Lesson 4
Answers

1. During the initial site survey, what are five important building characteristics to evaluate?

Answer:
a) the roof’s capability to safely hold the collectors and the installation crews loads
b) the roof’s orientation, amount of surface area that is shade-free area, and the age of the roof’s surface
c) the safeness of working on the roof
d) the amount of space near the conventional water heater(enough for a storage tank?)
e) the difficulty of doing the installation

2. What are the three common methods of installing the collector mounting clips?

Answer:
a) lag screws into the rafters
b) J-bolts next to the rafters
c) threaded-rod through a compression block with a spanner between the rafters

3. Where must the lag screw be when installing a mounting clip in a rafter and why?

Answer: The lag screw must be installed in the center of the rafter to maximize the holding capacity of the collector mounting clip. An off-center lag screw will have a reduced capacity to hold the collector mounting clip secure.

4. Why is a compression block needed when installing a mounting clip between rafters?

Answer: The compression block allows the threaded-rod connection between the mounting clip and the spanner board to be securely tightened without bowing the spanner board or the roof sheathing.

5. For a one-story building, what is a method of getting the collectors on the roof and how many people are required to do so?

Answer: Depending on the strength of the installers, the weight of the collectors, the ground-roof line height, the roof slope, and the roof line termination, two people can get light solar collectors on the roof as seen in the FSEC pictures. Generally, for heavy collectors, two people on the roof pulling on ropes attached to collector and one on the ground pushing the collector up a ladder is the method to use.

6. Although not given in the materials presented in this lesson, how could you get solar collectors on the roof of a two- or more-story building?

Answer: Given there is no interior stairway or passage that the collectors can be transported to the roof, the safest method is to use a high-lift device or a crane to get the collectors to the roof.

7. Why should you be careful when lifting shingles to make it possible to install copper flashings for the plumbing lines?

Answer: When lifting the shingles any rips or tears are possible pathways for water to leak into the building. Although properly repaired shingles may not leak, they do not give a professional, clean installation appearance.

8. What function does the flashing cap perform?

Answer: The flashing cap soldered to the inlet and outlet pipes allows leak-free movement of the plumbing lines due to thermal expansion and contraction.

9. Why is it necessary to clean and flux both surfaces of copper pipes and fittings before sweat soldering?

Answer: Cleaning and fluxing the copper pipe and fitting surfaces allows solder to flow and fill all the void between the mating surfaces, thus preventing leaks.

10. Why is it necessary to install the collector plumbing lines such that the collectors and the plumbing lines outside the conditioned space can be completely drained?

Answer: If the system must be drained for repairs, any fluids remaining in a low spot may freeze and rupture the plumbing lines. You may not think that freeze-protected systems with glycol heat transfer fluids need to configured this way, but given the fluid degradation potential the freeze protection level may be reduced enough to allow freezing.

11. What could be the result if you install a temperature/pressure relief valve near the collector outlet?

Answer: The outlet collector fluid temperature could exceed the temperature release limit allowing the release of the heat transfer fluid. For glycol solutions, the expelled fluid may be harmful to the roofing materials.

12. Why does the automatic air vent valve have to be installed in a vertical position?

Answer: Off-vertical installation may hinder air removal to the extent that the system becomes air-locked and fluid flow in the collector loop is stopped.

13. Where are the proper places to install a differential controller’s sensors?

Answer: Near the collector outlet and the bottom of the storage tank.

14. What is main reason that soft copper piping is installed between the storage tank and the collector inlet and outlet?

Answer: Using soft copper piping significantly reduces the chance of a leak in the plumbing lines between the collector connections and the storage tank. Every solder joint is a potential leak and the more of them in the plumbing lines, the greater the potential to have a leak over time.

15. Why install a check valve in a solar water-heating system?

Answer: A properly installed check valve prevents reverse thermosyphoning whenever the fluid in the collectors is cooler than the fluid temperature in storage.

16. In a freeze-protected solar water heating system, how do you fill the system with the heat transfer fluid and when is it best to do the task?

Answer: In the freeze-protected system, bib valves should be installed on either side of the check valve. Using a separate pump the heat transfer fluid is pumped (commonly out of a five- gallon bucket) into the bib valve on collector inlet side of the check valve. The bib valve on the storage side of the check valve is left open until the heat transfer fluid’s flow is steady. At that time the storage side valve is closed and then the pump is shut off and the collector side valve is closed. The best time to fill the system is early morning, late afternoon, or after sundown.

17. Why is an expansion tank needed in a freeze-protected solar water-heating system?

Answer: The freeze-protected system is a closed-loop and the expansion tank allows thermal expansion and contraction of the heat transfer fluid without rupturing the plumbing lines.

18. Why should a by-pass line and ball valves be installed between the solar storage tank and the conventional domestic hot water heater?

Answer: If the solar water-heating system needs to be repaired, the solar loop can be shutdown and the conventional water heater can provide hot water to the building.

19. Why is it important that you fill and pressurize the solar water heating system before installing insulation on the plumbing lines?

Answer: Filling and pressurizing the solar system allows the installers to locate and repair any leaks in the system. In other words, the plumbing insulation may conceal leaks that would only be found later after possible extensive damage done to the building and materials inside the structure.

20. After installing pipe insulation on the exterior plumbing lines, how do you protect the insulation from UV degradation?

Answer: Use a cover material such as paint, metal foil, or other UV-resistant materials.

21. After turning the solar water heater on and giving the building owner a walk-through, what printed materials should be left at the building?

Answer: Copies of the system components and their warranties and copies of the system’s operation and troubleshooting guides. Labeling the valves would be helpful to the building owner and for future reference for any system repair people.

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