Apricus Solar Water Heating System Installation and Operation ...

Apricus Solar Collector Installation & Operation Manual - USA1. Glossary & Conversions1.1. Glossary of TermsAnti-scald Valve (Tempering Valve): A valve installed between the solar water heating system and thefixtures to automatically mix the hot water with cold water to achieve a safe outlet temperature of 120° F (50°C). An anti-scald valve must stop all hot water flow if there is a loss of either cold or hot water supply.Anti-scald valves must be NSF or CSA approved.Closed Loop: A system that, typically, has an anti-freeze, heat transfer fluid circulating through a closed,pressurized solar collector piping loop. This “freeze resistant” fluid is separated from the main’s pressurewater by a heat exchanger. Closed loop systems are used in areas where freezing conditions are common.Direct Flow: A system that has potable water under the water main’s pressure flowing directly through thesolar loop piping into the collector and back down to the storage tank. This system is normally used inwarmer regions that do not have virtually no freeze risk.Drain-back: A system that uses potable water or heat transfer fluid in the solar collector loop, but the fluiddrains back down into a tank when the pump turns off, thus preventing overheating or freeze related issues.Expansion Tank: A metal tank with a rubberized liner (bladder) which is pressurized with air on one side ofthe bladder and accepts water from the closed loop on the other side. Because air can be compressed, theexpansion tank can accept the increase in fluid volume that results when the temperature of the systemincreases. This prevents dumping of fluid from the pressure relief valve (see below).Return Line: The plumbing line supplying hot water FROM the collector back to the storage tank or heatexchanger (compare to Supply Line, below).Insolation: Solar radiation level, expressed in Btu/ft2/day (kWh/m2/day).Peak solar radiation is about 317 Btu/ft2 (1000 W/m2).Pressure Relief Valve: Pressure relief valve is normally incorporated into the pump station of closed loopor direct flow systems. It opens if a set maximum pressure limit is reached, thus preventing damage to thesystem components. Some PRV are able to be used over and over, while others must be replaced afterthey have “blown”.Pressure & Temperature Relief Valve (T/P Valve): Pressure & temperature relief valve combines apressure relief valve with a temperature sensitive core which will open to dump hot water if it reaches 210°F(99°C). PRTV are common on hot water storage tanks, providing a means of releasing pressure and heat iffor example a faulty electric element or boiler thermostat causes the tank to be overheated.Supply Line (Flow or Feed Line): The plumbing line supplying water from the storage tank or heatexchanger TO the solar collector for heating (compare to Return Line, above).1.2. Conversions1 kWh = 3412 Btu = 859.8 kcal1 kcal will heat 1 litre of water by 1° C1 US Gallon of water = 8.34 lbs1 kWh/m2/day = 317.1 Btu/ft2/day1Btu will heat 1 lb of water by 1° FCopyright 2011 – Apricus Inc Doc: A7-05.4.1.4-PB-1.9 Page 6 of 126