The ultimate ideal or perfect temperature for the water in a hot water bottle does not exist. Personal warmth, the design and the material of the bottle decide on the perceived as pleasant and desirable warmth. How hot a hot water bottle should be is additionally influenced by external factors.
Never pour boiling water
When filling a hot water bottle, the question is how hot the water should be to achieve the desired effect. In general, boiling water is taboo. The resulting water vapor generates high pressure, which can lead to bursting of the hot water bottle.
The area in which the water temperature of the hot water bottle develops sufficient effect under moderate pressure is between forty and 65 degrees Celsius. Depending on the sensitivity and the type of bottle, heat starts at around 45 degrees, which can be felt to be too hot.
Bottle materials and protective covers
Common modern hot water bottles are made of rubber or rubber-like plastics. Also available are models made of metal such as copper or zinc sheet. When determining the water temperature, the thermal conductivity, the heat release mode and the heat storage are the physically significant factors.
- At the beginning, rubber conveys about eighty percent of the water temperature to the outside
- Laminated surface structures "distribute" the felt heat more evenly
- Metal bottles initially conduct almost one hundred percent of the water temperature
- Protective covers made from textile fabrics reduce the outside temperature by about 25 percent
- Rubber bottles are less zehn Metal bottles are completely cooled after approximately three hours
- Coatings from heat-storing gel cushions can slow down the cooling
- Temperatures and effectiveness
40 degrees: Lightly supplements body temperature and supports this degree rather "lukewarm" and sustainable, appropriate for children and enough. No risk of scalding in case of defect or metal surfaces
- 45 degrees: Prolongs the time of heat retention by about twenty percent
- 50 degrees: Scalding limit, for example, temperature adjustable shower fittings often have a safety button in this temperature level
- 60-65 degrees: High water temperature often set with hot water supply
- Tips & TricksWhen you are building or improvising a hot water bottle, you should ensure that it is permanently and securely sealed for fills of fifty degrees or more. Brittle materials tend to crumble and crack under heat.