If we calculated the sized flow rates for the boiler and collections from their maximum loads and delta T, for this model we would find:

Boiler: 0.68 l/s

Heating A: 0.16 l/s

Heating B: 0.32 l/s

Heating C: 0.41 l/s

The 0.68 l/s of the boiler does not match the 0.89 l/s total required by the heating collections. This is the inconsistency referred to in the error message. In other words,

0.16 + 0.32 + 0.41 =/= 0.68.

How can it be fixed? We can either balance the equation or we can remove the boiler from the flow sizing altogether. If we set the boiler delta T to “none” then it won’t be used in the pump sizing and it will just accept whatever flow is required by the collections. Alternatively, we could, for example, change the delta T to 11 for the collections currently using 8; when the components have the same sizing parameters the equation will balance:

0.16 l/s + 0.23 l/s + 0.29 l/s = 0.68 l/s