Who's in Control, Heater or Heater Controller

[Mrsirtang]

Hello All,

I recently had an Inkbird heater controller fail, that was only 3 months old. So, I contacted Inkbird support, and after a few e-mail exchanges with obvious trouble shooting steps, they sent a replacement in a timely manner. But my questions is, is it best to set the controller at the temperature that you would like to maintain, and set the heaters a few degrees higher ( I use Eheim heaters). Or, set the controller a few degrees higher, and set the heaters at the temperature that you would like to maintain?

 

[BeanAnimal]

I do the latter and only use the InkBird as a fail safe. As in I set the controller a couple of degrees higher. I’m sure to be in the minority by a factor of 10-1.

You have it backwards. Then Ink bird has a relay and a digital thermostat, the heater a bi-metal strip that fails due to fatigue due to its design (thermal cycling). The thermostat on the heater is the fail-safe. This is not opinion, just a simple fact of failure rates.

So set the heater (by physical feel of the thermostat) just above the set point of the tank when it reaches temp and the ink-bird turns it off.

 

[MnFish1]

I didn't read the rest - IMHO - you set the controller to turn off at your Max temp. Let's say - you have your heater set at 76 - you set your controller to turn off at 78. It's a double-check

 

[BeanAnimal]

I didn't read the rest - IMHO - you set the controller to turn off at your Max temp. Let's say - you have your heater set at 76 - you set your controller to turn off at 78. It's a double-check

you have it backward

the heater thermostat is the fail-safe and the temperature controller is the controller.

The controller turns the heater on and off and the heater thermostat only kicks in of the controller (unlikely) fails ON

The common failure mode of a bi-metal thermostat (what is in a heater) is ON. The have a fairly predictable 100% failure rate due to thermal cycling.

in the case of the ink bird or a ProfiLux, Neptune or Hydros, this also allows the controller logic to monitor the actual process of on/off duration and associated logic.

 

[workhz]

You have it backwards. Then Ink bird has a relay and a digital thermostat, the heater a bi-metal strip that fails due to fatigue due to its design (thermal cycling). The thermostat on the heater is the fail-safe. This is not opinion, just a simple fact of failure rates.

So set the heater (by physical feel of the thermostat) just above the set point of the tank when it reaches temp and the ink-bird turns it off.

I think of it like this. Do I want my very last fail safe to be the heater or the inkbird and I decided I wanted it to be the ink bird. Now I don't care if my heater fails and I'll know if it did. If the inkbird fails, do I really want to rely on a heater as the backup?

I'm not concerned about temp stability since it seems very stable as is.

 

[BeanAnimal]

Hello All,

I recently had an Inkbird heater controller fail, that was only 3 months old. So, I contacted Inkbird support, and after a few e-mail exchanges with obvious trouble shooting steps, they sent a replacement in a timely manner. But my questions is, is it best to set the controller at the temperature that you would like to maintain, and set the heaters a few degrees higher ( I use Eheim heaters). Or, set the controller a few degrees higher, and set the heaters at the temperature that you would like to maintain?

I don‘t know much about inkbird other than it has some alarm and timer features. Ranco temp controllers are industrial/commercial and have nearly a zero failure rate.

 

[BeanAnimal]

I think of it like this. Do I want my very last fail safe to be the heater or the inkbird and I decided I wanted it to be the ink bird. Now I don't care if my heater fails and I'll know it did. If the inkbird fails, do I really want to rely on a heater as the backup?

I'm not concerned about temp stability since it seems very stable as is.

You can think of it any way you wish… but there is a right and wrong way based on common failure modes. You simply have it backward. You are forcing a heater failure the way you have it setup and bypassing the intended purpose and robustness of a temperature controller.

Kinda like driving on the spare and keeping the real tire in the trunk in case you need it.

The internal thermostat on the heater will not fail if it used only as a fail-safe. There is no thermal cycling or arc damage From repeated make break contacts.

 

[JoJosReef]

Plug your inkbird into an inkbird?

 

[face]

Let the heater(s) manage the temp thats what it is designed to do. Then the controller is a fail safe set it to turn off at 80.

 

[BeanAnimal]

Plug your inkbird into an inkbird?

We can actually do the math on that…

In a real world critical control situation we would split the loads between controller, with each having multiple smaller heaters. This ads fail-safes for both too much heat and lack of heat, based on failure mode.

 

[907_Reefer]

My only problem with setting the heaters slightly higher than the Inkbird and using the IB to turn on and off the heaters, is that the IB can only be set to whole integers (at least in F), so I have a ~1.2 F temperature swing back and forth all day, repeatedly. That is less consistency than I would like. Can anyone confirm adjustability that is using Celsius? Otherwise I will dig up the documentation I have around here later on..

 

[BeanAnimal]

Let the heater(s) manage the temp thats what it is designed to do. Then the controller is a fail safe set it to turn off at 80.

Again, this is backwards. The controller is a reliable device far more suited to controlling the temperature than a piece of junk hobby heater. The failure modes of both devices are very different.

 

[BeanAnimal]

My only problem with setting the heaters slightly higher than the Inkbird and using the IB to turn on and off the heaters, is that the IB can only be set to whole integers (at least in F), so I have a ~1.2 F temperature swing back and forth all day, repeatedly. That is less consistency than I would like. Can anyone confirm adjustability that is using Celsius? Otherwise I will dig up the documentation I have around here later on..

That is an irrelevant swing IMHO… Even with tighter hysteresis settings you will still have an up/down oscillation as the heater reacts to the room and its own output. A true PID controller could tighten it up But I don’t see it being a need.

 

[JoJosReef]

I have a new Helio which has its own controller and plan to use an inkbird as low temp failsafe (Helio set to 77F, if heater breaks and temp drops to 75F, inkbird kicks on the backup heater). What I don't know how to do is save the tank if the Helio goes nuts and heats up nonstop. Thinking maybe one of the aquagadget smart switches with temp monitor...

 

[JoJosReef]

I have a new Helio which has its own controller and plan to use an inkbird as low temp failsafe (Helio set to 77F, if heater breaks and temp drops to 75F, inkbird kicks on the backup heater). What I don't know how to do is save the tank if the Helio goes nuts and heats up nonstop. Thinking maybe one of the aquagadget smart switches with temp monitor...

Side-note, if the temp goes over 78F, the inkbird will turn on the fans, but I don't think the fans will cool off the tank as fast as a broken "ON" heater will heat up the tank.

 

[BeanAnimal]

On the subject of failure. You should never fully submerge a heater or place it in an area where it has a chance for the envelope to be exposed. The temp probe should be in the same compartment as the heater and just slightly upstream.

My current titanium heater is going on 20 years old… it does not have a thermostat to fail and is plumbed through a bulkhead in the side of the sump.

 

[BeanAnimal]

I have a new Helio which has its own controller and plan to use an inkbird as low temp failsafe (Helio set to 77F, if heater breaks and temp drops to 75F, inkbird kicks on the backup heater). What I don't know how to do is save the tank if the Helio goes nuts and heats up nonstop. Thinking maybe one of the aquagadget smart switches with temp monitor...

I highly prefer Ranco’s over anything made for hobby use or IoT gadgets. They are still around for a reason. I now use the Ranco as a fail-safe and allow the ProfiLux to do the control.

 

[face]

Again, this is backwards. The controller is a reliable device far more suited to controlling the temperature than a piece of junk hobby heater. The failure modes of both devices are very different.

Doesnt matter if the heater fails. Because the controller is there to turn it off. Why would you want to burn out your controller cycling it on off tons per day when you could just chunk the heater after 2 years and get a new one. Let the heater do the work while the controller is the fail safe. I recommend 2 heaters as well for additional safety.

 

[BeanAnimal]

Side-note, if the temp goes over 78F, the inkbird will turn on the fans, but I don't think the fans will cool off the tank as fast as a broken "ON" heater will heat up the tank.

This also goes to heater sizing The ideal heater should be sized to run almost 100% duty cycle on the coldest day of the year. That means that it can’t overheat the tank quickly even if stuck on. Most people drastically over size their heaters.

 

[collins.jason.k]

Titanium heating elements here controlled by finnex controllers. Keeps the tank stable at 77 when needed, only in winter though here in Indiana. During the summer they never cut on and slowly warm to about 80 and hang there til fall.

 

[BeanAnimal]

Doesnt matter if the heater fails. Because the controller is there to turn it off that is the point. Why would you want to burn out your controller cycling it on off tons per day when you could just chunk the heater after 2 years and get a new one. Makes no sense at all. Let the heater do the work while the controller is the fail safe. I recommend 2 heaters as well for additional safety.

Respectfully, your logic is extremely flawed. Real temperature controllers have heavy duty power relays. They are designed to cycle high amp loads, over and over. Your heater is hobby crap with a 2 cent bi-metal thermostat with arcing contacts thats most common failure mode is to weld itself shut or break off and short itself (both resulting in continuous heating).

Commercial quality (Ranco, Johnson Controls, etc. ) controllers rarely fail.

Hobby heater thermostats have a high (almost 100%) failure rate DUE TO thermal cycling and arcing (the very act of operating). That is, by their very principle of operation, they self destruct due to their absolute garbage design. If the internal thermostat is not used (set a degree or two high as a fail-safe) and the heater head is kept dry, the failure rate nears zero and the thermostat will act beautifully as a fail-safe in the extremely rare event that your controller fails ON.

Most "controller failures" btw are not an actual controller failure, but operator error allowing the probe to be exposed to air or in a compartment other than the heater.

Again - the VERY PURPOSE and DESIGN of a temperature controller is to cycle on and off- by design, over and over - millions of times, reliably.
Moreover - most power relays/contractors fail OPEN - not CLOSED.

There is nothing to debate here, you simply have your logic backwards based on invalid assumptions and understanding of the devices, their operating principles, failure modes and probability of failure.

FWIW I have two Rancos that have almost 20 years continuous duty on them.