7
PERFORMANCE CHARTS FOR THE WATER HEATER PARAMETERS OF THE UNIT
How to use water heater diagrams
System Parameters: Air flow = 1450 m
3
/h. Outside air temperature =-25 °C. Water temperature (in/out) = 70/50 °C.
Air Speed. Starting from 1450 m
3
/h on the air flow scale draw a vertical line
till the air speed axis which makes about 3.2 m/s.
Supply air temperature. prolong the line
up to the point where it crosses the outside air temperature (
blue curve,
e.g. -25 °C); then draw a horizontal line
g
n
i
s
s
o
r
c
ll
it
t
f
e
l
e
h
t
o
t
t
n
i
o
p
s
i
h
t
m
o
r
f
water in/out temperature curve (e.g. 70/50 °C). From this point draw a vertical line
to the supply air temperature axis on top of the graphic (+28 °C).
Heating coil capacity. Prolong the line
up to the point where it crosses the outside air temperature (e.g. -25 °C,
red curve
) and draw a horizontal line
from this point to the right until it crosses
water in/out temperature curve (e.g., 70/50 °C), from here draw a vertical line
up to the scale representing the heating coil capacity (31.0 kW).
Water flow. Prolong the line
down to water flow axis at the bottom of the graphic
(0.38 l/s).
Water pressure drop. Draw the line
from the point where the line
crosses the black curve to the pressure drop axis. (9.8 kPa).
How to use water heater diagrams
System Parameters: Air flow = 3500 m
3
/h. Outside air temperature =-10°C. Water temperature (in/out) = 90/70 °C.
Air Speed. Starting from 3500 m
3
/h on the air flow scale draw a vertical line
till the air speed axis which makes about 4.65 m/s.
Supply air temperature. prolong the line
up to the point where it crosses the outside air temperature (
blue curve,
e.g. -10 °C); then draw a horizontal line
from this point to the left till crossing water
in/out temperature curve (e.g. 90/70 °C). From this point draw a vertical line to the supply air temperature axis on top of the graphic (+22,5 °C).
Heating coil capacity. Prolong the line
up to the point where it crosses the outside air temperature (e.g. -10 °C,
red curve
) and draw a horizontal line
from this point to the right until it crosses water
in/out temperature curve (e.g., 90/70 °C), from here draw a vertical line
up to the scale representing the heating coil capacity (42.0 kW).
Water flow. Prolong the line
down to water flow axis at the bottom of the graphic
(0.5 l/s).
Water pressure drop. Draw the line
from the point where the line
crosses the black curve to the pressure drop axis. (6.5 kPa).
In order to attain maximum power the water heater should be counterflow connected. In case of the direct-flow connection the water
heater has lower power but higher frost-resistant properties.
