In article ,
John writes:
Golan wrote in
news:ec4690a8-b340-4d8e-987c-732b73ac3732
@y5g2000hsf.googlegroups.com:

Hi.


i have a vaillant ecomax 613 condensing boiler with indirect cylinder.

at the moment the boiler thermostat is set to 65 deg and the cylinder
to 58 deg.

my question is it better to set up to boiler thermostat to max ? will
the boiler still work in condensing mode ?

The boiler would be running at its most efficient when the
return water
temp to the boiler is 54c

It still gets even more efficient at lower temperatures than that.
My condensing boiler runs at 40C return temperature for heating,
but the radiators were sized for low temperature operation.

A fast recovery cylinder will return the water to the boiler at
not much above the water temperature of the cylinder at the base
of the coil, so even if heating to 65C, much of the reheat time
will operate in condensing mode, until the return temperature
gets above 55C. With a standard (non-fast recovery) cylinder,
the return water is usually much hotter than the cylinder water
as the heat transfer to the cylinder water is not as effective.

Whether that will be sufficient in
cold
weather depends on your rad sizes and how much water you like
in your
bath.

If the same boiler does heating and hot water and doesn't have
independant temperature controls for each, then it's not possible
to reap the most efficient operation of the heating, as that will
be too cold for the hot water.

my gas engineer told my that the boiler is very efficient so it is OK
to run the hot water 24HR a day. we take 3 baths a day 2 in the
morning and one in the evening. should i set the programmer to run the
hot water for those times or let it run all the time ? what it
cheaper.

No timed twice daily would be better.

It's a shame how few heating installers actually understand the
physics behind their trade.

--
Andrew Gabriel
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