In this module, we will introduce the ALPHA pump’s constant flow and constant curve AUTOADAPT control modes for zone pump systems. You’ll gain a workable knowledge of what they are and how they work.

Let’s begin with constant curve AUTOADAPT. Designed for zone pump systems where the flow remains more stable throughout the year compared to e.g. zone valve systems and systems with TRVs In such a system, the flow is not a good indicator of the heat demand.

When the pump is set with constant curve AUTOADAPT, the pump each time starts up at a set point below constant curve 3. If the zone/room thermostat has not turned the pump off after an extended operation period then the pump assumes there is not enough flow and … ramps up the speed until reaching maximum performance. The pump will maintain this setting until the pump power switches off by the zone or room thermostat. This is repeated every on-cycle.

In warmer weather, there tends to be a lower heat demand. This means that on-cycles are typically shorter and there is usually no need for a maximum curve setting. On the other hand, in colder weather, there is usually a higher heat demand, which leads to longer on-cycles and a higher likelihood of needing a higher flow during peak demand during the coldest days.

By operating in a zone pump system, and not a single zone, a single pump increasing its flow causes the pressure loss within the shared load to rise accordingly, requiring all other pumps to compensate for the increased pressure loss and provide the same flow within each of their respective zones.

A safety feature is designed to overcome this issue by using the historical average flow of the zones to implement a minimum flow limit based on the normal operating conditions within the zones.
 
Now let’s explore constant flow. Constant flow is designed for zone pump systems where the design flow is known or where a constant flow is needed. It works by adjusting the speed of the pump to achieve a constant flow which has been set in the Grundfos GO app. Heat emitters in a zone are designed to a certain flow.

As the system pressure typically changes based on the number of zone pumps running at any given time, a constant curve will not secure the design flow in all circumstances flow. However, with constant flow, the pump will adjust its speed up or down to maintain the desired flow rate, ensuring that the pump will consume the optimal amount of energy.

That covers our introduction to constant flow and constant curve AUTOADAPT.