Cool-sky Apricus User manual

CoolSky Ltd 42 Milecross Road, Newtownards BT23 4SR
Tel: [phone]
Email: [e-mail]
Company Registration No. NI072166
VAT No. GB 108838970
Copyright © 2012 CoolSky
07209 - CoolSky Covers_Layout 1 06/02/2012 12:59 Page 1

Apricus Installation Manual
2
TABLE OF CONTENTS
Solar Thermal Introduction 3
Technical Specification of The Apricus Collector Range 6
Solar Pumping Station 9
Pump Sizing 10
Solar Expansion Vessels 11
Sizing and Designing your Solar System 18
System Sizing 19
Sizing the Solar Cylinder 21
Pipe Type and Size 21
Stagnation & Overheating 22
Connection of Multiple Collectors 25
Balancing Flow through Collectors 25
Wind & Structural Loading 26
Back-Up Heating Source 29
Anti-Scald / Tempering Valves 29
Closed Loop Max Incoming Pressure 29
Maximum Allowable Pressure 29
Electrical Supply 30
Labelling 30
Building Considerations 31
Health & Safety Considerations 32
Installation Guidelines 34
Manifold and Bottom Support Track Assembly 35
Other System Components 37
Collector Installation 38
Connection to Plumbing 44
Insulation 44
Installation of the Tubes 46
Commissioning The System 50
Post Installation 52
Clean Up 52
Maintenance & Repair 53
Maintenance Schedule 55
Troubleshooting Guide : 56
Home-Owner Maintenance 60
Glossary of Terms 63
Important Information 64

Solar Thermal Introduction
Introduction
CoolSky Ltd. are distributors in the U.K. and
Ireland for the Apricus range of Evacuated
Tube Solar Thermal Collectors. Since their
formation in 2002, Apricus have quickly
established themselves as a global company
with offices in USA, France and Australia with
sales in over 30 countries worldwide.
Apricus have a modern manufacturing facility
that includes a 6,500 m2factory floor,
administration offices and an R&D Centre.
Apricus Collectors conform to the European
Standard EN12975 and carry the European
SolarKeymark Certification ( Licence No. 011-
7S161R ) as a mark of their quality, reliability
and performance.
SolarKeymark is considered to be equivalent
to MCS Product Certification thereby
qualifying the products for financial
assistance under various funded schemes
where available.
All Apricus collectors, components and
packaging have been carefully designed so
that they can be efficiently recycled at end-
of-life.
Solar Energy
Solar Energy is the planet’s most abundant
source of energy with the added benefit that
it is both clean and free.
(Source : EU Commission Joint Research Centre)
Whilst the UK and Ireland are considered to
have mild and temperate climates there are
parts of the UK that can receive annual
radiation levels equivalent to 65% of the
radiation that is received in places like
Madrid, Spain, making both the UK and
Ireland suitable locations for Evacuated Tube
Solar Thermal Collectors.
The Apricus Evacuated Tube Solar Collector
provides an efficient solution for the capture
of Solar Radiation and is ideal for use in UK
and Irish climatic conditions. Although the
peak solar radiation period in the UK and
Ireland is in the months from May through
to August, the Apricus Evacuated Tube Solar
Collectors are highly efficient and able to
harness the energy of the sun throughout
the year and to also provide a useful
contribution to heating during the off-peak
months.

Apricus Installation Manual
4
Evacuated Tube Solar Thermal Collectors are
able to capture the available Solar Energy
and then transfer it as Thermal Energy to the
water heating system, thereby raising the
temperature in the hot water storage
cylinder, and offsetting the reliance to on
alternative fuels (such as coal, gas, oil or
electric) to provide hot water. Up to 70% of
the domestic hot water requirements can be
met by the Apricus Solar Collectors.
Since solar radiation levels depend upon
both the season and the daily weather
conditions it is always necessary to
incorporate a back-up water heater (typically
standard fossil fuel boilers or electric
immersion heaters) to ensure there is a
sufficient supply of hot water all year round.
Key Components of the Solar
Thermal System
Solar Energy is collected when the sunlight
strikes the black selective absorber contained
inside the evacuated tubes of the Solar
Collector.
Each tube contains a copper heat-pipe that
is in contact with the absorber. The heat-
pipe contains a small quantity of water
under a vacuum environment that allows the
water to start boiling at temperatures as low
as 30°C. The water vapour generated when
boiling rapidly rises to the top of the heat
pipe where it condenses and transfers its
thermal energy to the condenser and into
the copper header pipe within the manifold.
Fig. 2 Schematic showing the basic layout of a simple solar thermal
system.
The condensed fluid then flows back down
the heat pipe and is re-heated, thereby
restarting the thermal cycle again.
A circulating pump moves the heat transfer
fluid (a propylene-glycol anti-freeze mixture)
through the copper header pipe within the
manifold and back to the storage cylinder. A
solar heat exchanger coil within the storage
cylinder transfers the thermal energy from
the heat transfer fluid into the water within
the storage cylinder. The cooled fluid then
returns to the collector manifold to be re-
heated.
The operation of the solar loop is controlled
with a temperature differential electronic
controller. This ensures that solar fluid is
only circulated in the solar loop when there
is useful energy to transfer from the
collector into the storage cylinder.
Back-up heating using a conventional fossil
fuel boiler or electrical immersion should
also be provided for periods when solar
radiation is unable to meet the total hot
water demand.

5
Apricus Collectors
The Apricus Collectors are available in 3
Standard Models as follows :
APSE-10 10 Tubes
APSE-20 20 Tubes
APSE-30 30 Tubes
All the Apricus Collectors are certified to the
European SolarKeymark Scheme thereby
ensuring the installer and end-user of the
highest standards and quality in materials
and manufacturing, which also qualifies the
collectors for government funded schemes
requiring MCS Certification.
The Apricus Solar Tube consists of a circular
inner absorber tube that is coated with a
selective absorber layer of Al/N on Al. This
selective absorber provides each tube with a
highly selective radiation absorbing surface,
with typical absorption efficiencies of >92%.
The absorber tube is encased within a strong
borosilicate glass enclosure that is then
placed under ultra-high vacuum conditions
to ensure the ultimate performance in terms
of thermal insulation.
A getter coating at the bottom of the tube is
used to maintain the ultra-high vacuum level
within the tube throughout its operational
lifetime and to ensure maximum collector
efficiency is achieved.
Apricus tubes have a round absorber surface
within the tube, and hence, irradiation from
the sun always strikes the absorber surface
in a perpendicular direction. This ensures
optimum collector performance whatever the
time of day, morning, mid-day or afternoon.
This is reflected in the excellent IAM
(Incident Angle Modifier) figures for the
Apricus Collectors which makes them the
ideal choice of collector for the typical UK
and Irish weather conditions where peak
solar radiation is not guaranteed to be at
mid-day.

Apricus Installation Manual
6
Technical Specification of The
Apricus Collector Range
Model : APRICUS APSE-10
Aperture Area : 0.94 m2
Gross Area : 1.56 m2
Weight (Dry) : 35kg
Fluid Capacity : 0.2litres
Max Pressure : 8 bar
Stagnation Temp: 219°C
Absorption : 92%
Emission : 8%
Width x Length : 796 x 2005 mm
Height : 156 mm
Performance Figures :
η062.6 %
a11.595
a20.013
Model : APRICUS APSE-20
Aperture Area : 1.88 m2
Gross Area : 2.96 m2
Weight (Dry) : 64 kg
Fluid Capacity : 0.52 litres
Max Pressure : 8 bar
Stagnation Temp : 219°C
Absorption : 92%
Emission : 8%
Width x Length : 1496 x 2005 mm
Height : 156 mm
Performance Figures :
η062.6 %
a11.595
a20.013
Model : APRICUS APSE-30
Aperture Area : 2.82 m2
Gross Area : 4.35 m2
Weight (Dry) : 95 kg
Fluid Capacity : 0.71 litres
Max Pressure : 8 bar
Stagnation Temp : 219°C
Absorption : 92%
Emission : 8%
Width x Length : 2196 x 2005 mm
Height : 156 mm
Performance Figures :
η068.7 %
a11.505
a20.011
Key Features
Manifold :
Material : Anodised Aluminium
Insulation :
Material : 50mm Glass Wool
Conductivity : 0.043 W/mK
Tubes :
Glass : 1.8mm Thick Borosilicate
Absorber : Al-N on Al
Rubber Components :
Material : HTV (UV Stable) Silicone
Max Temp. : 300 °C

7
Storage Cylinders
Both copper and stainless steel storage
cylinders are available from CoolSky. These
cylinders are specially designed and
optimised for Solar Systems, comply with UK
regulations, and are fully compatible with the
Apricus Solar Collectors. Options are
available for both vented and unvented
systems.
As an added service we are also able to
provide cylinders that are designed and
manufactured to bespoke requirements.
Vented Solar Cylinders
The Standard Easy-Fit Vented Copper
Cylinders are available in either twin coil or
triple coil configurations and are specifically
designed to work in conjunction with the
domestic heating system.
One or two coils are designed to transfer
heat from an independent heating source,
(eg. transferring heat from a central heating
boiler or solid fuel boiler to the water in the
solar cylinder) and the solar coil, which is
manufactured from high efficiency finned
tubes with a large surface area, to transfer
heat from the solar panels into the solar hot
water cylinder with maximum efficiency.
We are also able to supply custom sizes
upon request giving you total flexibility in
the design of your complete system. In
general, solar cylinders are sized to suit the
number of occupants and the solar thermal
panel surface area.
Nominal Diameters :
400 mm –Only Twin Coil Available
450 mm –Twin or Triple Coil
500 mm –Twin or Triple Coil
600 mm –Twin or Triple Coil
Nominal Heights :
1050 mm, 1200 mm, 1300 mm
1400 mm & 1800 mm
Unvented Solar Cylinders
The Standard Easy-Fit Unvented Stainless
Steel Cylinders are available in a twin coil

Apricus Installation Manual
8
configuration and are specifically designed
to work in conjunction with the domestic
heating system.
Manufactured from Duplex Stainless Steel,
these cylinders provide fast reheat and
recovery and high value insulation. In
addition, for installers they are also light and
easy to handle
Standard Features:
Duplex Stainless Steel
25 Year Guarantee
Fast Reheat/Recovery
High Value Insulation
Nominal Diameter :
545 mm –Only Twin Coil Available
Nominal Heights :
1102 mm, 1290 mm, 1478 mm,
1782 mm, 2041 mm
Pressure & Temperature Relief
Valve (PTRV)
The storage tank must be fitted with a PTRV.
All tanks should be supplied as standard
with an approved valve.
Building Regulations
The installation of unvented hot water
cylinder for domestic applications is
regulated under Building Regulation G3 for
England and Wales, Technical Standard P3
for Scotland, Building Regulation P5 for
Northern Ireland and Technical Guidance
Document L for the Republic of Ireland. All
local, relevant and up-to-date regulations
must be adhered to by the installer. An
example schematic safety control layout for
a solar installation to comply with Building
Regulation G3 (England and Wales) is given
in the CIBSE Solar Heating Design and
Installation Guide.
Cool Tip
Rule of Thumb for sizing storage
cylinder in domestic installations:
100 litres per m2
Aperture Area of Collector

9
Solar Pumping Station
A Pumping Station is required in the Solar
Loop for the circulation of propylene glycol
heat transfer fluid around the solar loop.
The Pumping Stations are provided with the
following key features :
1. Flowmeter, flow rate regulation and
graduated scale regulation gauge 2-12
litre/min.
2. Isolation valves for filling/flushing of the
unit. Connections ¾"M with safety chain
and tap.
3. Circulating Pump - WILO solar STAR
ST15-6ECO, connections 1"BSP - 130mm
class. TF110, VDE, CE.
4. Return side isolation valve DN20, with
integrated bracket. Connection ¾"M
always open on one side.
5. Integrated high temperature check
valves. Closure at 90° and opening at
45°. Check valve opening 2kPa (200mm
c.a.)
6. Pressure gauge with integrated safety
relief valve (typ. 6Bar) with discharge
connection point for isolation valve and
expansion vessel.
7. Air stop device with manual integrated
vent.
Model Variations :
The CoolSky range of Pumping Stations are
available with either ¾” Flat Face Male
Gasket Fittings or 22mm Female
Compression Fittings.
A High Head (8m) Pump Version is also
available for larger installations.
2
1
3
4
5
6
7

Apricus Installation Manual
10
Pump Sizing
Sizing of the Solar Pump
The standard CoolSky Twin Line Pumping
station is supplied with a 3-Speed WILO ST
15/6 Eco Pump (6m head) as standard. This
is suitable for most domestic installations
with the pump speed selected to suit the
pressure drop of the piping. Speed 1 is
generally suitable for a short pipe run, such
as on a single-storey house. Speed 3 can
normally service a 3-storey, 90 collector
pressurized system.
If the pipe run is very long or there are more
than 90 tubes in the collector array, a larger
pump may be needed. For these installations
CoolSky supply a Twin Line Pumping station
with a 3-Speed WILO ST 15/8 High Head
Pump (8m head).
If multiple banks of collectors are installed in
parallel, the head loss should be calculated
based on the longest pipe run through a
single bank of collectors and, then, the
pump can be sized to meet the total flow
rate requirements.
Please Note that Drain-back Systems will
typically require a larger rated pump.
Flow Meter
The CoolSky Pumping Staions include a flow
meter as standard to ensure that flow rates
are at suitable levels and can be monitored.
The flow meter includes a restrictor valve
allowing the flow to be adjusted accordingly.
Flow Rate
A suitable flow rate range for each 30 tube
collector is in the range of 1.5 to 3.0 litres
per minute.
Cool Tip
Set the Flow Rate through the
collector array to :
0.1 litre / minute / tube
That is :
1 litre / minute for 10-tubes
2 litres / minute for 20-tubes
3 litres / minute for 30-tubes

11
Solar Expansion Vessels
CoolSky offer a range of different sizes of
Zilmet Solar Expansion vessels. These should
be sized according to match the
requirements of the system to which they
are connected.
(note : solar expansion vessels should be installed with
the hydraulic connection to the top as this will reduce
heat transfer into the vessel, as shown above)
The Solar Expansion Vessels include 12, 18
and 24 litre versions which have been
specially designed for solar. Other sizes are
available upon request.
The Membrane
Inside the expansion vessel there is a special
Zilan E solar membrane structured as a bag
membrane that separates the gas from the
solar liquid. The development of the
membrane is a result from long term Zilmet
field experience in the installation of vessels
in thermal solar systems.
The membrane is stable with the Pre-Mixed
Propylene-Glycol within the solar loop up to
50% mixtures and has a max. working
temperature of 110° C. The vessel can
accommodate short peaks of 130°C glycol
temperature.
The Zilan E solar membrane is also less likely
to trap air and consequently, there is a lower
likelihood of corrosion damage to the steel
vessel.
Expansion Vessels are manufactured in
accordance with the PED 97/23/CE and
EN13831 directives, which mean that they
are fit for use in closed solar energy heating
systems according to DIN 4757 and
EN12977.
Expansion Vessel Technical
Specification
Max. Operating Pressure: 6bar
Membrane Temperature: 10° - +100°C
System Temperature: -10° - +100°C
Factory pre-charge: 2.5 bar ±20%
Nominal volume: 12, 18 & 24 L
Colour: White
Cool Tip
The Cold-Fill Pressure of the Solar
System should be :
1.3 + (0.1 x Static Height)
Where the Static Height is in
Meters.
Expansion Vessel Pressure should
be re-set to 0.3 Bar less than the
Cold Fill Pressure.

Apricus Installation Manual
12
Expansion Vessel Connection Kit
CoolSky also provide an expansion vessel
connection kit to connect the expansion
vessel to the safety group on the pumping
station. Each kit includes a wall fixing
bracket and a self-closing system isolation
valve (so that the vessel can be removed for
maintenance without draining the fluid from
the system and to facilitate periodic gas
charge checks).
A pre-formed stainless steel flexible hose is
also provided to connect the vessel to the
system at the connection point provided on
the CoolSky Solar Pumping Station.
It is recommended that the Pumping Station
and Expansion Vessel are located as far
hydraulically away in the Solar Loop from the
Solar Collector as is practically possible. This
is to protect the Pumping Station and
Expansion Vessel from the very high
temperatures (i.e. >200 °C) that can be
generated by a Vacuum Tube Collector
under stagnation conditions.
Mounting the Expansion Vessel
Always mount solar vessels in a vertical
position and recognised best practice is to
connect to the provided connection port on
the pump station. Where possible, mount
below the pump station to negate heat
transfer.
Avoid mounting in close proximity to the
solar collector where temperatures can
exceed 130°C. In cases where this cannot be
avoided, it is highly recommended that the
expansion vessel be installed in conjunction
with a heat protecting ‘intermediate’ vessel.
Intermediate Vessels
Intermediate vessels are also available and
are recommended on solar thermal systems
where it is likely that temperatures within the
system will exceed the maximum allowable
working temperature of the expansion vessel
Cool Tip
Always check the internal pressure
of the Expansion Vessel before
fitting and reset to 0.3 bar lower
than the intended cold-fill pressure
of the Solar Loop.

13
or where the expansion vessel is in close
proximity to the solar collector.
It is particularly important that an
intermediate vessel is installed on systems
where the volume of the collectors exceeds
the volume within the flow and return
pipework. This is because during stagnation
periods, the very hot solar fluid in the
collectors can reach vaporisation point. If this
occurs, the very hot solar fluid is forced out
by the vapour, into the expansion vessel.
Intermediate vessels have inlet/outlet
connections and are installed just before the
main expansion vessel (as shown above). The
heat sink that the intermediate vessel
provides, reduces the working temperature
at the diaphragm, and hence considerably
extends the working life of the expansion
vessel.

Apricus Installation Manual
14
Sizing the Expansion Vessel
To size an Expansion Vessel for a Solar
Application the following equation can be
used :

   󰇛
          󰇜 󰇛  󰇜
   
Where
VEV = Nominal Expansion Vessel Size [L]
VSYS = Total Volume of System [L]
VSS = Volume of Safety Water Seal [L]
= 0.005 x VSYS
or
= 3 Litres
(whichever of above is greater)
β= Solar Fluid Expansion Coefficient
= 0.13 for CoolSky Fluid
VCOL = Volume of Collector
= 0.3 Litres for AP-10
= 0.5 Litres for AP-20
= 0.7 Litres for AP-30
n = Number of Collectors
PSV = Pressure Relief Valve Setting
= 6 Bar as CoolSky Standard
PMAX = Allowable Max Pressure in Bar
= PSV –(0.1 x PSV)
= 5.4 Bar (for a 6 Bar PRV)
HST = Static Height of System
= Height of Collector from Pump
PEV = Gas Pressure of Expansion Vessel
= 1 + (0.1 x HST)
CoolSky recommend that an additional
safety factor of 1.5 is applied to the VEV
value to account for the possibility of steam
in the solar loop.
Examples of typical domestic Expansion Tank
Capacities are given in the table below.
Apricus AP-30 Collector
Aperture
Area
[m2]
System
Volume
[Litres]
Static
Head
[m]
Expansion
Tank
[Litres]
3 6.9 5 18
10 18
6 7.6 5 18
10 18
9 8.3 5 18
10 18
12 9.0 5 18
10 24
The above are based upon a system using
the Apricus AP-30 Collector with 20 meters
of DN16 Flexible S/S Pipework and a Heat
Exchanger with 2 litre capacity.
The CoolSky Technical Design Team can
provide assistance and support for the sizing
of Solar Expansion Vessels for your
installation if required.

15
Solar Thermal Anti-Freeze
CoolSky recommend that a Solar Thermal
Anti-Freeze Fluid is ‘always’ used in Solar
Collector Installations. CoolSky supply a pre-
mixed (40% propylene glycol, 60% water)
thermal transfer fluid with additional
corrosion inhibitors for use with the Apricus
Solar Collectors. The fluid is supplied in 20
litre drums.
Only Thermal Fluids that are formulated for
use with High Performance Evacuated Tube
Solar Collectors should be used, as these
have special liquid corrosion inhibitors that
are able to vaporise and condense effectively
during normal collector operation.
The fluid is specially developed for
Evacuated Tube Solar Thermal collectors and
provides frost protection to -28°C.
Protective goggles and rubber gloves should
be used when handling the thermal fluid.
A full Material Safety Data Sheet (MSDS) is
available from CoolSky Ltd. upon request.
Disposal of the fluid should be in accordance
with local regulations.
Although some Solar Controllers are
provided with a Frost Protect Function it
must be highlighted that this only functions
when there is electrical power provided to
the controller and pumps. In the UK and
Ireland it is not unusual for extremely cold
weather conditions to be accompanied by
power outages due to falling power lines,
thereby rendering the Frost Protection
Function ineffective. Only the use of a
suitable anti-freeze fluid will protect the
solar collector from freezing in the combined
conditions of extreme cold and power
outage.
Apricus Evacuated tubes are not susceptible
to damage in cold weather, and Apricus heat
pipes are protected against damage that
could result from the freezing of the water
inside by the addition of a special frost-
protection additive.
Within the manifold and pipework of the
solar loop a suitable Solar Anti-Freeze fluid
must be used. Contact CoolSky for details of
suitable Anti-Freeze Fluids.
✖Freeze related damage is not eligible for
warranty claims.
WARNING:
Failure to implement effective (and
fail-safe) freeze protection may result
in rupture of piping and substantial
property damage.

Apricus Installation Manual
16
Solar Heat Dissipater
The Apricus HD-25 is an air to water radiator
designed to dissipate the energy produced
by one AP-30 collector.
Heat dissipation may be necessary when
solar thermal systems are designed for space
heating applications which may produce
more energy than is needed during warmer
seasons, or for systems where there is an
irregular or low summer demand, for
example, schools, holiday homes and sports
clubs.
The Apricus HD-25 is an ideal solution to
protect from excessive overheating and can
prevent premature ageing of the heat-
transfer fluids used in the solar loop.
Materials of Construction
Piping: Copper (Ag-Zn-Cu brazed)
Fins: 3A21 Grade Aluminium
Case: 3A21 Grade Aluminium
Dimensions
Height: 500mm
Depth: 172mm
Width: 375mm
Heat Transfer Area: 2.8 m2
Gross Weight: 6.6 kg
Inlet/Outlet Pipe: Ø15 mm x 1.0mm
Heat Loss Performance
When ΔT . 40°C, heat dissipation ≥1.3kW
For optimal performance ensure good
natural air circulation.
Installation Guidelines
Max Flow Rage: 15L/min
Ideal Location: Good natural air flow
Transfer Liquid: Propylene Glycol (≤50%)

17
Safety Valve Discharge Container
A high temperature discharge container has
specially designed to capture any propylene
glycol fluid that is discharged from the
Pressure Relief Vessel on the Solar Pumping
Station and to allow its recovery during
regular maintenance - neatly avoiding the
issues of potential damage to those areas
surrounding the valve.
The unit is manufactured from high
temperature grade plastic material that is
suitable for solar systems and up to 160°C
short bursts of glycol/steam. The captured
fluid is visible through the opaque tank
which is supplied complete with a drain
valve.
Technical Specification
Capacity 9.6 litre
Drain valve integral
Size 300 x 270 x 130mm
Clearance required 440mm high
Construction Plastic PE
Ambient temp -5° - +50°C
Storage -10° - +60°C
Short term discharge 160°C

Apricus Installation Manual
18
Sizing and Designing your Solar
System
When starting to design your solar system,
the first issues to consider are regarding the
installation site and the practicalities of
installing the solar collectors.
This section will provide you with detailed
guidelines about assessing the suitability of
any given site for the installation of the Solar
Collector.
Standard System Designs
CoolSky have developed a standard set of
system designs, which represent the most
commonly installed configurations in the UK
and Ireland. We recommend adhering to
these system designs. Any modifications to
the design should be checked by a qualified
engineer.
When using these designs it is important
prior to installation, to confirm that the
designs meet any local regulations.
All systems must be installed by authorised
persons. Upon completion of the
installation, the system may also need to be
checked by a plumbing inspector prior to
commissioning, depending upon local
regulations.
Free Bespoke Design Service
The CoolSky Technical Design Team can also
offer our customers a full bespoke design
service. System designs and configurations
for both small and large systems can be
tailored to our customers particular
requirements. Contact CoolSky for more
details on our Free Design Service.
Collector Direction
Ideally the collector should face as close to
due South as possible. A deviation of up to
15oto the East or West is acceptable and
will have minimal effect on collector
performance.
If installed due east or west, the solar
collector output will be considerably
reduced, with predominately morning output
or afternoon output for each direction
respectively. However, a dual collector
option exists with one collector facing east
and the second collector facing west. This is
commonly referred to as an “East-West
System”.
NOTE: Installations at or near due East or
West will mitigate the passive tracking effect
of the round absorbers within the Apricus
evacuative tubes. Collectors should not be
installed facing a northerly direction.
Collector Orientation
The collector manifold is normally installed
on the flat horizontal plane with the tubes
pointing downwards from the manifold. The
collector must not be installed up-side-down
(tubes pointing upwards) or with tubes lying

19
horizontally, as the heat pipes will not
function.
Drain Back Systems
In a drain-back configuration the collector
must be positioned with 2cm of drop per
meter.
Installation Angle
The solar collector must be installed at an
angle of between 20-80ofrom horizontal to
ensure optimal heat pipe operation. For
optimum summer performance for Domestic
Hot Water applications, as a rule of thumb
the installation angle is typically set as :
Install Angle = 0.7 x Location Latitude
In areas prone to hail, a minimum angle of
45ois advisable. Similarly, in areas prone to
high snow loads, 45oor higher is advisable
to encourage the snow to fall off the
collector surface.
Avoid Shade
Collectors should be located so that shading
does not occur between 9am - 3pm which
are the peak sun hours.
Partial shading due to small objects such as
antennas and small flues is not a problem.
If installing multiple rows of collectors
consider the shading of collectors on the
row behind (especially in the winter).
Location of Collector
The collector should be positioned as close
as possible to the storage tank to avoid long
pipe runs.
System Sizing
Domestic System Sizing
For residential domestic water heating
applications basic “rules of thumb” exist that
allow system sizes to be calculated using the
methodology outlined below.
For space heating or commercial water
heating system the sizing calculations are
more complicated. The CoolSky Technical
Design Team can assist our customers with a
free design service for these systems. Using
special state-of-the-art Solar Thermal design
packages we can assist in the design and
optimisation of all Solar Thermal systems no
matter what the size.
How much hot water is needed?
Ideally the exact daily hot water demand
should be provided through metering.
However, as this is not always available, the
daily demand can be estimated using the
following guidelines :
Cool Tip
Rule of Thumb for Optimum
Installation Angle
0.7 x Location Latitude

Apricus Installation Manual
20
Consumption
Demand
Liters of Hot Water
at 60°C per person
LOW 15
MEDIUM 30
HIGH 60
Guidelines for Domestic Hot Water Useage
A general Rule of Thumb for UK / Ireland is
to assume a requirement of 50 litres of Hot
Water per person per day.
The graphic below shows typical sizing
guidelines for collectors when used for
Domestic Hot Water production in the UK
and Ireland.
Guidelines for Collectors Sizing to Match User
Demand for Domestic Hot Water
Commercial Collector Sizing
Sizing a commercial system usually requires
the use of professional modelling software.
CoolSky can offer a free design service to
our customers for these jobs.
The table below gives guidelines to typical
Hot Water Demands in commercial
applications.
Type of Building Max. Liters of Hot Water at
60°C per person
Restaurant 6
Factory 15
Offices 14
Hotel 5* 136
Hotel (Avg) 114
Sports Facility 40
Hospital 128
Holiday Home 50
Camp Site 40
Typical Hot Water Demands in Commercial Type
Properties.
Cool Tip
Rule of Thumb to Estimate Hot
Water Demand at 60 ‚C in UK and
Ireland :
50 litres per person per day