Meaning of Delta 50 (75/65/20)

Meaning of Delta 50 (75/65/20) 

Delta 50° (75/65/20) - with Delta T of 50°C, means 75°C inlet water temperature, 65°C outlet water temperature and 20°C of room temperature. The average water temperature in this example is 70°C (i.e. 75° plus 65°, divided by 2).  If we then take the 20°C room temperature we are left with a temperature differential of 50°C or Δt 50°.  

Method

Add the flow water temperature and the return temperature together

Divide the answer by 2

Subtract the room temperature from the answer this gives you the Delta T temperature

Select the closest Delta T valve from the table and multiply the corresponding factor by the output provided for the particular radiator to obtain the output for your calculated Delta T valve.

If we then take into account the reduced inlet temperature eg you will be getting a heat source pump.
If we replace this with inlet water at 45°C inlet water temperature, 35°C outlet water temperature and 20°C of room temperature. The average water temperature in this example is 40°C (i.e. 45° plus 35°, divided by 2).  If we then take the 20°C room temperature we are left with a temperature differential of 20°C or Δt 20°.  
 
The conversion rate from T50 to T20 is 0.3039.
 
Eg a radiator 1800 x 500 has 795 Watts at Delta T50 x 0.3039 is 241 Watts (this is the T20 figure).