Fire box door size

A special section just for steam engines and boilers, as without these you may as well fit a sail.
ianrichards
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Boat Name: Isambard
Location: Calstock, Cornwall, UK

Re: Fire box door size

Post by ianrichards » Tue Oct 24, 2017 8:53 am

Thanks for the tip on the stack damper, neat idea.
Ian
barts wrote:On Rainbow, her Scotch boiler has a central firebox 13" inside diameter (the boiler is 24" in diameter). Being able to easily place firewood (16" x 2-3" x ~2-3") in the firebox is critical as the firebox is ~34" long and I'm often using the fresh firewood to shove the already burning pieces into the rear of the firebox. The door is often open for a bit as I load several pieces into the boiler at once, but this boiler reacts very slowly as it holds many gallons of water.

Our Otter has a Lune Valley style boiler I built that is oil fired. It responds quite rapidly to firing changes; if yours is similar you'll be likely working with smaller quantities of wood to keep more even steam conditions. Making it easy to spread the fire out will be important as well. You might consider having a stack damper (like an carburetor choke) above the boiler so that you can reduce the amount of cold air that rushes in when you open the firebox door; this could also be done w/ a lever & spring setup so that the damper closed automatically most of the way when the door was opened.

- Bart
Mike Cole
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Re: Fire box door size

Post by Mike Cole » Wed Oct 25, 2017 5:24 pm

ianrichards wrote:Excellent, thank you so much for that.
6x5 it’s going to be.
Could I trouble you to email me some pictures of your boiler.
I’m trying to determine the best layout for ash tray access, boiler doors etc.
My email address is ian@ian-richards.com
Many thanks
Ian
I have been trying for the last couple of days to take some pictures for you , while it is still light but I am ending up fixing the boys bikes and other stuff that gets in the way. If you use Facebook and join the SBA page ( you do not have to be a SBA member) then I think I did post some pics on there some time ago.
I have my boiler with the two drums running fore and aft and not port to starboard like others I have seen. I have just welded 25/ 30 mm steel angel about level with the bottom of the water drum to provide a simple mount for my grate, which is in 3 parts ( I have a small firebox door) this gives me about 9 inchs from the top of the fire to the bottom of the copper tubes.
I have a simple stainless steel open box welded up for the ashpan which rests about 4 inches under the grate. This ashpan is about 2 inches deep and accessed by a separate panel at the rear of the boiler. I have a simple air door under the fire door to control air flow. Burning wood, I find very little ash in the pan at the end each days steaming and you could steam for 3-4 days without empting it out. But burning coal fills it in a day.
My grate is just made of stainless steel strip 2mm by 15 mm , cut to 9 inch wide . 2 holes drilled in each and a rod in each hole , strip then a spacer then a strip and so on to build it up, the gaps are about 10-12 mm between strips. so lots of air.
I will try to get some photos to you.
Keep the questions coming

Mike
Mike Cole
ianrichards
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Joined: Wed Jan 11, 2017 12:30 pm
Boat Name: Isambard
Location: Calstock, Cornwall, UK

Re: Fire box door size

Post by ianrichards » Wed Oct 25, 2017 8:03 pm

barts wrote:... this could also be done w/ a lever & spring setup so that the damper closed automatically most of the way when the door was opened.

- Bart
Neat idea, will define try and sort something along those lines out.
Many thanks
Ian
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