Friend building a new house (around 6,000 sqft). He is deciding between standard 85% efficiency boiler vs. the 95% high efficiency. Upcharge is about $4,000.

Doing radiant in some of the house and then whole house is hydrocoil. Contract calls for 2 boilers, 180,000 BTUs each. That's the 85% ones. The 95% would be a weil-mclain ultra 3, 95% efficiency, one boiler (assuming the same 360,000 BTUs).

He'll have approx 9-10 zones, including the 120-gallon storage tank.

Any advice?

Thanks.