I picked up an older indoor boiler for a song and would like to install it. Going through the reams of codes and requirements I've discovered that in my jurisdiction a boiler needs to be UL 2523 listed. Since this boiler was manufacture prior to the drafting of UL 2523.... guess what... it's not listed. After contacting the "Office of Code Administration" about the issue I've been advised that a request for modification would require that "an equivalent level of safety can be demonstrated, (in this case perhaps by a listing in accordance with another standard, which might be a non-US standard". GREAT... what does that mean? I've back and forth with the code folks to identify specific requirements to meet with ZERO success except the boiler must meet UL 2523 requirements. I've ask for those requirements and they don't even know what they are. I've proposed 18" clearances, thermostatic mixing valve to maintain boiler temps, 600gal storage to minimize idling, low water cut off, auto fill valve, backflow prevention, expansion tank, mixing valve for DHW, pressure release valve, etc... no luck. I figure I could quit, buy a new boiler or keep barking up this tree... and barking is kinda fun. Any suggestions for other ideas or approaches?