PROPOSED CODE OF PRACTICE FOR
INSTALLATION, OPERATION,
MAINTENANCE and REPAIRS OF SOLAR
WATER HEATING SYSTEMS
Draft issue
Friday,
January 28,
2005
Authors:
ASJF SLIEP
OD DINTCHEV
JE NIELSEN
1
PAGE №
4
ITEM
1.
1.1
2.
2.1
2.1.1
2.1.2
2.1.3
2.1.4
2.2
2.2.1
2.2.2
2.2.2.1
2.2.3
2.2.4
2.2.5
2.2.6
3.
3.1
3.2
3.3
3.4
3.4.1
3.4.2
3.4.3
3.4.3.1
3.4.3.2
3.4.4.
3.4.5
3.4.6
3.4.7
3.4.8
3.4.9
3.4.10
4.
4.1
4.2
4.3
LEGENT
SCOPE
Normative reverences
GENERAL NOTES and METHODOLOGY FOR INSTALLATION
System Descriptions
The method of heating are briefly explained as follows:
The advantages and disadvantages between direct and indirect….
Advantages:
Disadvantage
Main installation methods:
Close coupled system.
Split coupled system.
General comments.
SHWT mounted below the panel (s)
Climatic conditions and limitations
Optional extra, Client's preferences and conditions
Important notes and information when assessing an existing installation
SOLAR COLLECTORS
Testing and Certification
Installation and Maintenance
Certification
Installation
Tilt angle of solar collector.
Shading of Solar Collectors
Roof Installation of Solar Collectors
General requirements
Typical Roofs construction and Roof covering
Collector fixing and support roof constructions
Temperature expansions of support structure
Collector operating environment
Rain water on the collectors
Aging of solar collectors
Pollution in the atmosphere
Collector Piping Installation
Control systems
General
Control wiring
High & Low temperature protection
4.4
High & Low temperature compatibility for materials and components
15
4.5
Freeze protection
17
4.6
Scald protection
17
4.7
Protection against scale forming due to water hardness
17
4.8
UV protection
17
4.9
Reverse flow protection
18
4.10
Pressure- and Temperature-relief Protection
18
4.10
5.
Release of trapped air
PIPE INSTALLATION
General
18
18
18
5.1
Galvanic action
18
5
5
5
5
5
6
6
6
6
6
6
7
7
7
8
8
8
8
8
8
13
13
13
13
14
14
14
15
15
15
16
16
16
16
16
2
5.2
Tubing
18
5.3
5.4
5.
Insulation of exposed pipes installation
Material selection
SOLAR HOT WATER STORAGE TANK (SHWT).
19
19
20
5.1
General requirements:
20
5.1.1
5.1.2
5.1.3
5.1.3
Testing and Certification
Installation and Maintenance
Certification
Compliance
20
20
20
20
5.1.4
supplementary heating
20
5.1.5
Direct heated SHWT
20
5.1.6
In-direct heated SHWT
20
5.1.7
SHWT with heat exchanger
20
5.2
Roof construction
21
HWT installation under the roof
21
SHWT support under and/or on the rafters
21
5.5
Existing electric HWT (hot water cylinder)
21
5.6
Guarantees and Specifications
22
5.7
Materials to be supplied by the installer
22
6.
TYPICAL INSTALLATION INSTRUCTIONS TO BE FOLLOWED…
22
7.
INSTRUCTIONS TO THE USER
24
8.
Decommissioning
24
9.
Scheduled maintenances
25
10.
Re-commissioning
25
11
Definitions
26
Literature references
27
Table 1 Typical roof slopes (collector tilt angles) for different centres.
9
Fig.1. Annual ambient temperature and solar radiations at the region of Pretoria
10
Fig.2. Annual ambient temperature and solar radiations at a plane tilted at 30 0 Pretoria 10
Fig.3. Annual ambient temperature and solar radiations at the region of Durban
11
Fig.4. Annual ambient temperature and solar radiations at a plane tilted at 35 0 Durban. 11
Fig.5. Annual ambient temperature and solar radiations at the region of Cape Town
12
Fig.6. Annual ambient temperature and solar radiations at a plane tilted at 38 0 Cape Town 12
5.3
5.4
3
PROPOSED CODE OF PRACTICE FOR INSTALLATION, OPERATION,
MAINTENANCE and REPAIRS OF SOLAR WATER HEATING SYSTEMS
1.
SCOPE
This document is intended to be used as guidance for a base and acceptable
standards for installation and maintenance of solar water heating systems and
their components namely: Solar collectors, Piping-installation for Fluid
transfer systems, Solar Hot Water storage Tanks (SHWT) and Control
systems. The document summarizes the main requirements for proper
installation and with the gain of experience form the installers and
manufacturers in South Africa, it is intended to be updated on regular basis.
More detailed information may be obtained in references [1] and [2].
Note: this document deals with domestic solar systems in the range of ≥ 50litres
and ≤ 400 litres, system > 400 litres are classified as ‘commercial and industrial’
units in addition to compliance this code of practice they shall comply with
Occupation Health and Safety Act No 85 of 1993 for periodic test and
inspection of pressure systems. Normally these systems are designed to clients’
specific applications and specifications and are not of the shelf products. The
installation procedure follows a similar pattern as detailed below.
Normative References:
The following normative references contain provisions that through reference
to the text constitute provisions of this code of practice.
SANS 0142: Code of practice the wiring of premises.
SANS 198: Functional control and safety valves for pressurized hot & cold
water supply systems.
SANS 0254: The installation of fixed electric storage heating systems.
SANS 0400: The application of National Building Regulation.
SANS-460: Class 0, 1, 2 or 3 for plumbing applications.
SANS 60335-2-21: part 2 (Electrical requirements),
SANS ISO 6509 & SANS151: Pipe fittings and Hot water tanks.
ISO 9459: Solar Heating-Domestic solar heating systems. (Indoor method)
ISO/DIS 11924: For checking safety.
ISO 9806-1: Test method for glazed liquid heating collector including
pressure drop.
ISO 8906-2: Test method for solar collectors.
4
2.
GENERAL NOTES and METHODOLOGY FOR INSTALLATION
General back ground knowledge of solar water heating and the concepts of
assisted and passive designs are minimum requirements to understand the
requirements of different types of installations and this code of practice. The
literature reference [3], [5], [5], [6] & [7] provides enough details for general
back ground information on specific details that are important to be able to
install professionally.
2.1
System Descriptions
Solar systems consist of solar panel(s), directly or indirectly Heated hot Water
storage Tank (SHWT) and all necessary connections, protection and
regulating valves, ready to be connected to new and/or existing hot water
systems. The directly heated systems have also two distinct types the one as
specified above and in the other is the solar collector panel is an integral part
of the SHWT. These types of system consist of number of thick walled pipes
connected in series enclosed in an insulted casing covered with transparent
cover. The size of these systems is normally < 50 litres.
2.1.1
The methods of heating are briefly explained as follows:
The collector on the pipe grid in the solar panel heats up when the sun radiates
solar energy, this energy is converted to heat. Heated fluid rises to the top due
to reduction in density. This heated fluid flows into the storage tank for
indirectly heated systems or through the jacket round the SHWT or into an
internally positioned heat exchanger heating up the water inside the boiler, at
the same time colder fluid flows from the SHWT, jacket or heat exchanger to
the bottom of the panel creating a thermosiphon circulation loop.
2.1.2
The advantages and disadvantages between direct and indirect system is as
follows:
The performance of both methods of heating is approximately the same
depending on the make type and type of solar systems, The indirect system
has the additional heat exchanger mass to heat this and will sacrifice the heat
input into the water. The additional valves in the direct systems are and
additional resistance the flow that also results in heat losses.
2.1.3
Advantages:
5
A system operating with the indirect heating method can operate in ambient
temperatures from – 200C to 550C with the correct heat exchange fluid for the
above temperature range requires no protection valves for the circulation loop.
If the circulating loop is hermitically sealed with a pressure relief valve it
reduces oxidation of heat exchange fluid and maintenance.
2.1.4
Disadvantage
A direct heated system needs extra components such as anti freeze-, non
return- and ball valves for isolation and service. It increases the cost of
maintenance and the risk of system failure. Problems such as liming up of
these components and the fluid path in the panel reducing the heating capacity
and the efficiency of the system in time, this is eliminated in an indirect
system if the maximum water temperature is not limited to ≤ 600Celsius.
2.2
Main installation methods:
2.2.1
Close coupled system.
The SHWT and the panel are mounted on top of the roof (or on a stand at
extra cost). This is the most effective and economical way of installation it
maximizes the thermosiphon principle.
2.2.4
Split coupled system.
The SHWT is mounted in the roof space, but must always be higher than the
panel outlet connection, to make use of the thermo siphon principle. This
method of installation is labour intensive and has the greater risk of damage to
ceilings and roof.
2.2.2.1 General comments.
It is SANS 0254 (The installation of fixed electric storage heating systems)
regulation that a drip tray is installed under the SHWT, to reduce damage due
to water spills from TP-, ER valves and leaks.
Additional installation time and materials, such as pipes and fittings, are
required to connect the Pressure & Temperature (TP) safety valve and
Expansion Relief (ER) valve to a point outside the roof.
2.2.5
SHWT mounted below the panel (s)
If the position of the SHWT is below level of the top of the panel(s) or at the
same height, a circulation pump, with intelligent pump and valve controls and
6
temperature sensors in panel and SHWT are necessary. Additional power
supply and valves are required, to control the circulation of the heated fluid.
2.2.4
Climatic conditions and limitations
The RSA has one of the highest solar isolation of the world. Conditions are
very similar to that of the Sahara and Australian deserts.
Climate conditions in the RSA vary between extremes. Temperatures may
vary between –15 0C and 40 0C. Freak temperature changes during the winter,
are sometimes as much as 37 0C in a 24 hour period, frost will damage the
solar panel if there is no anti freeze in the water of the heating loop. Hail
protection is provided with 4 mm thick hardened glass on the solar panels.
To obtain maximum benefit of the solar energy input into the system, the
solar panels must be exposed to the sun during the whole day, the entire year.
Trees and large buildings may cast unwanted shadows.
To ensure maximum benefits and a long service life, the correct decision of
position and choice of system must be made.
There are alternative solutions and optional extras available to cater for
specific needs in heating domestic water with savings on electricity.
2.2.5
Optional extra, Client's preferences and conditions
Optional extras, client's preference, demands, requests and requirements
which are not practical to implement, can have a negative result on the solar
system performance. If the proper functioning of the solar system is serious
affected, do not start with the installation until a solution is negotiated. If the
functioning is not seriously affected the quoted installation fees may not cover
the cost, evaluate these demands, requests and requirements, assess the extra
cost and add to the installation cost. See § 2.2.6 below.
The full implications must be spelt out in writing to the client if he should
insist to proceed, the client must take full responsibility. It may be wise to
cancel the deal, rather than to deal with an unhappy client.
2.2.6
Important notes and information when assessing an existing installation
Evaluate client’s special requirements, a rough guide 50 litres of hot
water/person /day is a rough guide to determine the size of system, this may
vary depending culture and personal habits etc.
7
The installation task must be confirmed after a survey is conducted of the site
and the condition of the existing installation and hot water requirements of the
client must be confirmed.
Determine the age of the exiting installation. look for potential pit falls such
as leaks, lack of pressure, poor workmanship or maintenance practice; roof
structure safe and fit for purpose, if in doubt consult a roof specialist.
a) Determine if there are any complaints on the performance and
weaknesses in the existing installation, or anything that may cause
problems when you couple the solar system.
b) Please note that existing problems will be blamed on the solar
installation if not pointed out in a survey report to the potential client,
Measure pipe length of hot water pipes must be as short as possible, 2m and
longer must be insulated, do not exceed 5m runs.
3.
SOLAR COLLECTORS
3.1
Testing and Certification
3.1.1
Solar Collectors shall be certified for passing the tests in accordance with ISO
in accredited laboratory by SANAS.
3.2
Installation and Maintenance
Installation of solar collectors shall be installed and maintained in accordance
with the manufacturer’s manuals approved by the appropriate inspection and
testing authority endorsed by SolaSure.
3.3
Certification
A certificate indicating system specifications, alternative approved collectors
for that system and detailed schematic diagrams shall be provided by the
manufacturer with all new systems.
3.4
Installation
3.4.1
Tilt angle of solar collector.
Typical guidelines are considered below:
The roof pitch (tilt angle) shall be preferable be North facing within 45 0 NW
and NE from geographic North. The minimum roof pitch shall be ≥ 10 0 to
8
stimulate the thermo siphon and preferable ≤ 30 0.
Note 1: Within the above orientation and tilt angles, the loss of solar energy is
small during the winter period.
Note 2: For angles > 300 additional roof strengthening is required to support
the HWT.
For optimum collector orientation + 100NE ± 20of North and tilt angles see
Table 1-Typical roof slopes (collector tilt angles) for different centres.
Nearest Centre
the weather
bureau collects
data on
irradiation
Latitude
Minimum
Slope (more
energy in
summer)
Mean Slope
(a balanced
energy intake
throughout
the year)
Maximum
Slope (more
energy in
winter)
Average daily radiation...
over the whole year for
the mean slope
Bloemfontein
29 04'
25 0
30 0
35 0 *
6,7 kWh/m2/day
Cape Town
33 059'
300
350 *
40 0 *
6,0 kWh/m2/day
Durban
29 058'
300
350 *
40 0 *
5,1 kWh/m2/day
Port Elizabeth
33 059'
300
350 *
40 0 *
5,8 kWh/m2/day
Nelspruit
25 026'
250
300
35 0 *
5,6 kWh/m2/day
Pretoria
25 044'
250
300
35 0 *
6,0 kWh/m2/day
Upington
28 024'
250
300
35 0 *
6,9 kWh/m2/day
Note 3: Tilt angles values marked by (*) will require additional roof reinforcement (see Note 2 above)
The tilt angles in above table are a summation of statistically collected solar
energy for the different geographic locations in shown in above table 1. These
angles vary for different latitude values and yearly weather patterns.
The horizontal global energy irradiation values are shown in Fig.1.
These values are monitored by weather bureaus. This information is statistical
data from measurements and serves as a guide only. A rule of thumb is
degrees latitude plus 5 0 for the tilt angle of installation.
9
Fig.1. Annual ambient temperature and solar radiations at the region of
Pretoria
Fig.2. Annual ambient temperature and solar radiations (including at a plane
tilted at 30 0 ) at the region of Pretoria
10
Fig.3. Annual ambient temperature and solar radiations at the region of
Durban
Fig.4. Annual ambient temperature and solar radiations (including at a plane
tilted at 35 0 ) at the region of Durban.
11
Fig.5. Annual ambient temperature and solar radiations at the region of Cape
Town
Fig.4. Annual ambient temperature and solar radiations (including at a plane
tilted at 38 0 ) at the region of Cape Town
From figures 1 to 6 above is evident that titling of the plane of the solar
collectors ensures evenly distributed solar input during the year.
The irradiation value for the daily energy on the panel must be sufficient for
the worst month when the ambient temperatures are lowest, say between
May- July periods when the demand for hot water is the greatest.
12
3.4.2
Shading of Solar Collectors
The installation of the solar collectors shall be such that the harvesting of the
solar energy will be not obstructed by trees, buildings etc. Attention should
be paid that the sun obstruction is seasonal and might differ during the year.
The intended installation space of the collector(s) must be free of shadows,
between 8:00 AM and 5:00 PM, from trees and other buildings right through
the year to estimate the shading of the collectors proper instrumentation is
recommended to be used by the installers.
3.4.3
Roof Installation of Solar Collectors
3.4.3.1 General requirements
Normally, the installations on the roofs shall be done in accordance with code
of practice SANS 0400. (The application of National Building Regulation),
part L.
For the collector angle of tilt is less than 20 0, the installation space for the
HWT in the roof is seldom sufficient and interconnecting piping becomes too
long for the efficient operation of the thermo siphon process. The working
space is difficult and very labour intensive thus costly.
In the above situation or on flat roofs, install a closed coupled system on top
of the roof at the best angle.
The addition of a circulation pump and temperature differential control is
recommended as an alternative if the client does not want the HWT on the
roof and this is located below the panels.
If pre-manufactured roof trusses are used in the construction, please verify
with the manufacturer, whether these trusses are strong enough to carry the
additional weight of panel and HWT.
The design may not allow for the extra load and supports to be attached to
these trusses. The client may lose the warranty on the structure if the
manufacturer is not notified.
3.4.3.2 Typical Roofs construction and Roof covering
There are several types of roofs covering on which solar panels can be
installed without much of problems namely; corrugated asbestos plate
galvanised or steel roof plates, Harvey tiles and cement or ceramic roof tiles.
13
Roof covered with a slate type of tile, such as Mazista, asbestos, shingles,
ceramic or cement type of slates avoid installation of the SHWT under the
roof space. The sealing the panel hot and cold water pipes require special
attention and sealing methods with a flexible seal to avoid frequent
maintenance. The roof rafter spacing is small and the tile covering is three
layers that are expanding and contracting with ambient temperature changes
Installation of solar collectors on thatched roofs should be done with special
precautions and in collaboration with a roofing contractor. The roof angle is
normally to steep and the thatching material under the system will rot with
time.
3.4.4. Collector fixing and support roof constructions
The installation of the solar collectors on the roof shall not obstruct the flow
of water consult the local Bylaws on the location of installation. The solar
collectors and the entire solar water heating system shall not introduce a load
on the entire building structure (roof, walls and the foundations) that could
lead to destruction of either of them.
Support constructions and collectors after installation shall not obstruct the
normal water flow and collection of the roof of the building causing water
overflowing on the roof coverage or water collection on certain parts of the
roof surface.
The type of collector roof fixing and support constructions depend on the type
of the system: thermo siphon (split and compact), integral and the type of the
roof and its waterproofing coverage: tiles, corrugated iron, Harvey tiles,
thatched roofs etc.
For thermo siphon systems on flat roofs a separate support structure for the
entire system is recommended. The tilt angle shall be within the limits ≥ 10 0
and ≤ 300, (See § 3.4.1 above).
Excessive winds typical for the installation location may require additional
supports and fixtures on the roof that are not necessarily recommended by the
manufacturer.
3.4.5
Temperature expansions of support structure
Installers shall take precautions to ensure that the temperature expansion of
the materials due to high working temperatures, does not affect the collector
integral structure, the roof structure or the entire building.
14
3.4.6
Collector operating environment
Installers shall install solar collectors and their accessories (pipes valves etc.)
according to the manufacturer’s recommendations. Care shall be taken on the
local supply water pressure, local working temperatures and local weather
conditions.
3.4.7
Rain water on the collectors
The installer shall facilitate the natural flow of the rain water to avoid water
penetration inside the collector assembly. Normally in South African
conditions, installing the panels on the optimum tilt allows the rain water to
flow without danger of accumulation and penetration could not occur. Snow
is rare in South Africa and it is not affecting the solar collectors.
3.4.8
Aging of solar collectors
Solar collectors shall be tested in compliance with ISO-9806-1&2 to
determine their resistance against various atmospheric conditions. The
manufacturer shall ensure that all material used for the collectors, piping and
support structure shall not degrade during their exposure to the sun and its
radiation (including UV radiation) during their designed operational period of
time.
3.4.9
Pollution in the atmosphere
South Africa has various zones where apart form the natural airborne
pollutants such as salt, abrasive dusts in addition there are many industrial
emissions such as SO2, NOx and acid rains. The solar collector materials and
accessories shall be not affected in a way that will disturb their normal
operation in the designed operational lifetime. The manufacturer shall apply
additional measures in order the solar collectors and accessories to be
operational without disturbances in the various geographical areas in South
Africa. Care shall be taken by maintainers to replace the faulty collector or
components with ones that are designed to work in the particular location of
the installation.
Dust collection of the collector aperture is leading to decreasing of the
collector performance and the manufacturer shall advice the users how and at
what interval of time the collectors shall be cleaned in the particular
installation location. Also installers shall provide conditions for system owner
to perform the periodical cleaning of the collectors without damaging the roof
and the system. Most collector panel apertures cover fittings are designed to
be cleaned by rain water.
15
3.4.10 Collector Piping Installation
Collector connection pipes are part of the solar water heating system and
installer shall provide sufficient slope allowing draining of the collector fluid
for the purposes of maintenance, repair or prevention of freezing at certain
geographic areas in South Africa.
4.
CONTROL SYSTEMS
4.1
General
Control system may employ various components such as: valves, pumps,
thermal sensors, heating elements, thermostats etc. these shall comply with
safety standards SANS 60335-2-21 part2 (Electrical requirements), SANS
198 (Functional control and safety valves for pressurized hot & cold water
supply systems) & SANS 0254 The installation of fixed electric storage
heating systems and SANS0142 code of practice the wiring of premises.
4.2
Control wiring
Appropriate wiring is done for normal operation of the system.
Manufacturers shall use materials capable to withstand the high operational
temperatures and UV radiation, which is typical for South African conditions.
Installers shall comply with the manufacturer’s recommendations regarding
the insulation and protection of the wiring system.
4.3
High & Low temperature protection
The system shall withstand prolonged high solar radiation without any draw-off
of hot water. A suitable heat energy dissipation facility shall be incorporated.
a) For pumped systems a fluid drawdown facility shall be provided with
temperature differential protection.
b) For thermal siphon systems heat controlled energy dissipation equipment shall
be fitted to the system, equipment of a passive design is preferred. Note; if this
protection is dependent on an electricity supply it shall be clearly defined in the
Operational Manual (OM). The maximum temperatures shall specify by the
manufacturer. See “ Minimum temperature protection”
4.4
High & Low temperature compatibility for materials and components
16
The materials and components selected for solar systems shall be such when
exposed to temperatures between 200 and -30 degrees Celsius for the solar
collector panels and between 98 and -5 degrees Celsius for hot water storage
tanks can withstand and perform they’re functions without any determination.
4.5
Freeze protection
The minimum allowed temperature for the system; all parts that are exposed to
outdoor conditions shall withstand temperatures as low as -20 degrees Celsius.
a) For direct heated system describe the method of freeze protection used for the
system. This freeze protection shall not be of the type that causes excessive
water losses.
b) If any of the indoor installed equipment that may be subjected to temperatures
below 0 degrees Celsius, this equipment shall be protected against freezing. .
If Heat Exchange fluid is used as freeze protection additives to the potable
water as freeze and corrosion protection shall comply with USA Code of
federal regulations, title 21, Food and Drugs, chapter 1, Food and Drug
Administration, part182, “Substances Generally Recognized as Safe” and Part
184,”Direct Food Substances Affirmed as Generally Recognized as Safe” for
fluids in Heat Exchange (HE) circuits, if mixing with the potable water in the
storage tank is a possibility due to failure common heat transfer surfaces.
The choice of fluid if used as an additive to water or any other liquid medium
shall be contained to prevent the fluid from deterioration as result of high and
low temperatures, a sealed system is preferred to prevent the additive from
oxidising.
c) Collectors and other equipment that are not effectively protected against
damage from freezing shall be labelled "Not suitable for frost areas unless
protected by a frost protection system or device”
4.6
Scald protection
4.7
For systems in which the temperature can exceed 60 degrees Celsius the
Operation Manual shall specify that an automatic mixing valve shall be
installed to reduce the water temperature below 60 degrees Celsius.
Protection against scale forming due to water hardness
Scale forming has a serious long-term effect on the efficiency and performance
of solar systems. If the solar systems are intended to be used in areas with high
water hardness and/or the temperatures may exceeding 60 degrees Celsius, the
systems shall be designed to prevent scaling on heat transfer surfaces in contact
with potable water or service access facilities shall be provided to remove the
scale and clean heat exchange- and internal surface of the heat collecting pipes
on the collector panels.
17
4.8
UV protection
Materials and components of solar systems that are installed outdoors shall be
resistant to UV radiation and other weather conditions over the required life
expectancy period. The Operation Manual shall define the life expectance,
maintenance frequencies, and life cycle cost of exposed components and
availability of spares to maintain the system in good working order for a
minimum of a 10-year period.
4.9
Reverse flow protection
4.10
Reverse flow protection shall be fitted to direct heated thermo siphon systems
with backup heating to prevent increased heat loss. The possibilities exist that
in a reverse flow can develop in cold nights or rainy days. Refer CSIR report
246 Chinnery.[5]
Pressure- and Temperature-relief Protection
In addition to the general safety requirements § 1 “general” above, all
unvented solar collector systems shall be fitted with an additional safety
pressure- and temperature-relief protection valve, The thermal discharge
rating shall not be less the than total output power of the collector at 99o
Celsius water temperature 1200m2 at 400 Celsius ambient.
4.10
Release of trapped air
Provision shall be provided to release any trapped air in pipe system with a
suitable air release valve, buffer or open vent.
5.
PIPE INSTALLATION
General
The pipe installation shall at al times be neat and tidy to ensure a pleasing
ecstatic appearance were exposed on the roof
The materials of the pipe installation shall be in accordance with the
following.
5.1
Galvanic action
5.2
All fittings in contact with potable water shall be galvanically compatible with
the material hot water storage tank surface in contact with this water.
Tubing
18
The tubing shall meet the pressure requirements of the system, tank and / or
heat exchanger.
Copper pipes shall comply with SANS-460 class 0, 1, 2 or 3 for plumbing
applications. The choice of the class of pipe depends on design, working
pressures, resilience and fatigue it shall have a resistance to stress corrosion
cracking, bio failing, crevice corrosion at joints and suitable for working life
requirements. For working conditions in excess of 150 degrees Celsius
maximum allowable stress 20 MPa. Note: Class 0 is suitable for soldering
only, class1, 2, 3 pipes are suitable soldering, bracing and compression
fittings. If components from copper alloy are used in the manufacturer the
absorber shall be resistant to dezincification and stress corrosion cracking, as
set out SANS ISO 6509.
Stainless tubing complying with the requirements of ASTM is dictated by the
system design, working pressure resilience and fatigue it shall have a S
Special matched pipes and fitting shall be supplied with a complete system.
5.3
Insulation of exposed pipes installation
Installation material supplied by other parties, take note that the fluid pipes of
the solar panel are made from copper, stay clear of galvanised components on
the HWT to the panel installation.
Do not use any commercially available plastic pipes, maximum allowable
temperatures are below 70 C for these types of pipes. Temperatures may
reach values in excess of 90 C.
Thermal insulation shall comply with clause 3.3 above but shall have the
following additional requirements: the insulation material shall not degrade or
outgas when subjected to maximum stagnation temperatures and is exposed to
sunlight and UV radiation under operating conditions. If necessary a good
outdoor paint finish or a aluminium foil cover shall be provided.
5.4
Material selection
Special matched pipes and fitting shall be supplied with a complete system.
Installation material supplied by other parties, take note that if the fluid pipes
of the solar panel are made from copper, stay clear of galvanised components
on the HWT to the panel installation.
Do not use any commercially available plastic pipes, maximum allowable
temperatures are below 70 C for these types of pipes. Temperatures may
reach values in excess of > 90 C.
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5.
SOLAR HOT WATER STORAGE TANK (SHWT).
5.1
General requirements:
5.1.1
Testing and Certification
SHWT shall be certified for passing the tests in accordance wit ISO-9459 in
an accredited laboratory by SANAS.
5.1.2
Installation and Maintenance
Installation of HWT shall be installed and maintained in accordance with the
manufacturer’s manuals approved by the appropriate inspection and testing
authority endorsed by SolaSure.
5.1.3
Certification
Certificate indicating system specifications, alternative approve SHWT for
that system and detailed schematic diagrams shall be provided by the
manufacturer with all new systems.
5.1.3
5.1.4
5.1.5
5.1.6
Compliance
The SHWT hot water storage container shall generally be in accordance with
SANS151. Systems with a capacity > 400 litres are classified as ‘commercial
and industrial’ units in addition to compliance this specification they shall
comply with Occupation Health and Safety Act No 85 of 1993 for periodic test
and inspection of pressure systems
Supplementary heating
Systems provided with facility for a form of supplementary heating (gas,
paraffin, wood, electrically heated, etc. This facility shall only heat 50% of the
SHWT to prevent for running of supplementary heating thus allowing for solar
energy input.
The provision of electrical heating elements and control thermostats for to the
tank shall be SANS 151 §5.5.
Direct heated SHWT
Single Shell SHWT, this tank is similar to a standard Hot Water storage Tank
(HWT) (see) with the addition of two additional inlets to connect to the solar
panel(s) and is better insulated.
In-directly heated SHWT
Composite Shell SHWT, this tank is similar to tank specified in a) above with
an additional jacket type heat exchanger installed around the storage tank.
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5.1.7
SHWT with heat exchanger
This SWHT is similar § 5.15 with the exception that it has an internal
removable (or fixed) or an external installed heat exchanger.
5.2
Roof construction
If the roof trusses are constructed from 150mm x 38mm wood at a pitch of
500crs with central king post (Class B Part L SANS 0400) or from good
quality gum poles 150mm diameter, the roof structure is normally strong
enough to support a solar system.
If pre-manufactured roof trusses are used in the construction, please verify
with the manufacturer, whether these trusses are strong enough to carry the
additional weight of panel and SHWT.
The design may not allow for the extra load and supports to be attached to
these trusses. The warranty conditions may be not applied and void if they are
not notified.
If the length pipe of panel hot water outlet to SHWT inlet is more than 1 m,
the efficiency of the system is affected and insulation of the hot water outlet
pipe from the panel is recommended.
5.3
HWT installation under the roof
The position of the ceiling and the space above the ceiling is factor to be
considered whether or not a split system can be installed, if in doubt, install a
close-coupled system on top of the roof at the correct angle.
SHWT installation under the roof: Check if SHWT can be raised above the
panel level a minimum distance 200 mm above solar panel hot water outlet
and sufficient space (of ~250 mm) above the SHWT to under side roof rafters
for pipe fittings and valves.
5.4
SHWT support under and/or on the rafters
Where possible SWHT the support structure must supported on the 220mm
thick walls.
Extra support fixtures are needed if only 110mm walls are available (note:
110mm walls are not load bearing walls).
If the roof trusses must be used as support, make sure that the construction
can carry the weight. Obtain professional advice if in doubt.
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5.5
Existing electric HWT (hot water cylinder)
If the installation of a SHWT is required to replace a faulty hot water system
isolate the HWT and connect the solar system to existing installation.
If the solar system is additional to a working hot water system (electrically
heated or by other means), retain the system and install the solar system as a
pre-feed to the existing hot water cylinder. Note that usually the electric water
heaters in South Africa are not well thermally insulated and the overall losses
of the system will be increased.
The SHWT hot water outlet may be connected to the existing HWT piping,
feeding the cold water inlet and re-direct the existing cold water feed to the
solar HWT.
If an existing installation and HWT is older than 20 years check “system
pressure”. If the pressure is ≤ 200 KPa avoid installing a high pressure (400
KPa) valve and connecting to the existing HWT in this installation. Hot water
installation especially galvanized pipes, welds on socket fixtures may have
hidden defects and are weakened this may cause the loss of the existing HWT.
Considerable energy cost savings can be achieved with this arrangements and
more hot water is available.
5.6
Guarantees and Specifications
Be aware that guarantees may be null and void if the installation is not done to
SANS or J.A.S.W.I.C. standards, and specifications. Panel guarantee is also
subject to correct installation procedures, environmental and/or climactic
conditions.
5.7
Materials to be supplied by the installer
Materials such as piping from the system to the existing installation, pipe
insulation, water proofing materials, wood for supports, coach bolts and nails
to build the structure supporting the SHWT and panel(s), drip tray, fitting &
pipes to connect to a point the relief valve(s) and PT valve outside roof space
to a drain. Note: it is compulsory that PT exhaust pipe shall be copper or
Sainless Steel.
6.
TYPICAL INSTALLATION INSTRUCTIONS TO BE FOLLOWED BY
INSTALLER
STEPS FOR ROOF MOUNTING SYSTEM:
1.
If required, reinforce trusses under roof to support the solar HWT.
2.
Install the HWT and solar collector(s) on the roof or structure. It is wise to
cover the panel during the installation and filling processes to avoid the heating
up of the panel(s). Use the packaging or cartons to cover it.
3.
Couple solar panel pipes in accordance with the attached sketches and parts list.
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Connect the hot and cold water to the HWT and start filling HWT with cold
water. (Important: when installing and connecting into an existing installation
before connecting, inspect the existing HWT, pipes, valves and fittings for
deterioration, faults and or blockages, replace if necessary, at extra cost). If the
regulating / expansion relief valve is old, replace this at extra cost. If the
installation is in accordance with SABS code of practice, the HWT may not
need draining of the hot water.
4. Fill panel and HWT jacket with heat transfer fluid. Check for leaks. Stop filling
if leaks occur, fix the leaks before carrying on with the filling process. If leaks
occur on the panel connections, be very careful hot fluid may be present due to
the lack of circulation, if the panel was not covered.
GO TO STEP 8
STEPS FOR A SPLIT SYSTEM HWT UNDER THE ROOF:
1.
Erect the SHWT platform at a height as per above requirements.
2.
Install the HWT on the platform (it is advisable to install this SHWT in
accordance with SANS. 0254 (The installation of fixed electric storage heating
systems) regulation that a drip tray is installed under the SHWT.
Proceed with connecting the hot and cold-water connections to the HWT and
fill HWT with cold water. (Important: when installing and connecting into an
existing installation before connecting, inspect the existing HWT, pipes, valves
and fittings for deterioration, faults and or blockages, replace if necessary at
extra cost.) If your regulating / expansion relief valve is old, replace this as
well. If the installation is in accordance with SANS standards, the HWT may
not need draining of the hot water).
3.
Install the solar panel on the roof or structure. It is wise to cover the panel
during the installation and filling process to avoid the heating up of the panel.
Use the packaging or cartons to cover it.
4.
Couple solar panel pipes in accordance with the attached sketches and parts list.
Make certain that all interconnection between the panel an HWT slope
continuous upwards to avoid air locks.
5.
Connect the outlet of the high temperature / pressure relief valve to some point
outside the building. Do not use any plastic pipe for this connection, boiling
water will damage this pipe and can cause considerable damage. (This is a
safety device to prevent the HWT from exploding.)
6.
Connect the expansion relief valve to some point outside the building. If this
valve is on the cold side, as shown, plastic pipe can be used for this connection.
This valve releases cold water to make place for expanding hot water. (Note:
This valve is shown be integrated into the regulating valve but can also be a
separated valve on its own.)
7.
Fill panel and HWT jacket with heat transfer fluid. Check for leaks. Stop
filling if leaks occur, fix the leaks before carrying on with the filling process.
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If leaks occur on the panel connections, be very careful hot fluid may be
present due to the lack of circulation, if the panel was not covered.
8.
Commissioning and tests
Finally, when the system is full of cold water and heat transfer fluid, remove
the covers from the panel (s) and feel the hot outlet fluid pipe on the top of the
solar panel, this will warm up immediately after exposure to the sun and
bottom intake pipe to the panel will remain cold. This test must be done on a
sunny day between 10:00 AM and 4:00 PM.
9.
If the system passes the test in step 8 above congratulation the Solar system is
working.
10.
If both hot and cold fluid pipes heat up, cover the panel and check all the
piping for wrong connections and sagging pipes. There may be air locks or
blockages in your system.
Go through the drawings and steps 3 to 8 above or contact the supplier/
manufacturer.
7.
INSTRUCTIONS TO THE USER
a.
To achieve the maximum saving on electricity cost, the usage of hot water
must be adapted to the availability of solar heated water. The HWT should
only be switched on during rainy, clouded or cold winter days or in the case
when excessive quantities of hot water are required (additional people or
special circumstances such as guests, illness, parties etc.).
If the electricity is switched on a daily basis right throughout the year
maximum savings are not obtained.
b.
c.
To test the system for the correct operation start the system without electricity
to the HWT and see if solar heated water will be sufficient for normal running
of your household.
If it is found that the hot water supply is not sufficient we advice to have an
additional timer installed to control selective boosting during the night and/or
the evenings. Contact The supplier or manufacturer for information.
NOTE: If the system requires an electrical connection a qualified installer
and or electrician can only do this.
8.
Decommissioning
Decommissioning of a solar hot water system is required if the unit has to be
removed or a major service or repairs are required
A major service or repair requires that the system shall be rendered “inactive” and safe to work on panels, SWHT, pipes, pipe insulation and
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protection components. Normally only required with damaged panels,
excessive leaks on piping and SWHT.
8.1
Proposed steps for decommissioning
General notes: Decommission step are necessary to render the equipment safe
to work on or so that it can be handled in safe manner.
a) Cover panels early morning before sun-rise to stop solar energy intake.
b) Perform a general inspection and /or test on the solar system, supplementary
heating, and the roof structure or stand supporting the solar to verify that the
system and support structure is for fit service.
c) Close main water supply valve to the solar system.
d) Close panel valves (if any).
e) Drain water from SHWT if connect the outlet pipe to a drain that can handle
hot water.
f) Drain water or heat exchange fluid from solar panels.
g) Inspect all pipe insulation, pipes and pipe fittings, for small leaks corrosion
ore other deterioration perform the necessary repairs.
h) Remove and replace the faulty equipment or perform the necessary service or
repairs.
9. Scheduled maintenances
i) Cover panels early morning before sun-rise to stop solar energy intake.
j) Perform a general inspection on the solar system and the roof structure or
stand supporting the solar to verify if the support system is for fit service.
k) Perform the maintenance as per manufacture instructions.
10 Re-commissioning
Follow the steps as § 6 where applicable.
11. Definitions
11.1 Acceptable, acceptable to
 The authority responsible for administration of the standards.
 In relation to the standards, inspecting and/or testing verification
authorities, institutions responsible for financing and administration
the solar initiatives.
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Literature references: .
[1] Solar Rating and Certification Corporation. (SRCC) Standards
Web site at :
http://www.solarrating.org/education/og300education.htm.
[2] Florida Solar energy Center (FSEC) Standards
Web site at:
http://www.fsec.ucf.edu/stds/st/index.htm
[3] Copper Brass Bronze Design Hand Book Solar Energy Systems
[4] Maksal tubes (Selection of Tubing, Performance of Copper Tubing
and Technical Specifications & Design Data).
[5] Solar Water Heating in South Africa. (With special reference to § 5
Thermo–Siphon Circulation and Reverse Flow) by D.N.W.
Chinnery;
CISR: Research report № 248.
[6] Primer for Energy Conscious Design. ( § 10) by Dieter Holm &
Reinhold Viljoen. (A publication available at DME.).
[7] Solar Engineering of the thermal processes ( chapter 12) by John A
.Duffie, William A. Beckman, Solar Energy Laboratory University
o Wisconsin-Madison
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