As a lifelong state licensed plumber that spent his whole life installing and repairing steam and hot water systems I can tell you professionally that a water heater is the very most in-efficient way to heat a building using your radiant heating system. The efficiency rating is a small percent of what a boiler is made for that purpose. But water heaters are cheaper than boilers------just so you know.
2008 Yamaha WR250R---by far my main bike.
2006 KTM 450EXC
2014 KTM690 Enduro--we'll see how good it is after 70,000 miles.
2013 Husky 650 TR650 Terra