Heater Program

[Rembee]

I have 2 150w heaters. Htr 1 set for 77 and heater 2 set for 78. I would like my Apex heater outlet to stay on unless the temp exceeds 81.0 deg. Here is my program. Is this correct?


[Heater 1]
Fallback OFF
If Temp < 80.9 Then ON
If Temp > 80.9 Then OFF

[pyton]

That will cause the the outlet to turn off and on over and over.

The outlet will turn ON at 80.8 and off at 81.0

If you want it on all the time EXCEPT if it reaches 81 just use

[Heater 1]
Fallback OFF
Set On
If Temp > 80.9 Then OFF

[RussM]

Pyton's programming will also allow the heater to be shut on and off as the temp fluctuates around the setpoint, possibly quite frequently. ;)

The easiest way to handle a heater is very similar to what you have, but with a slightly wider range:

Fallback OFF
If Temp < 79.0 Then ON
If Temp > 80.0 Then OFF

Note that there is no Set statement. Adjust the high and low setpoints as desired for the preferred operating temperature range


This way, the heater will be energized as the temp rises past 79, and will stay on until the temp hits 80. As the temp decreases, it will not tun on again until the temp goes below 79. This effectvely eliminates the frequent on/off cycling of both your current program and pyton's.

There are other ways, using Min Time or Defer, but the above is the simplest.

Also, you should add a failsafe to shut down the heater if the temp drops well below the expected normal measurement, which would most likely be due to a heater failure or a failure of the temp probe. The Apex will indicate about 20 degrees if the probe is disconnected or can read 20 when the temp probe fails.

If Temp < 75 Then OFF

This statement needs to be after other related programming.

[Rembee]

Pyton's programming will also allow the heater to be shut on and off as the temp fluctuates around the setpoint, possibly quite frequently. ;)

The easiest way to handle a heater is very similar to what you have, but with a slightly wider range:

Fallback OFF
If Temp < 79.0 Then ON
If Temp > 80.0 Then OFF

Note that there is no Set statement. Adjust the high and low setpoints as desired for the preferred operating temperature range


This way, the heater will be energized as the temp rises past 79, and will stay on until the temp hits 80. As the temp decreases, it will not tun on again until the temp goes below 79. This effectvely eliminates the frequent on/off cycling of both your current program and pyton's.

There are other ways, using Min Time or Defer, but the above is the simplest.

Also, you should add a failsafe to shut down the heater if the temp drops well below the expected normal measurement, which would most likely be due to a heater failure or a failure of the temp probe. The Apex will indicate about 20 degrees if the probe is disconnected or can read 20 when the temp probe fails.

If Temp < 75 Then OFF

This statement needs to be after other related programming.


Thanks guy's for the input.

I will go with the example that Russ gave. Now I have another question for Russ...lol. In your fail safe line of code, if the Apex probe did fail or was disconnected causing the Apex to read 20 degrees, wouldn't you want the outlet to stay on leaving your heater temp. controller to just do it's job. In this way, at least the heaters would still work.
I have the Finnex digital heaters which allows me to set each heater to a precise degree. I want my Apex to shut down all heaters in the event one of the heaters fail in the on position.

[RussM]

Doh! I apparently didn't read your original post closely enough.... My apologies to both you and pyton. Disregard my previous blathering. Since you are using the heaters' thermostats for primary temp control, Pyton is right on the money.

[Typlus5]

You must have better Finnex digital heaters than I had. I took mine off line due to the beep everytime the power was cut off/on. And, the auto recovery temp was 81...and, the Finnex controller was off by a couple degrees. I opted for the accuracy of the Apex and a simple titanium heater.

[eisaiasjr]

Something that was mentioned here that is EXTREMELY IMPORTANT!!!

When you disconnect your temp probe, your temperature goes to 20 degrees (I think its 20, or maybe its 50)

so, even if your temperature is correct by any chance your temp probe gets loose your tank will heat up to a nice boil...

Here is how you fix it...

Fallback OFF
If Temp < 77.0 Then ON
If Temp < 72.0 Then OFF
If Temp > 77.4 Then OFF
If FeedA 000 Then OFF

Best Regards,

Estefano

[david00061]

can you add a defer command st stop the on and off issue
If Temp < 77.5 Then ON
If Temp > 77.7 Then OFF
Defer 002:00 Then ON
Defer 001:30 Then OFF

[swearint]

Yes, the Defer will delay the outlet from turning ON or OFF by the specified duration.

Todd