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[Bunkerbarge]

If Greg doesn't mind me adding to his explanation I think it is useful here to also discus the differences between heat and temperature.  Heat is basically a measurement of internal energy which everything has.  Some things have a high energy and some a lower energy.  This heat energy is capable of transferring from one object to another by any one of the three transfer paths, namely conduction, convection and radiation. 

A consequence of heat is temperature but not necessarliy such that the higher the energy the higher the temperature.  For instance if you add heat to water from a burner the temperature in the water rises as it's internal energy rises.  When it reaches the boiling point though the heat energy is then used to change the state of the water to steam and so even though you may be still putting more heat into the water it's temperature will not rise.  This heat is known as latent heat and any given substance has a specific latent heat, which is the amount of heat required to change the state of a specific quantity of the substance.  If the substance remains open to the atmosphere continuing to add heat will not raise the temperature but will only continue to change the state of more of the water, as in a normal kettle and explains why the temperature of a kettle does not rise above 100 degrees C, depending on atmospheric pressure.

If you then contain the escaping steam it generates a pressure on it's container as more water is changed to steam until it reaches it's vapour pressure at which point the system is said to be in equilibrium.  Adding more heat then does two things, it increases the temperature of the steam and it increases the pressure, which remain related.  This is why for those of you with Cheddar Electronic Gas Control systems the probe in the boiler actually measures temperature and not pressure.

So that's the basics of what is going on in the boiler and again thanks to Greg for getting the ball rolling.

[RaaArtyGunner]

HELP.   
Guys remember the KISS principle 
Keep It Simple Stupid 
Yes a lot of us do need big spoons the bigger the better.
Reading this thread, If it sounds too complicated and difficult why would I want to start in steam, know nothing about it and at this rate will never do so.   
As for references to "Model Bots magazine articles" and public domain       that all depends on how you search and your current knowledge, no knowledge so what do you look for and where hence the questions for help.
We are not all on the same level    let alone sometimes not even the same wavelength  and we all don't have the same deep pockets.  
Now  I stand guilty of having completely got of the thread.   

[Colin Bishop]

Well, as far as Model Boats Magzaine is concerned it doesn't get much easier that this:

http://www.modelboats.co.uk/news/article.asp?a=4447

http://www.modelboats.co.uk/news/article.asp?a=4853

http://www.modelboats.co.uk/news/article.asp?a=4853

The other articles are available if you have a subscription or are willing to purchase them. The publishers are in business to sell magazines rather than give out free advice I'm afraid.

If you want to understand the subject then, as I have previously said, you need to put a bit of effort in yourself. It's not rocket science!

Colin

[vintagent]

If I may sing a chorus for those of us who want it simple...get on Pete Atkins' website and listen to the Locomotive song from Beware of the Beautiful Stranger. No more concise explanation is there for how a steam loco works! (The other songs are magnificent too!)

Also, don't forget, people like Raartygunner, that you could put a Mamod or SEL or Willesco "toy" steam plant in a boat and have almost as much fun because when it's out on the water chuffing away, nobody can see all the magnificence of the model engineering OR the lack of it. It's just a steam boat at a distance.  So some of the need for Cheddar, Monahan, etc. plant could be seen as a bit of one-upmanship.  Fair enough. Some are impressed by that.  Some, like me are as unmoved by that as by TV advertising.
Of course some people have no space, equipment, skill, etc. and can afford the above so have to have it if they must have steam. Equally fair enough.
All I'm saying is a glorified pot-boiler, a spirit burner and an oscillating plant will still give you hours of pleasure on rudder only.  But do test it first to time the length of run.  You don't want all the solder running out of the joints on your Mamod!

Fun IS available with a little imagination without breaking the bank.
Of course these little units can be made without the facilities of an engineering shop, too.

Regards,
Vintagent

[Circlip]

Well, as far as Model Boats Magzaine is concerned it doesn't get much easier that this:

http://www.modelboats.co.uk/news/article.asp?a=4447

http://www.modelboats.co.uk/news/article.asp?a=4853

http://www.modelboats.co.uk/news/article.asp?a=4853

  But what does this mean Colin, how does it help???????????   Do I have to do something??

  Regards  Ian.

[vintagent]

Having said all that above, I have just looked at the Maccsteam site and am frankly amazed at how remarkably inexpensive are his products.  I couldn't begin to produce those components at those prices.  I could make them all on my wee lathe, but I would have to ask myself it it was worth the trouble. A beautiful valve assembly with handwheel for £15???  Amazing.
I add that I have no connection with this company other than a bystander led to his website by another thread on this forum.

If I could justify spending there I wouldn't hesitate!

Regards,
Vintagent

[PMK]

I know that I'm not exactly the most popular bloke amongst all you steam buffs (probably my own fault for being a twonk in the first place), but could I throw a couple questions your way?.........

Did any of you go the Shepton Mallet gig in April? Just outside of the hall where ACTion, MMB and several other traders were doing their thing, was a chap with three of four models (VERY nice models), each fitted with their own steamplants. I was having a long chat with the man who built/owned them, and he was telling me about this wee electronic gizmo he'd installed in each model, only I didn't get to learn what those gizmos were because some other chap came along and we all got sidetracked. All I know is that they (gizmos) were some sort of safety device - something to do with preventing the engine from exploding. The only other thing I learnt is that each one cost the man something like £150.00 each. I was shocked by that because, when he popped the lid, I peered inside and saw just one 8-pin chip, a small on-board trimpot and a couple other discrete components. All pretty much bog-standard components, and no way was there anything to the value of THAT much. I'd guestimate that one could build the same and still see change from a twenty.
From this, albeit scratchy discription, would you steam boys happen to know what that gizmo might be?
Would you be perhaps interested in paying far less for a homemade one?

(Total apologies for taking your thread slightly off course).

[Bunkerbarge]

My guess PMK would be some form of gas contriol device.  The problem with a basic unit which pumps gas into the burner is that when you don't use the engine the pressure rises until the safety lifts, then you are simply wasting energy.  If you can turn the burner down to control the flame and prevent the safety from lifting then that is a huge advantage.  Mechanical ways of doing this are the attenuator valve, which uses a diaphragm pushed by the boiler steam pressure against a spring, to control the gas flow, or electronically like the old Cheddar Electronic Gas Valve, which is now produced by Stuart.  This uses a temperature sensor on the boiler to switch the burner from a ful flame setting to a pilot flame setting, thereby regulating the boiler presure.

I think I know the chap you are talking about and, if it's him, he makes absolutely everything from scratch.

[Bunkerbarge]

Well from what I can see above we have the opinion that anyone who has anything more complex than a Mamod is showing off and any teachings have to be in words of one syllable preferably not involving anything more technical than junior school physics and I suspect there are some who would struggle with that.  I accept that Macsteam products are beautiful and very reasonably priced however once you have looked at fitting out the boiler and added all the other bits you need you will still be a bit surprised at the total cost.

Bottom line I'm very dissapointed but there is obviously no demand for such a thread as this and maybe I will just have to accept that steam in model boats will be a victim of our society and die out with this generation.  I'm certainly not going to waste any more time on this thread.

[PMK]

"I'm certainly not going to waste any more time on this thread."

Don't give up. Some of us do read/do appreciate these things, you know.

I think you could be right about that gizmo, because, now that you mention it, I do recall a length of wire protruding from the box, terminated with a sensor on the end (presumably the temperature sensor you talk of). If this isn't too cheesy a question, what sort of temperatures do those boilers reach? In your opinion, does £150 sound like a lot to you?...or did I mishear the man? I would imaging that £150 is perhaps a small price to pay (especially in view of what those engines are worth) and at least safe in the knowledge that you're protected from any explosions or such, but would you agree that the same thing could be made a heck of a lot cheaper?
By the by, I'm not trying to cheapen things, and certainly not trying to muscle-in on anyone's profit, but I still think that you steam boys are perhaps getting a tad ripped-off?

[Circlip]

Nil Illigitum BB

[The Antipodean]

I have found this thread not only informative but entertaining as well.
As a not even an absolute beginner in steam I am curious to know more as I would love to build a steam tug at some point in the future as my situation has changed for the better and steam now looks as though it once again could be a prospect.
Bunkerbarge, you do wonderful explanations, I would think that if a person did not understand them they should maybe ask for clarification of the part they don't understand instead of saying the whole thing is useless.
From what I have seen in the steam forum, the people who have steam are always looking at encouraging more members to join them on the humid side of boating and I would guess they would actually be amazed that they had turned people away.
I would say it comes down to how much a person is willing to do to learn about a subject they say they are interested in, some want spoonfeeding and some are more than willing to do the research themselves.
Basically, if someone asks a question and it is answered, if someone else doesn't get it they should ask for a little more explanation and as long as the person who asked the initial question is satisfied with the answer then there is no problem at all.

Longwinded I know but my opinion on a good thread.

Ian

[Bunkerbarge]

"I'm certainly not going to waste any more time on this thread."

Don't give up. Some of us do read/do appreciate these things, you know.

I think you could be right about that gizmo, because, now that you mention it, I do recall a length of wire protruding from the box, terminated with a sensor on the end (presumably the temperature sensor you talk of). If this isn't too cheesy a question, what sort of temperatures do those boilers reach? In your opinion, does £150 sound like a lot to you?...or did I mishear the man? I would imaging that £150 is perhaps a small price to pay (especially in view of what those engines are worth) and at least safe in the knowledge that you're protected from any explosions or such, but would you agree that the same thing could be made a heck of a lot cheaper?
By the by, I'm not trying to cheapen things, and certainly not trying to muscle-in on anyone's profit, but I still think that you steam boys are perhaps getting a tad ripped-off?

Thanks for the support PMK, I can assure you it is very much appreciated.

This device does sound like an Electronic Gas Controller in which case you are up against the unit from Stuart Turner.  This includes the change over valve itself as well as the sensor and a gas pipe to connect the tank to the valve.  These are currently in the region of 140.00 UKP so you would have to do better than that to be competetive.  One possibility may be to sell just the electronics package and leave it with modellers to sort out thier own valve but I suspect most will want the valve including as well.  The way it works is that the valve changes over from full flame to pilot via an operating arm, which is moved by a micro-servo.  The servo gets it's signal from the control box, which in turn is activated by the temperature probe on the boiler.  The 'pot' you saw would be the pressure (technically temperature) set point so the unit is really only measuring the difference between the set point and the sensor input.  As you say it is pretty basic but very effective.

As for temperature if we take 100 psi, which is above what most model boilers should be working at, Cheddars are around 45 psi and Hemmens are about 80 psi, then the corresponding saturated temperature is 332 deg f or 167 deg C.  Test pressures are initially 2 x working pressure and subsequently 1.5 x working pressure so you could be looking at 187 deg C so I'd be looking for a sensor that can withstand 200 deg C.

[Bunkerbarge]

I have found this thread not only informative but entertaining as well.
As a not even an absolute beginner in steam I am curious to know more as I would love to build a steam tug at some point in the future as my situation has changed for the better and steam now looks as though it once again could be a prospect.
Bunkerbarge, you do wonderful explanations, I would think that if a person did not understand them they should maybe ask for clarification of the part they don't understand instead of saying the whole thing is useless.
From what I have seen in the steam forum, the people who have steam are always looking at encouraging more members to join them on the humid side of boating and I would guess they would actually be amazed that they had turned people away.
I would say it comes down to how much a person is willing to do to learn about a subject they say they are interested in, some want spoonfeeding and some are more than willing to do the research themselves.
Basically, if someone asks a question and it is answered, if someone else doesn't get it they should ask for a little more explanation and as long as the person who asked the initial question is satisfied with the answer then there is no problem at all.

Longwinded I know but my opinion on a good thread.

Ian

Many thanks Ian and again, very much appreciated.  You see it pretty much as I do and whereas I'm more than happy to give as much of my time as necessary I get a bit negative when I see complaints about the cost of steam plant and complaints about the fact that we are not teaching members at the right level.  I have put huge amounts of time and efforts over the last few years to try to get more modellers into steam and was very pleased to see our first Steam Convention at the Kirklees Model Boat club recently but people have to take steps themselves and show a degree of initiative as well.  It is not my responsibility to teach someone something, it is thier responsibility to learn and, as you say if they don't understand then ask the right questions. 

At the end of the day I went out and bought the books and read them and I expect a degree of the same from anyone who wishes to become more involved in steam.  If your attitude is that anyone with anything more complex than a Mamod or a Wilesco is showing off then please go and buy a Mamod or Wilesco and be happy with it.  There is a member on here who has an old launch with a plant that has been out of production for a long time however he did some research and found some information on it and I was able to complete a steam test for him and get him on the water.  I was more than happy to help him but the initiative and effort came from him in the first place.  Coincidentally as well his plant was of the Mamod/Wilesco type but he didn't see me as showing off with a Cheddar plant, he was just happy that I'd certificated his plant for him.

[steamboatmodel]

I have run a Wilesco D48 for a number of years in a Mabel style hull, and have had many hours of enjoyment from it. The main problem I find with it is the original boiler, to solve this I have been experimenting with different boiler designs. For the absolute beginner I think the Midwest engines/boilers are a good place to start. There have been many designs published over the years for simple steam engines and boilers here are a few that I had posted on the RC Groups Steam section;
http://www.rcgroups.com/forums/showthread.php?t=1226384

Building Simple Model Steam Engines
Books 1 & 2
by Tubal Cain

Making Simple Model Steam Engines
Model Marine Steam
by Stan Bray

Another Article/book to add,
Safety of Copper Boilers by Kozo Hiraoka this nine page article was first in Live Steam & O.R. (Vol. 40 No. 6 Nov-Dec 2006) and is included in Building the New Shay.

Introducing Model Marine Steam
By John Cundell and Jim King.

Model Making 1919 Edition
By Raymond Francis Yates
Also
Boys' Book of Model Boats
By Raymond Francis Yates
http://www.gutenberg.org/files/29064...-h/29064-h.htm

I have been building model steam engines and boilers off and on since 1967, but still find the articles for beginners enjoyable and quite often informative.
Regards,
Gerald.

[vintagent]

I said there would always be an element of the showing off about it. I did not aim the comment at you BB or anyone else.  I DID say "fair enough" if you read it, but my main point was that about forums becoming oracles which books once were.  And so people not in the know might expect to find it all on line.
By scoffing at them and telling them to read books they'll claim they have no time to source and also insulting their intelligence by saying they haven't even o level physics, you WILL put them off.
Now I don't actually spend time worrying about that, but a lot of more committed members of the "movement", steam or otherwise do and so anything likely to drive the raw beginner away is to be discouraged.  Your general attitude is one. " Read me or I'm off", type of thing for example.

My comments about the simpler plants available or makeable with limited equipment were all part of an encouragement into steam, but at a more affordable level than shelling out hundreds on proprietary gas powered, reversing blah, blah installed according to one missive in a model boat magazine.

I have a lot of books and delight in reading them and have designed a vee twin without help.  I shall also use an old design for a spirit fired boiler to use on my local waters.  It will be as the Mamod or Willesco or SEL, because they are what I know and what need no accreditation from a distant boat club.  The basic designs came from an old friend who did his seven years with the Southern Railway and as a steam enginerr had no peers.  he was a major member of the Gauge One Model Railway Society and designed and ran many a fine model, coal and spirit, gas not being around as such at that time.
Of course, I would be as fascinated as the next man to see any of these shiny bought -in palnts at work, just not prepared to pay the prices (except for Maccsteam as I have already indicated)  When I bought the castings for my Stuart Triple a good few years ago, they cost me 64 guineas delivered to my bedsit.

Regards,
Vintagent

[knoby]

Hi all, I have dabbled with steam over the years but by no means am I an expert or anywhere near that level. I thank BB for starting this thread & have found it informative so far. I have no engineering facilities & limited engineering skills, so have to rely on ready made parts which I use or modify as required.  I personally learnt what i know from other people, reading up on the subject & trial & error.

Usual beginners questions seem to be i have this hull what steam plant will work in it? or I have this engine what boiler do I need? Whilst they are valid questions, unless someone has experience of that exact installation, there isn't really any definitive answers. i cant think of a single instance where a modeller has installed a steam plant & not continued to modify or change things to overcome problems or improve the performance. Steam really isn't a 'plug & play ' type of propulsion & if thats not your type of thing, then maybe its not for you.

Please don't think I'm trying to put people off trying it, for a first steam model it may be best to copy an existing boat & plant installation, which should eliminate many of the problems. personally my enjoyment of steam  comes from learning to understand my steam plant & work it more efficiently.

Perhaps some of the steam modellers could post details of their models, types of plant installed & a brief description of why they chose that particular route to give an idea of the thinking behind it.

As for it being expensive, well yes a steam engine is always going to cost more than a 540 motor, simply because of the design & engineering that goes in to it, but do you get value for money? thats the real question. Having been reading nicks thread on the development of the new v twin I think you get a masterful piece of equipment at a very reasonable price.

I hope Bunkerbarge  keeps this thread up, its really good to encourage more steam models, the help & advice is second to none on this forum * I thank all who have helped me over the last few years.

cheers Glenn.

[gondolier88]

Right,

As promised, even if people do find it hard to pick out the points they need from a thread, I’m going to forge ahead with simple steam postings.

After explaining the principles of boiling water and getting the most from it I think an explanation of different boiler types and their relative advantages and disadvantages-

Following on from explaining that heating surfaces and boiler shapes are the most effective means of controlling the boiling water.

I will explain using examples both full size and model- the principles are EXACTLY the same.

First-

Pot boilers

These are simply a kettle with no lid and have a steam take off, usually permanent (no isolation valve) and run at very low pressures.

Usually they are fired by spirit, or in mo re recent years fuel tablets. They are lots of fun, very simple, very safe, pretty much impossible to get wrong and are as reliable as any highly engineered engine. For many, me included, pot boilers and simple engines were the way into the hobby.

Here is an example of a model pot boiler-

(Cant get it to post here- at end of post)

This a Mamod type boiler- the three connections are from the front- water filler cap, safety valve and steam take off.
These boilers are very inefficient, fuel hungry and poor steamers- BUT- they work, and well too. Water goes in- ¾ up the gauge glass (the sight glass in the brass casing on the end plate of the boiler), the fuel is lit and placed under the boiler and once steam is raised in a matter of seconds it starts to drive the engine- normally an oscillating engine (an engine that has no valve gear (the means by which steam admission to the cylinders is controlled) and the cylinders move on a pivot to negate the need for a connecting rod and giving ultimate simplicity)

These boilers can, and have been used in model boats, model buses, cars and fire engines and modified to power all manner of miniature vehicles, mill scenarios and steam workshops.

If you don’t know about steam look on any internet auction site for an example, your local newspaper ad’s, local toy auctions etc- anywhere really, or even buy a new one, they aren’t all that expensive- you will learn far more by having one of these fascinating and endearing hissing and fizzing little beasts than you ever will from any book.

Have a look here for more details of pot boiler models;

www.forest-classics.co.uk/Mamod.htm

More details to follow.

Greg

[PMK]

The servo gets it's signal from the control box, which in turn is activated by the temperature probe on the boiler.  The 'pot' you saw would be the pressure (technically temperature) set point so

Yes, that pretty much describes what I saw on that day, so I reckon you've answered my question. Although, as I said in the previous one, we got sidetracked so I didn't really get to see much else. I wish I could remember the gent's name, but if you were at the show, all I can tell you is that he had his pitch in that hall at the far the right-hand end of the building from where FLJ was standing. I'm certain he had at least three models on display - it may have been four. Nice bloke; answered all my Qs with no quibble, and would probably have answered more if the other chap hadn't come along.
I didn't find such a unit on Stuart Turner's page, but did spot this...

http://www.cornwallmodelboats.co.uk/acatalog/graupner-1966.html

This one differs in that it has a 3-digit readout, whereas the one I saw at the show didn't. Making such a 3-digit beast would be do'able, and still far cheaper than the retail price, but this is where I have to concede, because that valve thingy is waaay over my knowledge of anything steam.
As I said, I'm not muscling-in anyone or such, but merely intrigued as to what is was all about.
Listen, thanks for coming back with the answer.

[frazer heslop]

Having built various steam plants over the years with varying degrees of complexity including home built electronic boiler level control and gas attenuator valves I find simple steam plants to be the most enjoyable type  and believe that there is a need for simple concise information so that beginners can begin to understand what is required to build a safe working steam plant .At the end of the day how did most of us start out I know that if was not for the kindness of more experienced modellers and machinists I would never have been in the position of building and designing my own plants. It is up to the individual to seek out the relevant information but at least with help they will know where to look and with guidance hopefully model steam and steam boating should flourish and not die out with this generation.I would like to thank Bunkerbarge for trying to show and encourage people to think about steam.

[HS93]

Yes, that pretty much describes what I saw on that day, so I reckon you've answered my question. Although, as I said in the previous one, we got sidetracked so I didn't really get to see much else. I wish I could remember the gent's name, but if you were at the show, all I can tell you is that he had his pitch in that hall at the far the right-hand end of the building from where FLJ was standing. I'm certain he had at least three models on display - it may have been four. Nice bloke; answered all my Qs with no quibble, and would probably have answered more if the other chap hadn't come along.
I didn't find such a unit on Stuart Turner's page, but did spot this...

http://www.cornwallmodelboats.co.uk/acatalog/graupner-1966.html

This one differs in that it has a 3-digit readout, whereas the one I saw at the show didn't. Making such a 3-digit beast would be do'able, and still far cheaper than the retail price, but this is where I have to concede, because that valve thingy is waaay over my knowledge of anything steam.
As I said, I'm not muscling-in anyone or such, but merely intrigued as to what is was all about.
Listen, thanks for coming back with the answer.

this is probably similar to what you saw, just gas controle and they work very well.
http://www.stuartmodels.com/accessories.cfm/mainaccess_type/9/the_type/Electronic%20Gas%20Valve

[PMK]

PeeWee, I think that is indeed it. I suddenly remember that battery holder.
So, just to see if I learnt anything that day, am I right in thinking that...

1) The temperture sensor is connected to the unit?
2) And also a servo?
3) You preset the required temp' with the on-board trimmer...
4) and then, when the temp' is reached, will trigger the servo to operate the valve?

Is there a reason for the unit running from it's own separate battery?
There appears to be 2x servo connectors there. What is the second one for?

[HS93]

Picture of one, 1234 are for the sensor and battery then the pins are for servo + servo reverse

Peter

PS was that the right tv show the other week ?

[Bunkerbarge]

PeeWee, I think that is indeed it. I suddenly remember that battery holder.
So, just to see if I learnt anything that day, am I right in thinking that...

1) The temperture sensor is connected to the unit?
2) And also a servo?
3) You preset the required temp' with the on-board trimmer...
4) and then, when the temp' is reached, will trigger the servo to operate the valve?

Is there a reason for the unit running from it's own separate battery?
There appears to be 2x servo connectors there. What is the second one for?

1) The temperature sensor screws into a spare plug in the top of the boiler and connects to two of the terminals in the block.
2) The servo plugs into the servo pins, either way round to reverse the action
3) You preset the desired temp/pressure with the on board pot.
4) When the boiler reaches the desired temp/pressure the unit operates the servo which switches the gas valve over from full flame to pilot flame.

When the boiler pressure drops by about 10 psi the unit operates the servo again which switches the gas valve back over to full flame and the temp/pressure starts to rise again.

The great beauty is that when the model is in the middle of the pond and you are not exactly hammering around the burner turns down and stops wasting gas.  This means your model can stay out longer and you are not relieving pressure with the safety valve and spraying dirty water all over your model.

The unit is supposed to run from a dedicated battery to prevent interference when used in conjunction with an Rx battery.  The instructions also suggest that you attach the micro servo to the valve with a couple of supplied cable ties.  I think this is really naff so I made a much more robust arrangement for my own valve.  I also painted mine blue to match the rest of the boiler fittings.  In the picture you can make out the valve, the micro servo and the control box.

[PMK]

PS was that the right tv show the other week ?

TV show?
You've lost me.
Rather than mess up the thread, can we take this via PM?

Tnx for the explanation/picture, by the way.

[PMK]

BB~

Appreciate you coming back with all this info. And apologies if you've had to answer the same questions a millions time already.
Having any linkage other than cable ties makes sense - as too does the the separate battery idea. (Initially I thought the separate batt. was perhaps because of some safety/legal issues or such).
If you don't mind, just one more Q...
When the servo kicks in, does it have to travel at a certain set amount of throw for the valve, or does it only have to travel from full left to full right / vice-versa?
You mentioned that the sensor is screwed into the top of the boiler. Would you have a picture I might see?.. or perhaps point me to where you might have photos already on the forum?
One of my brothers, a heating engineer (plumber to you and I), says that's some of the neatest pipework he's seen. Neat colour blue and all.

[HS93]

If you think of it as a model carburetor with a slow running valve it move from open to shut BUT still allows it to pass a small amount of gas to maintain the flame, (like tick over) so when it is opens it the flame returns to the pre set max.

Peter

[boatmadman]

Just a thought on the temperature derived pressure control comments, is there any mileage in using a surface mount temp probe on the boiler shell, below water level and well insulated from the outside?

This would make such a unit an option for many people who dont have a spare connection into the boiler.

Ian

[HS93]

this is a ABC unit it has the same temperature sensor plus a slotted opto on the gauge glass and a dip stick in the water tank clever unit but not made at present.


Peter

[HS93]

finall bit of controle units that where available, its a engine controle for engines with valve gear that need an extra servo, it allows the forward reverse to be operated off one channel
it works by having a self centering stick (similar to reversable electric boats) as you open the throttle the second servo stays still, then as soon as you come back and pass the centre position the servo flicks on the valve gear and as you start to move the stick further it opens the throttle again so you only need one controle and two channel radio instead of three.
theses where a handy device, but sadly not available just looking for a Pic programmer to make one and his fortune  

none of these items are needed to make a engine go and I would say to anyone if you are new to steam get a basic plant , no extra valves and gizmo's and just run it for a time you will learn a lot more, then if you want start adding extras if you think you need them , the more you have the more that can go wrong.
ill take a few pictures later of the same type of units installed in my boats (when someone gets them off the shelf for me)

Peter

[vintagent]

Thankyou, Gerald, for the "other" viewpoint.
Somewhere I have one or two of those books.

I'll look up the others.
Once people start that way they can always move up to the more complex stuff, either ready to run or to make themselves.

Regards,
Vintagent

[flashtwo]

Hi Peter,

I built a PIC version of your description for my flash steam boat "Vital Byte" (see other threads).  The method was as you described with one radio channel representing astern-neutral-ahead and also the throttle position.

There was no problem with the PIC unit, but the flash boiler was directly connected to the engine without the usual throttle valve with the "throttle" signal being used to set the electric feed pump output to the boiler which, for a flash boiler, quite quickly alters the steam output to the engine.

I found in practice that, having found a good throttle/feed flow setting, that, on changing direction, I would loose the exact position on the transmitter throttle stick that I preferred.

In the end I used a separate channel for setting the feed flow ( and normally left the preferred setting) and used the throttle stick just for astern-neutral-ahead. I still retained the PIC in the circuit because I could precisely set the reversing gear linkage independently of the transmitter stick. The stick just had to move 20%, or so, away from the centre position to change direction.

I was using a Robbe F14 with the navy stick, but with the Futaba 6EX I am no longer using the PIC circuit since the transmitter can be set more precisely.

I would think my circuit would work well with a conventional throttle.

As regards the earlier comment about locating the temperature sensor on the outside  of the boiler, I would suggest putting it above the water level  to measure the steam temperature which is the temperature that directly relates to pressure. As long as it has good thermal contact (try using the thermal paste that Maplin sells for heat sinks) with the copper and is well insulated it should work just as well.


Ian.

[Bunkerbarge]

I think the biggest problem with the sensor mounted outside the boiler is a serious lag as you have to wait for the shell temperature to change rather than just the steam itself.  I stongly suspect the shell temperature actually varies very little so would not produce a useable signal for the unit.  There are usually spare plugs on the shell but if not you may have to connect some other items on a manifold to free one up.

I've attached a picture of the probe in the top of a Hemmens Ribbersdale.  I manufactured a fitting to enable me to combine the safety valve and the isolation valve but most vertical boilers have a couple of spare plugs.

[vintagent]

Gondolier, many thanks for the descriptions of the simpler end of things.  I think this thread should, perhaps, be split, so that the really simple end isn't mixed with the more complex stuff being described by PMK, BB, et al.
Such as the Beginners' Guide and the Intermediate Guide maybe?

Regards,
Vintagent

[gondolier88]

Thanks Vint', at least someone wants the simple things explaining!!!!

Greg