North Idaho ranch boiler sizing
The plan for the N Idaho ranch is nearing completion. The house will be slab on grade with hydronic floor heat. There will be a natural gas fired boiler supplying heat to the floor tubing and an indirect water heater. Zone 6, heating 1800 sq ft interior plus garage, Attic R 60, Slab R 20, Walls R 23 blown fiberglass, Windows triple pane U .24. My calculations put the design heat loss at 28,000 BTU/hr using outdoor temp of -10F.
The first contractor has proposed using a Lochinvar 85,000 BTU/hr input modulating condensing boiler. This boiler also comes with a 55,000 BTU/hr input. Both have a 5:1 turn-down.
I’m no boiler expert but it appears to me that they have proposed an over-sized boiler.
Before I have this discussion with them, can someone please confirm the smaller boiler will work or explain to me why they may have proposed the right boiler?
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