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piewie
16-09-2015, 07:49 AM
Hello everyone

I've got a couple of McQuay WHS 248.2 water-cooled chillers.

On one of them there is a controller issue where the chiller will start even if there is no water flow. The differential switches are working properly and the controller can see the change of state of the input when the flow is made or removed.

I think that the program in the Carel has become corrupted. Has anyone elese ever had this issue? Any suggestions?

Any help greatly appreciated.

keapog
16-09-2015, 10:09 PM
hello piewie !I have some experience with Carel controllers in air to water chillers made by Galletti Italy .
The display has different screens in mcQuay but the controller is basically the same and in maintenance menu there is a screen where you can put manually the status of an imput or output , so if someone has changed it than the controller will not "see" the flow switch . The screens are programmable by the end user so for sure it will be different from galletti and I can' t help you further .

keapog
16-09-2015, 10:14 PM
I am working for 8 years with these controllers and i have had no problems with Carel never.

HVACRsaurus
17-09-2015, 11:58 AM
Hi,

The following is an extract from a document that I have

When the unit starts, there has to be 20 sec of flow during the first 30 sec of pump operation. When the unit is running, the flow switch has to be open for 5 sec before the unit trips in flow alarm

Perhaps it's a timer?