Here is the code. Look at the comments, and modify the RAW number to number when the display show 30.0degC.
Code:
define osc 4
adcon1.7=1
ANSEL = %000001 'Disable Inputs Tranne AN0
ADCON1 = %10001110 
OSCCON = %01100000 'Internal RC set to 4MHZ
TRISA =  %00000001 ' impostazioni INP/OUT
TRISB =  %00000000 ' delle porte
'----------------------------------------------------
DEFINE LCD_DREG PORTB       'Porta B DATA OUT 
DEFINE LCD_DBIT 4           '0 --> Bit 0-3 : 4 --> Bit 4-7 
DEFINE LCD_RSREG PORTB      'LCD register select port - Porta B --> RS
DEFINE LCD_RSBIT 2          'LCD register select bit  - Pin RS B2
DEFINE LCD_EREG PORTB       'LCD enable port - Porta B --> EN
DEFINE LCD_EBIT 3           'LCD enable bit - Pin EN B3DEFINE LCD_BITS 4           'LCD bus size 4 or 8 
DEFINE LCD_LINES 2          'Number lines on LCD DEFINE LCD_COMMANDUS 2000   'Command delay time in us 
DEFINE LCD_DATAUS 50        'Data delay time in us

Rele   VAR    PORTA.6     '                  Pin 15
'--------------------------------------------------------------
'---------Define ADCin Parameters   
DEFINE ADC_BITS 10      'set number of bits in result
DEFINE ADC_CLOCK 3      'set clock source (3=rc)
DEFINE ADC_SAMPLEUS 50  'Set sampling time in uS


'    RAM Assignments and Variables
'=========================================================================== 
temp var word
temperature var word
samples var word
sample VAR BYTE
quanta con 1250
Tmax VAR byte
Tmin VAR byte
'===========================================================================
Tmin=16
Tmax=30
 
START:
Lcdout $FE, 1

low rele

main:   
sample = 1
samples= 0
FOR sample = 1 TO 20 'Take 20 samples
ADCIN 0, temp 'Read AN0 into temp variable
samples = samples + temp
PAUSE 50 ' Wait 1/4 seconds per reading
NEXT sample
temp = samples/20 'Average over 20 samples (Every 5 seconds)
temperature= temp */ quanta

if temp > 675 then high rele  'Instead 675 write the correct RAW number for 30degC 
if temp < 675 then low rele   'Instead 675 write the correct RAW number for 30degC 

LCDOUT $FE, 2 ' ritorna al primo carattere
lcdout $FE, 2, "Temp ",dec2 (temperature/10),".", dec1 (temperature/10),"C"
'lcdout $FE, $C0, "Tmin ",#Tmin, " Tmax ",#Tmax            FOR NORMAL OPERATION UNCOMMENT LINE 
lcdout $FE, $C0, "RAW:",dec temp 'this show the ADC value  FOR NORMAL OPERATION COMMENT OR DELETE THIS LINE

'When the display show 30,0 degC look at the RAW number on LCD and rewrite it in lines: if temp > 675 then high rele
'and if temp < 675 then low rele . 

goto main