Of course I'm not the only one on here on the prowl for saving the good used iron that abounds in the basements of older homes. I encourage everyone to enroll in the "save a coal boiler" movement. It occurred to me that there are lots of them around these days as more folks become aware of what they have... but just because they look purty, and burn coal doesn't mean they are a good idea to purchase at the asking price. So I figured I would start a thread on what to look for when purchasing and of course I'm counting on those with knowledge will add more information.
Here are a few of the things I look for:
1. Have the boiler and DHW been been pressure tested with water, boiler to at least 40 PSIG and the coil to at least 75 PSIG?
2. Does the interface where the DHW coil have a good solid and clean surface to mate to or is it half rusted away?
3. Is the boiler AME rated, and are there areas where the pressure vessel was welded, and if so is there an ASME R stamp evident to cover the repair?
4. Does the boiler have locations where leaks eroded the outer skin of the pressure vessel?
5. How does the interior of the boiler look? Is it scaly and black/rusty with heavy deposits?
5. Does the gear box have a good supply of clean oil, I've seen units filled with grease because they were noisy or leaked? Pull the cover and look at the worm gear if possible, using incorrect oil can eat the worm.
6. Are there signs that the unit was left sitting unused for an extended period of time? If so the chance of corrosion and leaks increases.
7. Is the unit repainted without replacement of wear parts such as bearings, seals, bushings, and other wear hardware?
8. Do the interior surfaces look as if the fly ash was never cleaned off and Is the flue pipe full of fly ash? If so look elsewhere for signs of wear due to lack of maintenance.
9. Are the grates cracked or warped? If so it probably was run improperly or at extremely high loads.
10. Are the edges of the auger knife edged and worn, and are there non standard parts installed instead of the shear pins? This can indicate that the drive train was stressed to the break point.
Overall if a unit is in it's original location you at least have a good chance of discovering flaws more easily. Once a unit is removed and cleaned, the signs of neglect are harder to spot. Once a unit is located, questions about where to get parts, if spares come with the unit and general sustainability and reliability are usually good ways to find out if the seller knows his or her product. If you are buying a unit from other than the owner, be aware that you run a higher risk of spending too much money and purchasing a unit with hidden defects (not necessarily due to deception, just merely because the seller doesn't know). If the unit is rebuilt make sure you can verify all the unseen items that were said to be replaced, and ask around about the seller to make sure this person is reputable. The bottom line to a happy buying experience is allowing for some surprises if you can't verify the unit is in fully operational condition.
If there is any area that the seller doesn't want you to see, or question that cannot be addressed before purchasing, either get some money off the price to compensate your risk or run and don't look back!
Happy Hunting!!
Good rules to live by. Now what are your rules for bailouts, please keep them simple stupid for me at least, oh and keep them real simple stupid for the government also, lol.
You get what you pay for! 
