I need to replace boiler and am looking at these 2 manufacturers. I like the warranty on the Slant Fin but smallest is 121 MBH which seems huge for my under 1600 sq house. The contractor for the Burnham recommended the MPO IQ83 at 74 MBH. I have also heard that the older Burnham V-series had leaks. Isn't the Slant Fin way oversized for me and does that not mean I am wasting oil? Does anyone have an opinion as to which is better or is there something else out there (no I cannot get gas).
The MPO is not a single pass pin-style boiler. It is a 3-pass boiler. That means the flue gases make 3 passes through the iron before they head up your chimney. To you it means less wasted energy up the chimney. I'm assuming since you didn't provide a Slant Fin model # that the boiler your speaking of is a traditional single pass pin-style boiler. Slant Fin does offer boilers similar to the MPO and in the same size range.
The boiler should be sized for the heat loss of the home not based on anything else. The old Burnham V7 which did have issues was a single pass pin-style boiler and totally different iron. You cannot compare the two.
"The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."