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[benjaml1]

Pretty as a picture.... 

[kiwimodeller]

Nick, that is all looking great. I am of the opinion that the parrallel secondary air holes around the circumference are the best design as far as quietness is concerned. I have finally arrived at one that seems to give very good heat and is quiet. It is interesting that when they work well the ceramic itself seems to glow red and the flame is almost clear. I meant to ask earlier if you have tried putting the jet holder straight on rather than at 90 degrees to the flue. In some installations it would be more convenient to have the gas line running along the keel line rather than coming from the side of the boat. Are there any good reasons not to put the jet in to the back of the burner? Nobody seems to do it. Cheers, Ian.

[MONAHAN STEAM MODELS]

Ian,

I see your point. The jet holder and the mixing tube for the burners used with our larger Belmont boilers enters straight on. With this mini boiler I chose to design this burner with the mixing tube entering at 90 degrees in order to keep everything as compact as possible.

[kno3]

In my experience burners with the gas jet placed at 90° are much more space saving than the straight variety. So the one you're using, Nick, is perfect for a compact plant.

[yogojr]

Kiwimodeller -Ian,

Noted your reply about the secondary parrallel air holes. Would you post some pictures?

Tom

[kiwimodeller]

Tom, I do not have pictures to hand and I am away shortly to go to Australia for 10 days. While there I will be visiting a boiler maker so might have more info when I come back. I was trying to say that with my limited amount of testing of various types of burners I had come to the conclusion that the burner shown in Nick's photo above which has a row of small secondary holes around the rim is much quieter and seems to burn more evenly than a Cheddar style one which has a smaller number of larger diameter  air holes in to the mixing chamber around the ceramic. The Cheddar design also uses a smaller diameter of actual ceramic and I do not think that is as good as it means that each flame "point" needs to be more intense to get the same total amount of heat. I would rather see lots of flames burning relatively gently and lots of smaller air holes which do not "roar" as the air passes in. It is interesting to play around with the size and number of air holes, both primary and secondary. To my mind it should have been possible to get the primary holes right and have exactly the correct pre - mixed gas and air mixture and not need secondary holes. However when I tried to achieve this I found that it was very hard to fine tune the primary hole size and even when I was close the burner was very temperamental. Small changes in ambient temperature and density affected it as did small changes in gas pressure as the gas temp dropped. I therefore decided that it was easier to have primary holes that I knew were too small and then gradually increase the number of secondary holes. Again a large number of small diameter secondary holes seems to be better than a few larger holes. Hope this makes sense. I have one burner now that works great in my small (6" x 3" ) boiler with 1 & 1/4" flue but still need to experiment with a bigger one. When this subject is done we can talk about chimney diameter versus flue diameter. I have been playing with restricted outlets. Cheers, Ian.

[Circlip]

Pity that some of your "Compatriots" on your side of the pond don't take the same attention to basic details that you supply on your products Nick. It's good to note that there is at least ONE non European supplier manufacturing steam generation equipment to such a high standard. You rightfully are, up there with the best.

  Many congrats Nick.

  Regards  Ian.

[yogojr]

Kiwimodeller - Ian,

Thanks for the reply and yep, all makes sense. All of my plants are Cheddar - Proteus, Puffin and Pintail. I've been having some burner issues on all of them. On the Proteus the issue was semi-clogged gas jet. Nick's suggestion of a little alcohol soaking coupled with blast from compressed air took care of that and the Proteus ran like a champ both on the bench and on the water. The Puffin, which is in a tug, has been a little more problematic. Jets are clean but having problems with flame out - both with superstructure on and off. My dad and I have both tried adding some additional air holes on the burner but went with a couple of larger holes not having the checked the forum first on what others are doing (lesson learned). That helped a bit but did not fully eliminated the problem. Smaller holes around the entire circumference makes sense so I'll try that next.

Safe and pleasant travels in Australia!

Tom

[MONAHAN STEAM MODELS]

Thanks guys for the kind words.

I have to admit that there are some days when I've been going at it for for 16 hours straight for multiple days in a row, that I ask myself why am I doing this? Does anyone even care? It sure as heck isn't for the money I can tell you that!  But when I hear thoughtful feedback from all of you I have to say what every doubts I had or what ever bitter mood that I was in goes away. Thank you for that.

Tom,

I'm glad to hear that your Proteus is running better. I think I know what you can do to get some more performance from the burners on your Pintail and Puffin. Both these burners should have come from the factory with #8 jets. Try replacing them with #5's. You should notice a big change in performance without having to modify the factory secondary air holes.

[MONAHAN STEAM MODELS]

One thing that I failed to mention earlier was that the new burner so far has require a #3 jet instead of a #5. I'm still experimenting with different air/fuel mixtures trying to find the best performance. I briefly installed a #1 jet last night but didn't get much of an opportunity to experiment with it because it was getting late. Going to try some more experimenting today. The number #3 jet is very economical on fuel consumption but is very sensitive to air mixtures and temperature changes. The #1 jet ran nicely so far but needs to be played with some more. The #5 jet seemed to run way too rich. I'm thinking that the #3 will be the winner but only testing will prove that.

[Canopus]

Yogojr,

You referenced flame out with a Puffin unit. I had similar problems with my Battleship Canopus 1899 with constant flame out. In the end I found this was due to two issues:

1) Insufficient air getting into the boat - Canopus is virtually totally enclosed and what was happening was a bubble of oxygen deprived air was forming on top of the boiler gradually expanding until it reached the burner and flame out! This may not be relevant if your boat is open to the elements. This took a long time to solve as when you take the deck off the hot air disappears and it re-lights fine - also in the bath it worked fine with no problem but on the pond would constantly flame out! Problem was the forward facing ventilators let the hot air out but with the motion of the boat they stopped the hot air comming out. Solution was to open up some of the secondary gun ports to permit better ventilation.

2) I had restricted the funnel diameter to fit inside the model funnel, no problem in doing this but every time I stopped the engine it flamed out with a loud "pop". Turned out that I had the steam exhausting into the funnel (per the original funnel design) which was fine but it did not reach the top oif the funnel. The differencve was on stopping or starting there was a shock wave caused by the exhaust steam which travelled back down to the burner blowing it out. The solution was easy just extend the exhaust tube to the top of the funnel - no more problems.

Hope this may help

Geoff