1
. Design Procedure & Combination Ratio
Allowable CR limit to avoid abnormal sound level risks in heating operation
f
If the CR exceeds 130%, in a specific case of heating operation, an indoor unit may have higher sound level than
the level specified in the technical documents.
f
In order to minimize the sound level, the system minimum operation ratio needs to be verified and considered as
follows:
※
Operation Ratio(%), OR
• Heat Pump system, H/P
OR (H/P) (%) =
Sum of nominal capacity of indoor units running in heating mode
* 100%
Sum of nominal capacity of indoor units
• Heat Recovery system, H/R
OR (H/R) (%) =
Sum of nominal capacity of indoor units running in both cooling & heating mode
* 100%
Sum of nominal capacity of indoor units
The Minimum Operation Ratio should be determined during the project design stage using Fig. 2.
Outdoor unit
All capacities of H/P & H/R (Single, Dual and Triple Module Systems)
Indoor unit
All indoor unit types
*)
except Wall-Mounted
Wall-Mounted
Operation Ratio
Nominal Capacity ≤ 4.5kW
Nominal capacity > 4.5kW
All capacities
10%
131%
145%
135%
20%
137%
153%
141%
30%
149%
162%
151%
130%
140%
150%
160%
170%
180%
5%
20%
25%
30%
All
ow
abl
e
Ex
tended
Combi
nati
on
Rati
o
10%
15%
Minimum Operation Ratio in Heating
Nominal Capacity
≤
4.5kW
Nominal Capacity < 4.5kW
Wall-mounted(all ranges)
Fig. 2 Allowable CR with respect to indoor unit type as operation ratio increases
Combination Ratio (Connection Ratio)