Using FLOWLIMIT functionality in practice

Using FLOWLIMIT functionality in practice

In this module, the advantages of using the FLOWLIMIT functionality in intelligent circulator pumps when balancing in heating systems will be made clear in a comparison between two systems.

In this module, we will compare two systems to give you a clear understanding of the advantages of using the FLOWLIMIT functionality in intelligent circulator pumps when balancing in heating systems.

Many heating systems may be out of balance, because flow commissioning is often poorly done.

Poorly balanced systems may lead to the building’s actual energy consumption exceeding the designed energy consumption with decreased Delta T and lower end-user comfort.

FLOWLIMIT removes the guesswork in the commissioning process and helps you balance your heating systems, as the intelligent circulator pump automatically can:
- adapt its performance in order to reduce flow;
- keep Delta T at the design flow level; and,
- keep return temperatures down.

Now, let’s look at an example using a condensing gas boiler application. In order for the flue gas to condensate, the return temperature from the HVAC system must be as cold as possible, typically below 57°C. The difference in boiler efficiency can be as much as plus or minus 10%, depending on whether the conditions for flue gas condensation are present.

Starting with a traditional system, let’s take a look at how the system curve will affect the flow.
The design flow temperature is 80°C and the return temperature 50°C, which in this case with a boiler capacity of 1000 kW gives a design flow of 28 m3/h.
If, however, the system curve is substantially lower than expected, the risk of overflow is imminent, and the flow could double to 57 m3/h.
The excessive flow would affect the Delta T and leave us with a return temperature of 65°C – and impossible conditions for condensation of the flue gas.

Now, let’s turn to a system with an intelligent circulator pump and the FLOWLIMIT function enabled. The FLOWLIMIT allows us to set a maximum flow to ensure that we do not exceed the exact required flow – in this case 28 m3/h.

The potential overflow area is thus eliminated, and the return temperature will stay below the 57°C to ensure optimum conditions for condensation of flue gas.
An added bonus of this is an increase in system efficiency of 10%, meaning 10% less gas is used. And the more efficiently a system operates, the less gas is required to do the job, which in turn makes for more cost-efficient operation.

That sums up a quick run-through of two systems, where enabling FLOWLIMIT in an intelligent circulator pump leads to a further increase in system efficiency of 10%, increasing your business potential due to greater focus on pump and system efficiency.