1. Solar Water Heating Bob Ramlow Chapter 9: System Operation and Maintenance Bruce Hesher Engineering Technology Brevard Community College

2. Safety All liquid type solar collectors can produce steam! Always: Cover the collector if working during the day and allow the collector to cool. Never: Open a closed loop system when the collector is exposed to the sun. Charge system when the collector is exposed to the sun. Severe burns can result and you can get gunk in the collector.

3. Burn First Aid Burns destroy skin, which controls the amount of heat our bodies retain or release, holds in fluids, and protects us from infection. While minor burns on fingers and hands are usually not dangerous, burns injuring even relatively small areas of skin can develop serious complications. If you think a burn of any type is significant, do not hesitate to call 911 immediately. http://www.mayoclinic.com/health/first-aid-burns/FA00022

4. Charging a Closed-loop System Any SWH system needs to be filled with water and have the air bled out. Charging a closed-loop system also includes the process of putting heat exchange fluid in and getting all of the air out of the collector loop.

5. Equipment Needed Charging pump. Three 4’ hoses with female hose fittings on each end of one and one end of the other two. Non-toxic glycol to fill the system. Distilled water to dilute the glycol. Channel lock pliers. Rags. Empty 5 gallon pail. Pair of gloves. Trouble light.

6. The charging pump needs to be a liquid transfer type with enough head to pump the heat transfer fluid to the top of the collector. A ½ horse power pump will pump 28 feet vertically. The pump needs male hose fitting on both of its outlets. The pump first pulls the fluid from a 5 gallon bucket. Once the system is full, the pump circulates the fluid to remove air bubbles. Finally the pump pressurizes the system to 32 psi at 60°F.

7. Locate the charging ports in the plumbing header. See page 83. Locate the charging ports in the plumbing header. See page 83. Filling the System p204 Place the pump near so that the 4’ hoses will reach the ports. Place the pump near so that the 4’ hoses will reach the ports. Attach the hose with 2 female fittings to the outlet of the pump and the other end to the fill port. Attach the hose with 2 female fittings to the outlet of the pump and the other end to the fill port. Open the input valve. Open the input valve. Attach a second hose to the glycol drain port and put the other end in the pail. Attach a second hose to the glycol drain port and put the other end in the pail. Open the charge port drain. Open the charge port drain. Attach the last hose to the inlet of the pump and put the other end into the pail. Attach the last hose to the inlet of the pump and put the other end into the pail.

8. Fill the pail with the pre-mixed glycol and water solution (see chapter 4). Tighten all hoses with the channel locks. Prime the pump if not self-priming. Hold both of the hoses in the pail to the bottom. Turn the pump on. Fluid will be pumped into the collector loop. Observe the level in the pail. Watch the pressure gauge, you want between 10 and 25psi. You can control the pressure by adjusting the inlet drain filler valve. Add more fluid to the pail as needed to keep it about ½ full. You can tell the loop is full when the sounds subside and the fluid level in the pail stops dropping. This procedure is not as detailed as the text but gives the idea.

9. Pressurizing the System After the collector loop has been filled slowly close the filler and drain valves. Maintain at least 10psi. Once both valves are closed, slowly open the filler valve and let the pressure increase to 32psi. Close the filler valve and turn off the pump.

10. Finishing Up After pressurizing the systems, clearly label all main lines with identification tags. After pressurizing the systems, clearly label all main lines with identification tags. Create a system documentation packet that includes your contact info and the user manuals of all equipment used in the system. Create a system documentation packet that includes your contact info and the user manuals of all equipment used in the system. Include in the users manual sections on operation, inspection, maintenance, and warrantee. Include in the users manual sections on operation, inspection, maintenance, and warrantee. We need to work on this for the BCC SWH trainer.

11. Controls and Power Sources All solar water heating and space heating systems (except thermo siphon and ICS systems) require pumps to circulate fluids through the solar loop. Even direct systems, popular in Florida, need to pump water through the collector. Pumps need to run whenever there is heat in the collector to be harvested. All solar water heating and space heating systems (except thermo siphon and ICS systems) require pumps to circulate fluids through the solar loop. Even direct systems, popular in Florida, need to pump water through the collector. Pumps need to run whenever there is heat in the collector to be harvested. If a pump runs when the collector is cool, it becomes a heat dissipation system! Some sort of control is needed. If a pump runs when the collector is cool, it becomes a heat dissipation system! Some sort of control is needed. There a 2 popular schemes: There a 2 popular schemes: An AC powered pump with differential controller. An AC powered pump with differential controller. A DC pump with PV module. A DC pump with PV module.

12. AC-Powered Controls These pumps run on 120Vrms house power. The differential controller monitors the temperature of the water in the tank and the fluid int the collector. It energizes the pump if the collector is hotter than the tank. The temperature difference at which the pump comes on is adjustable. Some controllers also detect when the collector temp is approaching freezing and circulate a small amount of hot water from the tank. Differential controller schematics: www.solorb.com/elect/solarcirc/diftemp2/ www.freeinfosociety.com/electronics/schemview.php?id=2127

13. DC-Powered Systems DC powered pumps use a solar module for energy. They may or may not have a controller. If there is no controller they run whenever there is light, even if the collector is cold! During low light conditions when the collector is not producing much heat the pump runs slow! They do have the advantage of working when there electric grid is down! Think after a hurricane. If used with a differential controller they have all the desired features.

14. AC and DC Systems Compared p215 Some types of solar water heating systems only work with AC pumps: Some types of solar water heating systems only work with AC pumps: Draindown and drainback systems need enough head to pump water up into the collector. they are Ac powered and use differential controllers. Draindown and drainback systems need enough head to pump water up into the collector. they are Ac powered and use differential controllers. AC pumps run at constant speed, but DC pumps slow down when less solar energy is being added to the system. AC pumps run at constant speed, but DC pumps slow down when less solar energy is being added to the system. DC pumps without controllers can circulate hot water through a cold collector on bright sunny cold winter mornings! They can also continue to heat the tank no matter how hot the water is. DC pumps without controllers can circulate hot water through a cold collector on bright sunny cold winter mornings! They can also continue to heat the tank no matter how hot the water is.

15. Adjusting a Solar Radiant Floor Heating System In most cases only seasonal adjustment of radiant floor heating systems is needed. There is a bypass valve that enables control of the amount of heat passed through the flooring. In most cases only seasonal adjustment of radiant floor heating systems is needed. There is a bypass valve that enables control of the amount of heat passed through the flooring.

16. Maintenance All mechanical systems require maintenance. Good equipment and installation will result in systems that require little maintenance. Good equipment costs a small percentage of the overall systems more than poor equipment and prevents warrantee service calls. Good equipment and installation will result in systems that require little maintenance. Good equipment costs a small percentage of the overall systems more than poor equipment and prevents warrantee service calls. Low quality equipment and/or low quality installation will cause problems. Take the time to do it right OR do it again. Low quality equipment and/or low quality installation will cause problems. Take the time to do it right OR do it again.

17. Periodic Inspection Periodically looking at system pressure, flow rate, and temperature will reveal most problems while they are still small ones. Letting a system go until something breaks results in weekend service calls and more extensive repairs. One of the easiest ways to check for problems is to monitor system temps. Look for any leaks. If found fix immediately before they cause other problems.

18. There are many manufacturers and distributors of differential controllers: www.solar.imcinstruments.com/ www.sssolar.com/controls.asp www.altestore.com Differential Temperature Controllers

19. ICS Systems p219 If the system is deployed where there is no danger of freezing the only PM is a periodic visual inspection. If the system is deployed where there is no danger of freezing the only PM is a periodic visual inspection.

20. Drainback Systems p219 Drainback system failure mechanisms: Pump failure: no hot water and no pump sound Loss of solar fluid: no hot water. Leaked solar fluid. Controller failure: no hot water and no pump sound Freeze damage: Symptom is usually leaking water.

21. Closed-loop Antifreeze Systems p220 The parts that tend to wear are: Pumps: A bad pump makes either no sound or ugly sound. Solar fluid: Test it. Expansion tanks: Can leak fluid or air. If the internal bladder losses its air

22. Checking Antifreeze p221 The proper fluid is propylene glycol. But, as it ages it looses its ability to protect from freezing and becomes acidic. You can test the pH of the fluid using litmus paper. The pH should not be below 7.5. the lower the number the more acid it is. Home Power magazine has an article on testing solar fluid. http://homepower.com/article/?file=HP135_pg12_TheCircuit_8

23. Solar Swimming Pool Systems Check for leaks, debris on the collectors, and make sure all fittings are tight. Make sure roof attachment is secure and that no rain water is penetrating the roof.

24. Air Collector Systems The weak link in air collector systems are the dampers. They should be checked and lubricated at least annually. The blower fan should also be checked and lubricated. In all air systems, air from inside the building is circulated through a collector. Check for shading of the collector. “Build it Solar“Build it Solar” has some interesting space heating articles.