Two Slant fin 300000 BTU boilers in 15000 sq ft condo complex. Approx heat load of 360000 BTU. 2 " main loop. All feed with 1" copper. Xtank shoved behind boiler with no way to change. Sticker said "Proudly installed by Dun-rite Plumbing & Heating". Had all I could do to keep from throwing up. It was 3 degrees this morning. Necked a 2" circ pump down to 1" 60' away. You should hear the velocity noise. Could not get the building over 53 degrees. They got what they paid for. The HOA don't understand "But we just put them in last year" There really is no cure for stupid.