Balanced all rads, tried @ Delta of 10,15, 20 and only 5C showing at the boiler even when all l/s fully opened up it still shows 5C at the boiler.
Anyway, was reading some old posts and saw this quote :
"If the system is running with a fixed pump speed and and automatic by-pass valve, the optimum boiler flow rate for a 20°C rise across the heat exchanger is proportional to maximum boiler output. When the boiler modulates its output, the temperature rise drops in proportion to the power.
As TRVs reduce radiator flow, the temperature drop increases. Unfortunately, the ABV mixes hot water with the return water and the temperature rise across the boiler actually decreases rather than increases. So, where there is the opportunity to operate with a 20°C rise across the heat exchanger, this is usually lost. With a 4:1 modulation range, the temperature rise at minimum output will only be 5°C."
Maybe explains all my efforts coming to nothing especially as my boiler modulates from 28kw to 7kw (4:1).
Would fitting a variable speed pump instead of the 3 speed one inside my combi (if it's possible) solve the problem?
Anyway, was reading some old posts and saw this quote :
"If the system is running with a fixed pump speed and and automatic by-pass valve, the optimum boiler flow rate for a 20°C rise across the heat exchanger is proportional to maximum boiler output. When the boiler modulates its output, the temperature rise drops in proportion to the power.
As TRVs reduce radiator flow, the temperature drop increases. Unfortunately, the ABV mixes hot water with the return water and the temperature rise across the boiler actually decreases rather than increases. So, where there is the opportunity to operate with a 20°C rise across the heat exchanger, this is usually lost. With a 4:1 modulation range, the temperature rise at minimum output will only be 5°C."
Maybe explains all my efforts coming to nothing especially as my boiler modulates from 28kw to 7kw (4:1).
Would fitting a variable speed pump instead of the 3 speed one inside my combi (if it's possible) solve the problem?
