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NUOS Plus - User Manual

  • Text
  • Appliance
  • Heater
  • Heating
  • Installation
  • Operating
  • Discharge
  • Maintenance
  • Electrical
  • Technical
  • Regulations
  • Nuos
  • Manual

Water connections Heat

Water connections Heat pump water heater - TECHNICAL INFORMATION FOR INSTALLERS The appliance must not operate with water hardness levels below 12°F; on the other hand (>25°F), it is advisable to use a suitably calibrated and monitored water softener in the event of particularly hard water; in this event, the residual hardness must not fall below 15°F. The 250I version has an indirect coil that is intended for connection to a water heating system, such as a solar system as show below. A manual reset overheat stat is supplied fitted to the product. For solar installations this stat should be wired so that in the event of over heating from the solar system the thermostat switches the solar pump of, thus preventing flow to the product. The overheat setting fro the stat should be set at a maximum temperature 70°C The 250I version coil has two ¾”G couplings, upper (inlet) and lower (outlet), on which to connect an auxiliary source. WARNING! It is advisable to carefully wash the system’s pipes in order to remove any residues of screw thread, welding or dirt which may hamper the correct operation of the appliance. General guidance Current guidance notes do not cover the connection of a solar thermal circuit to an unvented storage vessel (cylinder). However, if guidance is sought for compliance with current regulations the fundamental principle is to provide a failsafe means of shutting off the solar input to the heat exchanger if the cylinder temperature should rise above the set temperature of the cylinder’s energy cut out. (see Note 1). As with all unvented hot water systems, notification of intention to install should be given to your local building control. 13

Heat pump water heater - TECHNICAL INFORMATION FOR INSTALLERS Option A: A non self resetting mechanical shut-off should be installed on the solar primary flow to the cylinder. The mechanical shut-off should be suitable for use with a solar primary circuit (i.e. high temperature and glycol resistant). The mechanical shut-off should be integrated electrically with the cylinder energy cut out/s and if necessary the solar circuit temperature control, please refer to the solar controller manufacturer for further information. Option B: Where the solar controller and hydraulic system demonstrate that by no lesser means the requirement in Option A is satisfied by other means; certification by an approvals body is required to demonstrate that in the event of the stored water going over temperature, the heat input to the cylinder is isolated by physical means and is non self resetting. These systems should be clearly identified with reference to the approvals body. (See Note 2). Note 1 :Whilst most solar cylinders use a coil type heat exchanger other options such as external plate to plate devices , external annulars or ‘tank in tank’ systems may be used but the same control options always apply. Note 2 :Current approved bodies include the British Board of Agreement (BBA) , WRc-NSF Limited, or KIWA 14

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