Navigating Total Head Requirements in Home Heating Systems

What to consider while assessing the Total Head Requirement for your heating system?

Imagine a two-story home where the heating system needs to circulate hot water from a ground-floor heat pump to radiators and underfloor heating on both floors.


The vertical distance from the pump (located on the ground floor) to the highest radiator on the second floor is 6 meters.

The layout includes several bends and fittings in the piping, and the total horizontal distance of the pipes is about 30 meters.

  1. Vertical Lift Calculation:

The vertical lift is straightforward: it’s the vertical distance the water needs to be pushed upwards. In our example, this is 6 meters.

  1. Resistance Calculation:

Calculating resistance due to pipes, bends, and fittings is more complex. Each component in the system adds a certain amount of resistance, measured in meters of head.

As a rule of thumb, every 10 meters of straight pipe adds about 1 meter of head due to friction.

Each bend, valve, or fitting adds additional resistance. For example, a standard 90-degree bend might add the equivalent of 0.3 meters of head.

  1. Total Head Calculation:

Vertical Lift: 6 meters (from the pump to the highest point in the system).

Pipe Resistance: Assuming the horizontal pipes add about 3 meters of head (30 meters total length divided by 10).

Fittings and Bends Resistance: If there are 10 bends in the system, and each adds 0.3 meters, that’s an additional 3 meters of head.

Total Head Required: Summing these up, 6 meters (vertical lift) + 3 meters (pipe resistance) + 3 meters (fittings and bends) = 12 meters of head.

In this example, you would need a pump that can provide a flow rate sufficient for the heating demand at a total head of at least 12 meters. It’s always a good idea to have a slight margin above this calculated head to ensure the pump can handle any unforeseen resistance in the system.

By accurately calculating the total head requirement, as demonstrated in this example, you can ensure that the selected pump will be capable of effectively circulating hot water throughout the home, aligning with Plastmax’s commitment to delivering efficient and reliable heating solutions.

What is the difference between pump rated head and maximum head?

When selecting a hot water circulator pump with a requirement of 12 meters of head, it is generally more appropriate to compare and consider the pump’s rated head rather than its maximum head.

Rated Head: This is the height at which the pump can operate most efficiently and effectively, under normal conditions. The rated head is determined based on the optimal performance parameters set by the manufacturer. It’s the head at which the pump will have the best balance between power consumption and water moving capacity.

Maximum Head: This refers to the maximum height the pump can push water under ideal conditions. It’s the upper limit of the pump’s capability in terms of overcoming gravitational and resistance forces. Operating a pump at its maximum head regularly can lead to increased stress on the pump, potentially leading to quicker wear and reduced efficiency. While it’s useful to know the maximum head for extreme situations, it’s not advisable for sustained operation.

How to know the rated head of the circulator pump? 

Calculating the rated head from the maximum head of a hot water circulator pump is not straightforward, as these two parameters are determined by different factors and operational conditions. However, if you only have the maximum head information and need to estimate the rated head, you can follow a general approach, keeping in mind that this will be an approximation:

Pumps usually operate most efficiently at 60-80% of their maximum head. This range can vary based on the pump design and manufacturer.

To estimate the rated head, take a percentage of the maximum head. For example, if the maximum head is 10 meters, the rated head might be approximately 6 to 8 meters (60-80% of 10 meters).

It’s always best to consult the manufacturer’s data or technical sheets. They provide the most accurate information regarding the pump’s performance at different heads.

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