Where to position the steam outlet on a horizontal boiler ?

I am thinking of building a horizontal boiler for my next project : 65mm diameter and 80-90mm in length.

1.  Does it matter where the steam outlet is positioned. I know it goes on the top.......but should it be half way along the length or doesn't it matter ?

2. How would I build a steam dome and what are the advantages ? ( It may be more trouble than it is worth.)

Edited By Brian John on 11/03/2015 06:19:26

Does not matter about the position.

You could possibly bend out the bottom of one of your copper pipe caps to form a flange that follows the curve of teh barrel similar to whats shown in the current issue 4503 of ME. For a relatively low pressure boiler you could possibly get away without a flange.

How are you heating this? if thinking of a burner from below those proportions don't give a very big heating area for teh volume of water. By teh time you have made a firebox to contain teh flame you will only have 60-70mm length. better to come down to 50mm and make it say 150mm long or stick with your 63mm dia and go upto 200mm long.

On that larger size I would add a couple of external water tubes - like a "U" shaped pipe that will act like an element in a kettle and increase the heating area. A long trough for a burner or a row of your round ones would be needed in either case.

J

Quite a few people have written substantial books on boilers which indicates that there is a bit more to it than silver soldering a few bits of copper together and hoping for the best. I did this once and discovered that I had wasted precious time and resources. May I sincerely recommend that you look for a proven design or at least acquaint yourself with the various materials, formulae and calculations which will guarantee success.

Mick

Hi Mick

I noticed in your album your cordless drill filing machine.. free plan.. could you possibly drop me the link for the free plan or pm me

TIA

George

Hi George,

It's one of the MEW free plan reprint series:

www.model-engineer.co.uk/news/article/free-plan-light-duty-filing-machine/18851

An alternative version has just gone live:

www.model-engineer.co.uk/news/article/free-plan-a-fretsaw-and-filing-machine/20902

Neil

Neil

Thanks for the links ..both downloaded & stored..

George.

I will be heating using a metho burner, probably with a double burner or even triple burner to increase the heating area.

The firebox design will be very important.

Edited By Brian John on 12/03/2015 05:43:00

1. What thickness of copper plate is most suitable for building a firebox for the horizontal boiler ? It needs to be strong and yet fairly easy to bend into shape. I know 1.0mm would be too thick. I can buy 0.4mm, 0.5mm, 0.6mm or 0.8mm.

2. I have my eye on an Ozito jigsaw with metal cutting blades to cut the curves in the copper plate. How would you cut it ? I do NOT want to use a hacksaw ... I have recently discovered the joys of using power tools !

Edited By Brian John on 28/03/2015 04:06:24

There is no need to go to the expense of copper for the firebox. Mild steel will do 0.5 - 0.6mm should do fine on such a small boiler.

J

Brian does well scavenging... how would old water heater copper do? I happened across a youtube vid of a blacksmith recycling that into flowers to enhance his wrought iron gates and it seemed to anneal and workharden well..?

Which is the better material for the firebox : brass, copper or aluminium ? The price is about the same for all.

Edited By Brian John on 02/07/2015 09:19:27

Edited By Brian John on 02/07/2015 09:19:42

Brian, I'd go with steel, the other metals rob some of your heat. For sheet steel, look at old household appliances, anything, old microwave ovens, computer towers, paint tins.

Ian S C

Steel of the right thickness is not ready available where I live and then there is the problem of cutting it up. I have to make do with copper, brass or aluminium.

Brian, I think brass would be the best of the three, or you could use a bit of a baked bean tin.

Ian S C

Of the three I would probably go with brass too, Copper is a bit soft and not so nice to work with. Brass also gives you the option to silver solder where as the aluminium will need rivits or screws/nuts

I have had a few problems positioning the steam outlet bushing and the safety valve bushing in the top of my horizontal boiler. I have previously built three vertical boilers and these bushings sat evenly on top of a flat surface on top of the boilers so there was no problem.

But with this horizontal boiler the bushings sit on a curved surface. About an hour after I had silver soldered them on I realised that they were not quite vertical. So I had to remelt the solder and reposition the bushings (with a pair of pliers while the solder was still hot) to correct them otherwise the safety valve and steam outlet would have not been perpendicular. I will post some photos later after it has come out of the citric acid pickle.

How many times can you remelt silver solder before it loses its strength ?

Edited By Brian John on 04/07/2015 08:01:16

Here is the finished (?) boiler. I may paint it with heat resistant paint. It is resting on a cardboard mock-up of my firebox which will be constructed of 0.6mm brass ; two flaps will be added to the top to seal the gaps between the top of the firebox and the boiler. There will be an L shaped chimney at the other end.

Edited By Brian John on 04/07/2015 11:19:46

Edited By Brian John on 04/07/2015 11:20:17

I have added another fillet of solder to both steam outlet and safety valve. It looks much more respectable now. The photos below show the boiler in a test rig I have made up. I will fire it up tomorrow to see how it goes.

Testing out the new boiler and it works very well but a good firebox is essential here. A lot of heat is being lost so it should run much better when a firebox is constructed. I am waiting on the brass sheets from China.

I do have some questions though :

1. That is a lot of soot which is not visible on the vertical boilers because on those it is concealed by the fireboxes. I thought methylated spirits was a relatively ''clean'' fuel ?

2. I am going to have to paint this boiler but I am unable to find a heat resistant paint in Australia that will tolerate direct flame. What do they use in the UK when they paint their boilers ?

3. I will also have to bend a brass pipe (inverted semi-circle)  from the steam outlet so that my silicone tubing does not get cooked. Can this be done  without bending springs ? I always get a kink in it when I try it.

Edited By Brian John on 06/07/2015 11:06:24

Edited By Brian John on 06/07/2015 11:06:55

I can;t speak from using steam boilers but I always find that the yellow part of a flame has the most unburned components and sitting objects nesting at the top of the blue gets max heat. Alternatively you need to introduce more oxygen into the flame in the way a bunsen burner or gas torch does, perhaps, to get more complete combustion.