diff --git a/tools/esp8266/app.cpp b/tools/esp8266/app.cpp
index 2d5516d3..189a7117 100644
--- a/tools/esp8266/app.cpp
+++ b/tools/esp8266/app.cpp
@@ -317,12 +317,12 @@ bool app::buildPayload(uint8_t id) {
     for(uint8_t i = 0; i < mPayload[id].maxPackId; i ++) {
         if(mPayload[id].len[i] > 0) {
             if(i == (mPayload[id].maxPackId-1)) {
-                crc = crc16(mPayload[id].data[i], mPayload[id].len[i] - 2, crc);
+                crc = Hoymiles::crc16(mPayload[id].data[i], mPayload[id].len[i] - 2, crc);
                 crcRcv = (mPayload[id].data[i][mPayload[id].len[i] - 2] << 8)
                     | (mPayload[id].data[i][mPayload[id].len[i] - 1]);
             }
             else
-                crc = crc16(mPayload[id].data[i], mPayload[id].len[i], crc);
+                crc = Hoymiles::crc16(mPayload[id].data[i], mPayload[id].len[i], crc);
         }
         yield();
     }
diff --git a/tools/esp8266/app.h b/tools/esp8266/app.h
index e7e9ab61..00967f76 100644
--- a/tools/esp8266/app.h
+++ b/tools/esp8266/app.h
@@ -166,7 +166,7 @@ class app {
             while(length > 0) {
                 len = (length < 32) ? length : 32;
                 mEep->read(start, buf, len);
-                crc = crc16(buf, len, crc);
+                crc = Hoymiles::crc16(buf, len, crc);
                 start += len;
                 length -= len;
             }
diff --git a/tools/esp8266/crc.cpp b/tools/esp8266/crc.cpp
index 7c64d642..29f9b82f 100644
--- a/tools/esp8266/crc.cpp
+++ b/tools/esp8266/crc.cpp
@@ -5,6 +5,8 @@
 
 #include "crc.h"
 
+namespace Hoymiles {
+
 uint8_t crc8(uint8_t buf[], uint8_t len) {
     uint8_t crc = CRC8_INIT;
     for(uint8_t i = 0; i < len; i++) {
@@ -33,3 +35,4 @@ uint16_t crc16(uint8_t buf[], uint8_t len, uint16_t start) {
     }
     return crc;
 }
+} // namespace Hoymiles
\ No newline at end of file
diff --git a/tools/esp8266/crc.h b/tools/esp8266/crc.h
index c0323ebb..1c8de9e0 100644
--- a/tools/esp8266/crc.h
+++ b/tools/esp8266/crc.h
@@ -14,7 +14,10 @@
 
 #define CRC16_MODBUS_POLYNOM    0xA001
 
-uint8_t crc8(uint8_t buf[], uint8_t len);
-uint16_t crc16(uint8_t buf[], uint8_t len, uint16_t start = 0xffff);
+namespace Hoymiles {
 
+    uint8_t crc8(uint8_t buf[], uint8_t len);
+    uint16_t crc16(uint8_t buf[], uint8_t len, uint16_t start = 0xffff);
+
+}
 #endif /*__CRC_H__*/
diff --git a/tools/esp8266/hmInverter.h b/tools/esp8266/hmInverter.h
index 32a7505c..3b443873 100644
--- a/tools/esp8266/hmInverter.h
+++ b/tools/esp8266/hmInverter.h
@@ -81,6 +81,7 @@ class Inverter {
         RECORDTYPE    *record;  // pointer for values
         uint16_t      chMaxPwr[4]; // maximum power of the modules (Wp)
         char          chName[4][MAX_NAME_LENGTH]; // human readable name for channel
+        bool          initialized; // needed to check if the inverter was correctly added (ESP32 specific - union types are never null)
 
         Inverter() {
             ts = 0;
@@ -88,6 +89,7 @@ class Inverter {
             powerLimit[1] = 0x0000; // 
             devControlRequest = false;
             devControlCmd = 0xff;
+            initialized = false;
             fwVersion = 0;
         }
 
@@ -103,6 +105,7 @@ class Inverter {
             memset(name, 0, MAX_NAME_LENGTH);
             memset(chName, 0, MAX_NAME_LENGTH * 4);
             memset(record, 0, sizeof(RECORDTYPE) * listLen);
+            initialized = true;
         }
 
         uint8_t getPosByChFld(uint8_t channel, uint8_t fieldId) {
diff --git a/tools/esp8266/hmRadio.h b/tools/esp8266/hmRadio.h
index 57d95ec8..7decd2c2 100644
--- a/tools/esp8266/hmRadio.h
+++ b/tools/esp8266/hmRadio.h
@@ -59,7 +59,12 @@ template <uint8_t CE_PIN, uint8_t CS_PIN, class BUFFER, uint64_t DTU_ID=DTU_RADI
 class HmRadio {
     public:
         HmRadio() : mNrf24(CE_PIN, CS_PIN, SPI_SPEED) {
-            DPRINTLN(DBG_VERBOSE, F("hmRadio.h : HmRadio():mNrf24(CE_PIN: ") + String(CE_PIN) + F(", CS_PIN: ") + String(CS_PIN) + F(", SPI_SPEED: ") + String(SPI_SPEED) + ")");
+            DPRINT(DBG_VERBOSE, F("hmRadio.h : HmRadio():mNrf24(CE_PIN: "));
+            DPRINT(DBG_VERBOSE, String(CE_PIN));
+            DPRINT(DBG_VERBOSE, F(", CS_PIN: "));
+            DPRINT(DBG_VERBOSE, String(CS_PIN));
+            DPRINT(DBG_VERBOSE, F(", SPI_SPEED: "));
+            DPRINTLN(DBG_VERBOSE, String(SPI_SPEED) + ")");
 
             // Depending on the program, the module can work on 2403, 2423, 2440, 2461 or 2475MHz.
             // Channel List      2403, 2423, 2440, 2461, 2475MHz
@@ -101,7 +106,8 @@ class HmRadio {
             // enable only receiving interrupts
             mNrf24.maskIRQ(true, true, false);
 
-            DPRINTLN(DBG_INFO, F("RF24 Amp Pwr: RF24_PA_") + String(rf24AmpPowerNames[config->amplifierPower]));
+            DPRINT(DBG_INFO, F("RF24 Amp Pwr: RF24_PA_"));
+            DPRINTLN(DBG_INFO, String(rf24AmpPowerNames[config->amplifierPower]));
             mNrf24.setPALevel(config->amplifierPower & 0x03);
             mNrf24.startListening();
 
@@ -170,12 +176,12 @@ class HmRadio {
                 mTxBuf[10 + (++cnt)] = ((data[1]     )     ) & 0xff; // setting for persistens handling
             }
             // crc control data
-            uint16_t crc = crc16(&mTxBuf[10], cnt+1);
+            uint16_t crc = Hoymiles::crc16(&mTxBuf[10], cnt+1);
             mTxBuf[10 + (++cnt)] = (crc >> 8) & 0xff;
             mTxBuf[10 + (++cnt)] = (crc     ) & 0xff;
             // crc over all
             cnt +=1;
-            mTxBuf[10 + cnt] = crc8(mTxBuf, 10 + cnt);
+            mTxBuf[10 + cnt] = Hoymiles::crc8(mTxBuf, 10 + cnt);
 
             sendPacket(invId, mTxBuf, 10 + (++cnt), true);
         }
@@ -194,10 +200,10 @@ class HmRadio {
                 mTxBuf[18] = 0x00;
                 mTxBuf[19] = 0x00;
             }
-            uint16_t crc = crc16(&mTxBuf[10], 14);
+            uint16_t crc = Hoymiles::crc16(&mTxBuf[10], 14);
             mTxBuf[24] = (crc >> 8) & 0xff;
             mTxBuf[25] = (crc     ) & 0xff;
-            mTxBuf[26] = crc8(mTxBuf, 26);
+            mTxBuf[26] = Hoymiles::crc8(mTxBuf, 26);
 
             sendPacket(invId, mTxBuf, 27, true);
         }
@@ -210,7 +216,7 @@ class HmRadio {
             CP_U32_BigEndian(&mTxBuf[5], (DTU_ID >> 8));
             mTxBuf[9]  = pid;
             if(calcCrc) {
-                mTxBuf[10] = crc8(mTxBuf, 10);
+                mTxBuf[10] = Hoymiles::crc8(mTxBuf, 10);
                 sendPacket(invId, mTxBuf, 11, false);
             }
         }
@@ -224,7 +230,7 @@ class HmRadio {
                 buf[i-1] = (buf[i] << 1) | (buf[i+1] >> 7);
             }
 
-            uint8_t crc = crc8(buf, *len-1);
+            uint8_t crc = Hoymiles::crc8(buf, *len-1);
             bool valid  = (crc == buf[*len-1]);
 
             return valid;
diff --git a/tools/esp8266/hmSystem.h b/tools/esp8266/hmSystem.h
index 386484fa..1070445a 100644
--- a/tools/esp8266/hmSystem.h
+++ b/tools/esp8266/hmSystem.h
@@ -52,7 +52,10 @@ class HmSystem {
                     case 0x21: p->type = INV_TYPE_1CH; break;
                     case 0x41: p->type = INV_TYPE_2CH; break;
                     case 0x61: p->type = INV_TYPE_4CH; break;
-                    default: DPRINTLN(DBG_ERROR, F("unknown inverter type: 11") + String(p->serial.b[4], HEX)); break;
+                    default: 
+                        DPRINT(DBG_ERROR, F("unknown inverter type: 11"));
+                        DPRINTLN(DBG_ERROR, String(p->serial.b[4], HEX)); 
+                        break;
                 }
             }
             else
@@ -88,7 +91,7 @@ class HmSystem {
 
         INVERTERTYPE *getInverterByPos(uint8_t pos, bool check = true) {
             DPRINTLN(DBG_VERBOSE, F("hmSystem.h:getInverterByPos"));
-            if((mInverter[pos].serial.u64 != 0ULL) || false == check)
+            if((mInverter[pos].initialized && mInverter[pos].serial.u64 != 0ULL) || false == check)
                 return &mInverter[pos];
             else
                 return NULL;