hot water bottles

titus.a.duxarse

I bought myself a new hot water bottle this weekend as a “stand-by” for one of my old ones which is starting to show signs of wear. I was puzzled by one of the “instructions for use” which said I should only use water form the cold tap when filling my kettle. In practice, I rarely use a kettle; preferring to fill my bottle directly from the hot tap. This way it is never too hot to cause me burns or to damage the bottle. Could someone with a scientific brain please tell me why it should make any difference whether I use water taken from the hot or cold tap? After all, the water supply comes into my house through the same pipe!

Another “instruction” also puzzled me. It said I should change my bottle every 3 years. This surely has to be nothing more than a crude attempt to sell more bottles Mine last me very much longer than that, despite being in use 365 days a year - well almost. How long do you keep yours and what “signs of wear” encourage you to replace them?

mx-3

You should not fill from the hot tap, because the water is often stored in 2 dirty tanks before if reaches your kettle.
I keep my hot water bottles, until I feel a damp patch in bed...........

andrewmoorcroft

The person who wrote the instructions wrote them to be safe for all hot water heating systems and the protection of your health an kettle!
Also many people run a hot tap to fill a kettle to reduce the boiling time. This can be very inefficient. If the hot pipe is full of cold water then you can waste alot of water before the heated water reaches the tap. This is due to the length of pipe and the initial heat is lost into the pipe work before hot water eventually reaches the tap. The cold water is typically 20degC and the hot water after u've wasted loads down the drain is typically 50degC before you put it into the kettle and lose further heat to the kettle itself lowering it to 45degC! Boiling water is 100degC so the best you can hope for is switching the kettle on having already achieved the 1st 25degC rise of the 80degC required. This means that you will be using the kettle to heat the water from 45-100degC instead of 20-100degC. I've seen people run the hot tap for a minute to get the water at the hottest before they fill the kettle. They are under some misillusion that this have saved time and heating energy and ignore the water wasteage!