Air
Source Heat Pumps
How
do air source heat pumps work?
These units work
by absorbing heat from the outside air through
an evaporating coil. Now the units compressor
will pump refrigerant through the system to compress
the gas inside, this in turn will create large
pressures within the unit. The pressures create
heat that is transferred through a heat exchanger
to a primary water circuit.
What are the design
considerations for my home?
An air source heat
pump is fairly large in size, and will require
one metre of access at the front for maintenance.
They produce a small amount of noise (like a fridge
freezer). Often they are placed beside a garage,
down the side of the house, or mounted on brackets
on the wall of the property. A free flow of air
will be needed for the pump to work efficiently
and not to start short cycling reused air.
People talk about
3 phase electrical supply for the unit to work.
What are these?
3 - Phase electrics
are often needed for heat pumps that have high
KW inputs. This is because of the current they
draw from the grid. Without 3 phases lights may
flicker on and off during startup of the machine.
A normal home operates by taking one line from
the phase of the power lines above your home.
3 phases is 3 lives taken which increases the
amount of current available. This supply will
cost around £2000 to install and is not always
available so check before deciding on an air source
heat pump. Air source heat pumps installed by
Solo Heating Installations only require a 3 phase
supply if the output you is above 12kw.
What else will I need
for this system to work?
Air source heat
pumps work more efficiently at lower operating
temperatures. For this reason it is advised to
have underfloor heating throughout your home.
They will also need a buffer tank or thermal
store. This will stop them cycling on and
off in a short space of time. As a final step
the hot water will need a backup energy source
such as an immersion heater or small gas
boiler. The backup heat can come from many
different renewable
sources.
You
can find more information on Air Source Heat Pumps
at the Heat Pump Association Website
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Ground
Source Heat Pumps
How do ground source
heat pumps work?
Ground loops are
installed in the ground and are filled with an
antifreeze mixture. The liquid is pumped around
the coils by a large pump located at the ground
source heat pump unit. After the water is heated
through the stored heat energy in the ground,
a process of compressing refrigerant within the
unit will create high pressures that will release
heat to temperatures around 30-40 degrees. This
heat is transferred by a heat exchanger to another
circuit of water that is linked to a buffer tank
or thermal store.
What must I consider
before purchasing a Ground Source Heat Pump system
from Solo Heating Installations?
The pumps within
the unit will create a low humming noise that
may cause a nuisance if its positioned in a garage
below a bedroom for instance. They are often located
in utility or plant rooms as they will need some
access for any future maintenance.
Ground source heat
pumps work more efficiently in different ground
conditions. Some earths types around the UK will
not be as suitable to be drilled or they may be
of a material that does not conduct heat very
well to the ground loops. Ground such as wet soil
with underground streams will conduct the heat
very well, but at the opposite end of the scale
ground like hard rock will not conduct heat so
well. A full ground survey is recommended before
making any decision or starting any work towards
a ground source heat pump. Solo Heating Installations
can arrange this survey and any drilling works
needed.
People talk about
3 phase electrical supplies for the unit to work.
What are these?
3 - Phase electrics
are often needed for heat pumps that have high
KW inputs. This is because of the current they
draw from the grid. Without 3 phases lights may
flicker on and off during startup of the machine.
A normal home operates by taking one line from
the phase of the power lines above your home.
3 phases is 3 lives taken which increases the
amount of current available. This supply will
cost around £2000 to install and is not always
available so check before deciding on an air source
heat pump. Air source heat pumps installed by
Solo Heating Installations only require a 3 phase
supply if the output you is above 12kw
I've heard of high
prices for these systems, what will everything
cost?
As a very basic
guide, a ground source heat pump using the horizontal
loop type system will cost upwards of £8500. You
will then have to pay for the ground excavation
works. This is normally undertaken by the ground
worker whilst the plant machinery is on site.
If boreholes are used expect to pay around £1500
per hole with a normal installation comprising
of two.
You will save around
you £500 - £800 in energy bills per year and cut
your carbon emissions significantly. Ground
source heat pumps have a working life of above
25 years so you will be future proofing your property
against fuel cost rises. With the right technology
behind them, ground source heat pumps can provide
a working basis to create a truly zero-carbon
or even carbon plus home.
I've heard that the
slinky coil design can create problems with ground
freeze?
Currently at Solo
Heating Installations it is our opinion that slinky
coil design ground collectors are likely to cause
problems in the future with ground freeze. Because
of the energy extracted by the coils in a relatively
small area, radiant energy from the sun can't
keep up with the heat transfer into the pipes,
so slowly the ground around the coils will loose
heat that it cannot regain. It has been seen in
some circumstances that the ground completely
freezes over in the areas of the coil. It is claimed
that it can be worked out so that no problems
are created, but we say why take the risk? It
is our recommendation to use the horizontal ground
collector type (including open loop) or bore hole
type design. We would not install any other system.
Find
more about GSHP's here at the Ground Source Heat
Pump Association Website
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Gas
Condensing Boilers
How do these condensing
systems work?
Condensing boilers
work by using heat energy from a gas flame to
heat water. But where they are different is the
condensing boiler will reuse hot gases that would
normally escape through the flue and extract the
heat out of them. This lowers the temperatures
of the resulting flue gas' creating a condensation
effect. Condensing boilers only work in condensing
modes at around 55 degrees so any system designing
out of this temperature range will dramatically
lower the systems efficiency.
All boilers are
judged on efficiency by the SEDBUK which measures
each individual boiler and puts its efficiency
percentage into a bracket. Only brackets A and
B are currently accepted by the Building Regulations
Authority for new appliance installations.
Tell me about the
extra controls available to make these systems
work even better?
It is the law under
Part L of the building regulations that specific
controls for the system must be installed to increase
the efficiency of the system. Many other controls
often get overlooked that can further reduce your
fuel costs.
One of these controls
is a Setback Programmer and Weather Compensator.
These work by automatically turning the central
heating on at a specific time to reach a certain
temperature that the user sets. So if you want
the house warm at 7am, the setback programmer
will learn how long it will take to bring the
system to that temperature and start it up at
the relevant time. This can be combined with a
weather compensator, which reads the outside temperatures
and adjusts the internal temperature and setback
controls accordingly. Speak to Solo about bringing
your heating system into the 21st century and
cutting down your heating bills.
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Unvented
Hot Water
Should I choose an
unvented cylinder or a combination boiler system?
A hot water cylinder
provides a basis for stored hot water that the
user can draw off at any time without worrying
about the water 'drying out'. This drying out
often occurs with combination boiler systems because
they cannot cope with large demands and homeowners
end up getting no hot water through their taps
and showers. It can also lead to poor performance
during showers because fluctuations in pressure
will alter the water flow coming through the shower
head.
Combinations boilers
are useful in certain situations like flats and
small houses where they will not encounter larger
demands. But for detached houses with multiple
bathrooms and ensuites, Solo Heating Installations
always reccomend a hot water storage centre.
I've heard of secondary
return hot water systems. What are these?
A secondary hot
water return is used when the draw-off points
in the house are far away from the hot water cylinder.
Many people experience a long wait when they turn
on a tap before they get any hot water through,
this system will eliminate that. It will cut down
water wastage because you are not having to run
water of get the hot supply.
The layout includes
an energy efficient pump wired into the programmer
that will pump water around a loop to the hot
draw-off points within the house. The programmer
ensures the pump does not run all the time and
will reduce the energy required for the system
to the equivalent of running a small bedside lamp.
Solo Heating Installations
install secondary hot water returns with thermal
store designs. Traditionally it was not possible
to combine these systems because of the heat loss
sustained into the thermal store. We recommend
a small NIBE UKV buffer tank and hot water mixing
valve for the secondary hot water to return into
which eliminates this heat loss.
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Electric
Boilers
Are electric boilers
a better alternative to gas boilers?
Solo Heating Installations
had a client who did not have a mains gas supply
to his home and was deciding whether to put one
in at a cost of around £1200, or to stick with
electric boilers. After looking at the figures
Solo worked out that it was still cheaper to put
a gas supply in than run electric boilers systems.
This is true for detached homes with multiple
draw-offs but for small flats this is not the
case.
Electric boilers
in certain situations will remove the need for
Landlord Safety Checks and multiple gas supplies
to blocks of flats. This will reduce initial outlay
costs but not running costs for the end user.
Electric heating and hot water will cost you around
three times more to run than the gas alternative.
Solo Heating Installations
will always recommend you look at the gas or renewable
energy options before you choose electric boilers.
But electric boilers can be a great way to save
money on the initial outlay.
People talk about
3 phase electrical supplies for the units to work.
What are these?
A 3 - Phase electrical
supply is often needed for electric boilers. This
is because of the high current they draw from
the grid. Without 3 phases of power to your home,
lights can flicker on and off during startup of
the unit.
A normal 230v system
operates by taking one line from the phase of
the power lines above your home. 3 phases is three
lives taken which increases the amount of current
available. This supply will cost around £2000
to install and is not always available so check
before deciding on an electric boiler.
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Heat
Recovery Systems
There are many upgrades
available for heat recovery systems, are these
a worth-while option?
Upgrades to the
heat recovery systems that Solo provide include
better filters, climate cooling and air conditioning.
Upgraded filters
are an excellent choice for allergy sufferers
as they will filter an even greater amount of
particles out of the air. The filters we offer
are electrostatic filters that work at higher
efficiencies to the standard ones.
Climate cooling
is a step down from full air conditioning. It
will go a long way to cool the air as it passes
into the system during the summer months to ensure
your property remains ventilated but cooled at
the same time.
Air conditioning
upgrade will give you powerful control over the
temperature of the air coming into your home through
the heat recovery system. It will allow you to
bring the fresh ventilated air into your property
at a much lower temperature that the outside to
give that air conditioned coolness.
Where will the air
lines and grilles be installed?
It is most common
to run the flexible air ducts through voids in
joists and voids in the loft space. Often the
unit will be located in the attic eaves, with
the lines running around the house and dropping
down to each level. The grilles themselves can
be positioned on the ceiling or even the walls.
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Thermal
Stores
My architect has advised
me to go for a thermal store, what design considerations
are there?
Thermal heat stores
work on the principles of heat layering into different
temperature zones within the cylinder. It is for
this reason that the cylinders need to be tall,
roughly around six feet. They will therefore need
to be positioned in a room with clearance for
the cylinder and any adjoining pipework. Temperature
and pressure relief valves will need to discharge
into foul water drains.
There are so many
different thermal stores available to buy; how
will I know which is the right one?
The key difference
to the thermal stores is the amount of external
tapings available for the different heat sources.
It is always advisable to buy a thermal store
with the ability to install a renewable technology
in the future in case you decide to. Many renewable
energies such as Air Source Heat Pumps will require
a certain amount of water in the system to eliminate
any high pressure or cycling problems. They will
also have to be sized correctly to meet the demands
of the hot water draw-offs to the property. Solo
Heating Installations will be able to advise you
on the correct thermal store for your system at
the design stage.
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Solar
Panels
Do solar panels have
any payback period?
Solar panels are
currently one of the best renewable energies in
terms of payback. We can install a solar system
for around £3400, and because these systems can
save you £300 per year, they have a good pay back
period of around 10 years. Once you factor in
the £400 government grant available, and the steady
increase in fuel prices, the period reduces significantly.
My local authority
have insisted on using solar panels for my new
build?
As popularity for
solar panels increases, local authorities are
in some cases making it compulsory for homeowners
to install solar panels for their new home. If
you find this is the case, we would suggest installing
a large thermal store cylinder and for you to
consider underfloor heating on at least the ground
floor of your property. When solar panels are
combined in banks of 9sq metres or more, their
outputs usually exceed the hot water requirements
for the property and so the excess heat the panels
produce needs to be heat-sinked somewhere to avoid
damage. This is possible by either installing
heat dump radiators in an uninhabited room such
as a garage, or installing an oversized thermal
store that will allow the solar panels to dump
the heat safely.
I wouldn't like the
look of solar panels on my roof, is there another
place to mount them out-of-site?
There are now many
different possible mounting positions for solar
panel collectors apart from the roof. Solo Heating
can now install panels on flat roofs with special
mounting 'A' frames, or even have panels mounted
to the side of an exterior wall. It is always
a consideration to which way the sun faces to
determine the location of your panels. A SW to
SE angle is always preferred and for it to be
away from cast shadows.
Solar panels come
in two different designs, the evacuated tube design
and flat plate. The evacuated tubes are more efficient
but are often not chosen because people prefer
the look of the flat panel designs.
Do solar panels require
any maintenance activities?
Solar panels require
an annual check of the antifreeze fluid levels
which you can do yourself. Other than that, there
are few moving parts and little to go wrong.
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Combined
Heat and Power Units
Will I need a 3 phase
electrical supply for my CHP unit to work?
Although not a
frequently asked question, it will soon become
apparent to homeowners that in order for a combined
heat & power boiler to work in their home
they will need a 3 phase electrical supply. This
is because the unit produces electricity in 3
phases.
Normally a home
consists of a 230v single phase supply, this is
where one 'power' line is taken, but in certain
circumstances where more current will be drawn,
3 phases will need to be taken to increase the
voltage to 415v. A 3 phase supply is not always
available to be installed and will set you back
around £2000, so always check availability before
deciding to install a CHP unit.
Will the CHP unit
suit my home?
The BAXI CHP Boiler
will have minimum output level of 12.5kw for heating.
If your home has a lower heat demand, there will
be a need to install a buffer tank. This tank
is essentially an empty mass of water that gets
heated up and acts as a heat buffer between the
CHP boiler and heating system. Without this tank
the boiler would cycle on and off which would
eventually damage the pump and motor. A buffer
tank is roughly the size of a standard hot water
cylinder found in most airing cupboards. If you
unsure of heat demands for your property, or are
undertaking a renovation project, speak to Solo
Heating Installations about working out the heat
loss for your home.
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Underfloor
Heating
I've had experience
or heard of older systems having poor controllability?
With the older
underfloor heating systems, there was a long delay
in systems getting warm and keeping the systems
at the desired temperature was difficult. This
has all changed with modern systems being highly
controllable, now surpassing standard radiator
systems in terms of efficiency and comfort. Think
of the entire floor to your home being one large
thermal mass that emits heat evenly around the
floor.
Underfloor heating
systems have great health benefits for allergy
sufferers and will reduce dust traveling through
the air. This is because they do not work on convection
currents like radiators, with warm spots and cold
spots within the room, and so do not transfer
dust around within these convection currents.
Underfloor Heating
costs more than standard radiator systems, is
it a good option?
There is no short
answer to this as every situation is different.
For many of the new renewable or green technologies
to operate at an efficient level, underfloor heating
is a necessary part. This is because underfloor
heating operates at lower temperatures, units
like ground and air source heat pumps operate
at lower working temperatures so underfloor heating
is needed.
Underfloor heating
is also known to increase the value and salability
of your home, as homeowners see it as a very desirable
option. Quite often people will choose underfloor
heating on the ground floor and have radiators
upstairs. To lay the pipes on the ground floor
within the screed is always cheaper than running
them for the 1st floor.
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Biomass
Boilers
What do biomass boilers
actually burn?
The main substances
that will be burnt for a domestic biomass boiler
are wood pellets and wood chips. When factories
produce waste wood from manufacturing, this wood
is recycled into pellets. More and more short
crop cycle trees are grown and turned into fuel
for biomass systems. Its this sustainability and
the fact that they are in effect zero-carbon,
why people are looking more seriously at installing
a biomass boilers.
What are the main
design considerations for such systems?
Fuel
It's important
to consider ease of access to load fuel into the
hopper heads.
Space
Biomass boilers
are relatively large, and unless you want the
manual log loading systems, a large hopper head
and feed facility will need to be installed indoors.
Provision for such space must be taken into account
at the early planning and design stage. Many local
authorities will need to give prior approval when
you wish to install a biomass boiler, especially
in a protected area.
Cost
Biomass boiler
systems can be expensive to install at around
£8500 to £12000. But they can be a great alternative
to ground or air source heat pumps as they will
not require large amounts of electricity to run.
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LPG
Cylinders
Will I have to get
replacement cylinders myself, when the gas runs
out?
When your gas cylinders
run out, the homeowner will have to arrange with
a company such as Calor
to collect your cylinders. When they collect them
they will deliver a new set of cylinders at the
same time.
Where will I locate
my cylinders?
The propane cylinders
need to be situated outside of your home. Butane
cylinders can be installed within a garage as
long as certain criteria are met. The cylinders
will need to be upright, secure and have easy
access to change and maintain them. There are
also regulations affecting how far they can be
from windows, drains and air vents. Solo will
advise on the best places to locate the cylinders.
Underground bulk
storage cylinders cannot be placed below driveways
or near large deep rooted trees. They require
an access cover for maintenance of the valve assemblies.
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