Pressure loss is measured at the appliance inlet and meter test point recording readings on a U gaug. The pressure at meter may be lets say 21mb then the pressure at the appliance should be no lower than 20mb.
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Some boiler manufacturers allow a lower figure but this figure must be used with...
Just joined forum so apologies for late response but i don't like incorrect answers.
18-21kw would indicate the appliance is range rated to operate between 18-21kw. This means the engineer would determine what he wanted the appliance to be set at based on how many bathrooms/rads floors and...