It can be tricky to get the right boiler for the right job. There are several things that need to be considered. First is the proper size. After determining your BTU load you will need to derate the boiler for altitude based on manufacturers' specs. If the input load is less than 200,000 you could consider a high efficiency boiler, with sealed combustion. The next question is based on application. Do I need a copper fin boiler, stainless steel boiler or a cast-iron boiler? They all have their right application, and getting the right boiler for the right job is very important. High efficiency is not always the right answer. You need to consider your up front cost verses your long term savings. If the boiler costs an additional $4,000.00 for high efficiency and only saves you $8.00 a month it will take 500 years for you to see the savings. The margin of savings is also based on the size of the heating demand. For example, an atmospheric boiler in an 800 sq ft space will cost pennies more to operate than the $1500.00 more expensive high efficiency boiler. Whereas in a 10,000 sq ft space that extra 5 to 10% saved will be well worth the extra cost up front.