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?

 

[EeyoreIsMySpiritAnimal]

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..

Use Celsius, for sure.

 

[face]

Respectfully, your logic is 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.

Controllers rarely fail
Hobby heater thermostats have a high (almost 100%) failure rate DUE TO thermal cycling and arcing. If the thermostat is not used and the heater head is kept dry, the failure rate nears zero.


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

Maybe most of us are using inkbirds that are $30.

 

[BeanAnimal]

Maybe most of us are using inkbirds that are $30.

The inkbird is still exponentially more reliable than the hobby heater thermostat.

You are certainly free to use whatever method you wish. I am just trying to make sure those following along get a better understanding and/or help you if you are open to the advice.

To that end I would not use one. I would use a real controller like a Ranco - they are bulletproof.

 

[face]

The inkbird is still exponentially more reliable than the hobby heater thermostat.

You are certainly free to use whatever method you wish. I am just trying to make sure those following along get a better understanding and/or help you if you are open to the advice.

To that end I would not use one. I would use a real controller like a Ranco - they are bulletproof.

Ya if funds permit. I have used inkbird+2 undersized heaters for years with no issues. Its pretty much impossible to have issues with that method.

 

[MnFish1]

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.

I disagree. I use the controller to prevent an error. I.e. read the temperature - (if too low - alert) - if too high (i.e. the heater is broken) - alarm and shut off. The reason (my reasoning) - is that the heater is far more likely to fail than the controller - thus having the controller as the 'fall back' makes more sense. But - Imho - there is no right or wrong - an no real difference. Eitherway - there is a fail-safe.

 

[BeanAnimal]

I disagree. I use the controller to prevent an error. I.e. read the temperature - (if too low - alert) - if too high (i.e. the heater is broken) - alarm and shut off. The reason (my reasoning) - is that the heater is far more likely to fail than the controller - thus having the controller as the 'fall back' makes more sense. But - Imho - there is no right or wrong - an no real difference. Eitherway - there is a fail-safe.

If the heater’s internal thermostat is not used to control the temperature, the heater is extremely unlikely to fail. If it does fail (unlikely bad element), the controller will read low.

If the heater’s internal thermostat is used to control temperature. the heater is almost guaranteed to fail due to thermal cycling and arcing of the bi-metal thermostat.

So yes, both methods offer a fail-safe. One method offers a solution with long term reliability, the other forces premature failure of the heater.

 

[workhz]

So the heater is much less likely to fail if controlled by an external controller than itself? Any idea what kind of numbers we’re talking about here?

 

[n2585722]

I disagree. I use the controller to prevent an error. I.e. read the temperature - (if too low - alert) - if too high (i.e. the heater is broken) - alarm and shut off. The reason (my reasoning) - is that the heater is far more likely to fail than the controller - thus having the controller as the 'fall back' makes more sense. But - Imho - there is no right or wrong - an no real difference. Eitherway - there is a fail-safe.

I use it the way @BeanAnimal suggest. I have 2 50 watt heaters like you can buy at Petsmart. I use their internal thermostat as a backup and have them set 3 degrees higher than the controller. I have been doing it this way for a little less than 8 years. I have had only 1 heater failure and it quit heating completely. I now have them connected to individual outlets on my XP8 which has power monitoring so if that were to happen now I would know since I would get an alert for power out of range. I would also get that same alert if the bimetal strip were to turn off the heater. So far that has not happened. The controller outputs also have some other alerts such as maximum on time has been exceeded. This would also indicate an open heater. The temp input also has a range set so if the temp get out of that range an alert is also set. I think 8 years on a cheap heater is a good indication that this does works. In that 8 years I have not had any outlet failures on the power bars used. I have changed controllers during that time since I switched from the Archon to the Hydros system.

 

[Sleeping Giant]

set the controller at the temperature that you would like to maintain, and set the heaters a few degrees higher

 

[BeanAnimal]

So the heater is much less likely to fail if controlled by an external controller than itself? Any idea what kind of numbers we’re talking about here?

Quite literally almost no chance of failure if the internal thermostat is not used to a nearly 100% failure rate if it is. The difference is that real and that drastic. Hobby heaters are pure garbage with tiny bi-metal strips that act as the thermostat and electrical contactor. The thermal cycling and arcing simply destroy them. That is why they all eventually fail.

 

[MnFish1]

If the heater’s internal thermostat is not used to control the temperature, the heater is extremely unlikely to fail. If it does fail (unlikely bad element), the controller will read low.

If the heater’s internal thermostat is used to control temperature. the heater is almost guaranteed to fail due to thermal cycling and arcing of the bi-metal thermostat.

So yes, both methods offer a fail-safe. One method offers a solution with long term reliability, the other forces premature failure of the heater.

The one thing I would suggest is that it is a vast minority of people who own aquaria - use a controller in the first place - and I'm not sure there's a huge rash of heater failures (of course it can happen). So - though I completely agree with you that there is a theoretical possibility that a cheap heater would fail in reality IMHO - there is no difference. Either the controller is going to be cycling on and off - or the heater is going to be cycling on and off. It's kind of like the argument on how to put the toilet paper roll IMHO. I see advantages to both. But - just a quick comment. I have found Inkbird controllers (bought 2, both failed within a week) - somewhat unreliable. The other method I would not use is 2 heaters one set a little higher - such that if 1 heater fails 'off' - the other will take over. This does not leave any ability to prevent over-heating (I know you were not suggesting it - but I've heard others suggest it)

 

[workhz]

Quite literally almost no chance of failure if the internal thermostat is not used to a nearly 100% failure rate if it is. The difference is that real and that drastic. Hobby heaters are pure garbage with tiny bi-metal strips that act as the thermostat and electrical contactor. The thermal cycling and arcing simply destroy them. That is why they all eventually fail.

Thanks. I was under the impression that controlling with inkbird increased the on/off cycles and made the heaters fail sooner. Since that's not the case, I'll let the controller do the work once I get new heaters in there. I have eheim heaters currently. Didn't think they had bi-metal strips acting as thermostats. Mind you a thermostat in a car is a bimetal strip and they seem to last a while under pretty harsh conditions. Wish they could just figure out how to make heaters fail off instead of on.

 

[BeanAnimal]

and I'm not sure there's a huge rash of heater failures (of course it can happen). So - though I completely agree with you that there is a theoretical possibility that a cheap heater would fail in reality IMHO - there is no difference.

I honestly don't get these debates. Basic facts are ignored to validate an opinion instead of just a simple "wow never thought about it that way".

The advice is not theoretical or anecdotal - it is simple fact of operating principle and applied logic, verified by decades of evidence.

Temperature controllers are designed to switch a high current load on and off hundreds of thousands of times without failing.

A hobby heater heater is designed to be cheap and uses a bi-metal strip that acts as both the thermostat and the electrical contactor. This crude device takes a beating due to the thermal cycling (bending back and forth as part of its operation) and the large arc that occurs on every make and break cycle. The arc erodes the contact point and the constant bending back and forth causes metal fatigue. Failure is guaranteed.

There are (3) common failure modes.
1 - the contacts weld shut, leaving the heater on.
2 - the contact breaks due to fatigue and falls into the leads, leaving the heater on.
3- the contact breaks and falls away leaving the heater off

These failure modes account for close to 100% of hobby heater failures and limits their useful lifespan.

The internet is littered with failed ON heater threads. It is not a "rash" it is just the simple reality of their design and operation.

If the thermostat on the heater is set to just above the controller's set point, the bi-metal strip is pressed against its mating half to make contact. It stays that way unless the controller fails on (extremely unlikely). There is no arcing or metal fatigue and nothing to fail except the heating element itself.

Lastly -
If inkbird controllers are failing, then they are junk too - but that does not negate any of the logic above and in fact makes my suggestion even more relevant and further erodes your point.

By using the "controller" as the fail-safe and the heater as the "controller" you are simply putting it in a position to fail AND relying on (by your account) a controller that is likely to fail too. Thus, you are advocating using a heater in a mode that is likely to cause failure along with a controller that is likely to fail! That is not logical (at all). The smart thing to do would be to use the "likely to fail" controller in a mode where the heater is NOT likely to fail (using it as a fail-safe where the internal thermostat is not exposed to electrical or mechanical failure).

 

[BeanAnimal]

Thanks. I was under the impression that controlling with inkbird increased the on/off cycles and made the heaters fail sooner. Since that's not the case, I'll let the controller do the work once I get new heaters in there. I have eheim heaters currently. Didn't think they had bi-metal strips acting as thermostats. Mind you a thermostat in a car is a bimetal strip and they seem to last a while under pretty harsh conditions. Wish they could just figure out how to make heaters fail off instead of on.

Yes - your car thermostat is a bi-metal device. The difference is both scale and duty cycle. Your car's thermostat is fairly large and designed for longevity. It may cycle 500 times a year and will eventually fail. The thermostat in the hobby heater is tiny and cheap. It will easily cycle thousands or tens of thousands of times a year.

Yes - some brands of heaters have a "digital" thermostat or controller, usually solid state (SSR) switching. These are very similar to a "controller" with the major difference being robustness of the components and circuit design. Most are (like their electromechanical counterparts) hobby junk destined to fail.

My advice:

• avoid digital hobby heaters like the plague
• avoid GLASS or PLASTIC envelope heaters like the plague - thermal cycling causes failure.
• buy only quality titanium heaters
• never fully submerge a heater
• only use the internal thermostat (if it has one) as a fail-safe
• always run the heater in a compartment that can't expose the envelope to air
• always use a QUALITY controller (Ranco, or Profilux, Neptune, etc)
• always controller probe IN the same compartment as the heater NEVER away from it.
• always place the controller probe just upstream of the heater, not downstream.

People spend thousands (tens of thousands) on their aquariums and cheap out when it comes to the very device thats presence can (and will) wipe the tank out faster than any other piece of equipment.

Do yourself a favor, buy a good heater and a good controller. I can't knock inkbird as I have no experience with it, but anecdotally they do not appear to be anywhere near commercial quality. Ranco ETC series controllers are bulletproof and not expensive. They are used on tens of millions of pieces of commercial and industrial process, refrigeration and HVAC equipment worldwide.

 

[MnFish1]

Yes - your car thermostat is a bi-metal device. The difference is both scale and duty cycle. Your car's thermostat is fairly large and designed for longevity. It may cycle 500 times a year and will eventually fail. The thermostat in the hobby heater is tiny and cheap. It will easily cycle thousands or tens of thousands of times a year.

Yes - some brands of heaters have a "digital" thermostat or controller, usually solid state (SSR) switching. These are very similar to a "controller" with the major difference being robustness of the components and circuit design. Most are (like their electromechanical counterparts) hobby junk destined to fail.

My advice:

• avoid digital hobby heaters like the plague.
• avoid GLASS or PLASTIC envelope heaters like the plague.
• buy only titanium heaters
• never fully submerge a heater
• only use the internal thermostat (if it has one) as a fail-safe
• always run the heater in a compartment that can't expose the envelope to air
• always use a QUALITY controller (Ranco, or Profilux, Neptune, etc)
• always controller probe IN the same compartment as the heater NEVER away from it.
• always place the controller probe just upstream of the heater, not downstream.

There is no debate. Let me change my more verbose reply to this: Buy a good quality heater with a solid state controller - if you do - the difference between using your main controller or your heater controller as primary is negligible. It is also safest to use a controller with any heater. My only point was if you're using a controller and a quality heater - you will be covered, no matter which way they are set up. In my case - what happened was I was using the controller as you recommended (and it was a high quality brand you mentioned) - The controller failed - the power bar - and thus turning off power to the heater entirely - and did not send an alert. There is no perfect way to do it. Thats just my opinion - I have no criticism of your advice above.

 

[workhz]

People spend thousands (tens of thousands) on their aquariums and cheap out when it comes to the very device thats presence can (and will) wipe the tank out faster than any other piece of equipment.

Do yourself a favor, buy a good heater and a good controller. I can't knock inkbird as I have no experience with it, but anecdotally they do not appear to be anywhere near commercial quality. Ranco ETC series controllers are bulletproof and not expensive. They are used on tens of millions of pieces of commercial and industrial process, refrigeration and HVAC equipment worldwide.

I’ll look into that. Saving grace is that my tank is currently in a very stable temp room and I doubt if I had one of the heaters fail it would have enough power to nuke the tank. I need to do some calcs to see how much of a temp rise it would create if it failed on (assuming the fail safes also failed).

 

[BeanAnimal]

There is no debate. Let me change my more verbose reply to this: Buy a good quality heater with a solid state controller - if you do - the difference between using your main controller or your heater controller as primary is negligible. It is also safest to use a controller with any heater. My only point was if you're using a controller and a quality heater - you will be covered, no matter which way they are set up. In my case - what happened was I was using the controller as you recommended (and it was a high quality brand you mentioned) - The controller failed - the power bar - and thus turning off power to the heater entirely - and did not send an alert. There is no perfect way to do it. Thats just my opinion - I have no criticism of your advice above.

Thank you for the response. We can break failure modes into two general types, being overheating or failure to heat.

Both have different ramifications and fail-safe solutions beyond the scope of this thread.

Overheating is almost always a guaranteed disaster. Failure to heat, may or may not be. I will simply say that in situations where failure to heat will rapidly cause a disaster, then redundant heating (each with isolated fail-safe) should be employed at any cost.

I will also add, that it would be considered best practice to have out of band monitoring for any system that is highly susceptible to either failure mode. Dedicated aquarium controllers muddy the water a bit, as they fall someplace between a hobby device and a piece of rugged commercial equipment.

As it were - I prefer titanium heaters that do not have an integrated thermostat. If one is willing to invest $250 in a titanium heater, there are commercial process heaters with integrated thermostats and actual relays. While these may be exponentially more reliable than a hobby heater, I would still not run one without a controller (be it as the primary means of control or the fail-safe).

 

[BeanAnimal]

I’ll look into that. Saving grace is that my tank is currently in a very stable temp room and I doubt if I had one of the heaters fail it would have enough power to nuke the tank. I need to do some calcs to see how much of a temp rise it would create if it failed on (assuming the fail safes also failed).

I ran with the heater disconnected for years - no SPS though. Swings from high 60's to high 70's daily and seasonally depending in room temp, heat or ac, etc.

 

[BeanAnimal]

Mentioned above as well -

The vast majority of aquarium owners significantly oversize their heaters.

An ideally sized heater will run nearly a 100% duty cycle on the coldest (room) day of the year (be it winter or summer caused by AC, cold basement, high evap, etc.).

This creates a few ideal situations that both prolong the life of the heater AND add a layer of safety.

1) Far fewer temperature swings, as the heater will rarely cycle on/off and no chance of overshoot or hunting
2) Far less thermal stress on the seals and heating element due to thermal cycling
3) A very slim chance of catastrophic (and/or rapid) overheat in a fail-on situation
4) lower switched current is easier on ANY controller's components
5) smaller footprint and easier placement

figure out how many degrees your tank drops over 24 hours with no heat (or some fraction of that) and use that to derive the number of BTUs lost (1 BTU is the amount of heat required to raise 1 pound of water 1 degree F).

An electric resistance heater outputs 3.41 BTU/h per watt. So a 100W heater will impart 341 BTUs to the tank in 1 hour...

Buy the closes heater (nest size up) to your actual requirements, or better 2-3 small heaters that's total wattage adds up to the target wattage.

TLDR = a properly sized heater should run somewhere around 90%-95% of the time.

 

[MnFish1]

Mentioned above as well -

The vast majority of aquarium owners significantly oversize their heaters.

An ideally sized heater will run nearly a 100% duty cycle on the coldest (room) day of the year (be it winter or summer caused by AC, cold basement, high evap, etc.).

This creates a few ideal situations that both prolong the life of the heater AND add a layer of safety.

1) Far fewer temperature swings, as the heater will rarely cycle on/off and no chance of overshoot or hunting
2) Far less thermal stress on the seals and heating element due to thermal cycling
3) A very slim chance of catastrophic (and/or rapid) overheat in a fail-on situation
4) lower switched current is easier on ANY controller's components
5) smaller footprint and easier placement

figure out how many degrees your tank drops over 24 hours with no heat (or some fraction of that) and use that to derive the number of BTUs lost (1 BTU is the amount of heat required to raise 1 pound of water 1 degree F).

An electric resistance heater outputs 3.41 BTU/h per watt. So a 100W heater will impart 341 BTUs to the tank in 1 hour...

Buy the closes heater (nest size up) to your actual requirements, or better 2-3 small heaters that's total wattage adds up to the target wattage.

TLDR = a properly sized heater should run somewhere around 90%-95% of the time.

All good. IMHO - makes no difference - heaters are designed (whether thats correct or not) -to work without controllers.