INSTALPROJEKT katalog techniczny 2020

THERMAL SPECIFICATIONS
The thermal specifications of the radiators are presented in accordance with the PN-EN 442-2 standard in the form of normal output
(∆T = 50K temp. 75/65/20/°C) and the exponents of the average difference of “n” temperatures included in the technical data tables.
Outputs other than those given in the table can be calculated using the formulas presented below, or by means of a simplified method
with the use of conversion factors (see table opposite).
Radiator output at any temperature set:
F = F n [
∆T
] n
t
∆T z + t
where
p
= - t o
∆T n 2
F n - normal output (value included in technical data table)
∆T - average temperature difference
∆T n = 50K - average temperature difference for normal conditions (75/65/20 °C)
n - average temperature difference exponent (value included in technical data table)
t z - feed water temperature
t p - return water temperature
t o - ambient temperature
EXAMPLE USE OF FORMULAS
148
Radiator output recalculating for given temperature levels
DATA:
Radiator model: AST-50/120
Normal output for ∆T = 50K (75/65/20 °C): 883 W
Heating system temperature parameters:
Feed water temperature tz = 85°C
Return water temperature tp = 60°C
Ambient temperature to = 25°C
“n” exponent from the technical data table:
n = 1,2958
CALCULATIONS:
t
∆T z + t p 85 + 60
= - t o = - 25 = 47,5
2
2
∆T
47,5
∆T n 50
F = F n [ ] n = 883 [ ] 1,2958 ≈ 826 W