A Checklist for Winning Solar Thermal Value
Price is what you pay - Value is what you get.
I have my own story about glycol pumps which I'd like to share with all of you guys. We'll call it "The Big Bang" - or - "When Things Go Wrong on the Job"
As a 21 years young apprentice working for Walter Zimmerly -one of the best HVAC contractors I ever met (Augsburg, Germany), I was in charge of picking up materials and tools for my crew and other crews and getting the items to the job sites the following morning. I would typically receive a list at the end of the workday - after the various crews had already headed home.
One list contained a surprising item: "die SPUELMASCHINE" - if you translate the word to English - a Dishwasher!
Read the rest of this article here...
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High Summer Mode
DeltaSol features - using them right.
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RESOL controllers can do more that just controlling delta T. Every RESOL controller has watchdog functionality built-in. It starts with monitoring of Collector and Storage temperatures and comparing them with maximum allowable and set points. For example; many of you noticed that controller has settings like EM - collector emergency shut down and CMX- collector maximum allowable temperature. Why we need both of them? CMX- is highest tolerable temperature of the collector the system components can accept, providing that heat transfer media remains fluid. With other words, at that high temperature solar loop is still operable. EM on other hand is critical collector temperature - unsafe to operate system because of possible overheating and steaming of the heat transfer media.
That temperature is THE HIGH SAFETY LIMIT of Solar Collector in closed loop design system, where electronic control will shut the circulation off and only mechanical safety devices - expansion tank and PRV will take care of the system integrity.
Storage tank temperature has similar set points. STmax is the set point to which you want limit the DH water temperature in the tank. But the controller is programmed with non-adjustable DHW temperature HIGH LIMIT of 95 deg C/ 203 deg F. That is critical temperature for water we all know, very close to acting point of Temperature-Pressure Relief Valve (TPRV) every tank has.
Well, how RESOL overheating watchdog is working?
By normally sized systems, collector overheating could happened on hot scorching afternoon in July- August, when DHW reached set point, but there is one or two hours of direct sun light remaining. OCX is collector cooling function; I'd like to call it HIGH SUMMER MODE. And if it is activated (should be turned ON) than after reaching DHW set point (Sensor S2) the solar circulator R1 will stop and collector temperature (Sensor S1) will be monitored closely. Rising the temperature to CMX point, then R1 will be turned ON till collector temperature drops 5 deg C/ 9 deg F. Some of the heat will dissipate in the connecting pipes doe to heat loss, some will be moved down into the storage tank. The tank temperature would rise, but only to the HIGH LIMIT of 95 degC/203 deg F. If cooling of the collector this way is successful than overheating, steam and following callback will be avoided. But if not (because of oversized collector or undersized storage volume) the collector temperature will reach EM point and then only properly sized expansion tank and PRV should take care of the physical integrity of the solar DHW system.
How RESOL controller can prevent system overheating by low DHW demand when occupants leave on vacation, we will talk in the next news letter.
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Real VALUE, not just PR announcements
are getting SUN&WIND Energy readers. |
 More and more printed and electronic magazines trying to grab my attention and want me to spend my valuable time reading their blogs and columns. I don't know what about you, but I'm personally not buying 95% of their content, it is boring and out of real value to me and I think to any one whose involvement into Renewable Industry is not the Stock Exchange Market speculations and policy making.
I'm voting for S&WE Magazine as a Solar Caffeine consumer, - it worth my every minute spent reading it! What about you? |
