John Stumbles wrote:

If the Worcester Heatslave is the machine I'm thinking of it does indeed
have a CH + HW programmer, and it is a combi.

There seems to be a huge number of "heatslaves" some combi and some not.
Obviously decided that once they have a good name they ought to stick
with it!

Some combis come on from time to time to keep the water in the heat
exchanger hot so you have really instantaneous hot water when you turn
on a hot tap, so I guess this boiler uses the HW programmer setting to
determine when to do this. If the diverter valve is on the blink it

Yup could be...

(My Isar does the pre tempering bit, but it is not something you can
turn off as such)

might just explain why it carries on heating up for 10 minutes, and also
whey you only get lukewarm water after the initial spurt of scalding hot
water.

It's probably also well past its sell-by date.


--
Cheers,

John.

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