"TonyK" wrote in message
...
Hi

Just looking for a guide, not actual calcs, from someone who can give
an
authoratative "yes" or "no"...

Fitted a 330l pressurised cylinder (insulated) earlier this year and
to date
has been left switched on all the time due to high demand for hot
water
literally 24hrs a day. Now demand is dropping off dramatically and
will only
be needed Fri-Sun so...

Should the cylinder be switched off Monday - Fri am allowing the water
to
cool and reheat from what I asume would be almost cold on Friday pm.
Or, is
it more energy efficient to leave it on and let the thormostat
regulate
power consumption to keep it up to temp throughout the week?

Any ideas...

Tony

Turn it off. It probably won't be almost cold - my brother has a 150l
cylinder in his flat which was switched off last Monday and on Saturday
the water was still warm.

As the water cools it will be losing heat more slowly than when it was
warmer (if you see what I mean). Losing heat more slowly = more
efficient. You'll have to add less heat to get it back up to temperature
than you would have lost by maintaining it over the week.

In reality there's probably not that much difference. And bear in mind
that if you are heating electrically that the cost of the energy may
vary depending on when it is consumed.

HTH

Neil