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Can anyone sugest a way for me to automacily top up a boiler as the level drops whilst generating low preasure steam. Answered

Can anyone sugest a way for me to automacily top up a boiler as the level drops whilst generating low preasure steam.
I am building a small boiler steam generator for a sauna, my problem is that the boiler needs to be small and portable for backpacking and treking so therefore may only hold a couple of litres of water, the small tent style sauna will demand more than this. the boiler may be something simple like a kettle with a pipe attached to carry the steam into the sauna, but whilst taking a sauna i do not want to have to keep topping up the boiler, i have a constant heat source so no problems there. i also have a collapsable fold up plastic water carrier which i can suspend above the boiler as a reservoir but will need some sort of valve that allow the boiler to top up automaticlly. hope that all makes sense. thanks in anticipation.



6 years ago

i came up with an idea a year or two ago, i call it a percolator boiler, someone may have come up with something similar, steam's been around long enough that it's impossible to tell, since most of it is sitting in museums. my idea of using a turbo charger set up as a jet engine to fire a boiler was old news by the time i figured it out, one of jay leno's old steamers uses the tech.

i'm using red brick to represent the fire, ooh, fire... ooh... water as water, to help the coil pressure drop. water fills the big pipe, drops into the coil, heats up, pressure closes the big pipe off, pressure builds, sprays steam through the third check valve into a small pressure tank... or straight into a valve. the pressure would pulse slowly, so i figured a little tank would be nice. also, a relief after the third check, just in case.


Thanks for the sugestion, but i dont fully understand it. what are the valves? and what is the pressure vessel? I am a bit hesitant to use pressurised steam, for the purpose i am using it for i think a low pressure system would be better.

just check valves, to keep the water from going backward. the pressure vessel can be a bag made of high temperature resistant material, pretty much anything that keeps a little pressure. a similar thing is done with methane reactors, a plank with a rock is put across the tube that the reactor's made of, it's clear or black plastic, certainly not enough pressure to be dangerous.

the relief can be made of a bit of tubing, a bolt, plastic ball and a spring from a click pen.

if you're going to just use the pressure as it comes, you won't need it, but the vessel would keep it more steady, instead of 'no steam'...'whole lot of steam'...'no steam'...'whole lot of steam'... a leather bag under a rock would do well. it could also be just a container that holds really hot water, you don't really need it, but it's nice to have, maybe set it up for 5-10lbs, it's what pressure canners run at, and they're used safely all the time, by grannies.

How about a gravity fed drip system. Attach a small tube like and aquarium air tube to your supply and run that to your boiler. a valve in the middle of the tube so you could adjust to supply a continuous drip of water to make up for the lost water. By the second time you use is you should be able to adjust the valve for the correct amount of makeup water.

drip feed is an option but using a wood fired stove levels of heat can vary which would make difficult to always judge it, i would be more comfortable with some sort of simple valve. i chatted to someone today who thought that i may be able to have it self fill by the differences in atmospheric presure on the resiviour and the presure inside the boiler, but again do not fully understand this princible, any ideas.

Like what I had said in the other question, keep it simple. Just like canucksgirl said,fill the teapot from inside the tent. Use the hose that feeds the steam into the tent and a funnel to back fill into the pot when it gets close to empty. Once you know how long it takes to use up X amount of water you would know how much water to backfill to resupply the pot, and never have to open the tent. Simple, Neat, and Easy.

Take pics and make a ible to show off what you make.

The problem with having water come from a plastic water bottle is that the water is cold! Your boiler will then stop producing steam each time its topped up. So it wouldn't be any more efficient than getting out of the sauna to refill it...

What I would suggest you add (to the design I suggested before), is make the water tank into a 3 piece system that you can then take apart for travel.

Refer to the image I've created for you. Make a rubber gasket where the parts meet to keep water from leaking and secure the 3 parts with 2 large metal clamps.

It will be portable and you'll be able to store and heat more water at any given time.


collapsable boiler is not a bad idea will give some more thought to that and try and find a way of utilising the usual pans i carry with me as keeping weight down is a must. with regard to cold water being added to the boiler, i think that if it is a trickle feed and the heat source is high enough then it will make little difference. plus the loss of heat having to get out of the sauna would be greater. i could just have a trickle feed into the boiler bout judging just how much it needs would be a bit random.

The other way of feeding your boiler could be achieved using a funnel and tube from within the sauna. Have your water supply (preferably heated) inside the structure, and add water with a scoop as needed. If the hose is made of rubber it'll withstand the temperatures and can take the water from inside the sauna outside to the boiler, and the funnel can be with any material. Then there's no need to leave the sauna or design anything complicated.

You could use a float actuated valve similar to a toilet tank, and gravity fed water supply.

the problem would be the size of the float valve and wether it was suitable for boiling water. if you know of anything suitable please let me know.

A float system like Re-design suggested would work if you used a metal rod and a rubber float. Both materials can handle boiling temperatures and were primarily used in toilet tanks before they began making them in plastics. So check a plumbing supply store or simply make your parts with other materials.

Mercury switch broski


6 years ago

The way my commercial sauna steam generator does it,
  • It senses a lower water level
  • Cuts heating off
  • Turns water flow on
  • Senses a higher water level
  • cuts water flow off
  • Turns heater back on