boiler cladding how and why?

[Ian WelfordParticipant @ianwelford58739]

Having a TICH to complete I am wondering what to clad / how to clad the boiler to save heat etc.

LSBC doesn't mention it in his construction book but I feel it should improve efficiency?

I wondered about ceramic wool covered with rolled brass sheet but haven't found any guidance?

Thanks Ian

[Ian WelfordParticipant @ianwelford58739]

[julian atkinsParticipant @julianatkins58923]

hi ian,

the late jack davies carried out some tests and calcs printed in ME some years ago, confirmed by some others. the heat loss amounted to one shovel of coal every hour! however it is very useful (except on a hot sunny day) insulating the tanks if you have injectors fitted (this doesnt apply to TICH), and i always fit boiler cladding underneath boiler cleading to protect the paintwork and lining out on the boiler bands etc.

LBSC never specified boiler insulation or cleading, and most of his boilers are 'overscale' as a result if you wanted to fit cleading etc. on TICH none of this matters, so it's entirely up to you what you choose to do. all the non-LBSC designs specify cladding and cleading. just have a look at some of the other designs eg martin evan's ROB ROY etc.

there is a huge choice of different boiler insulation materials (cladding). for the cleading ive always used steel sheet as it takes paint better.

cheers,

julian

[nigel jones 5Participant @nigeljones5]

I recently remarked on a well running small 5" (cant remember!!) and enquired as to what it was clad with, as it obviously was. The reply was not what I had expected – lead! It had no heat loss issues to speak of and kept the shed warm for hours!

[julian atkinsParticipant @julianatkins58923]

hi fizzy ,

i dont think your contribution takes us much further re a proper discussion of the best types of boiler cladding! i cannot possibly believe that lead is better than ceramic fibre, kaowool, cork, aluminium foil wrapped in other stuff etc or even good old fashioned asbestos lagging of which ive still quite a lot.

cheers,

julian

[nigel jones 5Participant @nigeljones5]

Hi Julian – I think you missed the point somewhat. Indeed lead cannot be a better insulator than your afore mentioned items. What it indicated to me was that cladding is simply nor required, as backed up by your post. The lead was added purely to aid traction, but it steams like a witch! I was very surprised!

[julian atkinsParticipant @julianatkins58923]

fizzy,

i dont think i missed the point at all, and i can think of far better ways of adding adhesive weight than wrapping the boiler with lead! plus i dont like my boiler cleading paintwork and lined out boiler bands getting discoloured or peeling!

cheers,

julian

[nigel jones 5Participant @nigeljones5]

The point is that cladding is not required for thermal efficiency.

I am of course referring exclusively to cladding as per the post, and not to cleading. If there is no real gain for adding cladding then there is no merit in further discussion, surely?

[julian atkinsParticipant @julianatkins58923]

hi fizzy,

there is always merit in further discussion of these topics! i made it quite clear that apart from very hot days boiler cladding is important on side tank locos to prevent the tanks getting too hot if injectors are fitted, plus considerations re paint finish on the cleading and boiler bands. arguably there is more thermal loss in a larger boiler than a TICH if not fitted with cladding etc.

you can fit 3/8" or 1/2" thick plate running boards if you want extra adhesion!

what would be very useful is a resume of the most up to date types of insulation cheaply and easily available to the model engineer. ideally the thinnest material that has the best insulation characteristics. there are so many 'advances' in such materials in recent years that those 'in the know' so to speak might be able to help provide some up to date info and sources of suitable thin material as opposed to what the trade stock. what is stated in many published designs must be very old hat these days! i have never seen this topic adequately covered in ME.

i have a certain personal interest as my current loco being built has a very ornate livery (including the boiler and bands) which i am anxious to protect if possible.

cheers,

julian

[nigel jones 5Participant @nigeljones5]

OK>>MY varied experience has been with string, wood, polystyrene, glass fibre and fire clay, and to be honest I wouldnt recommend any of them unless you need to keep the paint cool (As Julian does). The cheap and thin polystyrene sheeting is availible from bnq.

[John OlsenParticipant @johnolsen79199]

I certainly don't have the experience to say what would be best, but one common misapprehension that I have noticed in this area is the idea that some sort of refractory is needed. Since the boiler cannot get any hotter than the wet steam inside it, and since that cannot be any hotter than the slightly elevated boiling point of the water at 100 psi, it is not actually necessary to use a refractory material. Refractories can stand very high temperatures, but may not be as good an insulator as some other material that cannot stand such high temperatures.

Another thing to bear in mind is that may good insulators actually depend on entrapped air to provide their insulating properties. So if the cleading puts any pressure on, they may crush down and not provide much effective insulation. Also if the material manages to absorb water or oil the insulating properties will be greatly reduced, at least, in the case of water, until it boils away.

This is all quite apart from the question of whether or not a quite thin layer of insulation will really do any good. It might help save the paint, although if the paint is on the cleading it may be that a thin layer of insulation will not make much difference, because the thermal resistance to the air is higher than that of the insulation.

John

[David JuppParticipant @davidjupp51506]

As well as saving the paint, insulation may reduce the severity of any burns resulting from touching the boiler exterior.

[Bob YouldonParticipant @bobyouldon45599]

Good morning all,

If i'm not mistaken, originally the WD 2-8-0 and 2-10-0s had only an outside cladding sheet with an air gap between the boiler surface and the cladding sheets when built.

Over the years I've seen all sorts of materials used on miniature locomotives including one elderly Maisie I stripped for overhaul had been insulated with a Kelloggs corn flake packet with the outer cladding from a National Dried Milk tin! Today I'll use a modern ceramic insulator for all my locomotives, with an outer cladding from hard brass sheet. Avoid any asbestos material at all costs, I don't fancy a half day out with an undetaker!

Regards,

Bob Youldon.

[clivelParticipant @clivel]

I recall reading about a Tich owner who used a thin sheet of Aerogel insulation to lag his boiler with.

His comment was that it made an enormous improvement to the little loco's performance.

Clive

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