Heatweb Controller Functions

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Heatweb Controllers combine the power and simplicity of Node-RED for logic control, an array of inputs and outputs for controlling HVAC equipment, and the latest communications technologies including MQTT and mesh networking, to provide a general purpose equipment control system.

This page lists the current applications.

HIU Control


HIUs (Hydraulic Interface Units) provide hot water and central heating for properties, driven by heat supplied from a central source.

Components include:

  • Control valves for hot water and central heating heat exchange processes (with feedback)
  • Flow sensor(s)
  • Temperature sensors
  • Heating pressure sensor
  • Heat meter
  • Central heating pump (mains relay on power, with PWM control and feedback)
  • Optional hot water return pump

TIL SPLIT Schematic.jpg

A building may consist of 150 properties, each with an HIU, and each building may be part of a much larger estate.

Substation Control

Sub-stations are larger commercial HIUs - for connecting buildings to networks, or even whole estates to wider networks. The control functions are the same, however they typically require two controllers for redundency, each controlling independent heat exchange circuits, combining to provide duty/assist/backup operation.

Sensors will typically be 4-20mA or 0-10v, and valves will be either Modbus or 0-10v.


Pump and Boiler Management

Pumps and Boilers are very similar - they are combined in groups to meet variable loads, and each generally have the following interfaces:

  • Volt free run input
  • Volt free fault output
  • 0-10v control signal
  • Modbus control (superceeds above for control with manual run left as safety interupt)

They will also require additional sensors to confirm operation:

  • Temperature sensors (for boilers)
  • Differential pressure sensors (for pumps)

Preferably, each pump or boiler will have a dedicated controller for redundency, communicating to provide duty/assist operation to meet targets.

The Node-RED environment allows the standard logic to be tailored to suit different environments and targets.

The various communications strategies ensure that engineers responsible for ongoing operation of the plant are immediately informed when there are problems.

Pressure Management

Pressurisation sets and water quality equipment often has relay or Modbus interfaces for alarms that require pulling into operational control.

Remote Sensing

Heat networks require differential pressure and temperature readings at various locations to manage pumps. Heatweb controllers are a simple way to provide basic sensing functions, feeding data back to other Heatweb controllers managing pumps.

Heat Network Management

All the above form a wider heat network, often connecting many thousands of properties. This wider system requires its own functionality, including load shifting, alarming, and reporting.

Most of this functionality will be cloud based, running in the virtual machine equivalent of a Heatweb Controller, using the same Node-RED funtionality, and allowing functions to be pulled from site controllers to cloud management as functionality requires. This end-to-end Node-RED approach is key to bringing transparency to heat network control systems, allowing for fault-finding by anyone competent in Node-RED, as well as technical advancement. Collaborative network logic out of the box.

There is also a desperate need for big data, specifically on how much hot water people really use at the same time. This is called diversity calculations in the trade, and is used to select plant and size pipes. However the standard methods applied generally result in systems many times larger than the real world loads, resulting in excessive heat losses and gross inefficiencies. Without decent data sets from different types of properties, it is impossible to write the technical papers requires to impement new guidance. This is an example of the Heatweb system providing realtime data on DHW use. https://heatweb.info/demos/dhw/livedhw.html

Heatweb controllers can provide centralised interfaces as an alternative to cloud based interfaces. A typical application may be driving a Node-RED dashboard on a TV display in an operations centre, tracking loads and alarms.

Thermal Store Control

There are rather a few permutations when it comes to thermal store control, especially once you start combining multiple heat sources and loads. The Node-RED environment is perfect for logic control, combining stardard logic with custom logic on a platform that both installers and end users can get to grips with if so minded.

Most systems can be covered with temperature sensors and relay outputs.