Overview of the heating mode functions ESIE02–01
2–38 Part 2 – Functional Description
3
1
2
4
5
3.2 Defrost Control
Applicable units ■ RY35-45E(A)Z7V1
■ RYP71-250B
Purpose The purpose of the defrost control is to prevent frost on the outdoor heat exchanger coil. This frost
forms when the unit is in heating position.
Starting conditions:
RYP71-250B
The defrosting starts when either condition 1 or 2 has been realized.
Heating integral
capacity
The integral heating capacity is calculated by using the indoor unit data (R2T - R1T) divided by the
compressor running time.
Condition 1 Condition 2
The compressor has been running for a total of 25 min since the start of heating or since the end
of the previous defrosting.
■ Outdoor heat exchanger temp. ≤ -3˚C, and
■ Outdoor heat exchanger temp. ≤ 0.4 x Ta - 5˚C
■ Compressor ON ≥ 5 min continuously, and
integral heating capacity diminishes (see
further in this section), or
■ Ta > -5˚C for 3 h accumulated
(if DS1-2 is ON, 40 min;
if DS2-1 is ON, 24 h), or
■ Ta ≤ -5˚C for 6 h accumulated
Above condition for 10 min accumulated.
Outdoor fan is ON (not in overload control) Outdoor fan is OFF (overload control)
-15 -10 -5
-5
-1
-3
-7
-9
05
Outdoor heat exchanger
temp. (Tc) (˚CDB)
Outside air
temp. (˚CDB)
Defrost activation range
Integral
capacity
Compr. ON time
Heating
Defrosting
Diminishing
integral capacity
Max. integral
capacity value
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