Does anyone have any experience w/Takagi tankless water heaters? I am thinking of installing 2 separate units in a 75 y.o. home - 1 for the domestic hot water, the other for the coil heat (2 handlers). The unit that I am looking at is their new TK-1S model with a max GPM of 6.9, it's about 4 GPM first hour. I love the idea that space will be saved (will hang them both on the wall) but I can't really find anything as to reliability and/or reviews of these or any tankless units. Any help here would be greatly appreciated.