Solar water
heater plans and designs
Solar hot water
heater plans, designs and system components
There are solar water heater plans and designs
that can be very
suitable for a DIY installation. Whether you're considering purchasing
a pre manufactured system or you're referencing
several plans and designs for a DIY installation,
understanding how the primary
and secondary components in these system's work will be vital.
Types of solar water heater designs
Solar water heater plans and designs can vary
from basic and simplistic to very detailed and complex. All
system plans and
designs can be classified as either passive or active plans.
Before taking on or even considering a
DIY installation, it would be wise to further familiarize yourself with
the differences in
passive and active designs, and decide which design type best suits
your consumption needs and regional climate.
Major design components
All solar water heater plans, whether simple or
detailed, are centered around the designs' major components. Whether
your considering a DIY installation or your attempting to tailor design
a
system, most of these major system components will be incorporated into
the solar water heater design.
- Solar
Hot Water Panels; are the heart and soul of a system,
collectors are responsible for harnessing the sun's free and renewable
thermal energy.
- Solar
Hot Water Tanks; enable the system to provide
hot water on demand and at times when the sun's thermal energy is
unaccessible.
- Solar
Hot Water Pump; is required in many solar water heater plans
in order to
circulate the fluids through out the system.
- Solar
Heat Exchanger; this major system component provides a
substantial amount of freeze protection, which will be required in many
climate regions.
Additional components required in all plans and
designs
Back Up Water
Heater
With
the exception of single
tank solar water heaters, a back up heating
source is absolutely required. The presence of a back
up source
further ensures that there's hot water rain or shine and day or night.
Conventional storage tanks or tankless hot water
heaters are the most often used back up source.
Temperature
Pressure Relief Valve
A temperature pressure relief valve should be installed at the hot water
outlet of the solar water panel. This plumbing valve
releases
excess water from the outlet of
the panel.
The
release of excess hot water avoids a very dangerous build up of
pressure in the panel, or collector. A pressure temperature relief
valve is an
important safety feature that's required by just about all
plumbing codes.
Tempering Valve
The tempering valve is another safety feature and
a must have in all solar water heater plans. It's plumbed at the very
end, after the back up heating source. A tempering valve mixes
hot
and cold water when the outlet water temperature is too high,
avoiding scalding
hot water from ever entering the indoor fixtures.
Solar Bypass
or Isolation Valve
This valve is required in solar water heater plans
to ensure an adequate supply. The solar bypass valve isolates the solar
hot water storage
tank in the case of an emergency, allowing the back up power source to
take over and supply hot water. This valve can also be manually turned,
allowing the sun to provide 100% of the daily hot water load during the
sunniest
and warmest times of the year.
Additional components required in active plans
and designs
Heat
Transfer Fluids
Heat
transfer fluids are used to protect the system from freeze. More times
than not either distilled water or an antifreeze solution is used. In
plans that require an antifreeze solution, propylene glycol
is most
often used.
Distilled
water is simply boiled water that's condensed. Boiling and condensing
removes all the mineral
impurities that can potentially damage all the metallic components
within
the loop.
Propylene
glycol is a non toxic antifreeze solution
that contains anti corrosion additives. Solar water
heater plans and designs that use propylene glycol may have
the added flexibility of incorporating a single
wall solar heat exchanger.
Differential
Thermostat Control
A
differential thermostat control is always required in solar water
heater plans and designs that contain an AC
solar hot water pump. This
control activates the AC powered pump when the panel (or collector)
temperature is hotter than the domestic water in the storage
tank.
The
differential thermostat control uses temperature sensor
readings from both the hot
water panels and the storage tank to efficiently activate and
deactivate the system's water pump.
PV Module
A PV module
is always required in solar water heater plans and designs that use a DC
solar hot water pump. The PV module is a small photovoltaic
panel,
or solar electric panel, that's wired to the pump.
This
control doesn't use sensors like a differential thermostat control,
instead PV modules gauge the intensity of the sun. When
the sun is shining
bright, the PV module activates the system's water pump and vice versa.
Drainback
Tank
A drainback
tank is required in all drainback solar water heating systems. When the
heat transfer fluid is not being circulated throughout the system, the
fluid is designed to collect in the drainback tank.
These tanks
are relatively small, ranging anywhere from 6 gallons to 15 gallons in
volume. In drainback solar water heater plans and designs the drainback
tank should always be installed above the panel, or solar collector.
Larger
drainback designs will naturally require larger drainback tanks.
Expansion
Tank
An
expansion tank is a must have in any closed loop solar water heating
system that uses antifreeze solution as a heat transfer fluid.
The expansion tank serves as a storage facility for the extra fluid
volume in the solar loop.
This is
required because the antifreeze solution will expand when it's
introduced to extreme heat. The expansion tank is an important
safety
feature, without it every major component in solar water heater plans
that incorporate antifreeze will be seriously compromised.
These tanks should be
sized to hold up to 40% of the antifreeze
solution before expansion. But going with a larger
size will only provide more insurance. These tanks generally range
in size, usually anywhere from 2 to 4 gallons in volume.
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