Kad smo vec kod defrost ja znam kako Daikin stara nordik serija odradi te inteligentne defroste. Ne znam za ova nova Nepura.
Ne bih o tome kako klima odredjuje kad da zapocne defrost, malo je komplikovano. Prvi uslov da temperatura bude ispod 2° i ta vrednost dobija iz air thermistor pa onda drugi uslov vrednoste is pipe termistore u SJ i UJ...
Nakon sto defrost zapocne onda ima dva uslova kad zavrsi:
1. Kad termistor izmenjivaca SJ otcita neka odredjena temperatura. Ne znam koja e ta temp, moze biti 10° moze 12°...
2. Kad prodzu 12 minuta. Znaci defrost nesme da traje vise od 12 minuta i ako za to vreme termistor nije uspeo da ismeri potrebna temperatura onda defrost nije uspesan. Klima se vraca na grijanje i radi tacno 24 minuta i onda sledi novi defrost.
To se zove dvojni defrost i moze se desiti u neki ekstremni uslovi kad ima snazni vetar sa bocne strane koji hladi izmenjivac pa on nemoze da dostigne tu zadatu temperaturu.
Daikin preporucuje da se klima zastiti sa stranicni vetar kad se ugradzuje u nordiske zemlje. Oznaceno sa strelice b.
Ove je SJ iz Optimised Heating 4 serija.
Vide se termistore koje sam spomenuo
Defrost logika objasnio je ekspert iz Daikina. Na engleski je:
" All units in the XRH range (RXTA/RXTM/RXTP) have good logic for defrost in/out, but only down to -28C approx. Below this temperature we are not extrapolating the defrost start temperature and it operates by guard setting (every 24 minutes) On the 40 class however, we have identified that if the unit operates for longer periods in low/moderate compressor frequency we can have a liquid build up in the indoor unit and that can result in a premature defrost due to incorrect refrigerant flow in the circuit. For this case we have a service software that changes the control logic of the expansion valve in a limited operating range. In mass production this has been fixed since some years ago.
The main reason for this behavior of double defrost is the logic of the unit. If a defrost is detected to be NG then the unit does a new defrost after 24 minutes. The defrost is stopped either by temperature reached on outdoor he (OK defrost) or by security timer (max 12 minutes defrost) and the temperature is not reached (not OK defrost, new defrost request ASAP = after 24 minutes) In most cases the temperature is not reached by wind component. "