Best oil to use in CH boilers.

[Anode]

My central heating boiler is a Baxi PF (Mark 1). The bearings of the fan motor seize-up solid if I do not oil the bearings every two months or so.

What sort of oil is it best to use in this high temperature situation? I have sometimes used light machine oil, the 3-in-One kind, and sometimes basic motorcar engine oil which is much thicker but presumably may be better at withstanding high temperatures.

I know little about choosing an oil for a specific situation, so anyone any advice to offer?

Regards.

[The Natural Philosopher]

Then you have a problem that is more fan motor related than lubricant related. Most fans are ball raced, and need little or no lubricant.

well thats dont to the oil of course..there are plenty of pertyy decent ones made for specialised use, but I have never heard of anyne lubricating fan motor bearing in my life.

the oil majors would know: they do research, but I suspect the oil would cost more then the new fan that you probably need..

[newshound]

I'm pretty sure mine has oilite (sintered and therefore porous bronze) bearings. They do see a fairly warm environment. I would consider using a drop of the thick silicone oil which is used for lubricating push-fit waste fittings, etc. Apart from having better non-oxidising properties than mineral oil it should have a fairly low vapour pressure, and therefore not dry out too quickly.

Tribologist

[Ed Sirett]

IME they are mostly plain bush bearings of steel on phosphor-bronze. However they should require no lubrication. geoff will know the exact details.

However they are lubricated for life and in many cases that's 15 years or more. The fact that you can get it to keep going is good news as that means you have a while to obtain a replacement (reconn'd from C.E.T. Ltd).

[Anode]

Ed, Your description of steel/phosphor bronze would seem to apply to this particular set of bearings, they are certainly not ball bearings.

The boiler (which I intended to say was a Baxi Solo 70/PF) was new 18 years ago, and it is only during the last eight years or so that oiling the motor bearings has been necessary. If I can continue to keep the motor running a bit longer for the cost of a few drops of oil, I shall be happy to do so.

When the bearings are freshly oiled, the fan will continue to revolve for up to 30 seconds after the electricity supply cuts off, and there seems to be no need for a replacement. After two to three months this time gets less and less, then more oil restores the situation. Twice, I let it go too long and the motor had seized up, but nothing had burned out and it was possible to get it going again for the cost of a few drops of oil.

Anode.

[Anode]

With the bearings in place in the boiler it is difficult to determine what they are made from, they are certainly not ball bearings but something more 'solid' as you describe. Years ago I used to make my own sintered bearings, using a vacuum chamber to get the oil into the sintered metal. I'll have a look at using a silicone oil, thank you for the idea.

Anode.

[geoff]

In message , Anode writes

The Solo1 fan has ball races

They are lubricated with grease, if your bearings have lost their lubricating grease, any other lubricant will only provide a short term fix, and the bearing race will already have started to wear

I do an exchange fan for £45 ++

[geoff]

In message , newshound writes

Absolutely wrong for the Solo 1

[geoff]

In message , Anode writes

A 70/4 - some of the really old ones did have phosphor-bronze bearings

The problem is getting into the bottom bearing

The proper oil is quite expensive, any light oil would do just to keep it limping on

[The Natural Philosopher]

If they *are* bronze, what may be the issue is that you have over lubed with the wrong oil and the things are clogged with gum.

wash the bearings out with a decent solvent and then use a good light oil like 3 in 1. Do that several times, and with luck the things will carry on for some time.

[Anode]

. geoff,

Thank you for your information. I think I am dealing with phosphor bronze bearings here. When oiled it runs very freely with no noticeable wobble on the fan spindle, so I think I shall continue with the oiling routine I have been using in the hope that I can keep it going for a bit longer.

Regards,

Anode.

[geoff]

Well, there is that

These bearing housings are sealed - how do you propose he does that ?

After that length of time, I would expect that the shaft would also be worn

18 years is an exceptionally long life for a boiler fan

[geoff]

In message , Anode writes

As I said, it's exceptionally old for a boiler fan

the problem is that sintered bearings adsorb (note the spelling) oil

eventually, the sponge like surface of the bearing gets clogged with kack (technical term) and lose the ability to retain the oil , which is , in effect, the bearing surface

Once the sintered bearing gets clogged, it loses the ability to retain the oil

You really are on borrowed time, although some do go on for ages

[Doctor Drivel]

Try fully synthetic motor oil like Mobil 1. This oil take very high temperatures. Just a drop will do. Worth doing to keep going before you replace the old crock.

[Andy Dingley]

The sort of handgun cleaning oils that are available on any American high street but damned awkward to find over here. Silicone or PTFEs containing oils, and in solvents that are plastic-friendly. They're decent light lubricants and they're especially resistant to water or temperature. Tri-flow or Break-free are brands to look for.

[geoff]

I can't offhand think of the name for the oil that sintered bearings are lubricated with - we've got some at work (of course) I'll look next week

It is expensive, though

[robert moore]

replying to Ed Sirett, robert moore wrote: you can buy theses bearings on e bay for 3 quid loads of u tube vids on how to fit ......hope this helps

[Brian Gaff]

. posted on December 9, 2008, 3:44 pm

Oh. Brian

[tabbypurr]

I suspect he's solved it after 9 years, don't you? Get yourself a sane portal to this place, news:uk.d-i-y

[Brian Gaff]

They seem to have improved the web site as now you can easily see the date of the posts if you are sighted. I mean I just followed the link. I suspect people have got used to not looking and now its there nobody realises it.

So if this thread is getting to this portal, please look up above the message and see the date before you reply. The archive they use seems to have a very long memory! Brian