Apparatus for heating liquid

A liquid heating apparatus for heating a liquid received from a liquid inlet to a liquid outlet, the apparatus comprising:

• a top portion with a burner unit, wherein the burner unit is arranged to burn a fuel so as to generate a flame, wherein the flame is directed downwards;
• a coil arranged for transporting the liquid between a coil inlet and a coil outlet, the coil comprising at least a first and a second layer of windings, wherein the second layer of windings are arranged around the first layer of windings and the coil outlet are connected to the liquid outlet;
• an external housing;
• an internal housing arranged at least partially within the external housing;
• and
• wherein the apparatus is arranged to be in a substantially upright position during operation, wherein the coil is arranged inside the internal housing, wherein a compartment between the internal housing and the external housing serves as a first liquid reservoir, so that the liquid surrounds at least a part of the internal housing, wherein the first liquid reservoir comprises:
• an inlet connected to receive the liquid from the liquid inlet, and;
• an outlet connected to the coil inlet, wherein the flame from the burner unit is peripherally contained by an inner part of the first layer of windings of the coil, wherein the first layer of windings is configured to direct the flame or exhaust gases downwards toward a bottom portion of the internal housing, and wherein the flame or exhaust gases are redirected from the bottom portion toward a space between the first layer of windings and an inner wall of the internal housing so as to allow the flame or exhaust gases to contact all of:
• the second layer of windings;
• the inner wall of the internal housing;
• and
• the first layer of windings.