26 – Part 3: Solar water heater system installation – Potable water piping
Potable water piping
The design and installation of the VELUX solar water heating system should be done
by qualifi ed individuals. It is important that good design and installation practice
be followed to assure that your system will operate properly. Failure to follow
installation guidelines for your VELUX solar water heating system could cause
component failure and possible safety issues. It is mandatory that all plumbing be
done in accordance with all local and state codes or warranty will be void. It Is also
necessary on all domestic plumbing mechanical connections to use both thread tape
and pipe dope. The potable water piping is located on the top of your solar storage
tank and marked Hot and Cold. It is recommend that unions or fl exible copper
connectors be used so heater can be easily serviced. Install a shut-off valve in the
cold feed near the solar storage tank to isolate the tank for future service.
1. Install the thermostatic mixing valve provided, as shown. Connect the “mixed” port to the hot water supply to the
home. Connect the “cold” port to the cold water supply to the home. Connect the “hot” port to hot water from the
solar storage tank.
Solar loop and potable water piping insulation and support
1. Insulate all exposed solar loop and potable water connections and piping. The ¾” cold water supply line to the solar
storage tank must be insulated with a minimum
1
⁄
2
” pipe insulation to a minimum distance of 5’ up stream the
storage tank, or to the wall if closer than 5’.
2. All piping must be supported at a maximum interval of 10’ and the piping supports must not crimp or compress the
insulation.
Freeze protection
The propylene glycol heat transfer fl uid provided acts as a freeze protection fl uid and must be used to protect the system from
freezing. The VELUX propylene glycol provided is rated as nontoxic. A 40% propylene glycol/60% water mixture should be
used, however, you must use a mixture most appropriate for your climate. Do not use a higher glycol to water concentration
than necessary, as this will adversely impact heat transfer effi
ciency. See the propylene glycol Data Sheet in the back of this
manual for recommended concentrations. A copy of the MSDS sheet must be left with the end user of the solar system. See
“Propylene glycol emergency overview” as part of the propylene glycol Data Sheet in the back of this manual. The collector
loop must be charged with a mixture of heat transfer fl uid and distilled or deionized water. The use of regular tap water as a
mixing agent is prohibited. Scheduled maintenance must be established to monitor and maintain the proper PH level of the
heat transfer fl uid in the system to protect the heat exchanger and other components in the system.
