1. Heat Network Efficiency

2. Type of Heat Loss Energy use is divided into the following:
Central heating loads
Hot water loads
Plantroom heat loss
Pipework losses at load
Pipework heat loss when in standby keep warm mode
HIU losses in standby

3. Return Temperatures
Data obtained from typical installations in London networks shows the reality of poor HIU performance. There should be no dots under the 30C line.
Courtesy of Guru Pinpoint System

4. Return Pipe Temperatures
With the return pipes at the same temperature as the flow pipe, the heat losses of the distribution network can be almost double what they should be.
Courtesy of Guru Pinpoint System

5. Return Pipe Temperatures
With return temperatures under 25°C at all time other then when running central heating, the most undesirable heat loss from return pipework is eliminated.
Return pipe losses within a building’s fabric incurred from use of central heating, contribute to the overall heating load and are not a true loss – just unmetered use.
Arguably, return pipes within a building’s fabric need not be insulated.
Fairheat HIU Testing Regime

6. Flow Pipe Temperatures
With return temperatures under control, the vast majority of heat loss occurs from flow pipework.
Maintaining all pipes at full temperature creates significant heat loss.

7. Flow Pipe Temperatures
Reducing standby flow rates reduces pipework temperatures and heat loss.
Domestic hot water can only be generated once colder water under 45°C is cleared from pipes.
Smaller pipes clear faster, allowing more of the network to go cold.

8. Flow Pipe Temperatures
The lowest heat losses are enjoyed when all peripheral pipework can be left to go cold.
Where users prefer faster delivery of hot water, at first use, then an HIU can be timed to warm up in preparation, just as with a traditional hot water cylinder.

9. Insulation Thickness
The heat losses detailed here are for a sit of 480 properties.
Beyond 50mm of insulation the gains become harder to justify.
Heat loss from pipe supports acting as a heat bridge can be significant.

10. Heat Network Calculator
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11. Heat Network Spreadsheets
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12. Boiler Efficiency
Condensing boilers enjoy greater efficiency at lower return temperatures.

13. Heat Pump Efficiency
The hotter the source, the greater the Coefficient of Performance (COP).
The cooler the target, the greater the COP.