1. Hydrostatic pressure heating system, heating system is full of water to run, so the circulating pressure can only overcome the resistance network can be; but some of the design of the hydrostatic pressure are also included within the loop resistance, which makes circulating pump unit volume increase.
2. The circulating resistance of pipe network system is estimated by the method, often more than twice the actual.
3. The design of thermal load is too large. Due to the existence of the design is not perfect calculation methods and conservative thinking, often make the thermal load of 50% to 100%. This makes the pump unit flow is much larger.
4. Pipe network system of hydraulic balance problems: due to the design of the indoor and outdoor pipe network hydraulic balance calculation, after the construction of the initial adjustment, to cause water imbalance and the phenomenon of the former heat is not hot. Many engineering units are considered to be the strength of the pump unit can not be used to increase the pressure of the pump unit
