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Is there a 3 pass oil boiler with a small rear clearance?
Are there any 3 pass boilers with a different design or at least with the rear manifold casting exiting somewhere other below the return pipe so that it can be inches from a foundation wall instead of feet?
I need to replace a 1992 Burnham V76 fired at 1.4 gph and the location doesn't have an extra 2 feet to accommodate a Buderus G115/215 style 3 pass with the rear exit flue trapped under the return and the relief valve. Someone must have figured out that the two side passages can be a Y shape and collect to a flue collar exiting upward.
The pin boiler was a pain in the neck to clean. I'd rather not do that again.
I get it that the 3 pass rear flue is a concept for direct venting through a side wall. I understand that slab houses don't have a basement.
in re: the boiler requirements: No DHW coil, load is 2x SSPH20 indirect pool heaters, plus 2 stage room heat. Stage 1 radiant pool deck. Stage 2 hot water coil in the air handler of a 3 ton dehumidifier. The boiler's firing rate is set by the time to raise the water temperature. Swim water bypass limits the heat load to return boiler water at 135 when both call for heat, but either SS20PH can transfer the entire boiler output by itself. Call for heat cycle is 30 minutes minimum, 1 hour typical. Space heat alone is a fractional duty cycle. The water heating load isn't a good fit with outdoor reset so intelligent controls are not a plus.