Hot water bottle best practice

[LndnGrl]

What's the best way to make sure a hot water bottle stays hot for as long as possible?

Should I be filling it to the brim so it's hard or only filling a bit and squeezing so there's room in it?

Should I wrap it in something? Mine already has a fleecy/felt cover.

Should I tip some out and top it up when I think it's cooler?

Don't fill it until it's firm! Water expands when it cools - you'll be forcing the rubber to stretch and causing undue wear and tear and in the long term higher risk of it splitting.

Re layers: depends what you're doing with it. More layers will keep the hot water bottle hot but also make it harder for the heat to get through to whatever you want the bottle to heat. If you're holding it against your body then more layers around both will keep the heat close, but over-insulating the bottle itself with be counterproductive.

Tipping out cooler but still warm water and topping up seems inefficient, unless you are reheating that same water on a stove. Better to let it cool completely, making use of all the heat energy, and then refill from scratch.

@nosyupnorth

Don't fill it until it's firm! Water expands when it cools - you'll be forcing the rubber to stretch and causing undue wear and tear and in the long term higher risk of it splitting.

Re layers: depends what you're doing with it. More layers will keep the hot water bottle hot but also make it harder for the heat to get through to whatever you want the bottle to heat. If you're holding it against your body then more layers around both will keep the heat close, but over-insulating the bottle itself with be counterproductive.

Tipping out cooler but still warm water and topping up seems inefficient, unless you are reheating that same water on a stove. Better to let it cool completely, making use of all the heat energy, and then refill from scratch.

Water contracts when it cools. It's only when it cools enough to freeze that it starts to expand.

You risk the water bottle bursting if you fill it till it’s firm. Recommended is max 2/3rd.

Get a wheat bag instead. Safer, less risk of mess and stays warmer longer ime.

Make sure you have a thick cover for it. I’ve fallen asleep on numerous occasions with a hot water bottle and ended up burning myself quite badly and needed specialist burns dressing. I still use on though as I can’t afford to have my heating on.

@Danikm151

You risk the water bottle bursting if you fill it till it’s firm. Recommended is max 2/3rd.

Thanks

@AchillesLastStand

Make sure you have a thick cover for it. I’ve fallen asleep on numerous occasions with a hot water bottle and ended up burning myself quite badly and needed specialist burns dressing. I still use on though as I can’t afford to have my heating on.

I want it for the daytime, I've got an electric blanket on the bed.

@Danikm151

You risk the water bottle bursting if you fill it till it’s firm. Recommended is max 2/3rd.

3/4

www.hotwaterbottleshop.co.uk/pages/the-essential-guide-to-keeping-warm-with-a-hot-water-bottle

Expel any air in it before you put the cap on, tip it upside down to drain any water which may have collected in the top and dry it off. If you know the column of the bottle and your kettle you can easily calculate how much water to put in without overfilling it.

I made a cover from an old sweatshirt, it's easy to wash and seems to be the right thickness to prevent burns without losing the heat benefit.

Volume not column

I gave up on them because I started to worry about leaks and burns!

So my best practice is by an electric heat pad instead.

I use a 3/4 full kettle for my HWB from boots (standard size?)

I squeeze out any air before fully tightening the lid so it's not firm.