Automatic bypass valve for feeding water for boiler.

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

Hi all folks!

 

I has searched after the alternatives to feed the water into the boiler without electronic water level controller for the boiler. There are no idea how do make the water level constant in the boiler automatical without electronic or manual controlled bypass valve or someone who has maked the practical mechanic automated bypass valve for feeding control of water level in the boiler in the internet.

 

Then i maked the feeding pump and automatic bypass valve who are affected by weight of the water in the boiler.

 

 The bypass valve are regulated by weight of water in the boiler. when the water are in lower level in the boiler, the spring in the bypass valve are lifting the boiler up due low weight of water, the feedpump are start to pump the water in the boiler until the weight of water are high enough to stop feeding the water into the boiler. The boiler are hinged to base plate. The same weight of water is the same amount of water in the boiler. Consumed steam is replaced with new water at the same time when the bypass valve balances whole time between consumed steam and water.  For unlimited runtime with model steamer, water pump can be connected directly to the fresh water of the lake, have a filter between the pump and fresh water in the lake to keep debris away from the boiler. Only the amount of fuel determines the runtime.

 

Look at the movies:

http://www.youtube.com/watch?v=8XqW6wdTgS0

http://www.youtube.com/watch?v=56rZn3C6ss4

 

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

[John OlsenParticipant @johnolsen79199]

Hej Jens,

 

If you can get hold of a recent issue of the Funnel, the magazine of the (British) Steam Boat Association, there was an article by Paul Eaton on this very subject.  There are a number of things that have been tried, both in full size industrial practise and in amateur steamboat sizes.  The weight idea sounds fine so long as the water is not too rough, but the same problem is likely with any of the ideas. If the boat is rolling a bit, how can you be sure what the water level really is?

 

Anyway, a couple of approaches that have been used:

 

1/ a float in the hot well of a condensing plant. If the hot well level goes up, the boiler level must have gone down. So the float closes the bypass.

 

2/  A tube attached to the boiler at the right level. Sometime a long sloped tube is used, sometimes a short closed one. It is arranged to drain back to the boiler. When the level is low steam keeps the tube hot.When it is high the tube is full of water and cools down. A temperauire sensor on the tube then opens an cloes the bypass. A car thermostat has been used for this, to directly open and close the valve.

 

regards

John Olsen

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

Posted by John Olsen on 02/08/2010 07:48:54:

Hej Jens,

 

If you can get hold of a recent issue of the Funnel, the magazine of the (British) Steam Boat Association, there was an article by Paul Eaton on this very subject.  There are a number of things that have been tried, both in full size industrial practise and in amateur steamboat sizes.  The weight idea sounds fine so long as the water is not too rough, but the same problem is likely with any of the ideas. If the boat is rolling a bit, how can you be sure what the water level really is?

 

Anyway, a couple of approaches that have been used:

 

1/ a float in the hot well of a condensing plant. If the hot well level goes up, the boiler level must have gone down. So the float closes the bypass.

 

2/  A tube attached to the boiler at the right level. Sometime a long sloped tube is used, sometimes a short closed one. It is arranged to drain back to the boiler. When the level is low steam keeps the tube hot.When it is high the tube is full of water and cools down. A temperauire sensor on the tube then opens an cloes the bypass. A car thermostat has been used for this, to directly open and close the valve.

 

regards

John Olsen

 

Hei John and all folks..

 
Moving the steam boat are not big trouble since the waterlevel are adjusted to mid of the boiler, then i am allowing the water can be high or low water level in the boiler without to overfill or run dry for water.

 

The number 1,  I am unclear how it works as you wrote. Can you add the pic of the float in the hot well of a condensing plant. The i can learn out how it works.

 

The number 2, also the thermostat who are heated by steam, then the bypass valve are closed to allow the feed water are pumed in the boiler.

 

Will it works in the small boiler who has 90 mm diameter and 110 mm height with the thermostat from the car engine? I am working as car mechanic and can have the thermostat available in the sparepart room. I want to try the thermostat controlled bypass valve.

 

The last question, the 2 alternative feed pump: The pump direct actived by steam engine or the pump in slow motion via gearwheel. Which of them are effective and reliable to pump the feed water into the boiler?

[John OlsenParticipant @johnolsen79199]

Hej Jens,

 

If you message me with an email address I will make a scan of the article for you.

 

The way the float system works is it assumes there will be a constant amount of water in the system. If it is in the hot well, then it is not in the boiler. So when the float rises, it closes the bypass valve and the pump starts pumping water into the boiler.

 

For the thermostat one, there will be some loss of heat from the setup, and this will affect a small boiler more than a large one. Once I get a copy of the article to you you will be able to see better how it works, and maybe carry out some experiments.

 

On your last question…I haven’t built a model steam launch so am probably not the best person to answer. My steam boat is 30 feet (9.15 metres) long, and is not finished yet. Generally in Model sizes, if the pump is to be driven by the main engine, it will need to be geared down. This is also better in larger sizes since it helps to keep the pump quieter. Pumps driven direct from the crosshead tend to be very noisy. You can also have a separate pump, and in a human carrying boat should…at least there should alsways be two means of pumping water into the boiler. In a model, especially gas fired, this is not so critical, since if the boiler gets low you just turn the fire off.

 

Another thing to consider…if you have the pump driven from the engine, and arrange for it to have an adjustable stroke, then you should be able to find a setting where the delivery of the pump matches the requirements of the engine over a wide speed range. So the boiler should stay at the right level without any automatic control. If the plant is fired with either alcohol or a small gas burner, then the level is not all that criticial anyway, since the burner should not be capable of harming the boiler even if it was dry. Actually that should be one factor in choosing the burner size for a small plant…assume that the plant will run dry at some point and choose a burner that will not be able to overheat it.

 

With a boiler the size you mention, provided that it is hard soldered, then an alcohol burner or a suitable size of gas burner will never be able to overheat the copper or the joints to a point where the strength is adversely affected. So the occasional low water event is not a worry. This is what Mamod and Wilesco depend on, as you can be sure that there will be times when the boiler gets lit under a boiler that has not been refilled, or where the water runs out before the fuel does.

 

regards

John

 

 

 

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