Combination Table / Design Procedure & Combination Ratio - Samsung VRF DVM S2 Technical Data Book

1. Design Procedure & Combination Ratio
Combination Ratio (Connection Ratio)
Definition of Combination Ratio, CR
Constraints of Allowable Combination Ratio
DVM S systems are normally designed to utilize a CR 50% to 130% to ensure effective load balancing between indoor units
and outdoor unit. As buildings have become more insulated, and usage and occupancy of buildings are highly variable,
more buildings can realize a higher load balancing between IDUs and ODU, thus higher CR (>130%) is often required. If a
system design exceeds 130%, risks associated to increased indoor sound level and reduced comfort levels should be
considered. Therefore, when it is necessary to design a combination ratio exceeding 130%, the following conditions must
be complied with: -
Design & Selection Procedure
• Design temperature
• Calculate cooling and heating loads (Zone peak loads/System Peak load)
• Power supply, piping length and level difference
(Max capacity at design condition should be greater than System Peak Load)
Yes
Sum of Nominal Cooling Capacity of Indoor units
CR =
Nominal Cooling Capacity of Outdoor unit
Determine DVM Design Condition
Select indoor unit for each zone
Max capacity at design condition should be greater than Zone Peak Load
Total nos. of indoor units exceed limit?
Decide Minimum Operation Ratio in heating mode
Calculated CR ≤Allowable Extended CR
@ Minimum Operation Ratio in heating mode?
Size up outdoor unit or change indoor unit type or capacity
Fig. 1 Design & Selection Procedure for Extended Combination Ratio
Select outdoor unit
No
No
Calculated CR
≤ 130% ?
No
No
* 100%
Yes
Go to the next step to
complete design
Yes