Pros and cons of 1,2 or 3 superheater tubes?

[Greg HParticipant @gregh]

Hi,

I'm building a boiler for a 3 1/2" loco and was wondering about the best way to go for the superheater. Some may know it's a Martin Evans Jubilee.

There were two boiler designs. the first had three superheaters, the second one superheater to allow for a siphon in the fire box.

For simplicity I was thinking of going with the single superheater design, but without the siphon. I note that most locos have two or three superheaters. The superheater element will be a single 3/8" OD tube (or possibly 7/16)

Are there any disadvantages to going with just the one superheater? I assume there is otherwise everyone would go this way.

Greg

Edited By Greg H on 10/01/2017 10:30:57

[Greg HParticipant @gregh]

[paul rushmerParticipant @paulrushmer83015]

It is going to be interesting this one, there are two camps; one no superheaters, one as many as possible! I know Doug Hewson in his standard 4 uses 8 but this is 5" gauge. Personally I would use 3 stainless steel radiant type if there is room. Lets see what every body else thinks.

Paul

[J HancockParticipant @jhancock95746]

Ah, Jubilee, I hope you have looked at the 'problem page' before making all the brake components !

[julian atkinsParticipant @julianatkins58923]

Hmm..

I wouldnt take too much notice of Paul Rushner's 3 stainless radiant superheaters on a 3.5"g loco.

Do not go down the firebox syphon route . They are hiddeous to make and fit in fullsize and miniature. The Rugby test plant results of comparing a Bulleid pacific with and without the Nicholson thermic syphons showed no difference.

I will have to look at the 2 tube layouts. I have both drawings. There may be all sorts of tweaks and alterations that can be employed to get the best tube arrangement. Martin Evans didnt get the best layout in some/most of his designs.

Cheers,

Julian

[Greg HParticipant @gregh]

I haven't done the brakes yet. I'll wait until the boiler and ash pan are in.

Hi Julian,

Martin Evans' tube layout looked a little random and uneven. Perhaps there was a special reason for this that I don't know.

Here's mine. I had to redo it to get the minimum 3mm ligiment between the tubes.

[Brian Baker 2Participant @brianbaker2]

Greetings, good luck with your Jubliee, I have built 2, plus I am looking at a bigger gauge one.

There is very little room in the smokebox, and I would always opt for the single flue, single radient stainless superheater option, since this is easiest to fit into the space available.

Forget the Thermic syphon idea, mainly for the reasons already given.

Speaking to Martin, this is the route that he suggested as being the best, and I have had great pleasure with this design. Mine is now laid up with a superheater leak, after 10 years hard running, including an IMLEC at Bristol, where I ran further than the 5 in gauge locos entrants.

Both my examples ran well and would notch right up.

regards

Brian

[paul rushmerParticipant @paulrushmer83015]

Hi Julian

Not wanting to hijack this thread but I have two 3 1/2" boiler conundrums re superheaters.

I have a commercial 9F boiler which came with 4 stainless elements, these are long enough to pass through the flue, combustion chamber and over the fire were should I stop them?

A Don Young 2P boiler to build. He specifies a single concentric element I do not like these I was thinking about 2 or 3 radiant type hence the comment. With your experience what would you recommend.

regards Paul

[Greg HParticipant @gregh]

Hi Brian,

Thanks for your thoughts. I'll stick with the one superheater.

I pleased to hear that it should be a good runner. When I set the motion up the valve movement still looked good when notched back and so I think it should also run ok when notched back.

Here's where I'm at with mine.

I'll continue bashing copper

 

Edited By Greg H on 11/01/2017 10:59:56

[julian atkinsParticipant @julianatkins58923]

Hi Greg,

Can you get the single large flue in the middle and top of the tubeplate? This will aid assembly, plumbing inside the smokebox, and withdrawal of the super heater element without removing the smokebox.

Hi Paul,

One radiant superheater element in one large flue should be quite enough in 3.5"g. The stainless element should extend as far back as possible.

Do not copy the Don Young 'concentric' type superheater element as it is less effective and takes up more room.

Instead use a welded stainless type with a return bend welded on.

Cheers,

Julian

[paul rushmerParticipant @paulrushmer83015]

Thanks Juilan

Paul

[Greg HParticipant @gregh]

Hi Julian,

Good suggestion, but unfortunately with the superheater flue in the middle the tubes do not fit so well on either side and so the total number of tubes would have to be reduced.

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