Vision Solar Systems
100 L Gravity Fed Type
1
Copyright © 2013 - 2016 Enervision. All Rights Reserved.
Issue 2.0 Mar 2013
Vision Solar Systems
100 L Gravity Fed Type
Installation, Operation
And Maintenance Guide
Vision Solar Systems - 100 L Gravity Fed Type
Copyright © 2013 - 2016 Enervision. All Rights Reserved.
Issue 2.0 Mar 2013
2
! IMPORTANT NOTICE
Please read this manual immediately on receipt of the equipment, before unpacking and
installation. Failure to comply with these instructions can render warranties null and void.
Care for your equipment and safety
Read these instructions before preparing to install the solar water
heating system. The instructions contain information that will assist
you in your task, provide information about what is contained in the
packaging, and information about the water heater’s performance and
characteristics.
Position the system so that the Tubes are out of reach of children and
children’s play areas. If necessary, a guard can be purchased to protect
the tubes from objects directed at them.
Position the system and any overflow pipes will guide any runoff
water into a safe area. If this is not possible, then a gutter must be
fitted to guide any overflow water into a safe point of discharge
If animals, particularly monkeys are a menace in the area, then
additional protection measures will need to be taken to prevent
damage or malfunction of the system. This protection should prevent
access, but not affect the sun reaching the collector.
Do not touch the inside of the tubes, if they have been subjected to
solar irradiance, the inside can be extremely hot.
.
Do not fill the system with water if the tubes have been subjected to
solar irradiance, the sudden contraction with the cold water will result
in the tubes cracking
The main storage water tank must always be vented to the
atmosphere.
Vent pipes must be open to the atmosphere
Do not fit any pressure controlling devices on the overflow or vent
pipes.
Vent pipes must be open to the atmosphere
Only use elements and thermostats approved by the manufacturer.
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Copyright © 2013 - 2016 Enervision. All Rights Reserved.
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The Electrical Element should be connected by a qualified electrician
registered with the Electrical Contractors Board. This will insure that a
correct and safe installation is completed.
Ensure that all electrical connections are kept dry and protected from
the ingress of water and moisture.
The installation should be performed or under the control of a
qualified person in terms of The National Building Regulations and
any additional regional requirements as set out by Local Building
Regulations
Try and use a plumber who is registered with the Plumbers
Registration Board (PIRB) AND who has completed the elective
course on Solar Installations, and who is familiar with the product.
The installation must comply with the National Building Regulations,
The National Water Regulations and the Local Water (Plumbing)
Regulations in the area where the installation takes place.
Avoid axial or twisting force on the pipes. Do not use a pipe wrench
on the pipe to tighten the connection. Always hold the pipe when
tightening the connection.
It is important to the operation of the system to use balanced pressure
to any mixing valves on the hot water outlet to prevent back feed into
the system.
We do not recommend connecting mixing valves to the system outlet.
While these systems contain no hazardous materials, it is always good
practice to recycle. Should you need further information, please
contact your local agent.
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Copyright © 2013 - 2016 Enervision. All Rights Reserved.
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INDEX
Care for your equipment and safety
2
Unpacking
6
Reporting Problems with This Guide
6
For Further Information and Technical Assistance
6
Principal of Operation
7
Performance
11
Specifications
13
Installation
14
Using a timer on the Electrical Heating
18
Cleaning
21
Routine Inspection and Maintenance
21
Trouble Shooting
23
Warranty Policy
24
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Unpacking
It is important when receiving the equipment that you confirm that all the components of the
system are received and are in good order. Listed below is a table of some of the most common
parts ordered with an indication of whether these parts are supplied as standard or as optional
equipment. Please check any additional parts against the original delivery note or invoice.
Description
Qty
Supplied
as Kit
Optional at
additional
cost
System Frame (Flat Roof or Pitch Roof as per Order)
1
Main Tank
1
Electric Element (Supplied fitted if ordered with Tank)
Thermostat (Supplied fitted if ordered with Tank)
Isolator Switch and Weatherproof Box
24 hour Timer with spring reserve
Reservoir Tank (with Ball Valve fitted)
1
58 x 2000 x 2 mm Vacuum Tubes
10
Cold Water Pipe Kit
Hot Water Pipe Kit
Overflow Pipe Kit
Drain Valve
2 x 4 Weatherproof Electrical Box with Isolator
Tempering Valve
Tube Guard (Expanded Metal cover for tubes)
Reporting Problems with This Guide
Please use the fax or email addresses below to report any problems you find in this
guide.
Enervision Technical Services
FAX: +27 11 395 4710
EMAIL: info@enervision.co.za
For Further Information and Technical Assistance
Enervision (Pty) Ltd recognizes the need to keep you informed about the availability of
current product information.
For up-to-date product information and a complete listing of sales offices, visit the
Enervision website at: http://www.enervision.co.za
For comprehensive product data sheets, Product Guides and application notes please
contact your local Enervision representative or email: info@enervision.co.za
For technical assistance, contact your local Enervision representative in the first instance,
alternatively phone 0861 111 270 or +27 11 395 3730 or email info@enervision.co.za
Vision Solar Systems - 100 L Gravity Fed Type
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Copyright © 2013 - 2016 Enervision. All Rights Reserved.
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Principal of Operation
Construction
The system comprises an inner storage tank, an outer cladding and an insulation medium
between the two. A cistern tank with a ball or float valve is attached to the main tank and acts as
a control valve to keep the main tank full. The solar collector consists of vacuum tubes that collect
the energy from the sun, and via thermo siphon, will heat the water in the tank. The tank should
be fitted with a vent pipe connected to the side of the tank, and raised to above the level of the
vent on the cistern tank. This will ensure that the tank is not subjected to any pressure.
These solar water heating systems consist of four major parts as shown in the picture and
detailed below:
The Thermal Storage Tank
The thermal storage tank is a stainless steel tank constructed from 304 stainless steel material
and, being a low pressure tank, we can use a technology we term “no-weld”. This involves all
the pipe connections to the tank using a long life silicon grommet type seal and the end caps
using a pressed and rolled seal. This eliminates welding from the tank and increases the
longevity of the tank as any weld points can act as points where corrosion will start. The tank
holds the potable water, is maintained full of water by the cistern tank, and has the collector
tubes connected to it. Water is drawn from the tank by gravity feed. The tank must be located
above the water outlet, and the pressure of the water is determined by the height of the tank
above the water outlet.
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The Collector
The collector consists of vacuum tubes that contain some of the thermal fluid (water) and are
connected into the tank via a silicon grommet type seal. The vacuum tubes are constructed from
two extremely strong Borosilicate glass tubes of different diameters and placed one inside the
other. At the one end the tubes are joined together and sealed and at the other end the inner tube
is supported. A vacuum is then drawn so that the space between them becomes a vacuum. The
vacuum prevents heat loss from the tubes (much like a thermos flask) and ensures that while the
inner tube can contain hot water the outer tube is cool to the touch.
In order to maintain the vacuum between the two glass layers a ‘barium getter’ is used (the same
as in television tubes). During manufacture of the vacuum tube the ‘getter’ is exposed to a high
temperature which causes the bottom of the tube to be coated with a layer of pure barium. The
barium layer actively absorbs any CO, CO², N², O², H²O and H² gasses from the vacuum tube
during storage and operation thus helping to maintain the vacuum. The barium layer also
provides a clear visual indicator of the vacuum status. It will turn white when the vacuum is lost.
The inner tube is coated with a special multi-layer coating forming a selective absorption layer
that assists with the collection of energy from the sun and transfers this energy into heat in the
water. The number of tubes used is chosen to cope with the volume of water in the tank which
needs to be heated on a standard solar day.
The Cistern or Reserve tank
The cistern or reserve tank is a small tank which feeds the main thermal tank. It contains a ball
valve which ensures that that the reserve tank is always filled to a certain level. If the level in the
main tank drops through the cooling (and reducing volume of the water) the ball valve will open
and top up the system. The ball valve is the only moving part in the complete system.
WARNING: Do not extend the pipe connecting the cistern tank to the main tank. This will
increase the pressure of the main tank which is designed to be vented to the atmosphere at a
height of less than 1m from the main tank.
The Backup Heating
In any heating system the time that hot water is not available must be limited. On cloudy days
the solar energy able to be harvested could be limited and, though there is a degree of energy
available, it may not be sufficient to heat the amount of water required. In this system a
thermostatically controlled backup electrical heating element is used to heat the water in the
tank.
NOTE: The element is supplied as an optional extra, and if required, should be included in your
order to your supplier.
Operation
Collecting the energy from the sun
As the sun’s rays fall on the collector or collector tubes the irradiance is transformed from the
light energy to heat energy in the water in the tubes. The coating used on the inside assists in
transforming the ultraviolet light from the sun into heat inside the tubes. This aids in collecting
some solar (UV light energy) on cloudy days.
The heated water inside the tube expands and become more buoyant. It moves up the collector
tube and eventually enters the tank, and it is replaced by colder water from the tank which is, in
turn, heated by the sun’s energy. This process, known as thermo-siphon, happens continuously
while the solar energy falls on the collector.
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Maintaining the energy in the thermal storage tank
The tank is constructed of double shell much like the tubes. The inner shell is stainless steel and
contains all the connections and seals for the pipes and tubes. This tank is open to the atmosphere and
is not under any pressure. The outer tank or shell is a thin sheet that protects the system and between
the two layers is a thick layer of thermal insulation that restricts the loss of heat from the water in the
inner tank. Using a low pressure tank to contain the thermal mass of water has its advantages. Firstly,
it limits the maximum temperature of the water in the tank as the water cannot rise above 100ºC – the
point at which water boils at sea level. Secondly, by not having a tank of hot water under pressure,
there is no need for management to ensure the safety of people, animals and possessions near the
tank.
Supplying the Hot Water
Water is supplied to the plumbing by gravity feed. This requires that the tank is mounted above the
water outlet to ensure a supply of water. The higher the tank is mounted above the water outlet, the
greater the pressure of the water at the outlet. Note that the tank is designed for zero pressure, to
extend the height of the cistern would place the tank under pressure, and this will affect the safe
operation of the system, and can be harmful to persons and property.
The Backup Heating
The need for backup heating is twofold – firstly, to compensate when there is little or no sunshine,
and, secondly, when water usage exceeds the daily solar heating capacity. In these situations the
backup element acts as a substitute heat source to the sun. It is a good practice to fit the timer to the
supply feed for the element. With electricity conservation being the objective, a timer with a
reasonable reserve (time it will continue to maintain time without the mains available) and the ability
to set up exclusion zones should be installed. This will prevent the use of the electrical element during
peak electricity usage period and also during the sun’s normal heating time.
Considerations
There are some considerations to take into account in a system like this as the performance of the
system differs to that of a normal hot water system.
1) The supply of water is via a gravity feed. Do not expect high pressures from the system. Flow
rates will depend on the height of the tank above the water outlet, and the restriction of the
pipe work to the water outlet.
2) The temperature of the water is dependent on the solar energy collected, and the amount of
water used. On sunny days with little water usage, the temperature can very high, and on
cloudy days with lots of water used, you can run out of hot water.
3) As the hot water is drawn from the system the water in the tank cools. This means that the
water temperature tapers off as the water is used. In other words, initially the water
temperature may be 65ºC, after half the water is used it may drop to 55ºC and at the end it
may be as low as 40ºC. This means you will initially use a low amount of hot water and mix
with cold water to get the water to the desired temperature and at the end you may be using
mostly hot water with very little cold water mixed in.
Safety and Operation
There are certain great safety features in this type of system;
1) The tank of hot water is at low pressure so the water cannot be superheated under pressure
and will never exceed boiling point. If left unused for an extended period of time the excess
solar energy collected each day will boil out into the cistern tank and, at worst, some water
can be lost through the overflow. This provides inherent safety of overheating and possible
bursting of the tank.
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2) The tubes are cool on the outside; consequently there is no danger of being burnt
should they be touched.
3) No pressure and temperature relief valve is needed provided that the system is
correctly installed, with the vent pipes not extended more than 1 meter above the main
tank.
On the operational side there are also some great features;
1) The ball valve is the only moving part. High quality brass and stainless steel valves are
used to ensure durability and consistent operation.
2) The system works naturally so it will not need any power to control or manage the hot
water. Even overheating and freezing of the main tank parts are inherently controlled.
3) Inherently freeze resistant with the water in the main tank. (Excluding connecting pipe
work)
4) Inherently protected against overheating by the low pressure vented tank design and
the latent heat absorbed by boiling water.
5) No glycol or sacrificial anode maintenance required.
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Performance
The output of the solar water will depend on the amount of solar irradiation that reaches the collector
throughout the day. On a good day, with 6-7 hours of sunlight, the glass tubes will collect enough
energy to heat the water up to 60ºC - 70ºC. You may even spot steam coming from the vent pipe as the
water reaches boiling point. This is quite normal if you have not been using water from the system. By
setting the tilt less than the latitude the system will work better in summer and using a tilt of more
than latitude will improve the performance in winter.
By facing the system a few degrees east of true north the water will heat earlier in the day and,
similarly, a little more west of north will mean the water will heat later in the day.
Shown below is the average solar irradiance for various cities in South Africa for collectors positioned
at true north and a tilt equal to the latitude:
Based on the above average solar irradiance, the average daily temperature rise of the thermal storage
water would be as shown in the table below. Note that these are average figures and, on any one day,
depending on the cloud cover and temperature, different results will be obtained:
Note that one needs to consider the amount of hot water drawn from the tank each day (the energy
used) and the residual temperature each day to determine what the actual storage tank temperature
will be, and what the total available hot water from solar heating only will be.
Based on at least this hot water input being used every day, in other words, that tank is in
equilibrium, without boiling, or running out of hot water (the balance coming from electrical heating
if this is required), the average daily saving in electricity is shown in the table below:
Solar Irradiance MJ/m²/day (figures from NASA 22 year average)
Area
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Johannesburg
21.5
21.0
20.7
20.5
20.6
20.3
21.5
23.1
23.5
21.3
21.4
21.5
Cape Town
26.2
25.6
23.5
19.9
16.0
15.0
15.5
17.2
20.5
23.4
25.2
25.6
Durban
18.6
19.1
19.0
19.1
18.6
18.1
18.8
19.8
19.2
17.3
17.7
18.4
Port Elizabeth
22.1
20.9
19.4
18.1
16.7
15.9
16.9
17.9
19.4
19.7
21.0
22.1
East London
21.0
20.3
19.2
18.6
17.9
17.0
17.6
19.1
20.2
19.4
20.3
21.3
Bloemfontein
23.9
22.8
21.6
29.8
20.1
19.4
20.4
22.9
23.3
23.0
23.4
24.2
Expected Average Temperature Rise of water in the Storage Tank from Solar Only
Area
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Johannesburg
17.0
16.6
16.3
16.2
16.3
16.1
16.9
18.7
18.5
16.8
16.8
16.9
Cape Town
20.5
20.0
18.4
15.8
12.8
12.0
12.4
13.7
16.2
18.3
19.7
20.0
Durban
14.8
15.1
15.0
15.1
14.7
14.4
14.9
15.6
15.2
13.8
14.1
14.6
Port Elizabeth
17.4
16.5
15.4
14.4
13.3
12.7
13.5
14.2
15.3
15.5
16.6
17.4
East London
16.6
16.1
15.2
14.7
14.3
13.5
14.0
15.1
15.9
15.3
16.0
16.8
Bloemfontein
18.8
17.9
17.0
16.4
15.9
15.3
16.1
18.0
18.3
18.1
18.4
18.9
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Always remember that the solar performance will depend on the amount of sun on the collector.
Cloudy weather will decrease performance and reduce the amount of energy harvested from the
sun. In addition, shade from trees and other objects during the day will mean that less solar
energy is harvested. There is a backup element that can be fitted to the system to cope with bad
weather and lower solar irradiation and also for abnormally high hot water demand. The backup
element is thermostatically controlled and is normally used in conjunction with a timer so that
the use of electrical energy can be controlled and used only when there is no solar harvesting
likely to take place.
In order to heat the water in the tank with the electrical element some time is needed to attain the
required temperature. Shown below is the graph of the time taken to heat water from 20ºC to
70ºC.
If the tank is at a higher temperature the time for 20ºC to the starting tank temperature can be
subtracted from the full reheating time. Note that you will need to take into account the timer
exclusion zones if these are active in the electrical element reheat cycle or alternatively put the
timer into the bypass mode.
20.0
30.0
40.0
50.0
60.0
70.0
80.0
0
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
Water Temperature in the Tank
Time in Hours
Reheat Time with Electric Element
1.5 kW Element
Average Energy Saving per Day (kWh)
Area
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Johannesburg
4.7
4.6
4.5
4.5
4.5
4.5
4.7
5.2
5.1
4.7
4.7
4.7
Cape Town
5.7
5.6
5.1
4.4
3.6
3.3
3.5
3.8
4.5
5.1
5.5
5.6
Durban
4.1
4.2
4.2
4.2
4.1
4.0
4.1
4.3
4.2
3.8
3.9
4.1
Port Elizabeth
4.8
4.6
4.3
4.0
3.7
3.5
3.7
3.9
4.3
4.3
4.6
4.8
East London
4.6
4.5
4.2
4.1
4.0
3.8
3.9
4.2
4.4
4.3
4.5
4.7
Bloemfontein
5.2
5.0
4.7
4.6
4.4
4.3
4.5
5.0
5.1
5.0
5.1
5.3
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Specifications
Description
Specification
System Type
TZ58/1800-10
Storage Tank
Capacity
100ℓ
Inner Tank Material
0.6mm US304
Inner Tank Diameter
375mm
Insulation Material
Polyurethane
Insulation Thickness
50mm
Insulation Density
36kg/m²
Outer Tank Material Optional
Zinc coated 0.4mm Painted
Steel
Outer Tank Diameter
475mm
Optimal Flow Rate
7ℓ/min
Fluid Type
Water
Tank Maximum Pressure
50kPA
Collector Tubes
Outer Tube Diameter
58mm
Material
Lead Free Glass
Thickness
2mm
Inner Tube Diameter
47mm
Material
Lead Free Glass
Coating
Multilayer SS-C/Cu
Aperture Area
0.95m²
Absorber Area
1.76m²
Performance
Estimated Life Span
10 years
System Output (16MJ)
12.89 MJ
Note: In order to allow for continuous improvement, Enervision reserves the right to update and
change specifications without prior notice E&OE.
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Installation
Tools Required
It is essential that the installation is completed by an accredited plumber who has been
trained in solar water installations and has completed an installation training course on this
type of solar system.
In order to complete the installation successfully the following tools are recommended:
3m Ladder (two recommended)
Ropes and slings
10mm Ring Flat Spanner
13mm Ring Flat Spanner
19mm Flat Spanner
22mm Flat Spanner
Small Flat Screw Driver
Adjustable Spanner
Copper Pipe Cutter
Gas Solder Unit
Solder Flux
Solder
System Location
The location of the solar water heater should be on an even surface facing true north. A variation
of 20 degrees either side of true north will have a negligible effect on the overall performance.
The collector must be in full sun, free from shadows, between the hours of 9am to 4pm
throughout all the seasons.
The tilt angle recommended for the collector is latitude plus 15 degrees. Increasing the tilt angle
will improve the winter performance while decreasing the tilt angle will increase summer
performance. The lower the latitude, the more critical the tilt angle will be to the overall system
performance.
Cloud cover will affect performance, if cloud is predominantly in the mornings, then try to face
the solar collector more west of north, and if cloud cover is in the afternoon, then facing the
collector more east of north will assist the performance. The Solar input as indicated on page 11
will provide an indication of the worst performing months of the year. In winter rainfall areas it
is recommended that the tilt angle is increased to improve winter performance.
Tips on finding True North
Satellite dishes point to PAS7/10. This is positioned 68 degrees East of North.
Some GPS systems will have a compass. Please confirm the accuracy of this before using it as
they will sometimes require movement to determine direction.
Use of a sundial type compass with a vertical shadow and a time of day can also be used to find
True North.
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Frame Assembly
Assemble the frame as indicated in the sketch below:
Ensure that all the bolts and nuts are tight.
Securing the System
Ensure that the intended location is sufficient to support the full weight the system when it is filled
with water, and that there will be negligible sag that can damage rigid materials such as tiles if there
is any movement.
The rear legs are attached to a spreader beam to spread the weight of the water in the tank across the
roof area. The spreader contains holes that allow the frame to be secured to the structure on which it is
mounted. Use suitable bolts and nuts to secure the feet to the structure. Ensure that all feet are secured
to a ridged part of the mounting structure. Any penetration of the roof structure must be suitably
repaired to maintain the waterproofing.
Failing to adequately secure the system to the structure can result in the frame flexing when subjected
to high winds. This can cause excessive stress on the frame, tubes and tank and can result in the tubes
fracturing.
Where extremely high winds are experienced, additional care must be taken in
securing the system and additional stainless steel guys may also be required to ensure
that the system is securely mounted.
Mounting the Main Tank and Reservoir Tank
Always secure the pipe connection to the tank with a spanner to prevent any axial or
twisting forces on the pipe. Use the mounting support bracket for the reservoir tank
and adjust the feet to ensure that there is no axial force on the pipe connection.
Remove the thread protection caps and nuts from the tank mountings.
Lift the main tank and position it on the frame curved tank mounting brackets, ensuring that
the bolts are not pushed into the tank. The tube holes should be pointing towards the front of
the frame and the pipe connections should be on the right hand side when looking at the
collector from the front. Put the tank bolts into the slotted holes in the tank mounting bracket
and lightly tighten the nuts onto the bolts.
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Rotate the tank so that the bolts are approximately in the middle of the slots.
Place the reservoir tank mounting bracket over the pipe inlet on the right hand side of the tank
near the pipe connections. Screw on the reservoir tank and turn until the thread is tight. You
will need to use a spanner to hold the pipe from the main tank. Once the tank is tight use the
plastic bolts on the bracket to support the tank and ensure that there is no axial force on the
pipe connection and ensure that there is no movement on the mountings.
Connect the drain valve that complies with SANS 1848-53 to the bottom outlet on the tank.
Connect the cold water pipe, as shown, to the reservoir tank. Ensure that the shutoff valve is
fitted to this pipe.
Connect the hot water pipe to the hot water output at the bottom of the tank.
Connect the overflow pipe to the reservoir tank as shown in the schematic.
Connect an additional overflow pipe to the side of the main tank as shown in the schematic.
For all these connections, again take care to support the pipe connection to the tank in order to
ensure that no axial or twisting force is applied to the tank pipes.
Connect the cold water shutoff valve to the cold water supply.
Test all connections for leaks. The shutoff valve on the cold water feed can be used to control
the water flow.
Enervision recommends that the hot water pipe from the geyser to the point of use does
not exceed 10m and that the pipe is lagged along the whole length.
In frost areas, cold water pipe and overflow pipes must be suitably lagged to prevent
freezing.
Additional
Overflow pipe
Overflow pipe
Cold Water
Supply
Hot Water
Output
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Inserting the Vacuum Tubes
Do not fill any tubes with cold water if they have been exposed
to the sun. The sudden contraction will cause them to fracture.
Keep the tubes covered and in the packaging when not preparing them for insertion into the tank.
Spray or dip the open end of the tube in a dilute soapy non-toxic water solution.
Pull the dust cover over the tube to about 150mm from the open end of the tube. Ensure that it is
placed the correct way round with the bevelled side away from the open end.
If necessary, re-wet the open end of the tube.
Insert the tube into the opening of the tank, working from the centre to the outside.
The tubes should be inserted well into the tank and then pulled back into the boot on the back box
mounted on the stand. Once the tube has been installed in the tank, move the dust cover into
position.
It is recommended that the supply and outlet pipework is completed before the tubes are incerted.
This will allow for a slow trickle water into the main tank to fill the tubes as the tube is inserted fill
with water. Alternatively cover the tubes with an opaque cover, such as canvas cloth or the
cardboard box until the system is filled.
Adequate precautions must be taken to prevent the tubes from heating in the sun. If this is not
possible, wait until the early hours of the morning, before the sun has had time to heat the tubes, to
fill the system with water.
Fitting the Electric Element
Any electrical work done on the system should be done by a
qualified electrician. There are various safety and legal
requirements that must be complied with.
In order to comply with the safety requirements, only Enervision Approved elements and thermostats may be
used in the system. Do Not fit an electric element without a thermostat.
If the system was ordered with an electric element, the element will be pre-fitted to the system.
The Code of Practice for electrical installations requires that a two pole isolator switch is fitted to the
supply to the element.
Vision Solar Systems - 100 L Gravity Fed Type
Copyright © 2013 - 2016 Enervision. All Rights Reserved.
Issue 2.0 Mar 2013
18
Using a timer on the Electrical Heating (Optional)
Fitting a Timer
Enervision recommends that a timer is fitted to control the supply to the element. This should
exclude the peak demand periods in the morning between 7am and 10am, in the evening between
6pm and 9pm, and also between 10am and 3pm when normal solar water heating is taking place.
(On cloudy days this time zone can be overridden if hot water is required in the early evening.)
MTD 2 Type Timer
This timer is a 24 hour timer with 15 minute programme intervals and a 7 day reserve.
Connect the electrical circuit as shown in the diagram below.
Programming the Timer
Each toggle in the programming dial corresponds to a period of 15 minutes. When the toggle is
in the right hand position, the element is on and when the toggle is ion the left hand position
then the element is off. To set the timer for Eskom DSM, switch all toggles over to the right.
Turn the dial and set the toggles from 7am to 3pm to the left position. Repeat the above for the
times from 6pm to 9pm.
Turn the dial so that the current time corresponds with the actual time. Note that the timer has
a 100 hour reserve. If the power is off for more than 100 hours the time will need to be reset.
Note: there is a manual override on the timer which allows the timer function to be overridden.
For normal timer operation the override should be in the upper position and to override must
be moved down.
The MTD8 or the TDDGT Type Timer
This timer is a 7 day timer with 1 minute programme intervals and a 15 day reserve.
Connect the electrical circuit as shown on the diagram below:
Vision Solar Systems - 100 L Gravity Fed Type
19
Copyright © 2013 - 2016 Enervision. All Rights Reserved.
Issue 2.0 Mar 2013
Programming the timer
Setting the time
If there is no display, press and hold the RESET button for a few seconds
Press and hold down the clock button while pressing the D+ button to the desired day of the
week.
Press and hold down the clock button while pressing the H+ button to the desired hour.
Press and hold down the clock button while pressing the M+ button to the desired minutes.
Release the clock button when the time and day is set.
Setting the Time Zones
Press P, Display will show the Time Zone 1 On time.
Use the H+ to set the hour.
Use the M+ to set the minutes.
Use the D+ to set the day of the week. Enervision recommends MTWTFSS as default. (cycles
MTWTFSS, MTWTFS, MTWTF, SS, MTW, TFS, MWF, TTS, M, T, W, T, F, S, S)
Press the P again. Display will show Time Zone 1 OFF time.
Press the H+ to set the hour.
Use the M+ to set the minutes.
Use the D+ to set the day of the week. Enervision recommends MTWTFSS as default.
Press P again to go to Next Zone and continue from the top, or Press Clock to stop setting
Time zones.
There are a possible 16 time Zones that can be set.
Vision Solar Systems - 100 L Gravity Fed Type
Copyright © 2013 - 2016 Enervision. All Rights Reserved.
Issue 2.0 Mar 2013
20
First Filling with Water and Commissioning
Do not fill any tubes with cold water if they have been
exposed to the sun. The sudden contraction will cause them
to fracture.
Two methods can be used for the first filling of the tank.
Method 1 – Filling while inserting the tubes;
In this method the installation of the system needs to be complete with all the plumbing connections
made except for the vacuum tubes.
Open the inlet supply valve and allow the water to fill the tank up to the holes for the
vacuum tubes. Adjust the water so that it just trickles out of the tube holes.
Check that the water contains no gritty deposits. (If this is the case, Enervision recommends
the fitting of a filter trap and implementation of a regular maintenance procedure to clean
the filters).
Prepare the first tube for fitting with the dust cover and soapy lubrication.
Insert the tube into the hole and then secure into the tailstock.
Continue with the next tube, all the time ensuring that the tubes immediately start filling
with water once they are fitted.
Once all the tubes are fitted open the inlet valve completely and allow the tank to fill via the
ball valve and reservoir tank.
Check that the ball valve closes once the tank is full and that no water is discharged from the
overflow.
Check all installed pipework to ensure that there are no leaks.
Open the drain and drain off 10 litres of water into a clean bucket. Check for any gritty
deposits and that the ball valve closes again. Repeat if necessary.
Switch timer into the override mode and switch on the isolator.
Monitor the current on the electrical element with a tong tester. (Do not confirm with
voltage measurements.).
The system is now ready for use and will require time to heat.
See performance information on page 11 to gauge the time it will take to heat the water
sufficiently.
Method 2 – Filling with the tubes fitted
In this method the installation of the system is complete including the vacuum tubes.
If the tubes have been exposed to the sun for an extended period, wait until the early
morning before filling the system.
If the tubes are fitted in the evening, less than 1 hour from sunset, the system can be filled.
Open the inlet valve completely and allow the tank to fill via the ball valve and the reservoir
tank.
Check that the ball valve closes once the tank is full and no water is discharged from the
overflow.
Check all installed pipe work to ensure that there are no leaks.
Open the drain and drain off 10 litres of water into a clean bucket. Check for any gritty
deposits and that the ball valve closes again. Repeat if necessary.
Switch timer into the override mode and switch on the isolator.
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