Gentlemen, .... What's our feelings on these new wall hung Navien 210/240 boilers, .... Gas fired.... heat and domestic hot water???...... On the secondary loop, how effective is a 600 sq. ft. radiant loop on the secondary with the use of a 3 way mixing valve?? Are there any recovery problems with domestic hot water usage, (without the use of a D.H.W. storage tank) ?.... Thanks, Frank S.