diff -r 18dd6eadba31 -r aad7789a40f2 thermferm/thermferm.c
--- a/thermferm/thermferm.c	Thu Feb 19 15:43:43 2015 +0100
+++ b/thermferm/thermferm.c	Thu Feb 19 16:08:05 2015 +0100
@@ -1364,9 +1364,9 @@
 			/*
 			 * Simple temperature control
 			 */
-			if (P_err < 0) {
+			if (P_err > 0) {
 			    Out = 100.0;
-			} else if (P_err > 0) {
+			} else if (P_err < 0) {
 			    Out = -100.0;
 			} else {
 			    Out = 0.0;
@@ -1412,13 +1412,13 @@
 //		    }
 //		    unit->PID_dState = pv;
 
-		    if (unit->heater_address) {
+		    if (unit->heater_address && ! unit->cooler_state) {
 			if (Out >= 1) {
 			    if (unit->heater_wait < unit->heater_delay) {
 				unit->heater_wait++;
 				syslog(LOG_NOTICE, "heater_wait + %d/%d", unit->heater_wait, unit->heater_delay);
 			    } else {
-				if (! unit->heater_state && ! unit->cooler_state) {
+				if (! unit->heater_state) {
 				    syslog(LOG_NOTICE, "Heater Off => On");
 				    unit->heater_state = 100;
 				}
@@ -1436,7 +1436,7 @@
 			}
 			device_out(unit->heater_address, unit->heater_state);
 		    }
-		    if (unit->cooler_address) {
+		    if (unit->cooler_address && ! unit->heater_state) {
 			if (Out <= -1) {
 			    if (unit->cooler_wait < unit->cooler_delay) {
 				unit->cooler_wait++;