In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
3x Oversized ModCon with Concrete Slab, New Home
I'm designing my new ICF home. 2900 ft2 slab heat 3-zones with master/slave zone synchronization.
I did a ResCheck DOE heat loss estimate with my proposed plans & got UA = 400
Location is Cripple Creek Colorado so my design Temp is about -30*F, thus at 70* indoor, my Delta T is about 100* 400 x 100 = 40,000 BTU/hr.
I have a new in box Buderus GB142-45.
Looks like this boiler is about 3x oversized after being derated for 10,000' altitude.
I did the math on my slab, 40yds concrete x 3,800#/yd (with rebar) = 152,000#
With a Specific heat of .2 it will take 30,400 btus to raise the slab 1*f
So at -30* my boiler duty cycle will be about 33%, at freezing (this is a guess) possibly a 10-15% duty cycle?
So my question is: Should I sell the Buderus & buy smaller ModCon OR will slab act like a large buffer tank & Buderus will perform fine with low duty cycles?