1. INSTALLER TRAINING COURSE
MODULE 1 BASIC SOLAR THERMAL

2. Introduction to SHW
 Earth Energy Resources
 US Solar Radiation
 Why Go Green
 Why SHW
SHW Technology
 SHW Components
 Different Types of SHW Systems
Sizing Solar Domestic Hot Water System
 Solar Fraction (SFn) and Sizing Guidelines
 Sizing Dependencies
 SHW Sizing
 Other Factors
Auxiliary Heating
 Basic considerations
 Preheating
 Dual Tank Systems
BASIC SOLAR THERMAL
COURSE OUTLINE

3. The mission of the Helio Partner program is to ensure that
Heliodyne installing contractors have acquired the knowledge
and skills to effectively promote Heliodyne products,
successfully install Heliodyne products, and to provide
lasting customer support to end-users thereby representing
the Heliodyne brand in the best possible way and in addition
increase for the dealer: productivity, customer satisfaction,
repeat sales and referrals.
BASIC SOLAR THERMAL
HELIO-PARTNER MISSION

4. Step 1. Successful completion of in person training or
completion of on-line training with 100% passing
score on the exam portion.
Step 2. Submit to Heliodyne current copy of applicable
contractor’s license and proof of liability insurance.
Minimum: $1,000,000.00
Step 3. Complete successful installation of a Heliodyne
Pro system with proof of performance through
Heliodyne’s on-line web monitoring system.
Step 4. Sign and return Helio Partner agreement.
BASIC SOLAR THERMAL
BECOMING A HELIOPARTNER

5. Helio Partners will have added visibility on the Heliodyne
web site dealer locator. The Heliodyne logo will appear next
to Helio Partner’s listing.
Homeowners and business owners will be drawn to Helio
Partners because they will know that partners have
successfully completed training, have installed Heliodyne
products, and carry adequate licensing and insurance.
Helio Partners will receive preference in receiving leads and
referrals that come from trade shows, advertising, and direct
contact with Heliodyne.
BASIC SOLAR THERMAL
HELIOPARTNER BENIFITS

6. BASIC SOLAR THERMAL
Solar Resources

7. BASIC SOLAR THERMAL
Programs, Legislation and other Support
• Higher fuel prices
• 30% federal tax credit
• Tax credits
• Grants and cash rebates
• Obama stimulus package
Go to: www.dsireusa.org
13

8. BASIC SOLAR THERMAL
U.S. Solar Hot Water Industry Growth
14

9. INTRODUCTION TO SHW
EARTH ENERGY RESOURCES
Solar Energy
World Annual Consump.
Uranium
Gas
Oil
Coal

10. INTRODUCTION TO SHW
EARTH ENERGY RESOURCES

11. INTRODUCTION TO SHW
WHY SOLAR HOT WATER
IT’S SUITABLE FOR ALL REGIONS
SHW ( HELIODYNE) GOBI 410
Output/day: 22.7 kWh
Area: 80 ft2 (2 panels)
Installed Cost: $7,000
PV (SHELL SQ 165-PC)
Output/day: 22.3 kWh
Area: 456 ft2 (18 panels)
Installed Cost: $30,000
Hawaii
Alaska
IT’S THE MOST COST-EFFECTIVE RENEWABLE
WAY TO HEAT WATER
Solar hot water systems perform efficiently all over the
US, from Hawaii to Vermont, and Alaska to Florida.

12. Introduction to SHW
 Earth Energy Resources
 US Solar Radiation
 Why Go Green
 Why SHW
SHW Technology
 SHW Components
 Different Types of SHW Systems
Sizing Solar Domestic Hot Water System
 Solar Fraction (SFn) and Sizing Guidelines
 Sizing Dependencies
 SHW Sizing
 Other Factors
Auxiliary Heating
 Basic considerations
 Preheating
 Dual Tank Systems
BASIC SOLAR THERMAL
COURSE OUTLINE

13. 1. Collector
2. Controller
3. Pumps
4. Heat Exchanger
5. Storage Tank
6. Tempering Valve
7. Expansion Tank
8. Air Vent
9. Pressure Relief
Valve
10. Auxiliary Energy
1
2
3
4
10
5
6
7
SHW TECHNOLOGY
SYSTEM BASICS AND COMPONENTS
8
9
Heat transfer fluid is pumped
through the collectors, heated
by the sun and circulated to the
heat exchanger. The fluid
exchange heat to the water in
the storage tank and returns to
the collector to be reheated.
This repeats as long as there is
sun or until the tank is charged

14. SHW TECHNOLOGY
COLLECTORS
THREE TYPES OF COLLECTORS
Unglazed Collectors
Vacuum Tube Collectors
Flat Plate Collectors

15. BASIC SOLAR THERMAL
Types of Thermal Collectors
Evacuated Tube Collectors
Flat –Plate Solar Collectors Unglazed Tube-mat Collectors
Integrated Collector Storage Collectors
24

16. BASIC SOLAR THERMAL
Comparing Collector Technologies
Source:
Home Power magazine

17. SHW TECHNOLOGY
COLLECTORS
UNGLAZED COLLECTORS
PRO
 Easy to install
 Inexpensive  Short Payback period
CON
 No insulation Efficiency sensitive to wind
and ambient temperature
 Low temperature range (75°F - 95°F )
 Aesthetics  May be considered visually
unpleasing
 Low durability
Unglazed collectors are typically made of
plastic tubes combined into an absorber
and used for residential pool heating to
extend the pool season

18. SHW TECHNOLOGY
COLLECTOR
VACUUM TUBE COLLECTORS
PRO
 Works well at high temperature ranges > 220°F
 Good for high temperature industrial applications
CON
 May be considered aesthetically unpleasing
 Relatively higher maintenance
 Sensitive to loosing vacuum
 High installation complexity
 Relatively expensive
 Relatively fragileDouble wall glass tube with vacuum
in between or a glass tube with a top
seal and a pumped vacuum
containing an absorber. The vacuum
efficiently insulate the absorber
minimizing collector heat loss and
sensitiveness to wind and ambient
temperature

19. BASIC SOLAR THERMAL
Evacuated Heatpipe Technologies
28
The sealed tube contains a small
amount of alcohol which vaporizes
when heated and condenses when
cooled

20. SHW TECHNOLOGY
COLLECTOR
FLAT PLATE COLLECTOR
PRO
 Simple and proven technology
 Low maintenance
 Highly durability
 High Performance in Cold and Hot Climates
 Cost-effective (More energy per Dollar)
 Easy Installation
CON
 Relatively heavy to carry
 Limited temperature range of up to 220°FConsists of an insulated weather
sealed metal box containing the
absorber and closed with a
transparent cover typically made
of tempered glass. Frame
Glass
Insulation
Absorber

21. BASIC SOLAR THERMAL
Flat Plate Collector
30
Features:
• Extruded aluminum frame
• Copper or aluminum absorber
• Black paint or blue sputtering
• Life expectancy of over 25 years
• Rated by SRCC
Installation:
Weight: 120 - 160 lbs. full

22. SHW TECHNOLOGY
COLLECTOR ABSORBER VARIOUS SURFACES
BLACK PAINT
 Low cost solution
 Recommended for warm climates with high
solar radiation α = 0.85
ε = 0.25
BLACK CHROME
 First generation selective surface
 Tough surface
 Recommended for cool climates α = 0.95
ε = 0.12
BLUE SPUTTERED
 State of the art technology
 Optimal heat absorption with minimal emission
 Suitable for all types of installations and regions
 Recommended for cool climates
α: Absorptivity  A measure of an object's ability to absorb incident energy
ε: Emissivity  The ability of a material to hold or release heat
α = 0.95
ε = 0.05

23. BASIC SOLAR THERMAL
Residential Flush-Mount Arrays
32

24. BASIC SOLAR THERMAL
Residential Tilt-up Arrays
33

25. BASIC SOLAR THERMAL
Residential Ground Mounted Array
34

26. BASIC SOLAR THERMAL
Small Commercial Systems
35

27. BASIC SOLAR THERMAL
Larger Commercial Systems
36

28. BASIC SOLAR THERMAL
Data Monitoring
40
Types of monitoring
• Manually read gauges
• Controller with digital display
• Wireless remote monitoring
• Web based monitoring

29. SHW TECHNOLOGY
CONTROLLERS
T1
T2
The controller senses the temperature in
the collector and the bottom of the
tank and start/stop the pump at
various differential temperatures ∆T.
Pump start setting is usually at 18°∆T,
while pump stop setting is usually at
5°∆T. ∆T start/stop settings are different
to avoid continuous start/stop of the
pump
Design Considerations
Stagnation/Overheating Protection
Provides high limit shut-off by turning off the pump
when a preset tank temperature has been
reached (Typically 180°F)
Other Types
 Timers
 Differential pressure

30. SHW TECHNOLOGY
PUMPS
The pumps main function is to circulate
the liquid in the solar loop from the
collectors to the tank or heat exchanger
and back into the collectors. Pumps in
closed loop systems are usually fitted
with a cast iron housing whereas pumps
in open loops with direct contact to the
portable water are fitted with bronze
housing to avoid corrosion
Design Considerations
Pumps needs to cope with the desired static
pressure of the system and overcome the
pressure losses in the pipes, collectors and
water heater and at the same time ensure an
adequate flow rate in the solar loop
Flow Rate
The flow rate in a solar loop is typically set at
0.025 GPM per ft2 of collector
Other Types
 Variable Speed Pump
Keeps a proper temperature in the collectors,
while using minimum electricity

31. SHW TECHNOLOGY
HEAT EXCHANGERS
THREE TYPES OF HEAT EXCHANGERS
Tube-In-Tube
Heat Exchangers
Brazed Plate
Heat Exchangers
Tube and Shell
Heat Exchangers

32. SHW TECHNOLOGY
HEAT EXCHANGER
TUBE HEAT EXCHANGER
Common tube heat exchanger
designs are coil-in-tank, tube in tube,
wraparound-tube and tube in shell.
Heat transfer occurs when one fluid
moves through the inner tube while a
second fluid moves in a different
direction on the outside of that tube.
PRO
 Low Flow Rate  Less Electricity  Not
Costly To Operate
 Fewer Joints
 Low fouling factor  Good option for high
SFn > 70%
 Resistant to high pressure
CON
 Relatively big in size
 Has to be insulated
Primary
feed
Secondary
feed
Tubes
Shell

33. SHW TECHNOLOGY
HEAT EXCHANGER
PRO
 Relatively small in size
 Relatively inexpensive
 High efficiency
CON
 Big fouling factor  Thus, sensitive to
water quality
 Should not be used with SFn above 40%
 Higher maintenance required
FLAT PLATE HEAT EXCHANGER
Composed of multiple, thin, slightly-
separated plates that have very large
surface areas and fluid flow passages
for heat transfer. Can be more
effective, in a given space, than the
shell and tube heat exchanger

34. BASIC SOLAR THERMAL
Tanks with Heat Exchangers
46

35. SHW TECHNOLOGY
EXTERNAL VS. COIL-IN-TANK HEAT EXCHANGER
Heat Transfer Efficiency
External Coil-In-Tank
EXTERNAL HEAT EXCHANGER
Hot-water tank
COIL IN TANK HEAT EXCHANGER

36. Stores the water heated by the
collector and is typically larger than
regular water heater to allow adequate
accumulation of solar energy
Design Considerations
Proper tank stratification (hottest water on top,
and coldest at the bottom) is important to have
maximum solar hot water efficiency. Tall slim
tank with a height equal to 3-4 times diameter is
optimal.
Choosing a copper or stainless steel tank over
an enameled tank can lengthen the service life
significantly but price is likely a factor 3-4.
Enameled tanks are fitted with sacrificial anodes
and if properly maintained can have a
satisfactory service life.
Solar storage tanks should have a proper
insulation (min. R16) to minimize heat loss.
SHW TECHNOLOGY
STORAGE TANK

37. The water in a solar storage tank can get
very hot (180 oF) so its important to regulate
the HW output temperature to prevent
scalding. The tempering valve can be set at
different HW output temperatures and
automatically mixes the hot solar water with
the cold water inlet. Typical set temperature
is between 120-140 oF
SHW TECHNOLOGY
TEMPERING VALVE
Other Types
 Anti-Scalding Valve
Like the tempering valve it mixes hot and
cold water to deliver water at a preset
temperature but functionsalso as a safety
valv by closing off the flow if the hot or cold
mixing supply fails
From
Storage
Tank
From Cold
Water Line
To Fixtures
M

38. SHW TECHNOLOGY
EXPANSION TANK
Design Considerations
Expansion tank should be designed upon a
ratio of the total volume of fluid in system
and allow for total potential thermal
expansion of fluid
The expansion tank absorbs excess
water pressure, and provides
overpressure protection which could
otherwise damage the plumbing
structure or exhaust fluid through the
pressure relief valve. Normally pre-
charged by manufacturer to a set psi.
DIAPHRAGM
BLADDER
Diaphragm Expansion Tank
 Sensitive to correct install (Has to be in
vertical position)
 Relatively large in size
Bladder Expansion Tank
 The flexible bladder maintains a
constant pressure on the fluid while
allowing it to expand and contract as it
heats and cools
 Not sensitive to correct install
 Smaller in size

39. Air valves are either manually operated
or automatic and is mounted in the flow
to allow air to escape. Air valves should
be installed vertically in pipe air locks
and/or at the highest point in the solar
loop. Air locks will restrict flow of the fluid
and reduce the heat transfer in the solar
loop.
SHW TECHNOLOGY
AIR VENT
Design Considerations
Since air valves are typically installed at the
collector return the fluid can be very hot (up
to 430 oF when stagnating). The air valve
thus needs to be compatibility with this
temperature. Most standard automatic air
valves jams after a few months which is fine
since all the air is usually out by then. When
refilling its recommended to replace the air
valve.
Other Types
 Micro-bubble air vents

40. The pressure relief valve protects
system components from excessive
pressures. Used to control or limit the
pressure in the system which can build
up by a temperature upset. For solar
loops its usually set at 125-150 psi.
Offers a higher degree of reliability and
is often required through regulations
SHW TECHNOLOGY
PRESSURE RELIEF VALVE
Design Considerations
Mandatory in closed solar loops and should
have a pressure rating lower than other
ratings of system components, typically
125 psi
Other Types
 Temperature-pressure relief valve
Protects system components from
excessive pressures and temperatures.
Typically set at 150 psi and 210°F

41. SHW TECHNOLOGY
TYPES OF SYSTEMS
Thermosyphon
Drain Back
Fully Flooded
(Indirect)
Fully Flooded
(Direct)

42. BASIC SOLAR THERMAL
Types of SHW Systems
• Open Loop Batch
• Non-freeze climates
• Lowest cost
54

43. SHW TECHNOLOGY
TYPES OF SYSTEMS
THERMOSYPHON
PRO
 No pump required
 No controller required
 Less space required
 Relatively inexpensive
CON
 Tank exposed to external environmental
condition  Efficiency Reduction
 Aesthetics  May be considered visually
unpleasing
 Not suitable for cold climates
 Strong support structure needed
 Sensitive to poor water quality (scaling)
 Not Scalable
The thermosyphon system uses natural
convection to circulate the liquid in a
vertical closed-loop which allows it to
operate without a pump or control. Tank
will need to be positioned above the
solar collector for the natural convection
to occur

44. BASIC SOLAR THERMAL
Integrated Collector Storage (ICS)
(also called a batch collector system)
• Simple installation (few parts)
• Mild freeze protection available
• Very economical
• Good for the tropical climates
56

45. BASIC SOLAR THERMAL
Chinese ICS Solar Water Heaters
57

46. SHW TECHNOLOGY
TYPES OF SYSTEMS
FULLY FLODDED (DIRECT)
PRO
 Simple and well proven technology
 Easy to install
 Cost effective
 Moderately scalable
CON
 Pump and controller required
 Not applicable in climates with temperatures
below 42oF
 Sensitive to poor water quality (scaling)
The heat transfer fluids in the solar loop
stays fully flooded. In warm regions the
heat transfer fluid is typically the
portable water coming directly from the
storage tank or water heater.

47. SHW TECHNOLOGY
TYPES OF SYSTEMS
DRAIN BACK
PRO
 Provides overheating protection
 Protects collectors from freeze damage
CON
 Requires drain back reservoir
 Can be more complicated to install  All
pipes and collectors have to drain back to
reservoir
 Limited to maximum height of pump
 Limited Scalability
The heat transfer fluid in the collector
loop drains into a tank or reservoir
whenever the solar pump stops. When
drained the system is protected from
overheating. In cold climates with
freezing, potable water can be used in
the collectors as they drain at night or
when there is no sun

48. SHW TECHNOLOGY
TYPES OF SYSTEMS
FULLY FLOODED (INDIRECT)
PRO
 Simple and well proven technology
 Easy to install
 Cost effective
 Easily scalable
CON
 Pump and controller required
 Care need to be taken to avoid freeze damage
 System sizing is critical to avoid overheating
The heat transfer fluids in the solar loop
stays fully flooded. In cold regions the
heat transfer fluid is typically an
antifreeze such as propylene glycol to
avoid freeze damage to the collectors.
As such the heat transfer from the solar
loop to the storage tank is done
indirectly using a heat exchanger

49. Introduction to SHW
 Earth Energy Resources
 US Solar Radiation
 Why Go Green
 Why SHW
SHW Technology
 SHW Components
 Different Types of SHW Systems
Sizing Solar Domestic Hot Water System
 Solar Fraction (SFn) and Sizing Guidelines
 Sizing Dependencies
 SHW Sizing
 Other Factors
Auxiliary Heating
 Basic considerations
 Preheating
 Dual Tank Systems
BASIC SOLAR THERMAL
COURSE OUTLINE

50. BASIC SOLAR THERMAL
Hot Water Usage

51. TERMINOLOGY
SIZING SOLAR SYSTEM FOR DHW
SOLAR FRACTION (SFn) AND SIZING GUIDELINES
Hot Water Demand = Solar Energy + Aux Heating
Consumption Production
Solar Fraction Considerations
 SFn of 100% will overheat and create
problems in the summer season
 An undersized system will not provide a
feasible rate of return on investment
A SFn of around 60-80% is optimal
Solar Energy
Hot Water Demand
Aux Energy
Hot Water Demand
Solar Energy
Aux Energy
SFn =
Solar Energy
Hot Water Demand

52. Space heating
requirements
of small low energy
house
Energyrequirementorgain(%)
Space heating
requirements
of large house
DHW
requirements
Solar yield
from
160 ft2
collectors
Solar yield
from 54 ft2
collectors

53. SIZING SOLAR SYSTEM FOR DHW
SIZING DEPENDENCIES
HOT WATER CONSUMPTION
 Load Type (Showers, Baths & hot tubs, Hot water appliances)
 Patterns (Morning/Night peaks vs. continuous consumption)
 Users (Number of people living in the household)
OTHER FACTORS
 Shading (Trees, Buildings)
 Space Limitations
COLLECTOR
 Tilt of the collector
 Orientation in relation to due south
 Collector efficiency
LOCATION
 Solar Radiation (Intensity)
 Climate (Clouds, Fog, etc)
 Seasonal Variations (Sun path during seasons, Day Vs. Night)

54. Design Assumptions:
 Domestic hot water temperature  120°F
 Glazed flat plate collector with good efficiency
 Tilt angle  35° (Optimum)
 Orientation  Due South (Optimum)
SIZING SOLAR SYSTEM FOR DHW
SHW SIZING TO VARIOUS HW LOADS
SFn = 58.6%
Sizing Storage Capacity
 1.5 Gl/ft2 of Collector
up to
 2.0 Gl/ft2 of Collector
Sizing Collector Array
 10 ft2/Pers: Low Hot Water Demand (15 Gl/Pers)
 12 ft2/Pers: Average Hot water Demand (20 Gl/Pers)
 14 ft2/Pers: High Hot Water Demand (25 Gl/Pers)
Example: Base case (used in following slides)
 4 Person Household
 Average Consumption (20 Gallons/Person)
 GOBI glazed high selective absorber
 Location: Boston, MA.
Sizing:
 Array: 4 x 12 = 48 ft2  2 GOBI 406
 Storage: 48 x 1.5 = 72 Gl  80 Gl

55. SIZING SOLAR SYSTEM FOR DHW
SFn SENSITIVINESS TO COLLECTOR ORIENT.
Change the Orientation to Southeast or Southwest
SFn = 56.5%  Base case SFn of 58.6%
Minor deviations from a due south collector orientation does not have a significant
impact on Solar Fraction
79
Design Assumptions:
 Base case
 Impact on SFn when changing collector orientation to Southeast/Southwest
 Impact on SFn when changing collector orientation to East/West
Change the Orientation to East/West
SFn = 41.0% compared to Base case SFn of 58.6%
Significant deviations from due south will require a relative larger collector array from
base case. A factor 2 on East/West orientations provides an adequate SFn. Storage
capacity should be calculated as if collectors were due south, however, using 2 Gl/ft2

56. SIZING SOLAR SYSTEM FOR DHW
SFn SENSITIVINESS TO COLLECTOR TILT
Note
Min. tilt in mild areas is 10° to
ensure that rain water drains off the
collector. In cold, snowy regions
min. tilt is 30° to avoid heavy
snow loads on the glass
80
Design Assumptions:
 Base case
 Impact on SFn with a collector tilt of
+/- 20%
 Impact on SFn with a collector tilt of
10
o
or 90
o
Change the Collector Tilt to 28
o
or 42
o
SFn = 52%  Base case SFn of 58.6%
Minor deviations from an optimum tilt of 35
o
does not have a significant impact on the SFn
Change the Collector Tilt to 10
o
or 90
o
SFn (10
o
)= 43.0% and SFn (90
o
)= 31.0% compared to Base case SFn of 58.6%
Significant deviations from optimum tilt will require a relative larger collector array from
base case. A factor 2 on 10
o
or 90
o
provides an adequate SFn. Storage capacity should
be calculated as if collectors were due south, however, using 2 Gl/ft2

57. SIZING SOLAR SYSTEM FOR DHW
SFn SENSITIVINESS TO GEOGRAPHICAL LOC
81
Design Assumptions:
 Base case
 Impact on SFn when changing geographical location further north
 Impact on SFn when changing geographical location to a mild region
 Impact on SFn when changing geographical location to a tropical region
Change the Geographical location to Vermont (White River Junction)
SFn = 50%  Base case SFn of 58.6%
Minor correction to collector array required especially if orientation and/or tilt is also slightly off
Change the Geographical location to California (San Francisco)
SFn = 66%  Base case SFn of 58.6% No corrections needed
Change the Geographical location to Hawaii (Honolulu)
SFn = 84%  Base case SFn of 58.6%
Solar fraction is on the high side and could cause over heating problems. Changing the
collector absorber surface from high selective to black paint would be beneficial

58. 82
 SHW systems need full sunshine to operate at
peak performance
 Shading should be avoided at all times and in
particular between 10 am – 2 pm
SIZING SOLAR SYSTEM FOR DHW
OTHER FACTORS
 Take in consideration deciduous roof
structure, and shading (trees, chimneys, etc)
 Roof conforms to current building codes for
loading
Sun Path
Roof Structure

59. Introduction to SHW
 Earth Energy Resources
 US Solar Radiation
 Why Go Green
 Why SHW
SHW Technology
 SHW Components
 Different Types of SHW Systems
Sizing Solar Domestic Hot Water System
 Solar Fraction (SFn) and Sizing Guidelines
 Sizing Dependencies
 SHW Sizing
 Other Factors
Auxiliary Heating
 Basic considerations
 Preheating
 Dual Tank Systems
BASIC SOLAR THERMAL
COURSE OUTLINE

60. AUXILIARY HEATING
PREHEATING
SRCC requires installation of isolation
valves to ensure that the solar system
can be taken out for service without
interrupting the hot water supply.
Tempering valves are typically installed
between the two tanks to prevent the
HW high temp limit fuses to blow if the
solar water is too hot.
Electrical
The solar storage tank is installed in the
supply line to the water heater (WH)
preheating the water. If the solar supply
temperature is above the WH set
temperature the heating element will not
come on. If not it will heat the water to
the desired hot water temperature as
normal. The solar controller and the WH
controller operates independently
Gas
Design Considerations
SHW SYSTEM WITH ELECTRICAL OR GAS WATER HEATERS

61. AUXILIARY HEATING
SINGLE TANK SYSTEMS
In a standard 2 element electric hot water
heater the bottom element should be
disconnected. The top element can be
connected to power and can serve as an
auxiliary heater for the top third of the
storage tank
The top element will reheat the top of the
tank irrespectively of possible solar gains.
Collector feed tube connects to cold water
supply. Collector return tube should ideally
exhaust below heating element separately
from the hot water supply line to ensure
that cold or luke warm water from the
solar system does not feed directly into
the hot water supply.
SHW SYSTEM WITH ELECTRICAL BACKUP
Design Considerations
The electric heating element functions
as back-up when solar energy is not
available or when hot water demand
exceeds the solar-heated supply
Solar Heat Transfer
Appliance

62. AUXILIARY HEATING
SINGLE TANK SYSTEMS
SHW SYSTEM WITH INSTANTANEOUS (ON DEMAND) WATER HEATERS
The solar storage is installed in the
supply line to the on demand heater. If
the temperature is above the WH set
temperature, the on demand heater will
not come on. If it isn't, the WH will heat
the water to the desired hot water
temperature as normal. The solar
controller and the on the demand
controller operates independently
On demand heater has to be designed for
high water inlet temperature coming from
the solar system. If it can’t, it’s
recommended to install an automatic
temperature sensitive by pass valve
around the on demand heater.
The on demand heater has to be
modulating i.e. heating to a preset hot
water output temperature only. Standard
incremental heating is not recommended.
Design Considerations

63. AUXILIARY HEATING
SINGLE TANK SYSTEMS
Using a bottom fired gas water heater as a
solar storage tank with gas as a back up
requires an electrical ignited burner which
can be connected to a solar controller
priority relay or the normally open terminal
on relay #2 on the Heliodyne Delta T Pro
controller.
A pilot flame burner does not work.
SHW SYSTEM WITH GAS BACKUP
The solar heat transfer appliance is
connected directly to the gas water
heater provided it has the required
storage capacity.
SolarHeatTransfer
Appliance
Design Considerations