Dual Heater Code with safe guards

[Snookin]

I have a 90g reef and just bought 2 150w heaters. I want my water to be consistently between 77-78 degrees. What code should I use and what safe guards should I have against over heating and temp probe failure?

[aquamanic]

If you put them on separate outlets you'll need to program both.

Examples of heater code are in the documentation (see sig). Hint: Don't use the Set command if you want your temp to float between two points, say 79.5 - 80.0.

For a safety, put a low temp limit where you DO NOT turn on the heater - for example, if the temp probe reads < 50 Then OFF (temp probes will read 20 degrees if they fail). Make sure you put the same statement but ON in your email outlet so you get notified.

Give it a try and if you get stuck, post your program and what the problem is.

[micaheli]

[heater1]
Fallback ON
If Temp < RT+0.0 Then ON
If Temp > RT+-0.1 Then OFF
If Temp < 68.0 Then OFF
If Outlet ReturnPump = OFF Then OFF
Defer 000:05 Then ON

[heater2]
Fallback ON
If Temp < RT+-0.1 Then ON
If Temp > RT+-0.1 Then OFF
If Temp < 68.0 Then OFF
If Outlet ReturnPump = OFF Then OFF
If Outlet Heater150 = OFF Then OFF
Defer 000:10 Then ON
If Power Apex Off 000 Then OFF



That's my code.... More than you probably need. Also, I'll be changing the safeguard to be in relation to RT.

--Micah

[Snookin]

Okay, Please look at this basic code I used. I programmed a separate outlet for each heater.

Heater/Outlet 1:
Fallback OFF Set OFF
If Temp < 77.5 Then ON
If Temp > 78.0 Then OFF
If Temp < 70.0 Then OFF
If Outlet Return = OFF Then OFF

Heater/Outlet 2:
Fallback OFF
Set OFF
If Temp < 77.0 Then ON
If Temp > 77.6 Then OFF
If Temp < 70.0 Then OFF
If Outlet Return = OFF Then OFF

Will this be good for a reef tank or should I add to or adjust this code?

[aquamanic]

You ignored my hint and inserted a Set. What that's going to do is have your controller try to keep your tank at exactly 77.5. Your heater is going to bounce on/off all day long.

If you really want the temp to drift between 77.5 and 78.0, then remove the Set OFF. If you want to keep it precisely at 77.5 then leave it in and remove the If Temp > 78 statement because it will never happen.

Also, if your heater has its own t-stat, then make your Fallback statement ON. This way your heater will continue to run even if the controller fails in the middle of a cold winter night.

[feh]

[heater1]
Fallback ON
If Temp < RT+0.0 Then ON
If Temp > RT+-0.1 Then OFF
If Temp < 68.0 Then OFF
If Outlet ReturnPump = OFF Then OFF
Defer 000:05 Then ON

[heater2]
Fallback ON
If Temp < RT+-0.1 Then ON
If Temp > RT+-0.1 Then OFF
If Temp < 68.0 Then OFF
If Outlet ReturnPump = OFF Then OFF
If Outlet Heater150 = OFF Then OFF
Defer 000:10 Then ON
If Power Apex Off 000 Then OFF



That's my code.... More than you probably need. Also, I'll be changing the safeguard to be in relation to RT.

--Micah

This is an old thread, but I was wondering what the purpose of this line was on the secondary heater- "If Outlet Heater150 = OFF Then OFF"

[Midnightt]

Wanted to post mine to see if it makes sense. Neither heaters have there own controller. First heater should be able to get the temp there but, if not after 2 hours I want the second one to help finish. First one is a 300 watt and the second one is a 500 watt.

Heater_1

Fallback ON
If Temp < 79.1 Then On
If Temp > 80 Then OFF
If Temp < 60 Then OFF
If Outlet ReturnPump = OFF Then OFF


Heater_2

Fallback OFF
If Outlet Heater_1 = ON Then ON
Defer 120:00 Then ON
If outlet Heater_1 = Off Then OFF


I had to add the last line of Heater_2 because it didn't shut off after Heater_1 switched off. I'm guessing it may have something to do with the order of operations?

[zombie]

What you are showing could exasserbate the problem. If something fails (such as temp probe being exposed to air), then you dont want to pump more wattage into it (even waiting for 2 hours) and make the problem worse. I have seen similar problems on my local reef club that someones tank got up to 95 degrees and cooked everything because a 400W heater got stuck on in a 90 gallon tank for 8 hours. My advice is to unplug heater 2 and put it up for sale on craigslist, reef club etc. Use the money you make from selling it to buy a 200W heater with a thermostat. Then set that one to fallback on and set the temp range 0.2 lower than heater 1 (on high and low).

You might be an engineer if...You have no life and can PROVE it mathematically.

[Midnightt]

So the code will work? I'm cycling the tank and at the end of the day to have float switches to handle what you said. I'll add that code when it is installed but, that's not done yet. 2 weeks tops.

Question was does that code make sense?

Final statement is I plan to alternate the 500 and 300 seasonally. That's the reason for the difference.

- - - Updated - - -

And the final thing is that the tank is in the basement. Hence the different codes wattage...

[zombie]

The code does what you want it to, but I personally would not use it because of the risk of cooking your tank.

What size is your tank?

Rather than rotating the two seasonally, you would be better off doing something along the lines of this

300W heater
Fallback OFF
If Temp <79.1 Then ON
If Temp > 80 Then OFF
If Temp < 72 Then OFF
If Outlet ReturnPump = OFF Then OFF

200W heater
Fallback ON
If Temp < 79.0 Then ON
If Temp > 79.5 Then OFF

Set the thermostat of the 200W heater to 81 degrees. This will make sure water temp stays reasonable during fallback, if your return is off for an extended period, if the temp probe fails, if the temp probe falls out of the sump or gets exposed to air, etc.

You might be an engineer if...You have no life and can PROVE it mathematically.

[Dubious]

This is an old thread, but I was wondering what the purpose of this line was on the secondary heater- "If Outlet Heater150 = OFF Then OFF"

I believe it was ment to be; IF Outlet Heater1 = OFF Then OFF
as safeguard?