firebird
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Post by firebird on Jun 24, 2024 12:35:40 GMT
Hi I'm well on the way with my build of Sweetpea now but I'm having trouble finding any info re the super heaters. When I built the boiler I included the 2 super heater flues. The flues are 3/4'' OD. I have tried a couple of 5/16'' tubes in the flues but they are a bit tight. I'm assuming I have to solder on a connector for the smoke box end. I have also tried some 6mm tubes and they go in easy. Any advice gratefully accepted Cheers Rich
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SteveW
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Post by SteveW on Jun 24, 2024 13:08:31 GMT
Firebird,
If it helps our club's Sweet Pea doesn't use any super heaters. Yes, it has the two big tubes for them and was used to regularly pull a number of loaded carriages on public runing days without any issues of lack of power/pull.
Are you sure you want and need them? They are not without a bit of faff.
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firebird
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Post by firebird on Jun 24, 2024 15:37:46 GMT
Hi Steve
On the SweetPea forum the general consensus is its best to use them. One of the benefits is, apparently, making the loco more economical on coal and water.
Cheers
Rich
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SteveW
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Post by SteveW on Jun 24, 2024 18:50:41 GMT
Hi Steve On the SweetPea forum the general consensus is its best to use them. One of the benefits is, apparently, making the loco more economical on coal and water. Cheers Rich Would suggest any improvement, given the staggering inefficiencies of these things, will somewhere between purely academic and three fifths of f' all and bring with it all the wonders of lubrication in the face of super heated steam. Your choice.
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Post by chris vine on Jun 24, 2024 19:54:56 GMT
I am not sure that the degree of superheat which will be achieved will have much effect on modern oils??!!
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Post by simon6200 on Jun 25, 2024 21:39:00 GMT
I’ve done the experiment with and without on a similar locomotive with two 3/4 flues. First ran it for a while without, then added two 1/4” copper spearpoint bronze-brazed elements. The difference was astonishing, especially with only two superheaters.
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firebird
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Post by firebird on Jun 26, 2024 7:12:02 GMT
Hi Simon
That's what the guys on the SweetPea forum say.
They recommend radiant type, the type that go all the way into the firebox which are best made of stainless steel??
Cheers
Rich
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Post by simon6200 on Jun 26, 2024 9:37:24 GMT
Yes, stainless radiants are the best. I have 4 x 5/16 radiants in my Springbok. But they must be welded by a good TIG welder, whereas I can make copper spearpoints myself. Also, stainless spearpoints must be welded in an open position then heated up and bent parallel. But you can’t get them as close as you can copper elements so might need larger flues.
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Post by andyhigham on Jun 26, 2024 12:31:54 GMT
I took a different approach on my Sweet Pea. A single 10mm stainless, threaded on each end tube ran from the smokebox, down the flue, looped round over the fire then back up the other flue to the smokebox. The superheater loads from the back and fittings screwed on inside the smokebox
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Post by steamer5 on Jun 27, 2024 8:59:00 GMT
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JonL
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Post by JonL on Jun 27, 2024 17:57:14 GMT
I'm very much in the pro-superheater camp. Even just swapping from non-radiant to radiant transformed my William.
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firebird
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Post by firebird on Jun 27, 2024 20:33:01 GMT
Thanks Simon, Andy, Kerrin and Jon
Some good info there
Cheers
Rich
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tenor
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Post by tenor on Jun 29, 2024 12:00:05 GMT
If you leave out the elements, a lot of flue gas takes the easy route down the big tubes while not giving up much heat, so you screw up the amount boiled. In my experience most designs have over large elements crammed into undersize flues. There is a lot of science in balancing the flow between SH flues and tubes. Evans, Young and LBSC were designing by guesswork. Martin
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Post by suctionhose on Jul 1, 2024 7:50:27 GMT
If you leave out the elements, a lot of flue gas takes the easy route down the big tubes while not giving up much heat, so you screw up the amount boiled. Martin So true! Many moons ago when dad and I were entry level live steamers, we blew an element and decided to try it saturated. 1. No steam and a burnt smoke box until restrictors were applied to the flues. 2. There wasn't much detriment to removing the superheaters indicating that they were of poor design. 3. Much was gained in performance from other sources, mainly valve gear and smokebox draughting, suggesting that the engine was lacking in many respects. We were falsely lured to believe superheaters were optional. Nothing further from truth!
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johan
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Post by johan on Jul 1, 2024 9:57:57 GMT
3. Much was gained in performance from other sources, mainly valve gear and smokebox draughting, suggesting that the engine was lacking in many respects. We were falsely lured to believe superheaters were optional. Nothing further from truth! Onion peel syndrome: you fix one thing and then the next one become apparent and you fix that etc etc. Typical in cases where you look for efficiency. Each bit does something, but you first have to fix the biggest ones before the smaller ones can be useful.
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