[clug] Hot water systems (was Re: 24" LCDs )

Sam Couter sam at couter.id.au
Tue May 5 10:59:24 GMT 2009

Alex Satrapa <alexsatrapa at mac.com> wrote:
> I'm pretty sure that 50C is the standard these days[1], to avoid people 
> accidentally scalding themselves with water hot enough to wash dishes in. 

It is. 50C takes a minute or more to cause actual burns to kids and
more than a few minutes for adults, yet hurts almost straight away. This
gives plenty of time for slow reflexes to remove your hand from the
source of danger, or plenty of screaming from the kid before they're
actually damaged.

65C burns in a few seconds, about the time it takes the pain message to
reach your brain, and way less time than it takes to realise why the kid
is screaming and to get it out of the bath. :(

> Nevermind that some lovely friendly bugs such as Legionella love 
> temperatures in the 35-45C range, but can't stand water hotter than 
> 55C[2].

Doesn't matter if you're not storing the hot water. Storage systems are
required to hit 65C or so at least once every 24 hours because of this.

> Most instant hot water systems will let you install a 55C  
> controller in the kitchen.

True, we didn't want to splash out for that though.

> My cynical self is wondering whether the folks recommending colder "hot" 
> water had shares in Dishlex. Then again, who is going to police the water 
> temperature?

Dishlex don't want colder water, it makes their dishwashers less
efficient and slower as they have to heat the water further.
Sam Couter         |  mailto:sam at couter.id.au
OpenPGP fingerprint:  A46B 9BB5 3148 7BEA 1F05  5BD5 8530 03AE DE89 C75C
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