The very latest
“Opting for a top-rated boiler and pairing
this with a cheaper cylinder is inevitably
going to adversely affect the end result”
store products tend to feature injection
foam, which again ensures improvement
in the speed in which heated water cools.
However, if you are looking to couple
a highly effective boiler with hot water
storage that can follow suit, opting for
vacuum panel insulation will provide the
The vacuum panel on its own can
improve efficiency by 30-50% even when
compared to injection foam models.
The way this works is simple. Heat
cannot travel through a vacuum, and a
10mm thick vacuum panel has the same
effect as 60mm of the very best foam
The panel is wrapped around the
cylinder wall, and the units are then
“double lagged” with a layer of foam
insulation that further reduces heat loss,
but also gives stability to the cylinder
casing and protect the vacuum panel.
With the all cylinders currently on
the market now receiving an ERP rating
from A-C, spotting the better performing
models is a much simpler task than
previously. Poor performing cylinders
below a C rating are now illegal, but
there are still significant differences in
Achieving the golden A-rated cylinder
range has eluded many key industry
players, but by continuing to innovate and
by utilising this vacuum panel insulation,
OSO has seen its Delta range meet that
target across all sizes.
Specifying a large A-rated model can
save up to £80 a year in energy costs
compared to the 15-20-year-old cylinder
that it could be replacing.
WHERE INSULATION COUNTS
Outside of vacuum panel models, cylinder
ranges with better ratings tend to have
A cylinder with 50mm of foam
insulation is already well insulated.
Marginal gains can be made by increasing
the thickness to 60 or 70mm. Beyond
that any gains are more than offset by the
practical difficulties of squeezing a bulkier
cylinder into a narrow airing cupboard.
Units with this level of insulation open
up the installation possibilities too as they
don’t always need to fit into an airing
cupboard. A loft or a garage can provide
an ideal alternative.
The amount of additional heat
loss that will occur because the
ambient temperature is lower in those
environments will be small, when
compared to the extra space created by
Vacuum panel insulation on its own can improve
efficiency by 30-50% over injection foam models
the removal of the cylinder from the first
Gains can be made where electric
cylinders are concerned too. Direct
cylinders are assessed for ERP on their
thermal efficiency in line with heat in
versus heat out.
Cylinder insulation is clearly very
important in this respect, but a new
advance in smart controls by OSO has
made a significant stride forward in
cutting energy bills.
The OSO Super SX iQ learns the
hot water usage habits of a household,
predicts demand and limits energy input
to match demand. The resultant energy
cost saving will amount to up to £60 per
year at today’s electricity prices, and these
prices are not going to go down in the
Efficiency is not always just about energy
efficiency. Space efficiency can be equally
important to a householder.
Back in the mists of time (1989), OSO
invented the bubble top system. Many
other manufacturers “borrowed” it during
the 1990s, some more successfully than
OSO dropped the bubble top unit some
time ago to replace it with an improved
design on the Super Series that has all
the space saving advantages of the bubble
unit, but which dispenses with the annual
bubble replenishment procedure normally
recommended as part of a service. The
Super Series design is now patented.
Cylinders with separate expansion
vessels do the job but take up a lot of
space. Bubble top units are more space
efficient, but the all-on-top design of the
Super Series with twin mini-expansion
vessels concealed under a lid, are
guaranteed not to lose their charge for
at least five years and gives a space saving
and maintenance friendly alternative.
The space saving features of Super
Series are accentuated with the SX IQ
because it heats and stores water at 70°C;
10°C higher than most other units.
The cylinder contains a blending valve
in its multifunction valve and blends
the water to 60°C at the outlet, thus
eliminating any risk of scalding.
This extra energy storage means that a
smaller cylinder can be specified, saving
further space and in practical terms
means that a washing machine can be
stored underneath the cylinder up to 210
litres in a standard airing cupboard. No
other product has that flexibility.
LAGGED FOR EFFICIENCY
To maintain efficiencies, it is equally
important to ensure that the interface of
pipework between boiler and cylinder is
correctly lagged and that modern heating
controls are used.
Heating costs in indirect cylinders can
also be affected by hard water. Opting
for a coil which is smooth will attract and
harbour far less limescale than a ribbed or
Cutting the effect of limescale acts
as insulation between primary and
secondary water. Building Regulations
Part L recommend that hard water is
treated to reduce calcium and preserve
the efficiency of the system.
In the worst cases, cylinders can just fill
up with limescale, and because the South
East and East of England in particular are
known hard water areas, the design of a
heat exchanger in a cylinder should always
be a factor to consider for installers in
So no, not all cylinders are the same
and this should be considered before
making a recommendation.
Quality, insulation, efficiency, space
saving opportunities and improvements
technology make a real difference to the
overall system and vary from product to
In the same way customers way up the
pros and cons of a boiler, the same needs
to be done on the cylinder front to ensure
the whole system meets, or exceeds,
ENQUIRY NUMBER 114
www.hpmmag.com | JUNE 2018 | Heating & Plumbing Monthly 49