Bosch greenstar combi frost protection

sbrown

Hi,



Does anybody know how to defeat the Bosch Greenstar frost protection?



There is a setting called "Risk of freezing at outdoor temperature" that has a range of 23-50 degrees F.  If you set it at 23, then the internal circulation pump runs when the temp is 23 or lower for frost protection. When it runs, the unit consumes 0.7 amps.  This adds up over time. The boiler is installed with 3rd party circulators and multiple zones with actuators, so the internal pump is only circulating the primary loop.  We use wood stoves and the boiler was meant to be used mostly when we want to leave the house for extended periods. The boiler is a combi and we do use it for DHW.  So the situation is that if we leave the boiler on in order to get DHW, the boiler never is idle due to the pump running 24/7. Is there any way to defeat this function?



Would it be possible to mount another temp sensor indoors and switch between indoor and outdoor temp sensors based upon whether we want to use the boiler for heat or not.? Is the temp sensor used for anything other than heat curve? DHW?



Unfortunately, we didn't know about this "feature" until we started using the boiler and saw electrical consumption jump.  The specs say it uses 6 watts at idle, but the reality is that it uses 6 watts as long as the outdoor temp is 24 or above. Otherwise it uses ~83 watts . A near constant 83 watts over the course of a winter adds up.



thx