Solar Water Heating Bob Ramlow Chapter 8: System Installation Bruce Hesher Engineering Technology Brevard Community College

Previous presentations have covered most of the relevant technologies involved in Solar Water Heating. This chapter details installation. Many systems use common components and have similar installation requirements. Home Power magazine has a great article on SWH: http://homepower.com/basics/hotwater/

Installing Solar Water Heating Systems Proper and thorough planning are important. An understanding of how SWH systems operating and the ability to visualize how a system can be incorporated into a structure are needed. There are options available to most installations and they need to be considered. The load analysis determines how many collectors are needed (usually one in Florida) and is the first task in the process. The solar window determines the best location for the collector but, you must also consider the location of the solar water tank (and optional heat exchanger).

Building structure and layout determine where the solar loop piping will be run. After deciding where the components will be located, make a list of all the parts needed. A sketch of the system is helpful. Decide on the type of mounting that will be used for the collector(s). If rooftop, how will the piping penetrate the roof? Use proper roof flashing and/or sealant. Measure pipe runs from collector to heat exchanger (or tank). Determine all of the pipe fittings that will be used (elbows. T’s, couplers, etc.). List and procure them.

The size of the collector array determines the size of the storage tank and heat exchanger. After you have figured all of the plumbing you can calculate the amount of solar fluid to use in the collector loop. If direct system, not needed.

Galvanic Corrosion Never mix piping of dissimilar metals; it will cause galvanic corrosion. Compatible metals are: Copper, Stainless steel, brass, bronze. Non-compatible metals are: cast iron, galvanized steel, black iron, and aluminum. To connect copper piping to a steel tank use a dielectric union.

Components of a Dielectric Union:   This is a dielectric union. This device electrically separates the water heater from the household piping. It also provides a convenient way to disconnect the piping for removal or servicing of an appliance, such as a water heater or water softener. Components of a Dielectric Union:  The big nut clamps the brass part to the steel threaded part. The black washer and purple insulator keep the brass and steel parts from touching. The brass part gets soldered to a copper pipe. The steel part is threaded onto a piece of steel pipe.

Handling Solar Collectors Collectors are typically shipped staked on a wooden pallet. Inspect for damage before uncrating. Collectors weigh 85 to 140lbs and are big and bulky. To transport short distances lay flat with glass side up. In shipping they should have caps over the pipe ends to keep moisture and dirt out. Getting a collector on the roof is not a one man operation! Keep safety first. Work when there is little or no wind. Always wear safety harness when working on a roof.

Mounting Solar Collectors Install mounting brackets before lifting the collector onto the roof. The mounting brackets provide good structural lift points. The mount supports must be into the center of the trusses or into spanner or blocking board. Consult your permitting office. Use at least 4 attachment points. The body of the collector should be above the roof by about 2” to prevent conducting heat into the roof. If the collector will be tilted at an angle other than the slope of the roof, prepare the mount before lifting the collector to the roof. See p165

Mount at a tilt angle of latitude (up to 15° more if improved winter production desired). Also camber the collector so the inlet pipe is 2-3° lower in order to facilitate draining. Use an angle finder (inclinometer) to find the roof pitch. Show in Sketchup

Ground Rack Mounting p178 When there is no appropriate roof space ground mounting can be done (except for thermo-siphon systems). All collector types have ridged frames that can be used for mounting. Wind loading of 130mph must be designed for east central Florida!

Mounting the Heat Exchanger (if used) p181 The storage tank and heat exchangers can be mounted at any time during the install. Het exchangers are always located near the tank. Locate the tank first. The heat exchanger is connected to the OUT to solar and IN from collector ports. Check tube lengths before making attachments.

Plumbing the System p184 Use only lead free solder! This is where Workmanship can cause problems. Lead free solder does not flow as well as leaded or until it reaches higher temperatures. Plan the route and pre-fit all connections. Clean both ends to be soldered. Work with clean hands. Apply flux. As the flux drips out, it draws the solder in. Heat the pipe on the far side from where the solder will be applied (solder flows to the heat). If working in a tight space use a ceramic tile to insulate. Do not breath fumes. Review tools & procedures on page185-192

Testing the System p192 Once the whole system is plumbed it is time to check for leaks. There are 2 methods: air or water. Using air has advantages: no mess and dry joint. A bushing with a Schrader valve (bicycle ball valve) can be attached to the system. Pressurize to about 50psi and watch the gauge to see if it is dropping. It not all is good. If so listen and feel for the leak. Once the collector loop is holding air, use water to rinse it and remove any left over flux. Then fill with propylene glycol and water mix.

Installing Solar Pool Heating Systems p193 Follow manufacturers instructions. Pool heating systems are common place and detailed instruction are provided. Manufacturer's also offer technical support. Everything needs to be mounted to facilitate draining. Black schedule 40 PVC and fittings are ok. Black is important to improve performance.

Installing Radiant Floor Tubing p194 Many layout pattern are possible. Delivering the heated fluid to where it is needed most can minimize the amount of tubing that needs to be run.