HTP FP-40SC User Manual

Flat Plate

This manual must be used by a qualified installer/service technician. Read all instructions in this manual damage, severe personal injury, or death.

Solar Collector

INSTALLATION

MAINTENANCE

Models FP-26SC FP-32SC FP-40SC

before installing. Perform steps in the given order. Failure to comply could result in substantial property

NOTICE: HTP reserves the right to make product changes or updates without notice and will not be held liable for typographical errors in literature.

120 Braley Rd. P.O. Box 429 East Freetown, MA 02717-0429 www.htproducts.com

The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk levels or to important product information.

DANGER indicates an imminently hazardous situation which, if not avoided, will result in death or serious

injury.

WARNING indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.

CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.

CAUTION used without the safety alert symbol indicates a potentially hazardous situation which, if not avoided, may result in property damage.

NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.

accordance with this manual before use.

FOREWORD

This manual is intended to be used in conjunction with other literature provided with the Flat Plate Solar Collector. This includes all related control information. It is important that this manual, all other documents included with this system, and additional publications, such as Solar Water Heating System Design and Installation Guidelines, be reviewed in their entirety before beginning any work.

“The solar energy system described in this manual, when properly installed and maintained, meets the minimum standards established by the SRCC. This certification does not imply endorsement or warranty of this product by the SRCC.”

Installation should be made in accordance with the regulations of the local code authorities and utility companies which pertain to this type of heating equipment.

FOR THE INSTALLER

For your safety, please read through this manual carefully before installation to minimize the risk of fire, property damage, and personal injury. Ensure the solar hot water system is properly installed in

INSTALLATION OR SERVICE OF THESE SOLAR PANELS IS REQUIRED TO BE PERFORMED BY LICENSED PROFESSIONALS WHERE SOLAR, PLUMBING, AND ELECTRICAL WORK IS REQUIRED.

The installer should be guided by the instructions furnished with the tank, as well as local codes and utility company requirements. Preference should be given to codes and requirements where they differ from the furnished instructions.

Additional publications whic h should gui de the installer include: Solar Water Heating System Design and Installation Guidelines, SRCC OG-300, available from Solar

Rating and Certification Corporation, 1679 Clearlake Road, Cocoa, FL 32922-5703, www.solar-rating.org. Code for the Installat ion of Heat Prod uc ing Applia nc es (lates t vers i on), available from the American

Insurance Association, 85 John Street, New York, NY 11038. The latest version of the National Electrical Code, NFPA No. 70. In Canada refer to Canadian Electrical Code C 22.1, from Canadian Standards Association, 5060

Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N6.

TABLE OF CONTENTS

INTRODUCTION ........................................................................................................................................... 6

ABOUT YOUR FLAT PLATE SOLAR COLLECTOR .............................................................................. 6

PART 1 – GENERAL SAFETY INFORMATION .......................................................................................... 6

A. METALLIC COMPONENTS .................................................................................................................. 6

B. FLAT PLATE COLLECTORS ............................................................................................................... 6

C. HIGH TEMPERATURES ...................................................................................................................... 7

D. SAFETY PRECAUTIONS ..................................................................................................................... 7

E. TEMPERATURE LIMITATION .............................................................................................................. 7

PART 2 – IMPORTANT INFORMATION ..................................................................................................... 7

A. SCOPE OF MANUAL ............................................................................................................................ 7

B. LOCAL STANDARDS AND AUTHORIZED PERSONS ....................................................................... 8

C. TERMINOLOGY ................................................................................................................................... 8

D. POSSIBLE SYSTEM DESIGNS ........................................................................................................... 8

1. OPEN LOOP SYSTEMS ................................................................................................................... 8

2. CLOSED LOOP SYSTEMS ............................................................................................................... 8

3. DRAIN BACK SYST EMS ................................................................................................................... 8

E. FLUID QUALITY ................................................................................................................................... 9

F. CORROSION ........................................................................................................................................ 9

G. FREEZE PROTECTION ....................................................................................................................... 9

H. WIND STRESS ................................................................................................................................... 10

I. SNOW LOAD ........................................................................................................................................ 10

J. STORAGE TANKS .............................................................................................................................. 10

K. HAIL RESISTANCE ............................................................................................................................ 11

PART 3 – IN STALLATION INFORM ATION .............................................................................................. 11

A. TRANSPORT, UNPACKING, AND INSPECTION .............................................................................. 11

1. COMPONENT LIST ......................................................................................................................... 11

2. COLLECTOR INSPECTION ............................................................................................................ 11

B. COLLECTOR DIMENSIONS AND WEIGHTS .................................................................................... 12

C. TOOLS AND MATERIALS .................................................................................................................. 12

D. SYSTEM DESIGN .............................................................................................................................. 13

E. DELTA-T CONTROLLER SETTINGS ................................................................................................ 13

F. STAGNATION AND OVERHEATING ................................................................................................. 13

G. CORRECT SYSTEM SIZING TO AVOID EXCESSIVE OVERHEATING .......................................... 13

H. COLLECTOR ANGLE, PLANE, AND DIRECTION ............................................................................ 14

1. COLLECTOR DIRECTION .............................................................................................................. 14

2. COLLECTOR ANGLE (TILT) ........................................................................................................... 14

3. COLLECTOR PLANE (HORIZONTAL OR VERTICAL) .................................................................. 14

I. AVOID SHADE ..................................................................................................................................... 15

J. LOCATION .......................................................................................................................................... 15

K. EXPANSION TANK ............................................................................................................................. 15

1. OPEN LOOP SYSTEMS ................................................................................................................. 15

2. CLOSED LOOP SYSTEMS ............................................................................................................. 15

3. DRAIN BACK SYST EMS ................................................................................................................. 15

L. LIGHTNING PROTECTION ................................................................................................................ 15

M. PIPE SIZING AND CONNECTIONS .................................................................................................. 15

N. CONNECTION OF MULTIPLE COLLECTORS ................................................................................. 16

O. POTABLE WATER ............................................................................................................................. 16

P. MOUNTING FRAME ........................................................................................................................... 16

Q. GALVANIC REACTION ...................................................................................................................... 16

PART 4 – MOUNTING INSTALLATION .................................................................................................... 16

A. MOUNT TYPES .................................................................................................................................. 16

1. TILT MOUNT (HTP Part # FP-SM) .................................................................................................. 16

2. FLUSH MOUNT (HTP Part # FP-FM) .............................................................................................. 16

3. RACK MOUNT (HTP Part # FP-RM) ............................................................................................... 17

B. GENERAL MOUNTING INFORMATION ............................................................................................ 17

C. TILT MOUNTS (HTP Part # F P-SM) .................................................................................................. 17

1. TRIANGLE MOUNTING FEET ........................................................................................................ 17

2. FRONT MOUNTS ............................................................................................................................ 18

3. REAR MOUNTS .............................................................................................................................. 18

D. FLUSH MOUNTS (HTP Part # FP-FM) .............................................................................................. 19

INSTALLATION ................................................................................................................................... 19

E. RACK MOUNTS (HTP Part # FP-RM) ................................................................................................ 20

INSTALLATION ................................................................................................................................... 20

PART 5 – ROOF / WALL ATTACHMENT SUGGESTIONS ...................................................................... 20

A. ROOF ATTACHMENT ........................................................................................................................ 21

B. WALL MOUNTING .............................................................................................................................. 22

PART 6 – PLUMBING CONNECTIONS .................................................................................................... 23

A. TEMPERATURE SENSOR INSERTION ............................................................................................ 23

B. HEADER CONNECTION .................................................................................................................... 23

C. AIR PURGE ........................................................................................................................................ 23

1. OPEN LOOP .................................................................................................................................... 23

2. PRESSURE OPEN LOOP ............................................................................................................... 24

3. CLOSED LOOP ............................................................................................................................... 24

D. PLUMBING CHECK ............................................................................................................................ 24

E. GLYCOL FREEZE PROTECTION ...................................................................................................... 24

F. INSULATION ....................................................................................................................................... 24

G. PUMP SELECTION ............................................................................................................................ 25

PART 7 – SYSTEM PIPING DIAGRAMS ................................................................................................... 26

A. REVERSE RETURN ........................................................................................................................... 26

B. BALANCE FLOW VALVES WITH METERS....................................................................................... 27

C. PRESSURE SYSTEM PLUMBING PANEL ATTACHMENT .............................................................. 28

PART 8 – MAINTENANCE ......................................................................................................................... 28

A. CLEANING .......................................................................................................................................... 29

B. INSULATION ....................................................................................................................................... 29

C. OTHER COMPONENTS..................................................................................................................... 29

D. STAGNATION ..................................................................................................................................... 29

PART 9 – TROUBLESHOOTING ............................................................................................................... 29

A. NO HOT WATER ................................................................................................................................ 30

B. REDUCED SOLAR CONTRIBUTION ................................................................................................. 30

C. REGULAR WATER DUMPING .......................................................................................................... 30

PART 10 – INSTALLATION CHECKLIST ................................................................................................. 31

MAINTENANCE NOTES ............................................................................................................................ 32

HTP CUSTOMER INSTALLATION RECORD FORM ........................................................................ 33

Only use this solar hot water system as intended and described in this installation manual. Any use other

Install all system components and piping in such a way that does not reduce the performance of any fire rated assembly. Failure to do so may lead to fire, property damage, personal injury, or death.

edges.

INTRODUCTION

ABOUT YOUR FLAT PLATE SOLAR COLLE CTOR

Your Flat Plate Solar Collector is designed to offer reliable hot water heating in hot, mild, or cold climates. Flat plate solar collectors operate in open loop, closed loop, and drain back solar systems, making these collectors ideal for a variety of installation designs.

Job site conditions will require your installation contractor to supply some or all of the following:

• Plumbing connections

• Piping and insulation

• Valves between your backup water system and the solar system

PART 1 – GENERAL SAFETY IN FO RMATIO N

NOTE: OBTAIN ALL APPLICABLE PERMITS BEFORE BEGINNING WORK. OBEY ALL LOCAL CODES.

than described will void warrant y and m a y lead to fire, property damage, personal injury, or death.

A. METALLIC COMPONENTS

To avoid injury, always wear leather protective gloves when handling solar collector components. All efforts have been made to make the metal components safe to handle, but there may still be some sharp

B. FLAT PLATE COLLECTORS

Be careful when handling the collectors, as they will break if dropped. When installed, collectors may break if struck by a hard object (e.g. a branch falling on the roof).

Failure to follow these warnings could lead to property damage, serious personal injury, or death.

If any system components are exposed to the following, do not operate until the affected component has

company by the consignee.

C. HIGH TEMPERATURES

• In sunlight, the copper plumbing ports can reach temperatures in excess of 300oF. Thick leather gloves must be worn when handling hot components to prevent serious burns.

• Keep solar hot water system and components away from children and animals.

• In an installed, fully plumbed system, if the pump is stopped in sunny conditions, the copper ports

and piping can easily reach temperatures in excess of 300 handling such components.

• Do not store combustible materials (dry leaves, tree branches, gasoline, etc.) in the vicinity of the solar system.

F. Caution should be taken when

D. SAFETY PRECAUTIONS

• Wear leather gloves when handling metal components and hot plumbing components.

• Adhere to safety regulations when working on roofs (or at a height).

• Always obtain engineer approval for installations in high wind regions.

• Assembly of the solar hot water system requires two persons with the ability to lift 75 pounds

each.

• It is best to install the solar hot water system on a cool, cloudy day.

been inspected by a qualified serviceman.

1. FIRE

2. DAMAGE

3. SUBMERSION IN WATER

Any claims for damage or shortage in shipment must be filed immediately against the transportation

Use of lead solder is expressly prohibited. Use of galvanized steel, CPVC, PVC, PEX, or any other type of plastic pipe is prohibited.

E. TEMPERATURE LIMITATION

To prevent scalding, the high temperature of the potable water must be limited using an ASSE 1016 tempering valve. This valve is usually located between the hot water storage tank and faucets in bathrooms, kitchens, etc. Tempering valves are mandatory under most codes and usually set to a maximum of 120

F. Tempering valves must be rated for high-temperature solar use.

PART 2 – IMPORTAN T INFORMATION

A. SCOPE OF MANUAL

This manual pertains only to the installation and operation of the HTP solar collector. Details for the installation, operation, and maintenance of the complete solar gas/electric water heating system, including, but not limited to: the storage tank, gas/electric booster, pump, system controller, valves, and other plumbing components, should be provided separately by their respective manufacturers.

NOTE: This manual is primarily a reference document for authorized installation individuals, as the solar collector is not permitted to be installed by non-authorized persons.

B. LOCAL STANDARDS AND AUTHORIZ ED PERSO NS

Installation must be completed in accordance with local standards and regulations. Installation must also be completed by a qualified tradesperson who holds relevant industry licenses or

certificates. The term “authorized person(s)” used throughout this document refers to a suitably qualified professional. Unless otherwise specified in Part 3, no part of the HTP solar collector may be inspected, repaired, or maintained by anybody other than an authorized person.

C. TERMINOLOGY

Solar terminology differs from region to region. To avoid confusion, please note the following:

Supply – The plumbing line running from the outlet of the collector to the tank. Return – The plumbing line running from the tank (or heat exchanger) to the inlet of the collector. This

line incorporates the circulation pump.

D. POSSIBLE SYSTEM DESIGNS

1. OPEN LOOP SYSTEMS

An open loop system has potable water circulating through the solar collectors. Open loop systems are recommended for hot or warm climates that rarely freeze. For rare incidents when ambient temperature drops below freezing, the controller can be programmed to provide freeze protection by circulating warm water from the tank through the solar collectors.

For open loop systems, the normal operating pressure should be less than 72.5 psi. This operating pressure is provided via use of a pressure limiting/reduction valve on the main supply line. An expansion tank is required in open loop systems.

An open loop system may allow the solar collectors to stagnate to prevent overheating of the storage tank. In the event of component failure, the pressure relief valve must be able to release the increased pressure, and should be rated to meet the maximum possible pressure output of the solar collector(s). Please see Part 3 for sections regarding overheating.

2. CLOSED LOOP SYSTEMS

A closed loop system uses non-potable heat transfer fluid (HTF) and must be pressurized to less than

72.5 psi. Closed loop systems require an expansion tank to accommodate HTF expansion. The system should be designed to minimize stagnation after the tank temperature has been met; extensive stagnation may increase pH levels and glycol deterioration.

The expansion tank and plumbing must be properly sized so that the safety pressure relief valve will not activate except in the event of component failure or extreme conditions. The pressure release must be set at no more than 90 psi. (There may be exceptions in engineered designs for tall buildings.)

3. DRAIN BACK SYSTEMS

The drain back method provides effective overheating and freeze protection, making these systems wellsuited for all climates. When storage tank water temperature settings are reached or the collector temperature falls below a set temperature, the pump shuts off, allowing the HTF to drain back into the tank. Some drain back systems use distilled water as HTF. Others use a propylene glycol/water mix.

Drain back systems require larger pumps to move HTF up and into the solar collectors. Mounting the drain back tank as high as possible within conditioned space will reduce pump size.

TOTAL DISSOLVED SOLIDS

< 600 ppm

TOTAL HARDNESS

< 200 ppm ÷ 17.1 = 11.7 grains

CHLORIDE

< 40 ppm

NOTE:

DAMAGE.

For drain back systems, the solar loop often operates at less than 25 psi, far lower than open or closed loop systems. These low operating pressures do not require an expansion tank. A pressure relief valve, installed on the drain back tank and piped in copper to an appropriate drainage location, will provide sufficient expansion protection. This pressure relief valve and drain outlet pipe must never be sealed or blocked. The pressure relief valve is intended to be operated for safety purposes only.

NOTE: Supply and return connections to the collector must use eccentric fittings or a fitting arrangement that allows full draining of header pipes. The collector or array can be mounted level or with up to ¼” pitch towards the return port to facilitate the drain back process. In addition, Collector plumbing should slope toward the drain back reservoir at ¼” per foot minimum to facilitate the drain back process. If continual slope is not achievable, consider a pressurized closed loop system.

E. FLUID QUALITY

Water quality is very important. Water in direct flow through the solar collectors must first meet potable water requirements; any fluid circulated through the collectors should be non-corrosive to copper. In addition, water quality must meet the following:

FREE CHLORINE < 5 ppm MAGNESIUM < 10 ppm

Table 1

In areas with “hard” water (water hardness greater than 200 ppm) where open loop format is used, lime scale may form inside the solar collector. Scale deposits will reduce collector efficiency and eventually plug the collectors. In such regions, it is advisable to install a water softening device to ensure the long term efficient operation of the collector, or consider a closed loop system.

In order to meet health and safety regulations, glycol used should be food grade propylene glycol, FDA rated as “generally recognized as safe” (GRAS). If using a glycol/water mix, distilled water is preferred. If distilled water is unavailabl e, the water must meet the above requirements. The glycol content of the liquid must not exceed 50%, unless the manufacturer specifies that a different ratio is recommended for use with solar water heaters. Glycol should be checked periodically to prevent it from becoming acidic. Please refer to guidelines provided by the glycol manufacturer regarding glycol maintenance.

F. CORROSION

Both copper and stainless steel are susceptible to corrosion when, amongst other factors, high concentrations of chlorine are present. The solar collector may be used for heating of spa or pool water, but levels of free chlorine must not exceed 5 ppm. Otherwise, the copper header could corrode.

HTP DOES NOT WARRANT THE SOLAR COLLECTOR AGAINST CORROSION-RELATED

G. FREEZE PROTECTION

Freeze protection must be implemented in any regions that may experience freezing conditions at any time throughout the year.

“Freeze tolerance limits are based upon an assumed set of environmental conditions. Extended periods of cold weather, including ambient air temperatures below the specified limit, may cause freezing in exposed parts of the system. It is the owner’s responsibility to keep the system’s freeze protection levels

NOTE: HTP DOES NOT WARRANT THE SOLAR COLLECTOR AGAINST FREEZE-RELATED

maintained in accordance with the supplier’s instructions if the air temperature is expected to approach the specified freeze tolerance limit.”

For open or closed loop systems: In areas with temperatures not falling below -5

C / 23oF, a differential solar controller with freeze protection may be used (e.g. requiring pump to circulate if the manifold temperature approaches freezing). In an open loop system, a freeze valve (which opens to allow water to dribble out) could also be considered.

For closed loop systems: For areas with temperatures falling below -5

C / 23oF, a propylene glycol/water mix should be used to provide freeze protection. Please refer to glycol manufacturer’s specifications about the temperature ranges the liquid can withstand. Only food grade propylene glycol, FDA rated as GRAS, should be used.

DAMAGE.

H. WIND STRESS

When installing the collector, please consider the issue of wind resistance and the resultant stress on attachment points. Adhere to relevant building codes/regulations regarding installation of such objects.

For flush mounting on a pitched roof, a minimum of four attachment points must be made (2 on the upper and 2 on the lower track), each with a minimum pull strength of 100 kg / 220 lb. If this cannot be achieved, additional attachment points must be made to achieve minimum strength levels.

If installing at a raised angle (tilt-up mounts, as seen in Part 5), a minimum of four attachment points must be made (2 on the upper and 2 on the lower track), each with a minimum pull strength of 150 kg / 330 lbs. If this cannot be achieved, additional attachment points must be made to achieve minimum strength levels.

It is the responsibility of the installation contractor to ensure that the frame mounting is of suitable strength. Where applicable, inspection by building department officer or equivalent should be completed to ensure the installation is in accordance with relevant regulations.

I. SNOW LOAD

In areas prone to heavy snowfall, the solar collectors should ideally be installed at an angle of 50 greater to help promote snow sliding off the collectors. In addition, it is advisable to raise the lower collector frame off the roof surface 15 – 20 cm / 6 – 8 inches or higher. Doing this places the collector above moderate snowfall accumulation and allows drifting snow to more easily slide out from under the collector, which helps ensur e that snow does not cover the collector array.

Please refer to local regulations regarding snow loading precautions.

J. STORAGE TANKS

It is recommended that the lever on the pressure and temperature relief valves (PTRV) on main pressure hot water storage tanks be operated once every 6 months to ensure reliable operation. It is important to raise and lower the lever gently, and be careful as the water released will be HOT. Failure to operate the PTRV on a regular basis could lead to failure of the component and the possibility of the storage tank exploding.

It is recommended, and may also be a local regulation, that, in order to expel water safely, th e PTRV have a copper pipe connected and run to an appropriate drainage location. The PTRV and drain outlet pipe must not be sealed or blocked.

properly could result in explosion and fire, serious property damage, serious personal injury, or death.

NOTE: HTP DOES NOT WARRANT THE COLLECTOR AGAINST FAILURE AS A RESULT OF DAMAGE INCURRED DURING TRANSPORT OR INSTALLATION.

NOTE: If the water heater is left in an operating condition and not used for two weeks or more, a quantity of highly flammable hydrogen may accumulate in the top of the water cylinder.

To dissipate hydrogen safely, it is recommended that a hot water tap be turned on for several minutes at a sink, basin, or bath, but not a dishwasher, clothes washer, or other electrical or heat producing appliance. During this process, there must be no smoking, open flame, or electrical appliance operating nearby. Hydrogen discharged through the tap will sound like air escaping. Failure to dissipate hydrogen

K. HAIL RESISTANCE

Solar collectors are surprisingly strong and able to handle significant impact stresses once installed. Testing and impact stress modeling proves that when installed at an angle of 40 able to withstand impact from hail larger than 1” in diameter. The ability of collectors to withstand hail impact is greatly influenced by the angle of impact, so installing the collectors at low angles does reduce their impact resistance.

or greater, collectors are

PART 3 – INSTALLATION INFORMATION

A. TRANSPORT, UNPACKING, AND INSPECTION

Solar collectors are normally transported in a protective crate. Boxes containing the mounting assemblies will generally accompany the collectors.

1. COMPONENT LIST

Please familiarize yourself with the components listed on the packing list. If any components are missing, and/or additional part(s) are required, please contact your supplier.

2. COLLECTOR INSPECTION

Inspect the delivered crate and ensure all collectors are intact. Before the freight delivery employee leaves, check boxes for correct type and number of mounts. Note anything out of order or suspicious on the bill of lading, even if damage is not apparent. If damage is sufficient to prevent the product’s use, it may be prudent to not accept all or part of the shipment and immediately alert your supplier.

DIMENSION A

3.30”

DIMENSION C

77.2”

97.2”

121.2”

WEIGHT (LBS)

113

153

GROSS FRONTAL AREA (FT2)

TRANSPARENT FRONTAL AREA (FT2)

23.6

29.9

37.4

ABSORBER PLATE AREA (FT2)

FLUID CAPACITY (gallons)

.90

1.05

1.22

B. COLLECTOR DIMENSIONS AND WEIGHTS

Figure 1: Collector dimensions. Copper union in illustration is field-supplied. Allow spacing to assemble fittings and unions.

FP-26SC FP-32SC FP-40SC

DIMENSION B

DIMENSION D

NOMINAL FLOW RATE (GAL/MIN)

Table 2

47.2” 47.2” 47.2”

50” 50” 50”

25.6 31.8 39.7

23.2 25.7 36.9

0.8-1.5 gallons per collector

C. TOOLS AND MATERIALS

Make sure you have all necessary tools, materials and accessories before beginning work on the solar system. Following is a list of minimum tools required; other plumbing components will be field supplied according to the installation needs.

Electric Drill Torch and Striker Drill Index (w/ ½” and ¾” Wood Bits) Putty Knife

Hack Saw High Temperature Joint Compound Tubing Cutter Tin Snips Solder Flux Tape Measure Emory Paper 24” Level Extension Cord Slip Joint Pliers Needle Nose Pliers Silicon Caulk and Roof Tar Pipe Wrenches, 10” and 14” Angle Iron Open End Wrenches, 9/16 & 7/16 Screw Driver 6” Flat Blade Screw Driver 6” Philips Wire Stripper or Knife Wire Cutters Black Latex Outdoor Paint Adjustable Wrenches 8” & 10” Aluminum Flashing Sheet

D. SYSTEM DESIGN

System design should be completed prior to installation. Solar collectors need to be installed correctly to ensure high efficiency and, most importantly, safe and reliable operation. Please seek professional advice for the design and installation of your solar heating system.

NOTE: Only authorized licensed contractors are permitted to install the solar collector.

E. DELTA-T CONTROLLER SETTINGS

Usually a Delta-T ON value of 8 – 20 may need to be altered slightly according to location and system design. Refer to the instruction manual provided with the chosen solar controller for appropriate settings.

F and Delta-T OFF value of 4 - 10oF is appropriate. These settings

F. STAGNATION AND OVERHEATING

Stagnation refers to the condition that occurs when the pump stops running. This can be due to pump failure, power blackout, or as a result of a high tank temperature protection feature built into the controller which turns the pump off.

If the system is designed to allow stagnation as a means of preventing tank overheating, the collector and plumbing in close proximity may reach temperatures greater than 395

F; components that may be

exposed to these high temperatures, such as valves, plumbing, or insulation, should be suitably rated. If the system is designed to allow stagnation of the collector when the tank reaches a set maximum level,

steam may form in the collector(s). In such a system, temperature relief valves or auto air vents should be isolated (using an isolation valve) on the collector outlet, as these options may not be able to withstand the high temperatures and allow stable stagnation of the collector (may dump hot water).

In the event of component failure or extreme conditions, the PTRV on the hot water stor age tank may open as a safety measure. Under such conditions, the collector will normally reach a maximum temperature of around 395

F. Any heat returning from the collector is generally not enough to cause a continued increase in tank temperatures (e.g. heat input is less than tank heat losses), and therefore is able to meet requirements in some regions limiting hot water dumping. A crackling noise may be heard coming from the supply line when hot water is used as the pressure in the system drops and steam forms. This is normal.

G. CORRECT SYSTEM SIZING TO AVOID EXCESSIVE OVERHEATING

The system should be sized so that overheating of the tank is difficult to achieve in a single day, even during hot, sunny periods. If the system is oversized, such that excessive heat is often produced during summer months, consider installing a drain back system, a heat dissipater unit, and carefully review the points in Part 3, Section H, Preventing Overheating.

H. COLLECTOR ANGLE, PLANE, AND DIRECTION

1. COLLECTOR DIRECTION

The collector should face the equator. In the northern hemisphere, this is due south, and in the southern hemisphere, due north. Facing the collector in the correct direction and angle is important to ensure optimal heat output. A deviation of up to 15 acceptable, and will have minimal effect on heat output.

Figure 2: Suggested placement of solar collectors

NOTE: In Figure 2, B, C, and D orientations (horizontal or landscape) are not recommended for drain

back systems.

from due south is

2. COLLECTOR ANGLE (TILT)

It is common for collectors to be installed at an angle that corresponds to the installation latitude. While adhering to this guideline, an angle of latitude +/- 10 output. The solar collector should be installed at an angle of between 20 – 80

is acceptable, and will not greatly reduce solar

to ensure optimal

operation. For year-round domestic hot water, the collector should be tilted to an angle of equal to the latitude of the

installation site. Add 15

to the latitude to optimize for winter performance (space heating). Subtract 15o

from the latitude to optimize for summer performance (pool heating). Given the formula above, a solar collector installed at 30

for wintertime advantage, and 15o for summertime heating.

N latitude should face due south at an angle of

Preventing Overheating To reduce summer heat output, angle the collector for optimal winter absorption. This is achieved by installing the collector at an angle of around 15

above the latitude angle (e.g. 45o at 30oN latitude). This angle corresponds closely to the angle of the sun in the sky during the winter months, thus maximizing winter output. Conversely, during the summer when the sun is high in the sky, the relative collector surface area exposed to sunlight is reduced, cutting overall heat production considerably (by about 15%). This option is ideal for installations where solar thermal is being used for space heating.

3. COLLECTOR PLANE (HORIZONTAL OR VERTICAL)

The collector could be installed vertically, but may be installed at an angle, such as sideways on a pitched roof. It is not recommended to install a drain back system in the horizontal or landscape style. In vertical installations, collectors may be installed level, or with ¼” pitch towards the return port. See more detail in Part 2, Section D, Number 3.

Failure to properly control HTF expansion may result in property damage, personal injury, or death.

I. AVOID SHADE

Collectors should be located so that shading does not occur between 9 AM and 3 PM local time. Partial shading due to small objects such as antennas and flues is not of great concern.

J. LOCATION

To avoid long pipe runs, the collector should be positioned as close as possible to the storage tank. Storage tank location should therefore be considered part of the location requirements of the solar collector. The storage tank should be located as close as possible to the most frequent draw off points in the building.

K. EXPANSION TANK

Expansion of HTF occurs as it heats. When HTF expands, it has to be controlled, as fluid cannot be compressed like air. A properly sized and installed expansion tank can accommodate expansion of HTF. If the expansion tank fails, a properly sized and installed PTRV will activate and protect the system.

See below for requirements pertaining to your application.