Technical Booklet P Sanitary Appliances Unvented Hot Water Storage and Scalding·Page 10·1.3
Limitations on Heating Sources
An unvented hot water storage system must not be heated directly by a solid fuel heating appliance or indirectly through a sealed primary circuit heated by a solid fuel appliance.
An unvented hot water storage system should not be heated – (a) directly by a solid fuel heating appliance; or (b) indirectly by a sealed primary circuit which is heated by a solid fuel heating appliance.
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