4. Capacity and selection data
TCGB0075 rev.0 - 11/2012
73
4
As the heating load has fallen to 9.0 kW as we are considering this point as regular heating load, it may be reselected
the needed unit. The RAS-5H(V)RNME-AF + RWH-5.0FS(V)NFE system would provide too much heating capacity so we
could take the RAS-4H(V)RNME-AF + RWH-4.0FS(V)NFE system for these new conditions.
YUTAKI S80
Maximum heating capacity (kW)
RAS-4H(V)RNME-AF + RWH-4.0FS(V)NFE
13.4
RAS-6H(V)RNME-AF + RWH-6.0FS(V)NFE
16.0
RAS-6H(V)RNME-AF + RWH-6.0FS(V)NFE
17.9
The maximum heating capacity for this new system for an ambient temperature of -5 ºC WB and a water inlet/outlet tem
-
perature of 47/55 ºC is
13.4 kW
. We follow the same procedure as in point a.i) to apply the correction and the resulting
heating capacity for this system is
11.43 kW
.
By help of the Maximum heating capacity tables the heating capacity for the new system has to be calculated for the cold
-
est days conditions (-10ºC).
The maximum heating capacity for an ambient temperature of -10 ºC WB and a water inlet/outlet temperature of 47/55 ºC
is
13.0 kW.
•
Step 2: Heating capacity correction for defrost and piping length
The actual heating capacity for the system selected in the coldest days of the year is calculated by applying correction fac-
tors for defrost and piping length, following the method used above.
Q
H
= Q
MH
x f
D
x f
LH
Q
H
: Actual heating capacity (kW)
Q
MH
: Maximum heating capacity (kW)
f
D
: Defrost correction factor
f
LH
: Heating piping length correction factor
-
Calculation of
f
D
:
The resulting defrost correction factor for our outdoor ambient temperature of -10ºC WB is
0.89.
-
Calculation of
f
LH
:
The resulting piping length correction factor is
0.992.
-
Calculation of
Q
H
:
Once the correction factors to be applied have been determined, the formula for actual heating capacity
of the unit RAS-4H(V)RNME-AF + RHM-4.0FS(V)NFE system can be applied:
Q
H
= 13.0 kW x 0.89 x 0.992 =
11.47 kW