Ground Source Heat Exchanger in eQUEST

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Hi All,
I was wondering if any one could share their thoughts on the modeling approach in equest for the following HVAC system .
A typical unit, at the zone level there is a 4 pipe FC unit with chilled water from a Air Cooled Scroll Chiller and hot water coming for a heat exchanger. the heat exchanger it self is getting it hot water from a central geothermal plant . there is no boiler in this system.
here are couple of approaches I tried.
Approach 1: Demand side--model a Water loop HP with lake/well as source and connect the loop to hot water coils (without the boiler), and for cooling, to represent a scroll chiller, model a Screw chiller and connect that to a CHW loop which finally connects to the cooling coils. Supply side-- 4 pipe fan coil unit.
Although what I just described represents closely to my actual system, I could not do it with out boiler on the demand side, moreover I had other loop connection errors both on the demand side and supply side.
Approach 2: Demand side--Model a HW boiler connect to a hot water loop and a Screw chiller connected to a chilled water loop , Supply side--- 4 Pipe FC unit. tweak the boiler parameters to fake a geothermal system in terms of loop temp and efficiency, which would be 100% . and put the boiler on a separate meter to deduct the boiler energy use(kw) in the end from the total annual energy use.
To a certain extent I am convinced that approach 2 would work. but I wanted to throw these ideas on the table to hear your comments and any new ways to model this above discussed HAVC system.
Thank you for your time and valuable suggestion.

Aditya Potipireddi

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