|
Post by talltuk on Jul 20, 2018 1:32:31 GMT -8
Hi folks
Had anyone here tried building a steel heat exchanger for hot water production?
The only example I can find, apart from the copper coil crew, is Milkwoods 2011 using what they call a donkey exchanger, basically a water jacketed box with the flue way zigzagging through it.
I was really interested in doing a boiler tube exchanger, a steel box with inch pipes running through it. Water goes in the box and flue gas runs through the tubes, just like a steam boiler.
All open vented of course, using gravitation and big inch or inch half pipes to a thermal store with a heat exchanger for instant hot water.
|
|
|
Post by wrekinwanderer on Nov 29, 2018 10:59:16 GMT -8
|
|
|
Post by coastalrocketeer on Nov 29, 2018 12:49:46 GMT -8
You could probably get more heat from your flue gas stream putting something like that at the top of a masonry bell,no? Insulated on the outside, the masonry mass would continue to heat water to DHW use temps for some time after the fire is out.
Could have the pipes do a U horizontally from the bottom of the tank and return near the top, in the top 1/3 or 1/4 of your bell, so it would hydrosyphon and heat the tank top to bottom.
If welded or soldered pipes are easier do, could use 90’s and have your pipes be a sideways rising V into the bell.
Thank you, you just gave me ideas of how I could rather simply make a bell heat a water tank without the tank being on top of the bell, which was my previous plan and more difficult to implement.
I will be using a multi coil setup with scavenged and soldered together 3/4” copper and scavenged solid conductor electrical wire wrapped soldered on as a heat transfer mesh.
The tank is a 15 gallon stainless commercial kitchen sink... or it will be a tank once I have the drain strainer basket welded on and a superfluous “counter section” and backsplash cut off.
I’m hoping that as long as the incoming flue gasses are not aimed directly at it, the soldered copper joints will hold up, as long as I keep the water tank full
|
|
|
Post by permaculturebob on Dec 9, 2018 9:19:40 GMT -8
I have an old steel Appalachian coal fired water heater. It is shaped like an r2d2 unit (star wars) with a feed opening where it's "mouth" would be and exhaust on the other side of it's head. The whole unit only stood a couple feet tall, about 1 foot diameter, probably 60 years old by now. It had inlet and outlet for water and the jacket was just that top hemisphere (with the two openings of course), a short cylinder below that was the firebox and another section below that for clean out. I used it with wood for quite a long time, set up a thermal siphon loop to a water tank a couple feet away, and depending on the wood quality took two or three loads and a half hr to heat a thirty gallon tank. It's still set up down in the greenhouse, but I'll wait till it stops snowing before venturing down to take pictures.
I thought about sealing the exhaust and feed openings, and actually purchased a 2 foot cylinder extension to provide the height for a riser and planned a 4" j tube rmh for it, I still might.
|
|
|
Post by wrekinwanderer on Dec 9, 2018 13:21:52 GMT -8
a boiler tube exchanger, a steel box with inch pipes running through it. Water goes in the box and flue gas runs through the tubes, just like a steam boiler . Hi Andy, Been researching the same thing, hence sending you the link to Peterberg's website.... An old cast iron radiator caught my eye the other day at the scrap yard. Perhaps another way to increase surface area, but without having to fabricate anything.... Mike
|
|