Outdoor boiler total saved.

The problem with my old one is that it was so inefficient (simple water jacket, single warped baffle between firebox and the smoke pipe) that it didn't make any extra heat that could be put into storage. It had its hands full just heating the house. Burning it wide open just meant more heat up the chimney. And me almost totally wrecked by the end of the winter from keeping it going the past 6 months.

With the new one, I only burn for maybe 6-8 hours a day, all winter. The rest of the time, storage is doing the heating.

 

Another aspect I forgot to add in my earlier post is that one of my electric furnaces is an early 70's model. Given the only need I have for it is the blower motor, I am no pressured to replace it with a more efficient modern unit. It will always be more feasible to maintain the present furnace than an upgrade. When I apply that cost on the OWB, I was halfway there already.

 

Even old electric furnaces are 100% efficient. Just like new ones. Sure, the blower motor of a newer furnace might be slightly more efficient but it also might be less durable.