, traditional engineering type with stereotypical workshop full of old scrap bits of electrical machines. It looked a lot like parts of “Mad Max”. As I picked up the fan (a few hours after dropping it off) the proprietor told me “I did it straight away as I knew you didn’t have any heat at home” bless him. Cost less than a replacement unit would have too.

So a big thanks to David Bowers, Electrical Motor Repairers and Mechanical Engineers 👍🏻👍🏻👍🏻