Bitesize Guide – District Heating Connections
Written by Julietta Manzaroli
District Heating Connections (DHC)
The repair or replacement of a heating system is not reflected in the SAP rating improvement and therefore does not have a specific score attached to either. A fixed value increase is awarded for repair and replacement of heating systems (including boilers and ESH).
It should be noted that renewable heating and DHC repairs are uncapped but can receive the uplift.
District Heating Systems (DHS)
A District Heating System (DHS) is a system that delivers heat through pipes or conduits to at least two domestic premises in at least two separate buildings, or a minimum of three domestic premises situated in a single building, for example a block of flats would require at least three. A District Heating Connection (DHC) is a connection of domestic
premises to a DHS.
The following are deemed DHC measures:
a) The connection of a domestic premises to a DHS, including a connection to an existing DHS or to a new DHS.
b) The installation at a domestic premises of a ground source heat pump which draws heat from a shared ground loop
supplying multiple premises (“shared ground loop GSHP”).
• A DHC measure must be to a working central heating system. Where a home does not have central heating system, a
wet central heating system must be installed as part of the DHC measure.
• Projects containing a DHC have a six-month deadline instead of the standard three months.
• DHS connections are not eligible to be installed as FTCH measures – they should instead be installed as a new DHCS
• The number of DHC measures installed or repaired is not capped under ECO4.
• Any heating system can be replaced with a connection to a DHS, provided the heating hierarchy is followed in off-gas
• A DHC cannot be installed where there is already a connection to an efficient DHS in the home.
• The installer of a DHC measure in an off-gas property must declare the fuel source on the DHC form.
• A DHC measure must be to a working central heating system. Where a home does not have central heating system, a wet central heating system must be installed as part of the DHC measure. Following a DHC installation, the property must be left with a full set of functioning heating controls. This includes a programmer, room thermostat, and thermostatic radiator valves (TRVs) on all radiators outside of the room that contains the thermostat.
• The DHC measure score includes a programmer and room thermostat but the score for the installation of TRVs are not included and should be claimed as a separate measure.
• Ofgem recommends anyone seeking to install DHC measure to engage with Heat trust at the earliest possible opportunity.
• A ECO4 Pre-installation Heating Checklist should only be completed for a broken DHC if the measure is the installation of a mains gas boiler that is replacing a broken DHC.
District Heating Connections (DHS).
DHS consumer protection standards
The first step when considering installing a DHC is to engage with Heat Trust.
Heat Trust is the current industry standard for consumer protection of DHS (other than shared ground loop GSHPs) and
due to their role in DHS, they have been specifically designated within the ECO4 Order.
Heat Trust https://www.heattrust.org/index.php/the-scheme-rules.
All DHC measures must be installed in line with the appropriate consumer protection standards. All DHC measures
(except ground loop GSHPs) must be registered with Heat Trust. Heat Trust can help you better understand the
requirements of the particular installation.
A ground source heat pump DHC measure, such as a system which has a shared ground loop connection where individual premises have their own heat pumps must be installed by, or under the responsibility of, a person who is registered with TrustMark for the purposes of that measure, and be subject to TrustMark’s quality assurance
framework, or an equivalent.
Where there is a single ground source heat pump that supplies multiple premises, these connections would requireappropriate consumer protection standards.
Repair of District Heating Connections
Broken DHC are eligible for repair if it is economical to do so and they are connected to an efficient DHS. If the DHC is connected to an inefficient DHS they are only eligible for repair in off gas properties subject to the off gas heating hierarchy.
In the case of off-gas homes, where a DHC is to a DHS that deliver heat that is generated wholly or partly from biofuel, oil or liquefied petroleum gas, the off-grid heating hierarchy only allows repairs as a last resort.