Worth the Effort? Pics added, per SD's instructions

[Quartlow]

As most of you know I built my own outdoor boiler last year, and its worked pretty good so far.
I didn't keep and accurate account of what I burned but I would have to say it was less than 5 cords, Probably closer to 4.
That included heating the greenhouse for 1month which is hard on the wood supply  :

Since the wife is thin blooded I've had it fired up for about 2 weeks now and its not using hardly any wood. In fact I just came in from fixing it. In the morning I can rake the coals around and toss in a couple scraps and its good for the rest of the day in this weather.

Well the gears got to turning a little bit ago. I figure if the boiler "thinks" its 70 degrees outside instead of 15 degrees I should use a lot less wood not having to keep up with heat loss due to it sitting outside, right?

I have a LOT of steel roofing sitting here and I was thinking of building a small structure over it. Sort of like one of those portable carports you see up for sale all over the place. I figured on framing it out of 1 inch conduit. Or maybe pipe which I may be able to get for free. Sheet it with steel roofing. Lay 6 inches of insulation over it and sheet it again. The residual heat from the burner should keep it nice and toasty warm in there.
Well in theory anyway

[submarinesailor]

Quartlow,

What you are talking about doing, real boiler people call a "poor man's economizer".  Using the waste heat from a boiler to improve the overall efficiency of a boiler.  Many types of the economizers are used today.  Some heat the incoming air, what you are talking about, but the biggest use is to preheat the incoming feedwater.  Many years ago, I worked on/around a very unique one.  It had a very large horizontal wheel filled 40 tons of rock.  In one section of this economizer, the exhaust gases flowed up thru the rock heating it.  The wheel then rotates this heated rock to the incoming section where it transfers its heat to the incoming air, increasing the incoming air temperature by 40 to 50 degrees.  This increased the efficiency of that boiler by several percent points.  The ones I worked on at the Pentagon used to exhaust gases to preheat the feedwater.  The rule of thumb for those boilers was that for every 40 degrees you reduced the exhaust temperatures, you increased the efficiency of the boiler by 1 percent.

What you want to do is plan/build this enclosure so that your combustion air receives as much heat as possible.  Have the air flow around the boiler before it enters the air intake.

Bruce

[Quartlow]

You got the poor part right Bruce.  :D
Most regular boilers are in a building. That in itself increases its effeciancy. Mine like most outdoor boilers is exposed to the elements to a certain extent.  I figured if I built a a small shed around it and insulted it heavy the heat  lost from the boiler should warm the inside of the shed.  There is a certain amount of heat that escapes. Lets face it a rocket scientest didn't build this thing, I did. What I know about building an open boiler system will fit ont he pin of a head.

The only time the exhaust generates any amount of heat to speak of is when the  draft blower comes on. When its idling I can lay my hand on the chimney pipe 16 inches away from the boiler.

I feel the theory itself is sound, but is it worth the time, effort and cash to do it?

[submarinesailor]

Quartlow,

I guess what I should have said, before I ran off at the keyboard, is that I think that it is and excellant idea and well worth the effort. 

Now if you are like me, you just need to find the time and money.  With all my ideas, its time and money.

Bruce

[Quartlow]

Join the crowd!!! At least I have the sheeting and the screws, just need the framing and the insulation.

[Quartlow]

Well It's done, its ugly  But its done. I scavenged a bunch of 1.5 inch pipe, made a frame out of that, layed R-19 insulation on it and covered it with galvanized tin. Finished it up yesterday. I fixed the fire at 10pm and havent touched it since. Granted it isn't that cold right now but when I opened the door this morning to check it it must have been 100 degrees in there. All together it cost me around $100 and most of that was insulation.

Needs a little sealing around the chimney yet and I'll do that tomorrow since its raining right now. I think its going to reduce my wood usage!!

[SwampDonkey]

And all of this worthwhile effort without pics?  Sigh.... : 

[Quartlow]

Just for you SD
From the back corner, the chimney is a piece of hydraulic cylander casing from an 8 inch cylander


Looking in the door



Granted like i said its been warm today. I still haven't added wood. Its about a 1/4 full right now

[SwampDonkey]

 Good job on the shack.

Ok, so now your ready for some cold Canadian air to test'r out.  ;D

[Quartlow]

not really,  I hate winter, well not so much hate as I don't enjoy it as much as do spring and fall

[Radar67]

Quartlow, is that a standard 55 gallon drum with mods, or did you use something else?

Stew

[Quartlow]

I strated out trying to mod a 55 gallon drum that didn't work so well. I had a local tank shop roll me a 24 inch tube out of 3/16 for the fire box and a a 36 inch tube for the outer jacket. The endplates are 1/2 inch that I had laying around