What size boiler is recomended for a S50 steam engine?

[Maxjon]

This one could be big enough to modify...

 

[Maxjon]

The D320 Boiler is 70mm high, x 80mm diameter....maybe too small to add a coal firebox/cylinder below it....
/

 

[Steamchick]

The difference us simple. A WilesCo or Mamod is a small kettle, relying on easy combust ability of fuel so it gets enough draught. Not good for coal. Coal needs a tall chimney for good draught to get enough air to burn. Or forced draught as with the loco type boiler using exhaust steam through a venturi funnel to develop the draught. But your engine will use so little steam, it won't be that effective. My Dad made a boiler 3 in Diameter, horizontal, with closed fire box, a tall chimney and exhaust steam forced draught. His Paraffin blowlamp didn't function well until he used a small compressor instead of exhaust steam to develop adequate draught. Coal needs more than even that draught.
But a small traction engine using more steam in the engine manages a coal fire in the firebox about 2 in x 2 in x 3 in high, then through flues to the smoke box with an exhaust steam blower... - because it develops more exhaust steam than small stationary engines in order to power the tractor along. Prtly because it runs around 80psi, not 15psi. (More than 5 times to puff!).
So, "been there and done it".
I suggest gas fired is the best option for your first boiler and engine, then build a bigger engine with boiler for coal firing, when you have developed steam running expertise using gas.
To train new guys at the local club, we have a couple of gas fired boilers - with old engines, that we loan to "Newbies" - and after a lesson or 2 in "What to do", and a supervised session, they can run them at shows for demo to the public. Usually they enjoy a couple of happy hours fiddling and tweaking and learning the foibles of steam demand by the engine versus gas supply to the burner, and how often to feed water, and the consequences of how that drops pressure a bit and you need more gas to keep the engine running while restoring pressure.... etc. They then take charge of the boiler and engine and get involved stripping and re-building anything needing on the set-up... All without making their first engine, or experiencing a loco, and coal firing.
One guy has since taken on a 5in gauge loco and is learning to run it around the track.... After 4 hours of track time, he still struggles to maintain fire versus steam demand versus watering... but is improving at each session. He has also learned to service the loco, as well as keep it clean, oiled, and in good condition.
Another guy has learned about engines by restoring a small traction engine, that is not yet restored to coal firing, but now runs on air as a demo in shows, after a strip and re-painting last winter. Next winter maybe the boiler will come off and be serviced for steaming next year?
It is good to learn from some simpler basic tasks before thinking of a full coal fired set-up.
K2

 

[Jasonb]

Even a small traction engine with that size grate such as a Minnie is a pain to keep the fire going, those that do run them get better results with the kerro soaked charcoal as I mentioned earlier.

If you are relying on the blast nozzle (exhaust steam) to give you enough draft to keep the fire going what do you do if you stop or slow the engine as the steam will not be constant. lets face it we all like to see an engine ticking over slowly not reving it's nuts off. You could use a blower but that draws more steam from a small boiler that will be trying hard to make enough

Boilers like that wilesco spare part will not be designed for solid fuel, there will be no radiant heat into wet legs and not much in the way of flue tubes.

 

[Steamchick]

Jason, we agree. Thanks for saying the same in a lot fewer words than I use.
K2.

 

[Maxjon]

The difference us simple. A WilesCo or Mamod is a small kettle, relying on easy combust ability of fuel so it gets enough draught. Not good for coal. Coal needs a tall chimney for good draught to get enough air to burn. Or forced draught as with the loco type boiler using exhaust steam through a venturi funnel to develop the draught. But your engine will use so little steam, it won't be that effective. My Dad made a boiler 3 in Diameter, horizontal, with closed fire box, a tall chimney and exhaust steam forced draught. His Paraffin blowlamp didn't function well until he used a small compressor instead of exhaust steam to develop adequate draught. Coal needs more than even that draught.
But a small traction engine using more steam in the engine manages a coal fire in the firebox about 2 in x 2 in x 3 in high, then through flues to the smoke box with an exhaust steam blower... - because it develops more exhaust steam than small stationary engines in order to power the tractor along. Prtly because it runs around 80psi, not 15psi. (More than 5 times to puff!).
So, "been there and done it".
I suggest gas fired is the best option for your first boiler and engine, then build a bigger engine with boiler for coal firing, when you have developed steam running expertise using gas.
To train new guys at the local club, we have a couple of gas fired boilers - with old engines, that we loan to "Newbies" - and after a lesson or 2 in "What to do", and a supervised session, they can run them at shows for demo to the public. Usually they enjoy a couple of happy hours fiddling and tweaking and learning the foibles of steam demand by the engine versus gas supply to the burner, and how often to feed water, and the consequences of how that drops pressure a bit and you need more gas to keep the engine running while restoring pressure.... etc. They then take charge of the boiler and engine and get involved stripping and re-building anything needing on the set-up... All without making their first engine, or experiencing a loco, and coal firing.
One guy has since taken on a 5in gauge loco and is learning to run it around the track.... After 4 hours of track time, he still struggles to maintain fire versus steam demand versus watering... but is improving at each session. He has also learned to service the loco, as well as keep it clean, oiled, and in good condition.
Another guy has learned about engines by restoring a small traction engine, that is not yet restored to coal firing, but now runs on air as a demo in shows, after a strip and re-painting last winter. Next winter maybe the boiler will come off and be serviced for steaming next year?
It is good to learn from some simpler basic tasks before thinking of a full coal fired set-up.
K2

Thanks for the sound advice K2! I look fwd to your knowledgeable replies!

 

[Steamchick]

Just trying to help you make your right decision. I am sometimes wrong as well, so check advice from others too.
K2

 

[Maxjon]

Just trying to help you make your right decision. I am sometimes wrong as well, so check advice from others too.
K2

I think most all the burner type Wilesco work on 20 psi, which you think should run the S50...Might work out economical to buy a Wilesco engine, to learn with, and ultimately use the boiler for the S50......

 

[Steamchick]

From engines I own, the S 50 is a similar size, perhaps a bit smaller, and we psi will drive it far too fast without a dynamo to use the power. I use around 5 psi to idle my engines. Steam volume is the problem for these tiny kettle boilers, not pressure. Enough flame will be OK,, but needs continuous water feed.
K2

 

[Maxjon]

From engines I own, the S 50 is a similar size, perhaps a bit smaller, and we psi will drive it far too fast without a dynamo to use the power. I use around 5 psi to idle my engines. Steam volume is the problem for these tiny kettle boilers, not pressure. Enough flame will be OK,, but needs continuous water feed.
K2

I was thinking the small kettle type will need a resivoir and pump. I'm keen to get the PM Research pump casting kit...

 

[Steamchick]

So simple I make hand pu,p's from bar stock.

 

[Maxjon]

So simple I make hand pu,p's from bar stock.

Nice I have plenty of barstock.....

 

[Steamchick]

Update on the little Mamod boiler project. This is just a little "fiddle" project to see what it can actually power... based on water heating ability and the small burner. (Maybe I should have just used a complete Mamod boiler?).
I have just bought a pressure gauge suitable range (from a coffee machine): another £20.
Air tested with a small compressor, of the size I use to run small steam engines similar to the S50:
The Safety Relief valve took a bit of tweaking to work reliably, but is now set FOR AIR at 1.1bar (16psi) = the right pressure according to the Mamod information I have gleaned... It will need re-setting for STEAM as the steam flow through relief valves changes their performance when in operation. By adjusting the top nut on the pressure relief valve I can change the relief pressure by as little as 1psi. And it manages all the air the compressor can give... I wonder how that compares to the amount of steam the burner will develop? - Watch this space!
K2