Environmental ppt gshp ashp

Module 1: Heat Producing Technologies
Heat Pump Systems
Objectives
At the end of this section you will:
• understand the fundamental working principles of a heat pump unit
• know the common types of heat pump unit
• know the types of heat emitters that are suitable for heat pump system installations
• recognise the top level regulatory requirements that apply in relation to heat pump
systems installation work
• recognise the fundamental requirements of building location and building features
for the potential to install heat pump systems to exist
• recognise the typical advantages and disadvantages of heat pump systems


Heat Pump Systems
What is a heat pump?
A heat pump is a device for converting
low temperature heat a to higher
temperature heat
Some heat pumps can also work in
reverse and convert high temperature
heat to a lower temperature
So how does a heat pump work? ………………

Heat Pump Systems
How does a heat pump work?
Most heat pumps make use of the mechanical vapour compression cycle commonly known as the
refrigeration cycle to convert heat form one temperature to another. The heat pump
refrigeration cycle works on a similar principle to a domestic refrigerator but in reverse.
Let’s look at how the heat pump refrigeration cycle works ………………

Heat Pump Systems
Heat pump refrigeration cycle
1. The low temperature heat (heat source)
enters the Evaporator which is a heat
exchanger . A refrigerant on the other side
of the evaporator is at a cooler temperature
than the heat source and heat is transferred
from the source into the refrigerant causing
the refrigerant to evaporate.
2. The now gaseous refrigerant enters the compressor, resulting in a rise in the temperature and
pressure of the refrigerant.
3. The refrigerant continues its course through the Condenser (which is also a heat exchanger)
transferring the higher temperature heat to either an air or water distribution circuit (often referred to as
the ‘heat sink’ or emitter circuit).
4. The refrigerant, now at a cooler temperature, enters the expansion valve, which reduces its pressure
and temperature to its initial state at the evaporator. The cycle then repeats itself.

Heat Pump Systems
How efficient are heat pumps?
Heat pumps are classified as a ‘low’ carbon
technology because they need some electrical
energy to operate.
Depending on the application, operating
conditions and type of heat pump utilised, heat
pump energy output can be 300% to 500%
more than the electrical energy input.
Heat Pump efficiency is referred to as
Coefficient of Performance (COP)
In its simplest form COP relates to heating output divided by the electrical power input. For
this example the COP is 4.0, calculated as follows:
Heating output (4kW) ÷ Electrical power input (1kW) = 4.0

Heat Pump Systems
Heat pump technology can convert low temperature heat from an air, ground or water
source to higher temperature heat for use in ducted air or piped water ‘heat sink’ systems.
The type of heat pump unit must be selected in relation to the intended ‘heat source’ and
‘heat sink’ arrangement’
Let’s now look at the options in more detail………….

External Air Source Heat Pump System Options
A variety of heat pump system arrangements are possible using the external air as the heat source.
Air source heat pump will typically operate at temperatures up to -20 oC. Air source heat pumps
can be single internal units that receive the incoming air through an inlet duct that passes through
the external wall of the building . An popular alternative is the use of an external fan coil
(evaporator) unit that is linked to an internal unit. Fan coil units can be noisy and this need to be
considered at the design stage.
Let’s now look at the ground source options ………….

Ground Source Heat Pump System Options
A variety of heat pump system arrangements are possible using geothermal ground heat as the heat
source. A variety of closed (sealed circuit) collector loop arrangements can be used.
SlinkyTM type collectors (illustrated) are sometimes used where available ground area (m2) is limited.
External ground source heat pump units (not illustrated) are also available.
Let’s now look at some more ground source options ………….

An alternative to horizontal ground collector loops is a
vertical collector loop installed in a borehole.
This type of installation requires a specialist drilling rig
to be used to create the borehole. A specialist
contractor is normally used to undertake the drilling
operation.
Vertical borehole collector loops are often used where
the geothermal conditions support the use of a ground
source heat pump but where the available ground area
(m2) is limited.
Click on next for more ground source options ………….

An ‘open’ vertical borehole ground collector loop is an
alternative to a ‘closed’ vertical borehole ground
collector loop.
With this arrangement , two boreholes are used and
the collector circuit is open and the collector circuit
fluid flows naturally from the open ended return pipe
to the open ended flow pipe. . This type of
arrangement requires the availability of a suitable
geothermal water source.
Click of next for water source collector circuit
options ………….

Water Source Heat Pump System Options
Where a suitable water source exists such as a lake or a pond, this can be a very effective
alternative to a ground source collector circuit. For illustration purposes the SlinkyTM type collector is
shown in a vertical position, but water source collectors are simply laid on the bottom of the lake or
a pond and weighted as necessary to keep them in place. ‘Open’ water source collector circuits (not
illustrated) are also an option.

Heat Pump Systems
How did you do?
Let’s now look at the ‘heat sink’ emitter circuit options ………….
Question Answer
What type of heat conversion process does a heat
pump use?
A refrigeration circuit
What types of heat source options exist? Air, ground and water
What types of heat sink circuit exist? Air and piped water
What is the typical % increase in energy output
from a heat pump in relation to the electrical energy
input?
300% to 500%
What does Coefficient of Performance relate to? Heat pump efficiency (heating output divided by
the electrical power input)
Click here to reveal

One of the factors that affects heat pump system efficiency is the
temperature difference between the heat source and the heat sink.
The closer the temperature between the heat source and the heat sink
circuit, the better the Coefficient of Performance.
Traditional ‘wet’ heating systems that incorporate a condensing boiler
use a mean (average) water temperature of approximately 70oC. A
heat pump system mean water temperature will typically be between
30oC and 40oC
The lower mean water temperature dictates that some types of heat
emitter and hot water storage cylinder are more suitable than others
for use with heat pump systems.
Heat Pump System Piped Water ‘Heat Sink’ (Emitter) Circuits

Heat Pump System Piped Water ‘Heat Sink’ (Emitter) Circuit Options
Heat pumps using a piped Water ‘Heat Sink’ Circuit can be used to heat domestic hot water storage
vessels (1), underfloor heating circuits (2), radiators (3) and fan convector heaters (4). However,
some of these are more suitable than others.
Click on each number for more information and when finished click on next
1
2
3
4

Domestic Hot Water Storage
Heat pumps can be used to heat a domestic hot water storage cylinder.
Standard type indirect hot water storage cylinders are not suitable for
heat pump system due to the size of the heat transfer coil. A ‘tank-in-tank’
hot water cylinder is the most appropriate for use with heat pumps. Some
heat pump units have an integrated ‘tank-in-tank’ cylinder.
The ‘tank-in-tank’ design provides a large surface to surface contact
between the heating circuit water and the stored domestic hot water.
This design is very suitable due to the lower temperature of the heating
circuit water in a heat pump system when compared to a traditional
boiler-fed heating system.
A ‘boost’ or auxillary heater is required to boost the stored water
temperature to standard 60oC domestic hot water storage temperature
‘Tank-in-Tank’ Hot
Water Cylinder

Underfloor Heating
Underfloor heating systems operate at a lower
mean (average) water temperature than a heating
system with radiators.
Therefore, underfloor heating is very suitable for
use with heat pumps.

Panel Radiators
Standard type panel radiators are designed to work at a mean
(average) water temperature of approximately 70oC.
A heat pump system mean water temperature will typically be
between 30oC and 40oC
To be effectively and efficiently used with a heat pump system, standard type panel radiators
would need to be significantly over-sized to enable the required heat output to be achieved using
a lower mean water temperature . This factor means that heat pump units are typically less
suitable for use with existing standard type panel radiator circuits that have been sized for a mean
water temperature of 70oC.
Low temperature, high efficiency panel radiators are available and these are more suitable for use
in a heat pump heat sink circuit. Where low temperature, high efficiency panel radiators are
used, the Coefficient of Performance will typically be lower than if underfloor heating is used.

Convector Heaters
Natural and fanned convector heaters are suitable for use
with heat pumps.
As is the case with low temperature, high efficiency panel
radiators, where natural and/or fanned convector heaters
used, the Coefficient of Performance will typically be lower
than if underfloor heating is used.
Fanned Convector
Heater

Buffer Tanks
Some heat sink circuits make use of a
component called a buffer tank. In basic
terms, a buffer tank is a vessel that
accumulates and stores heating circuit water
ready for use when needed.
Heat Pump System Piped Water ‘Heat Sink’ (Emitter) Circuits
Heat pumps are not designed or sized to meet short-term heat loads. For efficient operation a
heat pump heeds to be able to start-up and run for a period of time. Stop-start operation can
also shorten the life of the heat pump compressor.
Buffer tanks are also useful where an auxillary heat source such as a boiler is being used with a
heat pump. This type of system is known as a bivalent system.
Most air source heat pumps, particularly those with an external fan coil unit need to defrost
regularly. Buffer tanks are also useful to provide heat for the defrost cycle.

Heat Pump Systems – Regulatory Requirements
The installation of heat pump systems will require compliance with
a number of regulatory requirements including health and safety,
water regulations, electrical regulations. A competent installation
contractor will have a detailed knowledge of these regulations and
will ensure compliance.
Within this section we consider two primary regulatory
requirements in relation to heat pump systems:
• Building Regulations
• Town and Country Planning Regulations
Note: The requirements stated in this section relate to England and
Wales only. The requirements for Scotland and Northern Ireland
may differ.

The Building Regulations (England and Wales) comprise of 14 parts.
Seven of these parts may have relevance to heat pump systems installation.
Part Topic Relevance or possible relevance
A Structure Where heat pumps and other components put load on
the structure
B Fire Safety Where holes for pipes etc. may reduce the fire resistant
integrity of the building structure
C Site preparation and resistance to moisture Where holes for pipes etc. may reduce the moisture
resistant integrity of the building structure
E Resistance to the passage of sound Where holes for pipes etc. may reduce sound proof
integrity of the building structure
G Sanitation, hot water safety and water
efficiency
Hot water safety and water efficiency
L Conservation of fuel and power Energy efficiency of the system and the building
P Electrical safety in dwellings Safe installation of electrical controls and components

Town and Country Planning Regulations
Installing a ground source or water source heat pump system does not usually need planning
permission and should fall within permitted development rights.
Due to potential noise issues, most air source heat pump installation currently require
planning permission. However, this is currently being reviewed and as soon as relevant
standards and safeguards to deal with noise have been established air source heat pumps are
likely to be classified as permitted development.
The Local Planning Authority should be consulted for clarification, particularly for
installations in conservation areas and installations to non-dwelling building types.
*Listed Building Consent may be required even if planning permission is not
required.

Heat Pump Systems - Building location and feature requirements
For the potential to install to a heat pump system to exist, as a minimum
some or all of the following building and location factors will need to be
considered:
• an appropriate heat source (air, ground or water)
• the availability of a suitable location to mount the components -
particularly the potential for noise issues if an air source heat pump is
being considered
• The compatibility of the proposed installation with any existing heating
and hot water system unless a new heating and hot water system is to
be installed

Heat Pump Systems
How did you do?
Question Answer
What is the mean water temperature used in a
heating system connected to a heat pump ?
30oC to 40oC
What type of domestic hot water cylinder is most
suitable for use in a heat pump system?
A ‘tank-in-tank cylinder
What component can be used to prevent the heat
pump cycling on and off during short-term heat
demand periods?
A buffer tank
Which type of heat pump installation is most likely
to require planning permission?
Air source

Heat Pump Systems – Advantages and Disadvantages
Some example advantages and disadvantages are:
Advantages Disadvantages
Reduces carbon dioxide emissions Not usually suitable for connection to existing
heating systems using panel radiators
Efficiencies between 300% to 500% are typical. Initial installation costs can be off-putting
Relatively low maintenance is needed Air source installations can present a noise
issue
Improves Energy Performance Certificate
ratings
Ground source installations require a large
ground area or a borehole
Well Done! You have now completed the heat pump systems section.
Click on the forward arrow to return to heat producing technology system menu page

Environmental Technology System Awareness
Well done - you have now completed the Skills for Climate Change
‘Environmental Technology Systems Awareness’ learning tool.
Skills for Climate Change is a London Capital Colleges project.
Supported by Funded through Strategic partners

Environmental ppt gshp ashp

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