Specification text for HIUs based on 7 Series DS fully insulated DanfossFlatStation (VVX-I-R-FI)
-HIUs shall include a plate heat exchanger for instantaneous DHW production.
-HIUs shall include a plate heat exchanger to provide hydraulic separation of the system network and the dwelling heating circuit.
-HIUs shall have a fully insulated backplate and cover to minimise heat losses.
-The HIU enclosure shall fit within the following dimensions to optimise cupboard space; Height: 690mm, Width: 528mm, Depth: 235mm
-HIU controls shall be capable of closing against 4.5 bar primary system differential pressure.
-HIUs shall return primary system water below 25°C during DHW production at any load condition (full load and part load). HIU supplier shall provide documentation this can be achieved at dynamic load conditions.
-To maintain circulation of chemicals to the extremities of the heat network, as per BSRIA BG 50/2013, HIUs shall allow a trickle of bypass water through the primary pipework. The HIU bypass shall be temperature controlled so that the bypass only operates when flow temperatures are below a minimum set point as per Heat networks: Code of Practice for the UK CP1 (2015).
-The HIU supplier shall include documentation of testing of the HIUs DHW and stand-by performance against an established standard, such as UK HIU Test Regime (2015) administered by Fairheat, UK HIU Test Regime (2016) administered by the Building Engineering Services Association (BESA) or the Swedish Standard F:103-7e: Certification of District Heating Substations (SvenskFjärrwärme, 2009).
-In accordance with the Heat Network Code of Practice for the UK CP1 (2015) bypass flows within the HIU to maintain the DHW instantaneous heat exchanger in readiness shall be temperature controlled so that return temperatures are at least 5 °C below the outlet (tap) water set-point. Fixed bypasses within HIUs shall not be used.
-HIUs shall include pressure compensated and temperature regulated thermostatic control of DHW and heating enabling a constant pre-set secondary flow temperature regardless of primary pressure and temperature variations.
-HIUs shall include independent differential pressure control dedicated to the DHW controls and heating controls respectively.
-HIUs shall be fully WRAS approved.
-HIUs shall include a pressure absorber in the incoming CWM pipework to protect against water hammer and thermal expansion in the secondary pipework.
-HIUs shall include a variable speed pump for the space heating circuit with an energy efficiency index (EEI) below 0.23 to comply with the European Energy Efficiency Directive.
-HIUs shall include an EN 1434 (MID) class 2 approved energy meter.
-The heat meter within the HIU shall be either mains-powered or have a calculated battery lifetime of ≥13 years based on readings every 15 seconds
-The heat meter shall be mounted on the HIU in a position where it can be read by the end-user without the need to open or remove the cover of the HIU.
-A fixed full-bore bypass arrangement shall be installed to the primary heat network connections of the HIU to enable flushing of the system pipework without circulating water through the HIU. This valve arrangement shall include binder points to allow measurement of the differential pressure across the HIU.
Technical specification subject to change without notice
SAV Systems (UK) Limited, Scandia House, Boundary Road, Woking, Surrey GU21 5BX
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