Therma - Rad Draft.pdf - Hurlcon Heating

5 - CALCULATING WATER FLOW
To ascertain water flow requirement to a panel radiator the following information must be known.
- Output required from the radiator.
- Temperature difference between Flow and Return (∆T).
Then Water in flow l/s can be calculated by the formula
Flow in l/s = output kW
∆T x 4.18
Example
Required output of 2.0 kW
Boiler capacity - flow 80 o C return 70 o C thus ∆T = 10
The calculation is
Required Flow = 2.0
10 x 4.18 = 0.048 l/s ( x 3600 = 172.8 l/hr )
6 – HEAT CORRECTION FACTORS
For selection of the Panel size.
The Therma-Rad radiator heat outputs vary according to the difference between the room air temperature and the
average of the flow and return water temperatures (called mean water temperature). The data supplied is based
on 90/70 o C water temperatures and 20 o C ambient air temperature C f = 1
Flow Room
Correction Factor C f
water Temp Return water Temperature o C
Temp
o C 40 45 50 55 60 65 70 75
24 1.97 1.71 1.53 1.38 1.27 1.17 1.10 1.03
22 1.81 1.59 1.43 1.31 1.20 1.12 1.05 0.99
90 o C 20 1.68 1.49 1.35 1.24 1.14 1.07 1.00 0.95
18 1.56 1.40 1.27 1.17 1.09 1.02 0.96 0.91
15 1.41 1.28 1.18 1.09 1.02 0.95 0.90 0.86
24 2.10 1.82 1.62 1.46 1.34 1.24 1.16 1.09
22 1.92 1.69 1.52 1.38 1.27 1.18 1.11 1.05
85 o C 20 1.78 1.58 1.42 1.30 1.21 1.12 1.06 1.00
18 1.65 1.48 1.34 1.24 1.15 1.07 1.01 0.96
15 1.49 1.35 1.24 1.14 1.07 1.00 0.95 0.90
24 2.24 1.94 1.72 1.56 1.42 1.32 1.24 1.16
22 2.05 1.80 1.61 1.46 1.35 1.25 1.18 1.11
80 o C 20 1.89 1.67 1.51 1.38 1.27 1.19 1.12 1.06
18 1.75 1.57 1.42 1.31 1.21 1.13 1.07 1.01
15 1.58 1.42 1.30 1.21 1.12 1.06 1.00 0.95
24 2.41 2.08 1.85 1.66 1.52 1.41 1.32
22 2.20 2.20 1.72 1.56 1.43 1.34 1.25
75 o C 20 2.02 2.02 1.61 1.47 1.35 1.27 1.19
18 1.87 1.87 1.51 1.38 1.28 1.20 1.13
15 1.67 1.67 1.38 1.27 1.19 1.12 1.06
24 2.61 2.25 1.99 1.79 1.64 1.52
22 2.37 2.07 1.85 1.67 1.54 1.43
70 o C 20 2.17 1.91 1.72 1.57 1.45 1.35
18 2.00 1.78 1.61 1.47 1.37 1.28
15 1.79 1.61 1.47 1.35 1.27 1.19
24 2.85 2.44 2.15 1.94
22 2.58 2.24 1.99 1.81
65 o C 20 2.35 2.07 1.85 1.69
18 2.15 1.91 1.73 1.59
15 1.91 1.72 1.57 1.45
24 3.14 2.68 2.36
22 2.82 2.45 2.18
60 o C 20 2.56 2.24 2.02
18 2.34 2.07 1.87
15 2.03 1.85 1.69
Example.
Required 2.0 kW heating
Conditions
Flow temp 80 oC
Return temp 70 oC
Ambient air 22 oC
From the chart
Cf = 1.18
Corrected Radiator
2 kW x 1.18 = 2.36 kW
std output required.
Select the radiator size of
600 / 22 / 1000
with 2.49 kW std output
being closest to the panel
output required.
1. Outputs increase by approximately 2 % when top grilles are not fitted.
2. Correction factor for other temperature conditions available on request.
Therma-Rad Panel Radiators 5