Apex program

[hypertech]

This is the program for my second heater.  Its a larger heater and I intend for it to come on if the first heater can't keep up and push the temp back up higher.  If the temp stays below 76.4 for 5 minutes, it is supposed to come on until the tank reaches 77 and then turn off.  It also has a min on time of 5 minutes to prevent oscillations. 

 

At least, thats what I think it should be doing.  It looks like it is kicking on at 76.3 as expected and running about 5 minutes.  Then it turns off well before the tank reaches 77.

 

Any ideas why this isn't working as I expect?

 

Fallback OFF
Set OFF
If Temp < 76.4 Then ON
If Temp < 60.0 Then OFF
If Temp > 77.0 Then OFF
Min Time 005:00 Then ON
Defer 005:00 Then ON

[hypertech]

Now that I type this out, I think it is the Set OFF in line 2.  At the next execution when temp is starting to climb and reaches 76.5, there is nothing to set it on.  Does that sound right?

[wade]

 

If Temp < 60.0 Then OFF

 

Why have this line at all?

 

You also don't need min time and defer statements for a heater.  If you are concerned about it flicking on and off, use only the min time statement (that will make it only turn on if stable reading for x amount of time below your set point).

 

Mine is simply (below) and works just fine. No problems with it flicking on and off as the probe isn't that fickle.

Fallback OFF

Set OFF 

If Temp < 78.0 Then ON 

If Temp > 80.0 Then OFF 

[wade]

To be more specific the two less than statements are interfering with each other.  They are giving two parameters both of which may be true.  Drop the less than 60.  If you have another concern related to the less than 60, set up a virtual outlet and apply it.

[hypertech]

I don't think it is the less than 60 issue and I'm not sure I follow the idea that they conflict. 

 

That line is in there for a probe failure.  Sometimes when they fail they give you a bogus reading way off.  If that happens, I want it to shut off the heaters and email me rather than turn on the heaters and cook the tank.

[Origami]

Now that I type this out, I think it is the Set OFF in line 2.  At the next execution when temp is starting to climb and reaches 76.5, there is nothing to set it on.  Does that sound right?

Yes, that sounds right. It's completely redundant and can be removed.

 

I'm not sure if the order of the Defer and Min Time statements are important, but you may have to swap those two as well.

[Almon]

I'm not familiar with the Apex, but I think you only need the temp statements.

 

I use an older ACIII and have two heaters programmed with phenomenal success. It's super simple. A graph of the temperature over time shows the range of fluctuation to be no more than 1 degree. The temperature always stayed between 77.0 and 78.0.

 

The Apex can do this, right?

 

If Temp < 77.0 then HT1 ON

If Temp > 77.8 then HT1 OFF

 

If Temp < 77.2 then HT2 ON

If Temp > 78.0 then HT2 OFF

[Orion]

I don't think it is the less than 60 issue and I'm not sure I follow the idea that they conflict. 

 

That line is in there for a probe failure.  Sometimes when they fail they give you a bogus reading way off.  If that happens, I want it to shut off the heaters and email me rather than turn on the heaters and cook the tank.

The heater(s) internal thermostat will prevent the tank from being cooked if that happens. I have both my heaters set to 80, and the apex programmed for 78. The defer and min time statements are not necessary as stated above.

 

Now if you have a temp probe failure, AND a heater failure (runaway heater) at the same time(which isn't very likely) then your tank is just really having a bad day.

 

Sometimes it's best to just keep the code simple.

[mr.x-ray]

Not sure what you are gaining by having a back up heater. I have all of mine on one circuit and set at >77 off and <77 on. If you were insistent on a secondary heater I would make the biggest heater the primary and back ups at only .1 or .2 less then desired temp. The smaller heater as primary would be on longer trying to keep up. Also, not sure why people want such a swing in temp. eg <77 then on and <77.5 then off. IMO this is stressful for the livestock. <60 then off in not sure what this is for. So, IMHO if you want two separated heaters.

1) biggest heater as primary

2) program back up heater to come on at .1 less then big one.

3) Set temp > and < at same.

4) no defer or min or <60 in programming.

[Origami]

I always split my heaters in my large tanks as they are proven to be the most unreliable component in our setups. I don't trust my tank's survival to a single heater. In my current tank, I have three heaters set up to stage if the ones before can't keep up. I always put hysteresis into my temperature settings to keep the heater / outlet from banging on and off due to micro fluctuations in the temperature around the temperature probe. My tank temp fluctuates from 78.4 to 79 degrees throughout the day on most days. That's 78.7 plus or minus 0.3 degrees.

 

Heater_1: On at 78.6 Off at 79.0

Heater_2: On at 78.4 Off at 79.0

Heater_3: On at 78.2 Off at 79.0

 

As you can see, if the first heater can't keep the temperature above 78.6 degrees, the second will kick in. The third will kick in at 78.2 degrees. I could, I suppose, tighten up the range, but I've never really believed that level of regulation was necessary or proven beneficial.

[hypertech]

Mine are staggered by a half degree. I can't are how a half degree could hurt livestock. I once had a bio cube with metal halide. It swung several degrees a day and the tank did great.