Oil tank Evaporator building questions

[sluggish]

I am planning to build one for the upcoming season and was wondering if there is a decent set of drawings or dimensions on here somewhere. Recommended size of firebox inside? Maybe some do's and don'ts that you have learned along the way. Are you putting a port in the front or rear to introduce some forced air into the mix? Any kind of built in preheater setup? I'm not in a position to buy a nice shiny unit yet so I'm going to have to build. There is a fellow who has about a dozen lying around and letting them go for next to nothing so I figured I would pick up at least two, if I screw it up, I'll have a spare to start over with. Any recommendations for cutting them open? Looking for some ideas and experience here. Thanks

[psparr]

I'll try to remember pout up some pictures tomorrow for you.
I made mine to fit a 2x6 setup. Cut the top third or so off and used that section to extend it to fit the pans. I believe my fire box is about 16" from grate to pan and about 20" deep.
I have an ash door/draft door in the front below the feed door. If I were to do it again I would put in a pipe through the back for the forced air. Right now I have a leaf blower sitting in the ash door for aof. Not handy when loading wood.
Be sure to insulate everywhere and brick the fire box. If you don't insulate the thin steel of the oil tank will warp. I had a bear of a time my first year with the door warping when the wood would rip the insulation from it. My solution was to cover the insulation with some 20ga. Metal I had laying around. Just screwed it to the door over the insulation. Held up all season and probably this coming one as well.
The other thing I would have done differently is to have more bearing surface for the pan. The width of the oil tank is 27". I used 2" angle to rest the pan on. That brought the opening down to 23". It's hard to keep gasket material under the pan when it's boiling with only 1/2" of pan on it. Otherwise I'm really happy with it. Good luck!

[sluggish]

Great advice thanks. Were you getting warping because it was a thinner gauge tank or do they all do it. If so, what does it get insulated with, a blanket type insulation? I plan to fire brick it for sure. Pics would be fantastic, thx.

[optionguru]

Fire brick helps but you should really get arch board or ceramic blanket insulation. Put the insulation in then the firebrick over that. I only used fire brick in the firebox area, the rest has ceramic blanket. I've since built a bigger evaporator (shocker) but my oil tank had 2 full size 6" deep steam pans and 3 1/2 width pans, this gave me more surface area to the heat. I got about 8gph evaporation. I had an air door under the fire to get a little forced air effect. Look at my gallery, there are a few pictures of the arch and preheater set-up.

[psparr]

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Here's a couple pics I promised