Question from J Bingham, via e-mail:
What is the calculation to find the amount of water produced per kW in a condensing boiler flue? Is it 0.15 x kW?
Answer from Martyn Bridges, director of marketing and technical support at Worcester, Bosch Group:
Unfortunately, the answer to this question isn’t completely straightforward, as there isn’t one calculation or conversion factor that can be applied. As an indication, in laboratory tests when a 24kW condensing boiler of a SEDBUK A level is in fully condensing mode, i.e. at a 40ºC flow and 30ºC return temperature, you would produce around 80ml/kw of condensate, which is approximately 4.8 litres of condensate per hour. If however, the boiler is running at a higher temperature, such as 60ºC flow and 40ºC return, then the condensate production is likely to be around 25ml/kw, around 1.5 litres per hour. In summary, the hotter the boiler the less the condensate, therefore the single calculation you mentioned cannot accurately be applied.