This part of BS5871 specifies installation and maintenance requirements for independent gas-fired flueless fires, convector heaters and heating stoves of nominal heat input not exceeding 6kW burning 2nd and 3rd family gases for the purpose of heating rooms or internal spaces in domestic (see note3) or commercial premises. Specifically, it covers: fixed appliances that satisfy all the requirements of BSEN14829; fixed appliances that satisfy the combustion requirements of BSEN14829; convector heaters of nominal heat input not exceeding 4.2kW in the form of greenhouse heaters in respect of single appliance installations. NOTE1 Appliances a) and b) are only intended as a secondary heat source (see Commentary and Recommendations on 4.2). The heat input and ventilation, fixing and gas supply for convector heaters in the form of greenhouse heaters are specified in 8.4, 9.4 and Clause11, respectively. This part of BS5871 covers the selection of a suitable appliance, room sizing and ventilation requirements and other measures necessary to ensure a safe installation. NOTE2 Heat inputs in this document are based on net calorific value. [See also Commentary and Recommendations on Clause5, item b).] NOTE3 As well as normally constructed dwellings, domestic premises include any permanently sited caravans, holiday homes and residential park homes. (See IGE/UP/8 [9].) NOTE4 Convector heaters in the form of greenhouse heaters are available in two forms, those which are freestanding and those which are intended to be fixed to a wall or floor. This standard is not applicable to: mobile and portable appliances conforming to BSEN449; appliances in motor caravans and touring caravans; appliances in boats; installations in agricultural premises; or installations in transportable accommodation units. NOTE5 For the maintenance of existing installations of 3rd family flueless appliances in boats, see PD 5482-3.