John Rumm posted
On 03/11/2020 22:22, Theo wrote:
John Rumm wrote:
My thought was that it does
not leave much room for DHW at 60deg. to avoid bacteria.

Another trick you can play on some systems is split temperature
operation, when it uses different flow temps for heating the CH and DHW.
Heat pumps often have a flow temp much below 60C. The trick some of
them
use is to run an immersion once a week to boost the tank up to 60C - that's
sufficient to kill the bacteria.
Since the heat pump tries to keep the (well insulated) tank about
40C
anyway, it's only the weekly 20C boost that you're paying electric heating
prices for.

My Vaillant has an anti legionella cycle that you can enable. That
allows it to heat to the normal DHW set temp (60 in my case) for six
days a week, and then have one day where it heats to 70.


Good plan. Mine also has a silver crucifix attached to the HW tank, to
prevent it being occupied by vampires. So far it has worked very well.

--
Algernon