THE BASIC RADIANTEC SOLAR DOMESTIC WATER HEATER“What is the use of a house if you haven’t a tolerable planet to put it on?” – ThoreauIntroduction - The “Radiantec Basic Solar Domestic Water Heater” is a pre-engineered “packaged”residential solar water heater that will provide abundant quantities of domestic hot water for a typicalresidential family.The Radiantec Basic Solar Domestic Water Heater can serve as a point of departure for more versatilesolar energy systems. Useful supplements such as radiant underfloor heating, solar-assisted gardening, snowmelting, pool heating and passive cooling applications can be added to the basic system either initially or inthe future. For clarity, this manual refers only to the basic water heating system. We encourage you toconsult with Radiantec Company for appendices and other information about supplemental uses.The Radiantec Basic Solar Domestic Water Heater is intended in part tomeet the basic requirements of solar certification agencies and taxauthorities. The solar energy system described by this manual, whenproperly installed and maintained, meets the minimum standardsestablished by the Solar Rating and Certification Corporation (SRCC). Thiscertification does not imply endorsement or warranty of this product bySRCC.Please pay particularattention to any itemsshown in red as theywill relate to safetyconsiderations.Description and Operation The Radiantec Basic Solar Domestic Water Heater consists of a solar collectorarray, a solar hot water storage tank with "wrap around type" heat exchanger, a pump, an electrical controland other mechanicals. A simple control will turn on a pump whenever the temperature inside the solarcollectors is warmer than the temperature at the location where the heat will be used. When the sun comesup in the morning, the solar collectors become warm and the heat is passed to a "heat transfer fluid",generally water or a non-toxic glycol antifreeze solution.1

A thermal sensor near the solarcollectors sends temperatureinformation to the solar controller. Thecontroller compares this informationwith the temperature on the pipereturning from the storage tank. If thecollector temperature is warmer, thepump comes on and circulates the heattransfer fluid so that the heat energy istransferred to the solar storage tank.The Radiantec Basic Solar DomesticWater Heater can be technicallydescribed as a “closed loop, hydronic,antifreeze-based, indirect solarwater heater – In layman’s language,this means that a solar collector warmsup a solution of antifreeze and water.Then the antifreeze solution iscirculated by a pump from the solarcollector to a copper heat exchangerthat wraps around the bottom of thehot water storage tank, and then backto the solar collector to be reheated.COMPONENTSSolar collector arrayThree solar panels from Alternative Energy Technologies will make up the solar collector array. The modelnumber is AE-32 and the dimensions are approximately4’X 8’. The net solar aperture is approximately 90 squareft and is relatively large in comparison to many othersolar collectors. The net solar aperture is the actualamount of black solar absorption area that is exposed tothe sun and is a very important factor in performance.The solar panel is a shallow aluminum box with glasscover. It is essentially a heat trap, like an automobile on asunny day. Solar radiation passes through the glass cover into the collector where itturns into heat. The collected heat cannot escape easily by radiating back out. The heatis then carried away by a black copper absorber plate with attached fluid passages. Inother words, the solar collector turns solar energy into a hot antifreeze solution.2

The solar collectorThe solar storage tank holds 120 gallons of potable water. It isheated by a “wrap around type” heat exchanger made ofcopper tubing. Heated solar fluid from the solar collectorscirculates through the “wrap around” heat exchanger and theheat is passed to the water in the tank by conduction. The“wrap around” heat exchanger design gives the higheststandard of protection for the potable water: Double-wallventing prevents any contamination of water in the tank.SolarStorage TankElectricElementBack-up heating element - An electric element is locatedwithin the top 1/3 of the tank as a backup, and it is energizedwhenever there is insufficient solar energy available. Thewater heater maintains its own temperature independentlyfrom the solar control. For example, if you set the tankthermostat to 1000 F., the electric element will be activated bythe water heater control to maintain the set-point. Its positionThe solar storage tank with integralin the top third of the tank fosters thermal stratification such that“wrap around” heat exchangeronly the top third of the tank is heated electrically while thewater towards the bottom of the tank remains at a cooler temperature so that solar energy may contribute tothe domestic hot water need. The electric element should be set to the minimal acceptable watertemperature. Some users will shut the electric element off manually at the electrical box during favorablesolar conditions. In some cases, very high temperatures within the tank could trip the breaker in the tank andneed to be reset by pressing the red button.3

SOLAR MECHANICAL PACKAGEThe Solar Mechanical Package contains all of the parts needed to operate aclosed-loop system, including filling, draining, etc. A fuller explanation of thefunction of the components in the mechanical package is in the following“Installation Manual”. In a closed-loop system the solar fluid is circulatedfrom the solar collector to the tank heat exchanger by means of a pumpwhenever solar energy is available. The system is said to be closed because theworking fluid remains within the system and is never removed except formaintenance. All components of the Solar Mechanical Package, includingthe pump, can become very hot during operation.SOLAR HEAT TRANSFER FLUIDAn antifreeze solution is the medium that transfers heat from the solar collectors to the solar storage tank.The solution will be a 50-50% solution of propylene glycol and water, which is non toxic (see attachedtechnical data sheet).Freeze Protection - The solution will prevent damage from freezing down to -50 degrees F.High Temperature Protection - The antifreeze solution has a higher boiling temperature than water.Corrosion Protection - The antifreeze solution has corrosion inhibitors for long service life.Lubrication - The antifreeze solution serves to lubricate the pump for long service life.The solar fluid can be dangerously hot under certain conditions. Do not open the fill and drain valvesin the “Solar Mechanical Package” if hot.THE SOLAR CONTROLLERThe Radiantec Solar Controller serves several useful functions: Displays the temperature at important points in the system.Operates the pump either fast or slow according to solaravailability.Activates a heat dump.Signals system malfunction.4

Solar Controller Operation – There are two electrical temperature sensors (S1 and S2). S1 is placed whereit will read the temperature of the fluid coming out of the solar collectors and S2 is placed on the pipingreturning from the storage tank where it will read the temperature going back to the solar panels. Thecontroller compares the two temperatures, and if S1 is greater than S2 by a selectable amount, the pumpcomes on and fluid circulation begins between the solar collectors and the tank heat exchanger. When thetemperature difference is small, the variable speed pump runs slowly and when the temperature difference isgreater, the pump runs faster. The variable control feature has many benefits including improved low sunperformance, less control cycling and conservation of electrical energy at the pump.The placement and insulation of thetemperature sensors is a very important.Performance can suffer by 20% or moreif the sensors are not installed properly.See the installation manual for moredetails.The heat dump - The Radiantec Solar Heat Dump is a supplemental method for controlling undesirableoverheating of the solar energy system by automatically consuming some domestic hot water and sending itdown the drain. The occupant can select a lower setting for the activation of the heat dump if it desirable tohave lower overall temperatures in the solar system. Whenever the temperature at S1 (coming out of thesolar collectors) is greater than a selectable temperature (default is 250 degrees F), the heat dump isactivated.The solar heat dump is a small solenoid type valve that sends a small 1/4” stream of water down the drain.The effect is to slowly and gently cool down the entire solar energy system without consuming very muchwater. The volume of a typical heat dump is only about ten gallons and it tends to occur twice per day ifthe structure is not occupied and once per day or not at all if the building is occupied. Operation of the heatdump will not compromise a septic system because of its low volume and high temperature, whichfacilitates bacterial action.Stagnation – A solar heating system is said to be in stagnation when the solar collectors are exposed tosunlight but the heat is not being taken away and put to use. This condition can occur for any of thefollowing reasons: Pump failure Controller failure Electric power failure An air bound system Under stagnation conditions, the temperature in the solar collectors may go as high as 275 degrees Fand the system pressure could go to 50 psi. As a condition of certification, solar collectors must be able towithstand prolonged periods of stagnation. Nevertheless, these very high temperatures could eventuallycause appearance problems with the solar panels due to out-gassing of materials within the panel andsubsequent condensation in the inside of the glass cover sheet. Also, temperatures above 250 degrees F willeventually degrade the glycol and cause it to require early replacement. Stagnation is an abnormal condition5

that should be corrected but it is not an emergency.Freezing Conditions – The glycol portion of the Radiantec Basic Solar Domestic Water Heater will not beharmed by freezing conditions; however the solar storage tank will need to be protected if the building isunoccupied.PERFORMANCEThe variability of solar energy and also the variability in the usage patterns of the occupants mean that mostsolar energy systems will be supplemental. Solar domestic water heaters are usually designed to provide 6090% of the need of a typical family of four. It is generally not practical to design a solar energy system thatwill meet 100% of the needs under every circumstance because the over design needed would raise costeffectiveness and architecture issues.ROUTINE MAINTENANCE AND NORMAL OPERATIONThe Radiantec Basic Solar Domestic Water Heater is nearly maintenance free. Nevertheless, it should bechecked periodically for normal operation. When the sun comes out, the pump should run and the systemshould make abundant hot water. The pump should not run at night. It would be normal for the solar systemto run slowly on a cloudy day and make less hot water or hot water at a lower temperature. It is normal forthe heat dump to activate for short periods of time under very sunny conditions when there is little use ofhot water.Periodic rainfall should keep the solar panels free of dirt and dust. You may rinse them off with a gardenhose if they get dirty, but do not do this when the panels are very hot.The antifreeze solution should be checked every two years for acidification and freeze level protection.Normal PH is 8.6 and replacement is indicated at 7.0 or below. The PH test can be done using litmus teststrips or an electronic PH meter. The antifreeze solution may last up to 25 years if it is not exposed to air.This simple inspection will eliminate corrosion and allow a very long service life for the system. To test thelevel of freeze protection, use a hydrometer or antifreeze test strip. You may be able to find a test strip thattests both the PH and the level of freeze protection. A specification sheet for the Anti-freeze can be reviewedat the end of this manual.Inspect the external pipe insulation periodically for UV damage and repaint as needed.The pressure in the glycol loop as indicated by the pressure gauge should be checked periodically. It shouldbe between 5 and 25 psi. Lower readings might indicate a leak and higher readings could indicate astagnation condition.Condensation within the solar panelsIt is not unusual for moisture to condense on the inside of the solar panels. Condensation can be removedperiodically by allowing the system to operate at high temperatures by restricting domestic hot water usebriefly. Expansion and contraction of the solar panels can draw in morning dew. Small air vents areprovided on the back of the solar panels but they are not always fully adequate.6

ABNORMAL INDICATIONS AND TROUBLESHOOTINGHigh or low pressure - Low pressure in the glycol loop could indicate a leak. High pressure in the systemunder full sun could indicate high temperatures in the solar collectors caused by stagnation. Call for service.No hot water - If there is no hot water in cloudy conditions, the reset button for the electrical element mayneed to be reset. Very hot water on sunny days could trip the element. If this is a nuisance, you can lower theoverall temperature of the system by changing the setting of the heat dump.Leaks - If there is a leak in the glycol solar loop, it will be necessary to shut down the system and drain it inorder to make the repair. Call for service. Do not perform work on a solar heating system under full sunconditions unless you are a skilled solar technician. If there is a leak in the potable hot water portion ofthe system, do not make repairs under full sun conditions.Power failure - A power failure during sunny periods will shut down the solar pumps and cause a no-flowsituation. Temperatures within the panels will get very hot. It is not necessary to do anything. When theelectrical power returns, there may be considerable noises from expansion and contraction, but normaloperation should resume within a couple of minutes.Electrical problems - If there is a problem with the electrical control, the system is likely to run constantlyor not at all. Problems with the temperature sensors are indicated when the display flashes a high or lowtemperature indicates a series of dashes (---------). This indicates a short or open circuit in the sensor wiringor a defective sensor. Turn the controller to the “ON” position until it is convenient to make the repair. Thesolar system will run constantly until it is repaired, which will not harm the system.SHUT DOWNIt is not necessary to shut down the solar system if the building will not be occupied for a brief period oftime. If no hot water will be used for more than 60 days or if the water must be shut off to the heat dump, itwould be best to shut the system down by doing the following: Disconnect the electrical power.Drain the system.Cover the solar panels with a tarpaulin.HAZARDSSolar collectors can become very hot when they are in direct sunlight and no fluid is taking away theheat. Use great caution when collectors are in this condition. Do not stand near the collectors or thepressure relief valve.Do not work on a solar heating system when it is in direct sunlight without covering the panels.The solar heating system can generate SCALDING HOT WATER. Never send water of thistemperature directly to faucets or other fixtures. Always provide an approved anti-scald valve tolower water temperature to the fixtures by mixing cold water in with the hot.7

PARTS LISTBasic Radiantec Solar Domestic Water HeaterSolar Collector: Alternate Energy Technologies, Model AE-32Solar Storage Tank: Rheem Solaraide HE, Model 82V120HE-1Pumps: runs up to 100’: Grundfos UPS15-55SFCController: Azel Technologies Differential Temp and Variable Speed Control, Model SH-08 v3Heat Transfer Fluid: Camco Boiler Anti-freeze -100oPiping: All CopperSystem Operating Parameters: Pressure should be between 15 and 20 psi Difference between the thermometers should be at least 8o F. if the sun is shiningWARRANTIES Supplemental Manifold: 1 year from date of installation, not to exceed 18 months from date ofpurchase. PMP: 1 year from date of installation, not to exceed 18 months from date of purchase Pumps: 24 months from date of installation, but not more that 30 months from date of manufacture Solar Control: 3 year warranty from date of purchase Solar Storage Tank: 6 Years on parts and tank Expansion Tank: One year from date of installation, not to exceed 18 months from date ofpurchase Air-Eliminator: 1 year from date of installation, not to exceed 18 months from date of purchase Pressure Relief Valve: 18 months from date of purchase Pressure Gauge: 18 months from date of purchase Mixing Valve: 1 year from date of installation, not to exceed 18 months from date of purchase fromRadiantec8

AE-32 Solar Panels: 10 years from date of purchase. No guarantee for freeze damage Any other component not listed is warranted for 18 months from date of purchaseTo file a warranty claim for all components in the system, please contact a Radiantec Company customerservice representative for details on how to proceed at 1-800-451-7593.ESTIMATED COMPONENT LIFEWhen installed and maintained as directed in this manual, one can expect many years of trouble-free servicefrom this system. All components in this system are subject to the conditions of the installation. In locationswhere hard water is present, mineral deposits can prematurely foul-out the design life of these components.Periodic maintenance is required to insure that these components are well protected from such damage.The solar collectors used in this system have a design life of 30 years. Water storage tanks are designed for12-20 years of use. The lesser components, such as pumps and valves are designed for 5 years, however,are more likely to foul, as described above, if not maintained properly.REPLACEMENT PARTSContact Radiantec for replacement parts at 1-800-451-7593.Our mailing address is: Radiantec Inc. P.O. Box 1111, Lyndonville, VT 05851.SERVICEIf the system requires service, first contact the person who installed the system. You may also contactRadiantec for contact information for a referral. 1-800-451-7593.Use this space to write down system specific information:System Name:System Model Number:Name of Service Company:Address:Phone Number:9

IS IT A RADIANTEC SYSTEM?If you have used the recommended materials and followed the directions, you have the assurances that gowith a Radiantec System. These include a warranty, continued customer support and code compliance.On the other hand, if you made important changes without our consultation, then it is not a RadiantecSystem. Please understand this distinction. It is not fair or legal to associate the Radiantec name withincorrect products and designs. It is harder for us to support you if we do not know what you did.Please understand that the toll-free customer support number is for the benefit of our customers.If you have technical or code problems with other materials and applications, we would still like to helpyou, but it will be as time permits and on the following number (1-802-626-8045). Unapprovedmodifications to the Radiantec Basic Solar Domestic Water Heater can create an unsafe condition andmight void the warranty.Installation Manual – The InstallationManual for the Basic Radiantec SolarDomestic Water Heater containsimportant information and is anessential part of this owner’s manual.10






The Radiantec Basic Solar Domestic Water Heater can be technically described as a “closed loop, hydronic, antifreeze-based, indirect solar water heater – In layman’s language, this means that a solar collector warms up a solution of antifreeze and water. Then the antifreeze solutio