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3 BEFORE FITTING A COMBINATION BOILER THE INSTALLER
MUST CHECK:
1. That a risk assessment has been completed to determine the most appropriate anti-scald
device to be used for the various applications, to limit the temperature of hot water outlets
including bidets, taps and showers. DHW setpoint 9 has a nominal flow temperature of 70°C at
the boiler.
Consult local building control regulations which apply to the installation for further reference.
2. What the maximum hot water demand placed on the boiler is likely to be. Not every
installation is suitable for a Combination boiler. Systems requiring very high hot water flow rates
may be better suited with a Warmflow unvented cylinder.
3. That the mains are capable of supplying up to 24 litre/min with a minimum dynamic pressure
of 1.8 bar at the boiler. This is to ensure that the boiler can achieve its maximum output. To
protect the appliance and to prevent excessive flow rates, the appliance is equipped with a 3-
bar pressure reducing valve to limit the maximum water supply pressure to 3 bar. A 0.16 litre
expansion vessel is also fitted to the domestic circuit to accommodate DHW expansion when
outlets are closed. It may be necessary to supplement this expansion vessel in larger DHW
systems.
4. The hardness of the mains water supply. Systems with hard water must be fitted with a
suitable chemical scale preventer (e.g. Fernox Quantomat or Combimate).
5. That the flow from any one hot water outlet does not exceed the maximum recommended.
This applies particularly to baths which are usually fitted with larger taps and larger bore supply
pipes. It may be necessary to restrict the flow to these taps by reducing the bore of the supply
pipework (e.g. 15mm) or by fitting a restrictor into the pipework.
6. That any outlet, when opened, does not starve all the other outlets of hot water. If more than
one outlet is open at the same time then the total flow from all the outlets should not exceed the
maximum flow rate of the boiler.
7. That any showers being supplied with hot water by the boiler are compatible with this type of
appliance.
It should be noted that the boiler has been factory fitted with an 18 litre/min flow restrictor.
The manufacturer’s guarantees are void if the appliance is not installed and commissioned in
accordance with the recommendations made herein.
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