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are we ready?

boilers in small- to medium-sized
properties, where domestic hot water
is produced instantaneously. This
eliminated the need for a hot water
storage cylinder, leaving many newer
property designs without space for
one. Heat pump output powers do not
support instantaneous heating of hot
water, meaning upgraded systems
will once again require the use of a
hot water store (or means to store the
thermal energy produced for hot water).
This presents a major challenge for
transitioning homes with combination
boilers over to low temperature systems.
Similarly, microbore circulating
pipework has been widely used since future low carbon technologies. deliver six to eight per cent efficiency
the 1970s. In high temperature systems This paper highlights that hybrid improvements and should not
the primary circulation flowrates approaches could be an effective way be overlooked as part of a wider
are relatively low, so the higher flow to accelerate the move to low carbon programme of change.
resistance generated by microbore pipes heating. Use of a control system ensures This is especially relevant where
does not cause issues. that the most suitable technology is properties have already received
However, low temperature systems, used, with a heat pump satisfying the insulation upgrades. Perhaps most
such as those using heat pumps, majority of a home’s demand. important of all, this paper has shown
require much higher circulation rates. The remaining gas boiler would only that extensive retraining of the
It is likely that many existing systems be used for support during the coldest installer base will be necessary for any
will require replacement of at least days of the year when demand is successful transition.
some pipework where new heating highest. Again, homeowners will need This will ensure correct
appliances are set to be installed. incentives to take this step, not least assessment of existing systems,
It is likely that radiators were also sight of lower running costs. as well as the identification of
sized based on higher flow temperatures, The paper also shows there remains appropriate technologies and system
meaning some will need to be replaced a significant number of households improvements, including design,
to achieve a sufficient heat output. These using a mains gas combination boiler. installation and commissioning.
kinds of major retrofit exercises will In many cases, major changes to All low carbon technologies require
be expensive and disruptive for many pipework, controls and heat emitters this to ensure the theoretical energy
people. Yet there is now an urgent need will be necessary in these properties, savings are realised in practice.
to transition existing building stock over notwithstanding the lack of a hot Consumer awareness campaigns will
to newer low carbon heating and hot water store. also be needed to help homeowners
water systems. These systems are best suited to understand why transition is vital.
As such, homeowners will likely replacement with a hydrogen boiler, but This should include information about
need incentivising so that proactive the infrastructure necessary to deliver differences in performance and why
work can be carried out. This will this system is still in development. behavioural changes are necessary to
mean appropriate consideration of Clear commitment from the extract the best energy savings and
heat pumps, hybrids and preparing for government in support of a hydrogen carbon reductions. The campaign can be
hydrogen boilers. grid will be necessary to incentivise backed by installers but would benefit
boiler manufacturers to develop H₂- from targeted advice from trusted third-
PREPARING FOR THE FUTURE ready models. party consumer advice bodies.
Ensuring systems are suitable for Projects like HyDeploy, the UK’s first Clements added: “There are many
heat pumps or other low temperature demonstration of hydrogen in homes, challenges ahead, but also a number
heating systems will mean retaining will be essential for proving the fuel’s of opportunities, not least in providing
the hot water store. In new builds, it viability and more should be rolled out extensive retraining for the UK installer
should be mandated that space be across the country. base. The Heating up to Net Zero paper
retained for future installation of looks at these in detail, highlighting the
a cylinder, while older properties OPPORTUNITIES different ageing systems that circulate
should be encouraged to replace. There are many challenges ahead but heat and hot water in our homes, and
As with many heating appliances, also a number of opportunities. Existing aims to ensure they are adequately
old cylinders are relatively inefficient, boilers are more efficient if operated covered by future government policy.”
having a much higher heat loss, poor at lower primary flow temperatures,
thermal transfer characteristics and a though this may require upgrades to The Heating and Hotwater Industry
very simple interface with the heating system piping and controls. Council (HHIC) is a member organisation
system. The introduction of a cylinder However, mandating low committed to using its knowledge and
scrappage scheme, or discounted temperature system retrofit measures expertise to define practical solutions
purchase scheme for DHW cylinders would reduce the cost of adding a heat for decarbonising heat and hot water in
or thermal stores, would not only make pump at a later date. UK homes and businesses. Read the full
hot provision more efficient but equip Low temperature heating systems whitepaper Heating up to Net Zero at
homes with appliances necessary for with existing gas boilers can also www.hhic.org.uk

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