new addition flue gas HX for modified OWB

[cumminstinkerer]

For those of you that haven't seen check out my thread about my modified homemade boiler. Now I am on to the step, I am building a fire tube HX to go in the flue outlet. Here are some pics of the HX. It is not finished yet but am hoping to have it finished and installed this weekend.

 

[Dutchie84]

how is water going to contact the tubes if they are sealed inside the plenum?

 

[cumminstinkerer]

how is water going to contact the tubes if they are sealed inside the plenum?

Sorry I should have made it more clear that I was not nearly finished, when those pictures were taken the tubes and headers were just setting in the plenum, since then I move the tubes around and have cut holes and welded in bungs for the inbound, outbound, and vent lines. Then I center the tubes and welded them in place, I was able to pressure test last night and had one spot on a tube to header connection and one header to plenum seam that very slightly weeped. A touch of the carbide burr and a little touch up weld, all is good. I am on track to install the creation this weekend. More pics and updates to follow.

 

[cumminstinkerer]

Here are some updated pictures of the exchanger progress, Going to be installing today after work, Hopefully all goes well

 

[cumminstinkerer]

I got the HX installed Saturday evening and was able to get things fired back up around 9:15 pm, had some other issues come up that delayed me getting to the project until later in the day. When I fired up my storage was offline, and was just running the main loop, took until 10:30 to get the 150 gallon main loop from 29.3 C up to 73 C with the house calling for heat. Without the HX that would have been at least double that amount of time. The inlet to the HX was running at 450-580 F surface temps, I haven't gotten a flue temp probe yet, and outlet was 140-180 surface temps. The plenum on the HX is 10ga so I think it would be safe to say internal gas temps were easily double the surface temps. Sunday I brought the 250 gallon storage online and charged it which took from 10:30 am to 12:10 pm from 70F up to 180 F I was very impressed considering the house did call for heat once in there and the wife was doing laundry and dishes. Sunday afternoon I climbed up on the roof and check the chimney and was thoroughly amazed, all new pipe and there was not enough ash or creosote on the inner walls to even make a mark on my fingers. All and all I am very happy, time will tell how often I will have to clean the tubes but I plan to check them this weekend just for safety. I am still pondering adding turbs of some form to at least part of the HX tubes but I want to see how bad the tubes get before I decide on a material.

 

[ken morgan]

Cummin Stinker sorry I had to I am a ford Man So I am a total newb to this type of stuff, so bear with me on what seems obvious. so the HX is a heat exchanger? and water runs through it to be heated by the hot gasses prior to entering the chimney? does it build pressure in any fashion and if so how do you control the pressure?

 

[cumminstinkerer]

I'll fire back Jarhead lol, Was Army myself. Yes it is a heat exchanger, the hot gasses pass through the sixteen tubes that are surrounded by water, the main fire box is also water jacketed. although I now have it lined with fire brick up to the baffle. My whole system is open to atmosphere so it doesn't build pressure. I was not to keen on the idea of a possible bomb anywhere near me. the HX has its own separate vent and the boiler has two that all lead up to an open tank mounted above the whole system that is approximately half full of water. I was hoping you would see this part and the boiler mods and maybe incorporate the secondary burn stuff into your build, this HX might even be beneficial for you if you could jacket the tubes and blow air around them. I was loosing a lot of energy up the stack before i built this part. The worst part of all the mods was getting the air flows, and hole angles set right between the primary and secondary air circuits. I am rather pleased with it now, I can get the secondary tubes and firebrick baffle glowing red hot when it is firing, it usually takes a minute or two to light the secondary burn after it comes off idle, once it does watch out the stack goes clear and the heat really starts getting put out. I am still working on getting longer times of fire versus idle time, I think I'm gonna have to add more water yet, the whole system now holds right at 410 gallons.

 

[ken morgan]

I'll fire back Jarhead lol, Was Army myself. Yes it is a heat exchanger, the hot gasses pass through the sixteen tubes that are surrounded by water, the main fire box is also water jacketed. although I now have it lined with fire brick up to the baffle. My whole system is open to atmosphere so it doesn't build pressure. I was not to keen on the idea of a possible bomb anywhere near me. the HX has its own separate vent and the boiler has two that all lead up to an open tank mounted above the whole system that is approximately half full of water. I was hoping you would see this part and the boiler mods and maybe incorporate the secondary burn stuff into your build, this HX might even be beneficial for you if you could jacket the tubes and blow air around them. I was loosing a lot of energy up the stack before i built this part. The worst part of all the mods was getting the air flows, and hole angles set right between the primary and secondary air circuits. I am rather pleased with it now, I can get the secondary tubes and firebrick baffle glowing red hot when it is firing, it usually takes a minute or two to light the secondary burn after it comes off idle, once it does watch out the stack goes clear and the heat really starts getting put out. I am still working on getting longer times of fire versus idle time, I think I'm gonna have to add more water yet, the whole system now holds right at 410 gallons.

Cool beans. I have been out for a while, and now I work on the local bases as a contractor repairing various equipment that they use in the messhalls and restaurants. Our real house is by Yokosuka naval base in the kanagawa region. I bought the cabin at fuji to get away from the city, and the retards that infest that area. being that I come to camp fuji all the time for work you would think I would get bored with the boonies....not at all...busy building a homemade crossbow to get some of these Japanese deer and wild boar that are overrunning the area

I think that heat exchanger idea would be great for my outdoor bath i am building. I got me a 850 liter (about 250 gallons) insulated stainless steel tub that was from a milk farm. they used it to chill the milk as soon as it comes from the cow and prior to pasteurizing. I poured a small concrete pad next to the cabin for the tub to sit on, and am now collecting large pieces of lava rock to build up the area around the tub to cover the outside of the tub and make it look like a natural hot springs from the outside. Originally i was planning on buying a gas water heater and just suck up the bill for the gas......but that water boiler system you made looks mighty tempting to me.

Matter of fact the way it sits on the side of a slop on the property I could probably incorporate your whole design as is, and just semi bury the back and sides of the stove/boiler with just the top, and the exhaust pipe showing.....prospects are interesting....

 

[cumminstinkerer]

and now for an update. I have in recent times added variable speed controls to my draft fans and done away with the butterfly throttles. I also added chain turbulators to the HX, a bit tricky since it is essentially horizontal, with a maybe a 15 degree upward angle. I used 5/16 chains the length of the tubes, 18" and laid them out so each link was 90 degrees off from the previous one and the put a small weld on each link. I have also added an O2 sensor but am still working kinks out in that. One more piece of the puzzle's material will arrive tonight. I am going to make a grate out of tubing that will also supply the primary air through a series of holes in each grate, the idea being to more evenly distribute the primary air and get the entire load to gassing off instead of just working from the one end.

 

[cumminstinkerer]

got the primary air grate built and installed, fired for the first time last night, it works amazing, after a little tweaking of the fan speeds we are running extremely high temps to the inlet of the hx and she has no smoke out the pipe, super bright secondary flame. the entire fire chamber was white when i checked it this morning

 

[warno]

You need to take some pics of your mods. I know your phone camera is crap but we need pics. Lol

 

[cumminstinkerer]

oooh alright, i'll get my wifes digital camera and take some, maybe later today after i haul some logs home

 

[cumminstinkerer]

so with lots of help from two great forum members, warno and Tcaldwell, i got my boiler at 6%dialed in pretty sweet, can carry it pretty well through the burn at 6% O2, clear exhaust and awesome heat output. thank you very much guys.