FEATURE
DOMESTIC BOILERS
& RENEWABLES
“To ensure homeowners’ hot water
demands and expectations are met, it’s
important to install the right heating
system for the property”
Combi or system boilers:
which is the best installation?
It’s common knowledge that combi boilers are the most popular installation choice in the UK,
however, there are instances where a system boiler may be more appropriate. Scott Ditchfi eld,
sales director – specifi cation at Potterton, gives his top tips on how to choose between the two.
Today’s new homes generally
have combi or system boilers
installed, with the latter being
teamed with unvented cylinders
to provide hot water.
Providing they are sized correctly, both
will be equally effective space heating
systems but must be installed in the right
type of property in order to meet the hot
water demands of the people living there.
The occupancy of a home, as well as its
size and number of bathrooms, must be
a key consideration for installers. Today,
more people are living under one roof
than ever before.
MULTIGENERATIONAL LIVING
According to the Intergenerational
Foundation think tank, over 500,000
households have at least three generations
living in the same house, and that number
is expected to rise to 556,000 by 2019.
As space tends to be at a premium
in properties like these, installers must
ensure the heating systems they choose are
appropriate both in size and effi ciency. For
elderly residents in particular, they need
to be suffi ciently heated and provide a
comfortable, homely environment.
Previously combi boilers were seen as
unsuitable for bigger homes with intensive
hot water demands. Traditionally, a system
boiler was recommended for properties
with more than one bathroom.
Providing it is paired with an adequately
sized storage cylinder and appropriate
controls, system boilers can supply
guaranteed hot water to more than one
outlet at a time. However, cylinders take
up more room and are not aesthetically
pleasing, so provisions must be made for
an appropriate area to house them.
There is also a short downtime once
all of the stored water has been used
while the boiler refi lls the tank with
a fresh supply of hot water. However,
if the cylinder is sized correctly to
the occupants’ needs, the risk of this
occurring is minimised.
UNVENTED CYLINDERS
Unvented cylinders are installed because
they deliver exceptional fl ow rates; they
can provide powerful showers and fast
fi lling baths without a signifi cant drop
in performance if more than one tap or
shower is used at the same time, making
them ideal for larger properties with
multiple bathrooms.
These systems are also a good choice if
luxury products such as multi jet showers
and jetted air baths are fi tted, which rely
on fast fl ow rates to work effectively.
However, for smaller dwellings with
fewer bathrooms and fewer occupants
a combi boiler remains the most
appropriate choice.
Combi boilers combine the
characteristics of a conventional boiler,
unvented storage cylinder and cold water
storage tank within one unit.
They are easy to install and offer a
The occupancy of a
home, as well as its
size and number of
bathrooms, must be
a key consideration
for installers
continual supply of virtually instantaneous
hot water without requiring a storage
cylinder – which frees up valuable space –
or any hot water controls.
What’s more, manufacturers are now
launching combi boilers with larger
outputs and these are fast becoming a
more effi cient alternative to system boilers
for dwellings with higher demands.
An example of this is Potterton’s latest
addition to the Assure range – a new 36kW
model designed specifi cally for new build
projects. This combi boiler has a fl ow rate
of 15l per minute at a 35º temperature rise,
and its larger output means it can be used
in homes with more than one bathroom.
The Assure 36 has a fi rst-class SAP
rating and is the lightest 36kW boiler on
the market, making installation quick and
easy. It is also compact enough to fi t in a
standard kitchen cupboard which gives
installers more fl exibility when siting the
boiler and is a perfect solution for those
living in multi-generational homes where
space is precious.
To ensure homeowners’ hot water
demands and expectations are met, it’s
important to install the right heating
system for the property.
By ensuring that the heating system
chosen is suitable for the size of property,
an appropriate amount of hot water is
delivered, space is maximised and the
homeowner is left satisfi ed.
ENQUIRY NUMBER 115
42 Heating & Plumbing Monthly | OCTOBER 2018 | www.hpmmag.com
/www.hpmmag.com
