My oil boiler is 20 years old and I fear is close to requiring replacement. I'm wanting to know what is the best, most efficient, and price friendly boiler system to install. I have limited space as the boiler has to fit in a garage closet space of 53" x 43" with a 16" x 18" chimney taking up the rear left corner of the closet space. I'm wondering if it is possible to fit an indirect water tank over the boiler in order to take advantage of not keeping boiler temperature in the summer months. My current oil boiler has an internal coil for domestic water and supplies heat to a second floor 1000sq condo thru one hot water base board zone. Any help would be greatly appreciated!