Table of Contents
Advertisement
PRE - INSTALLATION
3
PRE - INSTALLATION
3.1
GROUND SOURCE HEAT PUMP OPERATION
As the outside temperature gets colder, the heat demand of a house
increases and the output of an ground source heat pump will decrease.
Eventually it becomes so cold outside that the output of the heat pump
alone is not able to heat the building effectively. The Greestore range of
ground source heat pumps therefore allows for monoenergetic and
bivalent operation.
Monoenergetic means that in the event of very low external
temperatures a 3-stage electrical booster heater in the indoor unit will
automatically be activated to provide additional heat and keep the
building warm.
In bivalent operation a second heating appliance (e.g. gas or oil boiler) is
used to supplement the heat load.
3.2
SELECTION AND SIZING OF A HEAT PUMP
It is essential that heat pump systems are designed to operate efficiently
in order to meet the building heating needs and the expectations of the
customer. In order to achieve this, the following design activities must
be completed prior to installation:-
• Pre-design assessment - Determine the suitability of a heat pump
system for the building based on the customer requirements,
expectations and building type.
• Detailed design - Complete building heat loss calculations and
domestic hot water usage assessment.
• Specification - Select a suitable heat pump and system components
based on the detailed design. Calculate and communicate the
predicted energy use and running costs of the system to the
customer.
A suitable design methodology for the above is detailed in MIS3005, the
Microgeneration Certification Scheme (MCS) heat pump installer
standard. Worcester, Bosch Group recommended that this standard is
followed for heat pump systems. The standard covers the design,
installation and commissioning requirements to ensure that 100% of the
building heat loss can be met efficiently by the heat pump system. A heat
pump system must be designed to this standard to be eligible for
government financial incentives e.g Renewable Heat Incentive (RHI).
The Worcester Bosch Group design team offer a heat pump sizing
service which is MCS compliant. To request this service, download and
submit the form using the guidance notes from our website address:
www.worcester-bosch.co.uk/hp
3.3
HEAT LOSS
The total heat loss of the house is calculated from the addition of fabric
and ventilation heat losses.Fabric heat loss is the transmission of heat by
conduction through the building structure, i.e windows, walls, roof and
floor. Ventilation heat loss is heated air escaping from the house and
being replaced by cold air from outside.
3.3.1 CALCULATING THE HEAT LOSS OF THE HOUSE
It is essential to accurately calculate the heat loss of the house to ensure
correct sizing of the heat pump system. The heat loss is dependent on
the construction of the house, room sizes, external and internal design
temperatures and air change rates. The heat loss calculations should
satisfy the requirements of BS EN 12831.
3.3.2 ESTIMATING HEAT LOSS
Estimating the heat loss of the building is useful in determining the
suitability of a heat pump system. However, assumptions based on floor
area (e.g. 50 W/m² for new build etc.) and SAP (the governments
Standard Assessment Procedure) should not be used for the detailed
design and specification stage. It should be noted that the heat loss for
4
non standard houses i.e. houses with large areas of glazing, high
ceilings, log burners etc. or houses in exposed locations may deviate
significantly from any rules of thumb.
In existing properties, boilers are often oversized and should therefore
not be used to determine the actual heat requirements of the house.
However, estimates may be made on the basis of the existing energy
consumption of the space to be heated.
This installation manual does not cover all the necessary details to
calculate the heat loss. The information given here is provided to remind
the heating system designer and installer of the process and
considerations.
4
HEAT EMITTERS
Worcester, Bosch Group heat pumps are fitted with weather
compensation controls as standard. However, for a heat pump to
perform to its highest energy efficiency, the central heating emitter
circuit should be designed so that the flow temperature is as low as
possible.
As a guide, the system should be designed using the following maximum
flow temperatures;
• Underfloor heating: 35-40 °C
• Radiators: 45-50 °C
If underfloor heating has been installed, it is important to remember that
the underfloor system designer should have been informed that the heat
source will be from an air source heat pump. It is also important to
remember that radiators should have been correctly sized to work
effectively with lower flow temperatures.
A tool to aid installers and end users to understand the relevance of
building heat loss and heat emitter selection on heat pump performance,
has been created by the joint trade associations. The 'Heat Emitter
Guide' can be downloaded from the following website:
www.microgenerationcertification.org
5
REGULATIONS AND STANDARDS
Installation of this heat pump should be done in
accordance with MCS/MIS 3005.
This appliance must be installed and serviced only by a competent
person in accordance with the current: IEE Regulations, Building
Regulation, Building Standards (Scotland) (Consolidation), Building
Regulations (Northern Ireland), local water by-laws, Health & Safety
Document 63S (The Electricity at Work Regulations 1989), IS 813
(Eire) and other local requirements.
The relevant Standards should be followed, including:
BS7074:1: Code of practice for domestic and hot water supply
EN:12828: Central heating for domestic premises
BS7593: Treatment of water in domestic hot water central heating
systems
BS814 EN 14511: Requirements heat pumps for space heating
BS EN 378: Safety and environmental requirements for heat pumps
The Health and Safety at Work Act 1974
The Management of Health and Safety at Work Regulations 1999
The Construction (Health, Safety and Welfare) Regulations 1996
The Construction (Design and Management) Regulations 1994
The Lifting Operations and Lifting Equipment Regulations 1998
Where no specific instruction is given, reference should be made to the
relevant codes of Practice.
Potable water: All seals, joints, compounds (including flux and solder)
6 720 806 768 (2013/02)
Advertisement
Table of Contents
