Novasun 150L Instruction & Installation Manual - page 5
Copyright © 2014
Ikhwezi Solar (Pty) Ltd, Novatherm CC, Solar Assist (Pty) Ltd
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5.
Frost, scaling and hail resistance, stagnation
5.1
Hail resistance
Novasun collectors are hail resistant with 4mm toughened glass and have
passed SABS hail tests.
5.2
Freeze protection
Solar hot water systems can be classified as (i) direct: freeze resistant, (ii)
direct: non freeze resistant or (iii) indirect.
5.3
Direct systems – Freeze resistant & Stagnation
In traditional direct systems the water to be used in the household circulates
through the collector, transferring solar energy into the solar geyser.
The Novasun SWH new technology panel however contains a fully insulated
indirect heat exchanger located in the collector that acts as a freeze
resistant mechanism. The pipework connecting the solar geyser with the
collector must be insulated with Insulflex insulation material.
When installed with a PEX-lined Solartherm Cylinder it can be used
in all SA climate locations (i.e in areas where frost occurs and
areas, where ambient temperature may fall below 5°C) and in
areas with very high ambient temperatures due to its built-in
overheating (stagnation) prevention technology.
Contact Solar Assist to discuss your water quality and conditions.
5.3.1Direct systems: non-Freeze Resistant
In direct systems the water to be used in the household circulates through
the collector, transferring solar energy into the solar geyser.
Direct systems are used in frost-free locations, where ambient
temperature never falls below 5°C and where water quality is good (i.e. less
than 600ppm total dissolved solids/minerals).
5.3.2Indirect systems
In indirect systems the potable water used in the household does not
circulate through the collectors, but remains in the geyser and is heated
indirectly by a heat exchanger.
There are two basic types of heat exchanger, namely a jacketed system
where an inner cylinder is surrounded by a secondary outer layer and an
internal heat exchanger where the solar geyser contains an internal copper
pipe structure.
In both cases the solar loop (i.e. the pipe work to and from the collectors)
contains a heat transfer medium (i.e. propylene glycol/water solution) which
is physically separated from the potable water.
Propylene glycol has a lower freezing point and prevents the liquid in the
collectors from freezing and damaging the collector through expansion that
occurs when ice forms. Only food grade glycol should be used.
Indirect systems are used in locations where frost occurs and the ambient
temperature drops below 5°C and/or where water quality is poor (i.e. more
than 600ppm total dissolved solids/minerals).
These collectors are resistant to freezing when installed with an indirect
geyser and the solar loop filled with a solution of propylene glycol and
water. Water alone must not be used as a transfer fluid. The glycol / water
solution should be mixed in a glycol to water ratio of 1:3 (i.e. 33% glycol).
5.4
Scale resistance
Indirect systems: containing a glycol solution also prevents scale build up
inside the collector in areas of poor water quality. It is important to note that
the geyser cylinder itself may still be affected by water quality by way of
build-up of scale on the outside of the heat exchangers.
Ensure you are familiar with the relevant tank manufacturer’s warranty
terms and conditions in respect of water quality, particularly as it relates to
anode replacement in case of enamel-lined tanks.
Direct systems: If a direct system is used in areas of poor water quality
the manifold inside the collector and solar loop may be subject to a build-up
of scale. This may be avoided through the use of a water softening system.
This is good practice regardless of type of system, as the water will affect
other household appliances in any event.
Novasun SWH System: In the event that the Novasun SWH collectors
experience scale build-up, the manifold can firstly be flushed with a mildly
acidic solution (e.g. vinegar water mix solution or Scale-away solvent) and
thereafter with fresh water prior to re-commissioning. We recommend that
your service provider perform visual checks every 18 to 24 months and flush
the collector as a preventative measure.
The fitment of an appropriate water softening device in the water feed to
your system is good practice.
6.
System placement and orientation
A number of basic fundamentals need to be observed when installing any
solar hot water system.
6.1
Collector orientation
Optimum system performance is achieved when the collectors face directly
North (i.e. true North) when installing in the Southern Hemisphere. The
closer the collector is to directly facing the equator the greater the amount
of solar radiation the collector will be exposed to and the greater the
potential for heating.
Angles up to 45° either side of North will not have a major effect on the
system performance given the state of the art technology used in the
construction of the Novasun systems. Therefore, roofs that are orientated
away from North are also acceptable for installation.
Outside of the 45° range one could consider utilising more collector surface
area or using a mounting frame to adjust the orientation back to North.
6.2
Shading
With a system orientated to face North, the time period when the collector is
exposed to the most direct solar radiation is between 10h00 and 16h00.
Solar collectors with an East bias will achieve a greater gain in morning
hours and those with a West bias will do so in the afternoon.
Care should be taken to ensure that the collectors are not subjected to
excessive shading from trees or adjacent buildings, particularly between
09h00 and 16h00. Also bear in mind that tree growth could lead to future
shading issues.
If the installation takes place in summer, it is also important to take into
account the lower solar angles in winter, which result in longer shadows.