IHIU Sequel Functionality

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The iHIU uses a revolutionary new heat exchanger layout with plate heat exchangers in series, allowing the whole system to be accurately controlled using a single control valve for both hot water and heating.


  • 40kw Domestic Hot Water, max 10 bar, 10-60c, with 65c Primary.
  • 15kw Indirect Central Heating with fitted controls as follows:
    • speed controlled central heating pump
    • 8 litre expansion vessel
    • 3 bar pressure relief valve
    • pressure gauge (visual indication of low pressure must be provided to occupants)
    • mains filling loop
    • automatic air vent, accessible to occupants
  • fixed orifice bypass on primary, outside heat metered circuit, that closes as load on system increases. (Options for thermal or fixed flow bypasses)
  • Control of system to be performed by a single valve, as follows:
    • full bore
    • fast acting, < 6 seconds for full open to close
    • visual indicator of valve position
    • 100% shut-off against 10 bar differential pressure
    • anti-tamper
    • automatic close on power failure
  • control system to provide the following:
    • hot water temperature control
    • sterilisation program
    • central heating time and temperature control
    • weather compensation option
    • primary return temperature limitation
    • closure of primary valve on drop in DHW flow
    • variable hot water priority, reducing or stopping central heating load as needed to satisfy hot water demand
    • differential pressure limitation
    • primary flow limitation
    • measurement and logging of primary flow rate and temperature, independent of heat meter, for confirmation of heat meter readings
    • fault alarms (timestamped and stored to memory) to include:
      • loss of mains power
      • casing opened
      • high-low central heating pressure
      • high-low primary pressure
      • failure of central heating pump
      • failure of control valve
      • overheat
      • inaccuracy in heat meter reading (flow or temp)
    • option during installation to connect to local WiFi, or to generate WiFi hot spot for network control
    • network control to allow for both engineer and user interaction
    • if using network control, users should be able to programme:
      • hot water temperatures
      • central heating times and temperatures
      • system switch off
      • all these settings should be time programmable, daily, weekly, monthly, and prolonged absence (holidays)
    • if using network control, engineers should be able to:
      • view system logs, including faults
      • edit any system settings pertinent to function of system
      • perform software updates
    • if connected to a network with internet access, system will provide following functions:
      • log data to remote server
      • remote software update
      • fault alarms, emailed where appropriate, to type of fault
      • primary limitations on flow and kW to adjust and match to available output from plant
  • Option for battery backup to allow hot water function to continue in a mains power failure
  • Option for fitted heat meter, with further option to have front of meter user accessible through casing cutout
  • Unit dimensions to be no more than 550mm wide, 350mm deep, and 550mm high
  • All components front serviceable
  • Casing fitted with security bolt
  • Wiring centre to be DIN rail based, with independent security cover
  • valve cable to be protected
  • Options for isolation valves
  • All feeds into property to top of unit, primary flow & return, and cold mains in
  • All services to bottom of unit, cold & hot mains, and primary flow & return