Reset of chilled water on York chiller

[hvacdoctor]

has anyone installed leaving water temperature reset on a York YCAS chillers? Want to reset water 44-55F based on outside air temperature.

no luck with York on this one.

[york56]

Remote Setpoint Reset
The chilled liquid leaving temperature setpoint programmed
into the micro can be remotely adjusted to a
higher value using repeated timed closure of "dry" contacts
connected to Terminals 13 & 17 of TB4 in the
logic section of the control panel (See Section 9 [1.12]).
The duration of the contact closure will decide the
amount of adjustment. This is achieved as follows :
The maximum allowable reset value can be programmed
from 2ºF - 40ºF (1°C - 22°C), as appropriate to the application
- see Section 6.4. Once the maximum reset is
programmed, an input contact closure of 11 seconds
provides the maximum reset. Closure for less than 11
seconds will provide a smaller reset. For noise immunity,
the micro will ignore closures of less than 1 second.
To compute the necessary contact closure time to
provide a required Reset, use the following steps:
Reset Temp ={ (Contact Closure - 1sec) X Programmed Max Reset}
Offset 10 sec
For example, with a programmed setpoint of 44ºF (7°C),
after a 4 second pulse and a programmed maximum
offset of 40ºF (22°C), the temperature offset would
equal:
Reset Temp = (4 sec - 1 sec) X 40ºF
10 sec
Reset Temp = 120°F sec
10 sec
= 12ºF (6ºC)

[hvacdoctor]

thanks for the post. I will run this by tech to see. I was thinking that York would allow a remote BAS signal to interface with there chiller controlls. SO a simple 0-10 or 4-20MA signal would work? I will check your instructions. Thanks

[york56]

If there is a Microgatway on that Chiller then that could be possible.

[aggievision]

If the BAS is linked to the setpoint control point on the chiller panel you could reset the temperature remotely. I am not sure having such a high chilled water temperature would be ideal. I have typically seen a range of 44F-48F.

[aggievision]

Also include a condenser water temperature reset in addition to the chilled water reset. Improves your efficiency. Use a outside air wet bulb temperature as a reset criteria

[DFZ]

you can do pwm direct to the control board, or if it has the optional reset boards you can go voltage or current to the reset board which will do pwm to the control board.