Good Morning,

I have individual boilers (Trinity Ti-150) in each of the 20 apartments that
run on natural gas and supply the domestic hot water and the heating hot
water for each apartment in my proposed system. I have to model the
baseline and the proposed system as PTAC systems. How would you model the
proposed system properly to account for the efficiency improvement due to
the proposed system configuration.

As per the simulation guidelines for my program (NYSERDA MPP NC) I have to
model the baseline as having two equal sized boilers. Currently in the
Water-Side HVAC detailed design I have two separate loops. One is a Hot
Water Loop with two separate boilers where I each boiler capacity is half of
the total capacity of the propsed system. The other loops is a DHW loop
that has a capacity equal to the sum of the individual boilers' capacities.
Essentially I am counting the boiler capacities twice.

The as-built system consists of:

-(20) Trinity Ti-150 In-Unit Boilers (for the cased hydronic heat
distribution system that is also used for DHW)

-(20) Maytag Rooftop AC unitsM1200 Product Line - Model PSA2BD-KA Series

-Additional components: a Maytag Air handler (M120 Product line -B5VM
Series), a H20 Coil (Cased Hydronic Heating Unit), and a Amtrol 30 EXTROL
Expansion Tank

Any and all advice or suggestions (no matter how detailed) on how model this
system would be greatly appreciated. I can send out any necessary eQUEST
files if necessary.

Kevin Kelly, LEED AP