2in1 tankless heating and HwH combo boiler. 这个不需要画图可以装在每个unit里but need direct vent out. Labor is around $2000, boiler+parts is around $3000.
或者Gas boiler + electric HWH. Gas boiler or HWH requires chimney一般要求要放在地下室。electric boiler 可以放在apt里，这样可以避免租客抱怨放很久的冷水才有热水。
