Defrost settings for Daikin RY100F+ FHYB100

[rdepoort]

Hi everybody:
I have an old Daikin RY100F (ext unit) + FHYB100 (ceilling unit with plenum), R22 gas, with a BRC1B62/52 remote contoller to heat/cool a 1500 sq ft or so house (installed 1999).
It works fine except for 10-15 days /year (when temp # 28-36 °F) and more or less humid: too much frost on the ext unit, and the defrost procedure runs whenever it wants (and not long enough): As a results, ice builds up on the heat exchanger, and in extreme case I have to use a steam generator to get rid of it! Also, the temp from the ceiling outlets varies between 86 (no heat pump really!) and 122 °F (quite happy!) for say 32-35 °F outside: try your luck!

I derived a remote switch (from the force defrost switch on the control board on the outside unit) in one of the rooms to force it to defrost whenever it ices too much: better than nothing but not really practical and not top notch in terms of efficacy.
I believe it is possible to modify the defrost interval and/or time parameters from the settings on the BRC controller: I checked, I found 18 settings (from 10 to 29), and half of them with 2 numbers (example: 0 – 01 for setting 10).

I can’t find the info on the web, and would really appreciate if someone could tell me which settings control defrost parameters, and what are the values for shorter interval/longer defrost time.

Thanks in advance for any info.

[VRVIII]

Hi everybody:
I have an old Daikin RY100F (ext unit) + FHYB100 (ceilling unit with plenum), R22 gas, with a BRC1B62/52 remote contoller to heat/cool a 1500 sq ft or so house (installed 1999).
It works fine except for 10-15 days /year (when temp # 28-36 °F) and more or less humid: too much frost on the ext unit, and the defrost procedure runs whenever it wants (and not long enough): As a results, ice builds up on the heat exchanger, and in extreme case I have to use a steam generator to get rid of it! Also, the temp from the ceiling outlets varies between 86 (no heat pump really!) and 122 °F (quite happy!) for say 32-35 °F outside: try your luck!

I derived a remote switch (from the force defrost switch on the control board on the outside unit) in one of the rooms to force it to defrost whenever it ices too much: better than nothing but not really practical and not top notch in terms of efficacy.
I believe it is possible to modify the defrost interval and/or time parameters from the settings on the BRC controller: I checked, I found 18 settings (from 10 to 29), and half of them with 2 numbers (example: 0 – 01 for setting 10).

I can’t find the info on the web, and would really appreciate if someone could tell me which settings control defrost parameters, and what are the values for shorter interval/longer defrost time.

Thanks in advance for any info.

Hi
The defrost control parameters for these units are adjusted by dip switches located on the outdoor unit PCB.
DS1/1 = ON will increase defrost start temperature by 4 C.
DS1/2 = ON will reduce minimum compressor run time between defrosts from 3hrs to 1hr.

[rdepoort]

Hi
The defrost control parameters for these units are adjusted by dip switches located on the outdoor unit PCB.
DS1/1 = ON will increase defrost start temperature by 4 C.
DS1/2 = ON will reduce minimum compressor run time between defrosts from 3hrs to 1hr.

Hi VRVIII:

Thanks for your prompt reply: I had already noticed the dip switch on the board, and had fiddled with it with no real success: I think that when the temperature is close to 0°C combined with high humidity (ideal for freezing frog), the 4° difference and the drop from 3 to 1 h interval allowed by the switch is not enough. I wonder if the two are not controlled by differential resistor values: in which case, a rotatory switch with 3-4 resistors instead of the fixed resistor for a given switch position could do the trick by allowing me to raise the temp and decrease interval to 45 min for extreme conditions. What do you think of it?

I have soldering iron + multimeter + some understanding of basic electronics.


Maybe I should send an SOS message to see if someone has the diagram of the EC9529B PCB that controls the RY100F unit.

Cheers