Rogue heat problem mystery

[badassissimo]

So... I bought some decent heaters and a thermostat this summer. Everything ran great! I had to move. The thermostat seemed to not work so I called dr. foster and smith and got a replacement. I was supposed to send it back but decided to wire it up to another tank since the heater decided to go rogue and start over heating. Both tanks ran fine with separate thermostats. We finally closed on our house and moved yet again. The 20 gallon with the original thermostat is heating and regulating fine. The thermostat inside the heater is broken. The thermostat controller is doing its job nicely. The other one was reading temperature but not turning on the heaters? Tank was COLD this morning after a cold front last night. Not good... I put the heaters on the power strip and unplugged the controller. today, the heaters were set on 79 and still went to 90. What in the world?!?!?! I can't win for losing! The heaters are back on the controller and the temperature is dropping slowly. I don't understand worth a flip why this is happening. I get the 300w in the 20 gallon going down... I've had that heater for years. I don't understand the out of control controllers. I really have no idea why both 400W heaters in the 75 gallon I just bought this summer were heating wide open today up to 90 degrees....

Ideas?

 

[Drstrangelove]

You apparently have three or more heaters, at least 2 tanks, and at least 2 temperature controllers. My impression is that you have one clear problem: a faulty temperature controller which you have decided to use even though it's faulty and should have been returned. Ime, once there is one clear problem, it needs to be fixed prior to troubleshooting other problems.

So my idea is return the faulty controller and get a good one.

As an aside, I would say that having 300 watts on a 20 gallon and 400 watts on a 75 gallon is probably excessive, especially on the 20.

 

[BMac91]

As an aside, I would say that having 300 watts on a 20 gallon and 400 watts on a 75 gallon is probably excessive, especially on the 20.

I was thinking the same, I typically only use (2) 250-300 watts on 125, 210, and my incoming 240. We live in similar climates, why are you using such large heaters?

 

[skjl47]

Hello; I have not had the newer style heaters apart as yet so this may not apply. I have taken apart the style of heater used for prior decades so this is my basis.
The heaters I have used have a thermostat made from a bi-metal strip with contact points. The bi-metal strip bends one way when cool and the other way when warm.
When cool the bi-metal strip moves the contact point toward another contact point in a fixed place. When the contact points touch a circuit is closed and the electricity flows thru the heating element.
After a time this heats up the heater's glass tube which in turn heats up the water. This heat also makes it's way to the bi-metal strip which moves the other way and breaks the contact. When the contact is broken the electricity stops flowing and the heater is turned off.

What happens over many repetitions of this on and off cycle is the contact points arc each time the cycle happens. During that brief arc a small amount of material is transferred from one contact point to the other. That material eventually builds up enough so that the contact points never break contact. This leaves the heater stuck in the on position.

For those old enough to recall contact points in an automobile distributor it is the same sort of thing and has the same solution. Get a small flat metal file called a points file. I take my heaters apart enough to expose the bi-metal strip and the two contact points. I use the points file to take off the build up from between the two contact points. I gently stick the points file between the two contacts and file the protrusion down until the surfaces are flat again.

I have done this for my heaters many times over decades. This is the more common problem when heaters are stuck on.

When heaters are stuck off it usually a break in the circuit somewhere. If it is the actual heating element then I have no fix as this is a high resistance wire usually coiled too tight to fix and get back into place.

The newer heaters may have some different sort of thermostat. I do not know yet as I bought one a year or so ago and it has not failed yet.

Good luck

 

[krichardson]

It appears as if Dr. Strangelove has uncovered the problem but a four hundred watt heater is quite excessive for a mere seventy five gallon tank.I can get by with a 250 on my 180 in my unheated basement.

 

[badassissimo]

You apparently have three or more heaters, at least 2 tanks, and at least 2 temperature controllers. My impression is that you have one clear problem: a faulty temperature controller which you have decided to use even though it's faulty and should have been returned. Ime, once there is one clear problem, it needs to be fixed prior to troubleshooting other problems.

So my idea is return the faulty controller and get a good one.

As an aside, I would say that having 300 watts on a 20 gallon and 400 watts on a 75 gallon is probably excessive, especially on the 20.

Yes, there seems to be a lot going on. Gotta remember, I don't have a control. I only have variables. 300 and 400 may be too much but I had read that having a high watt heater that is meant for a bigger aquarium would mean it would run less and not be worked as hard. This has been my mentality with most equipment. It usually saves me money in the long run because equipment breaks less. I think this is somewhat proven since neither of the three heaters has stopped working. I thought the data available would be relative toward deciding if the controller was being overworked or simply was not as capable as advertised.

 

[badassissimo]

Hello; I have not had the newer style heaters apart as yet so this may not apply. I have taken apart the style of heater used for prior decades so this is my basis.
The heaters I have used have a thermostat made from a bi-metal strip with contact points. The bi-metal strip bends one way when cool and the other way when warm.
When cool the bi-metal strip moves the contact point toward another contact point in a fixed place. When the contact points touch a circuit is closed and the electricity flows thru the heating element.
After a time this heats up the heater's glass tube which in turn heats up the water. This heat also makes it's way to the bi-metal strip which moves the other way and breaks the contact. When the contact is broken the electricity stops flowing and the heater is turned off.

What happens over many repetitions of this on and off cycle is the contact points arc each time the cycle happens. During that brief arc a small amount of material is transferred from one contact point to the other. That material eventually builds up enough so that the contact points never break contact. This leaves the heater stuck in the on position.

For those old enough to recall contact points in an automobile distributor it is the same sort of thing and has the same solution. Get a small flat metal file called a points file. I take my heaters apart enough to expose the bi-metal strip and the two contact points. I use the points file to take off the build up from between the two contact points. I gently stick the points file between the two contacts and file the protrusion down until the surfaces are flat again.

I have done this for my heaters many times over decades. This is the more common problem when heaters are stuck on.

When heaters are stuck off it usually a break in the circuit somewhere. If it is the actual heating element then I have no fix as this is a high resistance wire usually coiled too tight to fix and get back into place.

The newer heaters may have some different sort of thermostat. I do not know yet as I bought one a year or so ago and it has not failed yet.

Good luck

I will see about this.... I am unsure how to take my submersible heaters apart but I think I could start with the older one as a ginea pig and give it a shot.

 

[philipraposo1982]

Larger heats do work less in smaller tanks but with greater risk. Faulty heater staying on could easily cause a tank to cook up the fish. Smaller heaters are not able to do this.

 

[badassissimo]

Did some more swapping and resetting. Controller definitely doesn't want to do. Heaters don't want to control. How do I take apart a heater?

 

[badassissimo]

Larger heats do work less in smaller tanks but with greater risk. Faulty heater staying on could easily cause a tank to cook up the fish. Smaller heaters are not able to do this.

News to me. I would have liked to know ahead of time but the feedback on different threads I've seen over the years seemed so opinionated. I guess I learned my own lesson.