On 01 Apr 2021 16:40:56 +0100 (BST), Theo
wrote:

T i m wrote:
If it includes actually *needing* a bowl full of washing-up
temperature water several times a day than anything 'instant' is going
to have to be pretty powerful, as is any local water store, if not
either quite high capacity or high power (for reasonable recovery
time).

I was wondering about feeding an instant electric heater from a hot water
supply.

This might sound strange, but hot water supplies aren't always hot:
- there's the leg of cooler water before the hot water comes through
- in a tank system the boiler may not have run recently and the water be
lukewarm
- the storage temperature may be lower than you would want for washing
dishes

Is there any reason not to feed such a heater from say a 30-60C supply?

Coincidentally I have referenced such an idea elsewhere and belive
someone here is already (successfully) doing such a thing.

I set the temperature on our Multipoint to not be too hot (for hands)
when running at full temperature but there may be a slight conflict of
interest between the temp required at the basin and the sink (the sink
maybe wanting it hotter for heavy soiled crockery / cookware if we CBA
to use the dishwasher).

A mate has a very long house with the indirect HW tank in the middle
of the building and the main bathroom at one end. I'm guessing it
could be ~20m between the two and with those stupid 'waterfall' type
taps it takes *ages* [1] to get hot water at the basins especially if
it's not been used for a while.

Cheers, T i m

[1] Longer than I would tolerate if I had his space / money. Given
it's low pressure, a tiny direct HW cylinder with immersion in series
with the hot feed in a cupboard nearer the bathroom would be what I
would do.

The other two bathrooms are nearer the HW cylinder and he has Quooker
taps in the kitchen and utility room. ;-)