there is no heat directed to the water 150 in the reservoir 120 so it does not become hot thus the heat application is efficient with little or no heat being lost there is no attempt to heat or keep heated the entire reservoir only the portion in wick 200 furthermore as the water is drawn into the feeder wick 210 residues are not left in the reservoir 120 as a result of heat forced evaporation and so the reservoir remains clean of such residues any impurities in the water 150 are left within the evaporative wick 200 as the water is evaporated it is envisaged that wick 200 is disposable and replaced at a regular frequency the frequency of replacement will vary depending on the quality of water 150 used pure water such as distilled water will enable the evaporative wick 200 to last for several months whereas tap water 150 may require replacement of the evaporative wick 200 within weeks or even days depending on the quality of the tap water however it would be possible to construct a wick which was not disposable from more durable materials if this was desired it will be appreciated that the construction and form of the wick as described in this implementation are such that it.