More Steam please!

[kiwimodeller]

I have a Windermere launch fitted with a Saito V4 engine and a Cheddar Puffin boiler and burner set-up. I have just fitted a Saito steam whistle and took it out for a sail for the first time since fitting the whistle today. It has accentuated a problem that already existed in that the Cheddar boiler does not seem to be able to keep up with the demand for steam. If I let pressure build up to 30 or 40 PSI before opening the steam valve the boat goes really well but after about 10 minutes of running at between half to full throttle the pressure is down to 10 to 15PSI. Although the engine will still run on this I would like to be able to make more steam. Has anybody tried changing the Cheddar jet or drilling more air holes in the ceramic burner holder to get more heat out of the burner? This is the only way I can think of to get more steam consistantly. I have tried adjusting the position of the jet in the holder but the actual temperature of the gas out of the flue does not seem all that hot. Any suggestions? Thanks, Ian.

[derekwarner_decoy]

Hi PD's - goodness Ian after my last    comment  - all I can say with understanding you are somewhere between 'enthalpy' & 'entropy' - these are real words we learnt all those years ago & I promise I didn't make them up @ Babelfish

I am sure SANDY will come back & give you the evil eye  :hmmm  :hmph & suggest that if the steam GOD   wanted more steam out of the boiler he/she  would have made it [the boiler] bigger or controlled it better

As a fuel saving alternative, you could always go & purchase one of the  single or dual diaphram proportional GAZ to steam output regulators from that other country - you know the one, just around the corner from Italy & Spain & accross the straits from Dover to Calais - I am sure the quality of the equipment is great but you will get better operating instructions in the words from a wapper from a Mc Donalds 1/4 Pounder :rant  :rant

Please   if I offended any particular ethnic group by talking about their food wrappers - but like what directions do you get when you read the words on a PIZA Hut box :?:        - Derek

[steamboatmodel]

Hi Ian,
To get more Steam  :yeah you have two options, either talk very nice  to Sandy and get him to build you a nonstandard (Yarrow or Scott) boiler with a high output burner . or    start building your own :luck . I have chosen the later route , when I became unhappy    with the steam output of the standard boiler supplyed with my Wilesco D48 boiler and engine set, but beware that this route leads you down the road to wanting to build the whole unit yourself    :yeah and becoming a "Model Engineer"
Regards,
Gerald

[sandy_ACS]

I have a Windermere launch fitted with a Saito V4 engine and a Cheddar Puffin boiler and burner set-up. I have just fitted a Saito steam whistle and took it out for a sail for the first time since fitting the whistle today. It has accentuated a problem that already existed in that the Cheddar boiler does not seem to be able to keep up with the demand for steam. If I let pressure build up to 30 or 40 PSI before opening the steam valve the boat goes really well but after about 10 minutes of running at between half to full throttle the pressure is down to 10 to 15PSI. Although the engine will still run on this I would like to be able to make more steam. Has anybody tried changing the Cheddar jet or drilling more air holes in the ceramic burner holder to get more heat out of the burner? This is the only way I can think of to get more steam consistantly. I have tried adjusting the position of the jet in the holder but the actual temperature of the gas out of the flue does not seem all that hot. Any suggestions? Thanks, Ian.

And Derek said.

I am sure SANDY will come back & give you the evil eye  

Ok, so Hi PD's...Ino casta de eevil eye ona nobody...comprendheh!...    :music

Ian. the answer lies in your description af your installation....the cheddar boiler is designed/matched to a twin cylinder engine (Puffin) with 2 x 11mm cylinders, with similar stroke. Even on this engine the boiler was unable to keep the steam pressure up at more than 30 -35 PSI.

Your Saito has 4 of, I believe, 12mm bore x 12mm stroke...even given the fact that the Saito is single acting...at any point in a single revolution you will always have more than 2 cylinders full of steam...hence the boiler cannot produce enough for this engine.
You are also adding the additional steam requirement for a whistle...need I say more...  

As for the modifications to the Cheddar burner....adding a larger jet will not actually give you any more heat...it may send more gas through...but it is highly unlikely that this will be burnt fully and is more likely to reduce the amount of heat generated...furthermore..increasing the size of the auxilliary air holes will have the same effect...more cold air will be permitted to enter the flue...and so upset the balance ...and will almost certainly reduce the available heat. :rant  :rant  :sob

The only way to get more heat is to use a bigger surface area burner...since, with ceramic burners, the heat generated is proportional to the surface area; not only that, but the heat output is non-linear and approaches a square law...i.e double the area and you quadruple the heat generated.
The problem you face Ian, is that you can't fit a larger burner to the Cheddar flue...at least not a ceramic one....perhaps you should investigate a blowlamp type of burner...somewhat noisier, and tricky to get balanced correctly, but can be more powerfull for a given dia.

As you know, I use a 28mm ceramic burner (the Cheddar burner is 22mm in dia) in my ACS boilers, which are much the same size as the Cheddar units, but they have a much larger centre flue of 42mm dia. and a larger heated surface area.

If you look at the surface area difference between these two burners then mine is approx 0.6 times bigger in total surface area and will provide around 2.5 times the amount of heat output. The jet size is the same in both burners.

 :hmmm  :hmph    :sob

In short Ian, I think YOUR GONNA NEED A BIGGER BOILER!!!!    :rant

You could perhaps do what Gerald has suggested, and have a go at building one yourself.

Best regards to all

Sandy.
[/quote]

[kiwimodeller]

Thanks all for the good news (even if some have to wrap it up in funny words or McD's wrappers). I only have a basic understanding of the mechanics of steam engines and boilers, after all I served my time as a car mechanic (just think, 6 weeks ago I coodent efen spell Meckanik and now I are one  :lol:) but I did think that introducing more gas and more air in the correct proportions would produce more heat and therefore more steam because the water temperature stayed at boiling point. I understand Sandy your points about surface area of the ceramic boiler and also about area of transfer between the heat and the water but I would have thought that increasing either would be some help? What about putting an ACS 28mm burner in to the Cheddar flue? The Saito V4 is only 9mm bore by 10mm stroke and single acting (and using  a near enough figure for Pi of 3.14159 that gives I think a capacity of 2.54cc) as against the Puffin being about 2.09cc if it is 11 by 11mm so maybe I am always going to be pushing the proverbial up a Scottish mountain with a teaspoon but it is not too much of a problem and I will put up with it if I have to. It is a nice wee boat with a nice wee motor and goes well enough on 10PSI that I can get a lot of pleasure out of it. The Saito T2 which is the next project and the subject of our correspondence Sandy is the one that is 12mm bore and stroke. Incidentally at the sailing day I met the other Ian you have been dealing with and he was extolling your virtues especially when he found out from the club boiler inspector that with the valve on his boiler set to 35PSI he does not have to have a boiler cert of any sort.  Cheers, Ian.

[zubi]

Ian, Is your boiler well insulated? If not you could start with properly insulating the boiler and all the steam ducts. Also prevent the burner from loosing any heat - it should all go into the boiler. Best wishes from Tokyo, Zubi