Index: firmware/App/Modes/ModeTreatmentParams.c
===================================================================
diff -u -r3741b7bb1a2e35a0b3618a9212f277f1937ee75f -r7e0d7c16341ea0ccd9b806a2db97553498d10365
--- firmware/App/Modes/ModeTreatmentParams.c	(.../ModeTreatmentParams.c)	(revision 3741b7bb1a2e35a0b3618a9212f277f1937ee75f)
+++ firmware/App/Modes/ModeTreatmentParams.c	(.../ModeTreatmentParams.c)	(revision 7e0d7c16341ea0ccd9b806a2db97553498d10365)
@@ -683,19 +683,19 @@
 
             case TREATMENT_PARAM_UF_VOLUME:
                 result  = ( ( value.sFlt >= hdInstitutionalRecord.minUFVolumeL ) && ( value.sFlt <= hdInstitutionalRecord.maxUFVolumeL ) ? TRUE : FALSE );
-                result |= ( value.sFlt <= NEARLY_ZERO ? TRUE : FALSE ); // There might be a minimum UF volume set in the institutional record but a treatment with 0 vol should be allowed
+                result |= ( fabs( value.sFlt ) <= NEARLY_ZERO ? TRUE : FALSE ); // There might be a minimum UF volume set in the institutional record but a treatment with 0 vol should be allowed
                 break;
 
             case TREATMENT_PARAM_HEPARIN_DISPENSE_RATE:
                 result  = ( ( value.sFlt >= hdInstitutionalRecord.minHeparinDispRateMLPHR ) &&
                             ( value.sFlt <= hdInstitutionalRecord.maxHeparinDispRateMLPHR ) ? TRUE : FALSE );
-                result |= ( value.sFlt <= NEARLY_ZERO ? TRUE : FALSE ); // Even if the minimum is not 0, 0 is accepted meaning heparin can be turned off
+                result |= ( fabs( value.sFlt ) <= NEARLY_ZERO ? TRUE : FALSE ); // Even if the minimum is not 0, 0 is accepted meaning heparin can be turned off
                 break;
 
             case TREATMENT_PARAM_HEPARIN_BOLUS_VOLUME:
                 result  = ( ( value.sFlt >= hdInstitutionalRecord.minHeparinBolusVolumeML ) &&
                             ( value.sFlt <= hdInstitutionalRecord.maxHeparinBolusVolumeML ) ? TRUE : FALSE );
-                result |= ( value.sFlt <= NEARLY_ZERO ? TRUE : FALSE ); // Even if the minimum is not 0, 0 is accepted meaning heparin can be turned off
+                result |= ( fabs( value.sFlt ) <= NEARLY_ZERO ? TRUE : FALSE ); // Even if the minimum is not 0, 0 is accepted meaning heparin can be turned off
                 break;
 
             default: