Gas-fired appliances
13. A gas-fired appliance shall be—
(a)so located as to be easily inspected and maintained,
(b)so located and either insulated or shielded that its use shall not cause or be likely to cause danger due to the presence of flammable material,
(c)so constructed and located as not to impose undue stress on pipes or fittings, and
(d)so fastened or located as not to work loose or move in relation to the vehicle.