HLAH wrote:

I am on the point of deciding on a new hot water cylinder and I am now
wondering about getting a "Superduty" cylinder - a cylinder with instead of
a primary coil of one tube, a cylinder having a coil with four smaller tubes
and hence greater surface area to transfer heat. Now the idea is to improve
efficiency by reducing cycling and also reducing the temperature of the
return flow and promote condensing.

" The installation of a Superduty will reduce boiler
operating times and cycling periods resulting in
savings of up to 40% compared with systems using conventional indirect
cylinders."

40% is I am sure BS but is a decent efficiency saving likely?

All in all, it should be well worth having the faster cylinder -
especially if you have a condensing boiler to heat it. However be
careful about what you expect to "save" here. It going to be mostly time
rather than energy. A given mass of water will still take the same
amount of energy to raise its temperature. Also a modern boiler will
modulate to match the actual heat extraction rate of the coil in the
cylinder - which will go a long way to reducing much cycling on even a
relatively "slow" cylinder (reducing the cycling *does* reduce the fuel
used a little).



--
Cheers,

John.

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