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Design Guide: Heat networks (2021) (pdf)
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Design Guide: Heat networks (2021) (pdf)

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Design Guide: Heat networks explains how to design a heat network such as a communal heating system or district heating system and is intended as a complement to CP1: Heat Networks: Code of Practice for the UK.

The two publications are also available for purchase together in a Heat Networks Bundle.

A heat network is a piped system that distributes centrally generated heat to dwellings, buildings or properties to be used for space and hot water heating. This Design Guide focuses on the hydronic issues: how to control flows and temperatures around the network to get the best carbon savings from central heat sources. It is mainly intended for small and medium-scale networks, such as those serving multiple apartment blocks or housing estates.

It should be noted that although the guide addresses the design of heat networks, the same principles could also be applied to cooling networks or to any large heating or chilled water system. Indeed, if self-contained heating and cooling systems within buildings are to be suitable for future connection to a network, then the designs for those systems should follow the same principles.

The guide is written for building services design engineers with previous experience of closed recirculating commercial heating and chilled water systems, and is not intended to enable an engineer with limited design experience to undertake a full design.

The complexity of design issues associated with heat networks requires experience of heating and cooling load calculations, as well as pipe and pump sizing calculations. These topics are not covered in detail in this guide.

This publication is now available in PDF format only.

  • Definitions
    • Symbols
    • Notation
  • Introduction
    • Scope
    • Intended readership
    • How to use this guide
  • Design overview
    • Design objectives
    • Key features of a good design
    • Generic system layout
  • Energy centres
    • Heat source categories
    • Energy centre design
    • Role of buffer/thermal store
    • Sizing buffer/thermal store vessel volumes
    • Heat losses from the storage vessel
    • Sizing the heat sources
    • Heat source on/off sequencing
  • Network distribution
    • Priorities
    • Network distribution operating temperatures
    • Network operating pressures
    • Network flow rates
    • Network distribution pipe sizing
    • Network distribution pump sizing
    • Pump minimum flow rate
    • Parallel pumping
    • Pump bypass
    • Pump speed control
    • End of run bypasses
    • Network pipe insulation
  • Building connections
    • Direct connection
    • Indirect connection via a heat substation
    • Connections to existing plant rooms
    • Connections via HIUs
  • End user systems
    • End user system flow rate
    • Terminal devices and their control
  • Energy metering
    • Regulations and guidelines
    • Heat meters
    • Metered data
    • Automatic meter reading
    • Design for network metering
    • VWART values
    • Design for billing and prepayment
  • Commissioning and ongoing maintenance
    • Pipework protection
    • Pre-commission cleaning
    • Ongoing system protection
    • Flow balancing
    • Peak flow condition
    • Minimum flow condition
    • Simulated load testing
    • On-site acceptance tests
    • Post-commissioning
    • Metering systems
    • Energy monitoring

Annex A: Temperature gradients

  • Calculating heat losses from exposed pipes
  • Calculating temperature drop in network distribution pipes
  • Calculating heat losses from pre-insulated pipes

Annex B Variable speed pumping and pump speed control

  • Pump speed control

Annex C Control valve theory

  • Flow characteristic
  • Valve authority
  • Control valve actuators

Annex D Control valve sizing

  • Motorised on/off valves
  • Thermostatic radiator valves (TRVs)
  • Pressure independent thermostatic radiator valves (PITRVs)
  • Two-port control valves
  • Pressure independent control valves (PICVs)

Annex E Terminal device categorisation

  • Natural convection/radiation (passive)
  • Forced convection (active)
  • Plate heat exchangers

Author: Chris Parsloe

Peer Reviewers: Olof Jangsten (Ramboll), Valeria Khnykina (FVB) and Richard Smith

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