Chiller Code

[blk94rs]

Im in the planning phase for my AC3....it will be here on Friday!!!

I plan on setting it up to run my chiller as well. I have a PCI CL-280 chiller. I modified my chiller to run as on/off (bypassing the built-in digital thermostat) so I can control it completely with the AC3.

What will the code look like to control the chiller? I would like it to turn on at 81 degrees and stay on until it drops the tank time by 2 degrees.

Or is there a better way to run a chiller?

[kenargo]

Temp based on/off is common and easy:

If Temp > 81.0 Then COL ON
If Temp < 79.0 Then COL OFF
If Temp > 90.0 Then COL OFF

The last line is insurance; if the temp probe fails it tends to read 120 (+/-) so the last line will turn off the COL timer if the tank is unreasonably hot (you can go higher if you want but it's good to have a line like this).

If you want to run seasonal temps (higher in the summer, slightly cooler in the winter you can use RT in place of temps; there are examples in the manual for both.

[blk94rs]

Thanks, kenargo.

Will this cause the chiller to be on any time the temp is between 79 & 81 degrees? Or will it not come on until the temp hits 81 degrees, then turn off once the temp drops to 79 degrees?

So for heater & chiller control it would be as follows (assuming I want my temp to be between 78 & 81 degrees)?

If Temp > 81.0 Then COL ON
If Temp < 79.0 Then COL OFF
If Temp > 90.0 Then COL OFF
If Temp < 78.0 Then HET ON
If Temp > 80.0 Then HET OFF
If Temp > 90.0 Then HET OFF

What about if the tank is unreasonably cold? Should there be any added code (added insurance) for that?

[blk94rs]

So thinking about this further, if the temp for some reason goes about a set point, I would like to have my MH lights turn off as well... It seems simple enough to code:

If Temp > 83.0 Then MH1 OFF

Does it need to have another line of code to turn the MH's back on? Will the code to turn the MH's back on interfere with the normal timer code for turning them ON/OFF?

[ciphros]

To answer about the chiller code, it will not turn on until above the temp for If Temp > xxx Then COL ON, and will run until it hits the temp for If Temp < xxx Then COL OFF. Another good idea is to use a statement to keep your chiller from turning on and off if your temp probe starts to wander around (has happened to me twice, just replaced the probe again this week - this one was my fault though). Use this statement to keep it off for 15 min. after it turns off before it will be alowed to run again:

Max Change 015 M Then COL OFF

You have it right for the temp command to shut down lights. You don't need to worry about a statement to bring them back on, as they will come on due to the time statement that turns them on once the temp returns below your setpoint to shut the light off.

Here's the code I use for turning off my 3 MH bulbs and then my Actinics as temp increases (note - I use max change statements on the lights too):

If Temp > 80.5 Then MH1 OFF
If Temp > 80.8 Then MH3 OFF
If Temp > 81.2 Then MH2 OFF
If Temp > 81.4 Then AT1 OFF
If Temp > 81.4 Then AT2 OFF
Max Change 030 M Then MH1 OFF
Max Change 030 M Then MH2 OFF
Max Change 030 M Then MH3 OFF
Max Change 005 M Then AT1 OFF
Max Change 005 M Then AT2 OFF