This guide introduces Intelligent pump control in Leanheat® Monitor: what it does, how the critical point in the network is found, and what the master controller does with it. The step by step instructions are in How to set up Intelligent pump control.
What Intelligent pump control does
With Intelligent pump control the circulation pumps are controlled by the pressure measured out in the network instead of only at the pumps. A critical point data relay monitors the differential pressure (dP) measured by source ECL310 controllers placed at remote points in the heating network. On every readings period Leanheat Monitor compares the source values, selects the lowest one (the critical point) and writes it to a master ECL310 controller that controls the circulation pumps. The master controller then adjusts the pump differential pressure so that the required pressure is maintained where it is actually needed, compensating for pressure losses in the piping.
How the critical point value is chosen
The critical point is not a fixed location. It is whichever of the source controllers reports the lowest differential pressure at that moment, so the point the pumps are working towards can move as the load in the network changes.
The comparison is repeated on every readings period, which is set on the relay and can be as short as 10 seconds.
Source values below a configured minimum threshold are filtered out, and the lowest of the remaining values is the one that is relayed.
The relayed value can be smoothed, so that short fluctuations out in the network are dampened before they reach the pumps.
Up to 20 source devices can feed one relay.
How the master controller uses the value
The master controller works with two differential pressures. At the pumps it measures its own, dPM, as the difference between the supply and return pressure sensors S9 and S10. From the network it receives dPS, the lowest endpoint value sent by the relay.
The endpoint value is the leading one. The controller compares dPS with the endpoint setpoint and adjusts the desired pump differential pressure until the pressure at the critical point is correct. That desired value always stays between the configured minimum and maximum pump pressure, so the pumps are never asked for more or less than the installation allows.
If the endpoint value stops arriving, or endpoint control is switched off, the controller falls back to its own measurement dPM and controls on the fixed setpoint "dP Set Master". An alarm can be raised when the endpoint value has been absent for longer than a set time. In Leanheat Monitor it is shown as the "dP - endpoint missing" alarm.
On the Application tab of the master controller you can see which of the two the controller is using. The underlined label, dPM or dPS, is the value it is currently controlling on, and the signal symbol next to the pump speed indicator (M3) shows that the differential pressure is coming from the remote side.