View Full Version : Aermec water chiller set point

Daz man
28-03-2017, 09:05 PM
Hi all,

A quick ask re: an Aermec water chiller.

I have an AL75 alarm showing on the Carel controller stating "Anti Freeze alarm"

Since up'ing the water temp set point this alarm is no more.

A general rule of thumb, what water set point would be adequate for a chiller serving a commercial/retail building? I've been advised that anything lower than 9 degrees is more for processing applications, please advise?


install monkey
28-03-2017, 09:25 PM
yep ive always seen minimum of 10 deg setpoint- unless it has glycol in it- but ive only worked on small stuff

28-03-2017, 10:10 PM
Hi Guys!
Commercial Chillers are happy down to 6c normally.
Once you start going lower you would normally expect to have a glycol based system.
Sometimes a system can be ran at lower temperatures, when controlled on LWT and not RWT.
Low loads, low on refrigerant and poor or low flow can all have a big effect.

28-03-2017, 10:36 PM
Hi Daz Man.
Which controller do you have?
Only on the newer one AL75 is High discharge temp circuit !.
As I say I may well be looking at totally the wrong controller!

Daz man
28-03-2017, 11:40 PM
Hi Grizzly,

Its a Carel Pc02. AL75 (I will double check) however its deffo a Anti freeze alarm.

Thanks for the reply

Daz man
28-03-2017, 11:42 PM

LWT? apologise for my dimness I know RWT is return water.

Daz man
28-03-2017, 11:53 PM
LWT = leaving water? Is this correct guys?

29-03-2017, 06:10 AM
Hi Daz Man.
Yep Leaving Water Temperature it is.
You may be correct with the fault code as I was looking an a version 5 I think it is.
I don't have a table for AL75 in my version of the PCo2 manual.

Daz man
04-04-2017, 12:00 PM
Hi all,

Please see attached pictures. I've noticed that the water temp is monitored by Inlet and not LWT. Is this correct for a water chiller set at 10oC? When operating and trying to achieve this set-point the antifreeze B8 probe is hovering around -2.6oC But the chiller is happy and does not trip out. The antifreeze alarm is set in the Carel at -6.0oC with a diff of 2.0oC. Do I need to change the water monitored to LWT?1473014731147321473314729

04-04-2017, 03:43 PM
I would check your sensors to see if you are getting the correct readings Italian chillers usually have a 12 degree set point and fully loaded give a 5 degrees difference between inlet and outlet water temps.
Anti freeze set point is usually 3.9 degrees

04-04-2017, 08:31 PM
Is the chiller controlling on leaving or return water temperature?

If the differential is more than 6K at full load then you need to look at the water flow rate.

Daz man
09-04-2017, 08:00 PM
Hi Frank,

Controlling on Inlet?


09-04-2017, 08:28 PM
Hi Daz.
is there still an issue.
The diff between the entering water temp and the leaving does not seem much.
what were the suction and discharge pressures when you logged these settings.
How loaded stages were in operation?
The anti freeze probe reading does seen suspect
Do you have any binder points so you can check the kpa. diff across the chiller.
1.1 c split is low if working hard, suction pressure will tell a lot.
What refrigerant is it running on.

I would be looking at the operating pressures and temps, to try and prove whether its charge or flow related.
More info needed at the moment.
Low charge or sensor malfunction seems favourite at this moment in time.