I have an old warmair central heating system that I just love to bits but do have an issue with the Johnson and Starley fan unit. This is part number 1000-0500370. There is a really stupid design fault with this unit as the fan bearing is a sealed one with no way of lubricating it. The fact that the hot air blows over it has an obvious effect of the bearing drying up and causing a unit failure. The cost of replacement is really quite steep at around £350 for a new fan unit. It isn't a DIY job to replace the bearing so you're pretty much stuck to replacing the whole unit. I have searched everywhere for someone who does a refurbishment of the unit but aren't any showing up. I guess if there were it would still be costly anyway.
TAKE NOTE: I have sorted this out and applied it over around 8 years or so. First of all, the reason that this has become a topic now is that the bearing started squealing again yesterday and shut the fan down. So what's the fix? Easy. The bearing end cap is a dome shape on the outside of the unit. I drilled a very small hole in the cap to allow access. I then obtained a syringe with a very small diameter needle and filled it with a mix of ordinary 3 in 1 oil and ZX1 additive. Initially just a small squirt of the ZX1 before using the mix. The info on it is here: https://www.team-zx1.com Place the needle into the hole in the end cap and tape the syringe to the unit's side wall or elsewhere so that it provides a slow drip feed into the bearing case. Within 3 minutes of awful squealing and crackling, the bearings picked up the oil and now work perfectly well. Of course the use of oil, even small amounts in a heating system might seem questionable but I think that a very slow release of the mix over the long term will be fine. As I said I've been using this method for donkey's years with no problems.
There is a similar problem with Myson fan assisted radiators, and many other devices using sintered bronze bushes, the problem is what bit turns, want the steel shaft to turn in bronze bush, but some times the bronze bush turns in the housing, if this happens the wear to housing means very quickly the play is unacceptable.
So you really need to oil before it has seized, once it has seized it is hit and miss which bit turns.
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