Chiller program

[wbeavers]

Here is what I have written.

If Temp >RT+0.4 Then COL ON
If Temp <RT+0.0 Then COL OFF
If Temp >92.0 Then COL OFF
If Temp >RT+1.2 Then ALM ON
If Temp >RT+1.5 Then T51 OFF
Max Change 030 Then T51 OFF
If Temp >RT+2.0 Then T52 OFF
Max Change 030 Then T52 OFF

What I want to do is when the chller(COL) comes on I want the chiller pump(CLP) to come on one minute later. Then I want the pump to run for two minutes after the chiller stops.

I want to add this. Is it correct?

If Tmr COL = ON Then CLP ON
Max Change 001 Then CLP ON
If Tmr COL = OFF Then CLP OFF
Max Change 002 Then CLP OFF

 

[Deleted member 143833]

No, the lower statements will not do what you want.

Max Change only guarantees that the specified device will be on/off for the indicated amount of time and you can only have 1 Max Change per timer (you cannot have an On and an Off for the same timer).

Specifically to your code; the Max Change On statement will guarantee that the CLP stays on for at least 1 minute (that time starts when CLP turns On) if COL is On for more than 1 min then Max Change will have no affect. The Max Change (Off) will not allow CLP to turn back on for at least 2 minutes after it is turned off, even if COL turn on immediately CLP will not turn back on for 2 min (the time starts when CLP is turned off), if CLP if off for more than 2 minutes then the Max Change Off will have no affect.

Another way to explain it: Max Change On will not allow the device to turn Off until it has been on for the indicated number of minutes. Max Change Off does the opposite; it will not allow the device to turn On until it has been off for the specified number of minutes. The clock that Max Change uses starts when the device 1st changes state.

I don't have a solution for you but hopefully this helps with the understanding of what Max Change does. If I think about a way to do what you wish I will let you know, for now you'll need to have COL and CLP turn on at the same time

 

[wbeavers]

If Temp >RT+0.4 Then COL ON
Max Change 005 Then COL ON
If Temp <RT +0.0 Then COL OFF
Max Change 010 Then COL OFF
If Temp >RT+1.2 Then ALM ON
If Temp >RT+1.5 Then T51 OFF
Max Change 030 Then T51 OFF
If Temp >RT+2.0 Then T52 OFF
Max Change 030 Then T52 OFF
If Temp If Temp >92.0 Then COL OFF
If Tmr COL = ON Then CLP ON
If Tmr COL = OFF Then CLP OFF

SO this is the right code then? I did right in a 5 minute minimum on, and a 10 minute minimum off.

 

[wbeavers]

Whoops made a mistake here is the code.

If Temp >RT+0.4 Then COL ON
Max Change 005 Then COL ON
If Temp <RT +0.0 Then COL OFF
Max Change 010 Then COL OFF
If Temp >RT+1.2 Then ALM ON
If Temp >RT+1.5 Then T51 OFF
Max Change 030 Then T51 OFF
If Temp >RT+2.0 Then T52 OFF
Max Change 030 Then T52 OFF
If Temp If Temp >92.0 Then COL OFF
If Tmr COL = ON Then CLP ON
If Tmr COL = OFF Then CLP OFF

Third line is (If Temp <RT +0.0 Then COL OFF)
For some reason it won't appear in my post.

 

[Deleted member 143833]

Without the 3rd line I can't tell when the COL will be turned off but this is what the program should do:

When the tank if > .4 over seasonal tempo COL will turn 'on', it will stay on for 5 minutes, no matter what. Line 3, I guess is the temp that the COL will turn 'off'.

Then there is some stuff for alarm (ALM) and to turn off yout lights (T51) when it gets too hot. If the lights do get turned off they will not be allowed to turn back 'on' for 30 min.

If the temp gets really-really (> 92) hot COL turns off (I suspect this is in case the temp probe fails; good to have!)

Finally, if COL is 'on' the CPL is 'on' and if COL is 'off' then CLP is 'off'

Looks good.