In article ,
Adam Funk writes:
On 2018-01-24, Andrew Gabriel wrote:

In article ,
Scott writes:

I thought biological detergents worked best at low temperatures?

The enzymes only work up to about 40C, after which they're destroyed.
The detergent in the powder will work hotter.
So, a modern machine (last 35 years) should fill at no more than 40C
anyway, and for a hot wash, it will crank the temperature up in stages.
There are other reasons too not to dunk clothes directly in 60 or 90
degree washes, but to work up to that in stages - some dirt which
is removable at lower temps will cook on at higher temps and be more
difficult to remove.

We had a hot-and-cold-fill machine until about 10 or 15 years ago.
Would it have filled with a mixture of hot and cold water even for the
60° or 90° programmes?

My Hotpoint did. Initial fill was always 35C in that machine.
It went up in a few steps at perhaps 10 min intervals to 60C,
and then straight to 90C (which I only ever used a couple of
times in 25 years).

It started with cold first, and only switched on the hot when
there was some cold in there, presumably to ensure it didn't
damage the washing enzymes before they could be used. Worked
well when it was about 2 feet from a multipoint heater, but
not so well after moving it somewhere where the hot wouldn't
run through the pipework before it finished filling. That's
why machines tend not to have hot fill anymore.

--
Andrew Gabriel
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