Non-domestic gas-fired convection air heaters for space heating not exceeding a net heat input of 300 kW, without a fan to assist transportation of combustion air ....(abbreviated)
Non-domestic gas-fired forced convection air heaters for space heating not exceeding a net heat input of 300 kW, without a fan to assist transportation of combustion air and/or combustion products
Non-domestic gas-fired forced convection air heaters for space heating not exceeding a net heat input of 300 kW, without a fan to assist transportation of combustion air and/or combustion products