RESOL DeltaSol Controller features - use them to save service calls.
RESOL controllers can do more then just controlling of delta T. Every RESOL controller comes with watchdog functionality built-in.
We previously have discussed OCX - High Summer Mode or 'Overheating Watchdog Mode' - when a few extra sun hours in high summer could be safely utilized in the solar storage by charging it over the set point, but keeping the tank temperature below the safety high-temperature limit of 95C/203F.
But what will happen if Solar Thermal system maintainers have to deal with two weeks of extra sun hours at a time our customers are away on holidays? Should we go on vacation at the same time and be back on time and ready for a service call? Not with RESOL, my friends!
Two Functions: OREC and OCX
OREC is recooling function; I'd like to call it 'Vacation Mode'. How it works? If OREC is activated (turned ON in programming menu) the solar pump remains active, and so long the deltaT is present, solar collector will charge storage tank over the set point SMX, but only to the high limit of 95 degC /203 deg F.
During the night the solar pump will run and move the stored heat out of the tank back to collectors. The storage tank will cool down, but only to the set point SMX. In other words: the system will run with reverse deltaT.
That will effectively prevent overheating by appropriately dimensioned systems. My advice for Vacation Mode: lower the Storage Tank Maximum (SMX) to 30 degC/ 86 degF , so that system has more capacity to deal with unused sun energy.
Both functions OCX and OREC can be used simultaneously.
If your customer can't trust himself with re-programming the controller for 'High Summer' and 'Vacation Mode' please advise him to call you before he/she is leaving the house and guide him through the menu. Or, just stop by for 2 minutes to make all adjustments yourself. Saves you an unpaid service call. My personal wish to RESOL is to make access to OREC easier - one button push.
Another effective way to deal with overheating is to design multi-load system. It could be two storage tanks, DHW tank and pool/spa or just a heat dissipater like a cast iron rad or an air handling unit - you name it. DeltaSol BS Plus comes with pre-programmed 2 -load layouts for different setups. By changing the load priority is very easy to maintain system temperature in acceptable ranges.
How PRIO (priority setting) has to be applied and programmed we will discuss here soon.