Acrylic Tanks

[Bullrock74]

I can see I am fighting a losing battle...why would ambient room temperature affect the water's temperature if the room is always cooler than that of the tank water? I don't think I'm buying especially cheapo heaters. I suspect perhaps I am paying more attention to my heater than others are.

 

[T1KARMANN]

I can see I am fighting a losing battle...why would ambient room temperature affect the water's temperature if the room is always cooler than that of the tank water? I don't think I'm buying especially cheapo heaters. I suspect perhaps I am paying more attention to my heater than others are.

well i can tell you 100% that heaters do have a themostat in them

they do click on and off when heating so they dont burn out the eliment once the water has reached the corect temp they will not click back on

most heaters will heat slightly over the pre set temp so if you want you tank temp at 79 then set the heater @ 77-78

did you not read the instructions that came with the hearter

 

[PaPeRo]

I can see I am fighting a losing battle...why would ambient room temperature affect the water's temperature if the room is always cooler than that of the tank water? I don't think I'm buying especially cheapo heaters. I suspect perhaps I am paying more attention to my heater than others are.

The reason why you see this temperature fluctuation from the fixed setting on your heater is due to ambient room temperature. When a room gets colder than the tank temperature your heater tries to bring the temperature up to where you set it. The heater is only rated to bring the temperature up by a few degrees for a specific volume of water even when the heater is constantly ON. So if your heater is underpowered it will never be able to maintain 78F if the room temperature is too low. It will always be lower than 78F even though that is where you've set it. In actuality you've set the thermostat higher than 78F but since your room is colder, your thermometer will read 78F. That's why in the summer you have to turn it down because it was actually set higher than 78F so to get 78F in the summer you'd have to set it to the actual temp of 78F. I hope that makes sense. Most modern high quality heaters have thermostats.

It works the same way as chillers which can only cool a specific volume of water a specifc number of degrees.

 

[andywg]

The reason why you see this temperature fluctuation from the fixed setting on your heater is due to ambient room temperature. When a room gets colder than the tank temperature your heater tries to bring the temperature up to where you set it. The heater is only rated to bring the temperature up by a few degrees for a specific volume of water even when the heater is constantly ON. So if your heater is underpowered it will never be able to maintain 78F if the room temperature is too low. It will always be lower than 78F even though that is where you've set it. In actuality you've set the thermostat higher than 78F but since your room is colder, your thermometer will read 78F. That's why in the summer you have to turn it down because it was actually set higher than 78F so to get 78F in the summer you'd have to set it to the actual temp of 78F. I hope that makes sense. Most modern high quality heaters have thermostats.

It works the same way as chillers which can only cool a specific volume of water a specifc number of degrees.

Exactly right, and well put.

 

[Bullrock74]

See below.

 

[Bullrock74]

In actuality you've set the thermostat higher than 78F but since your room is colder, your thermometer will read 78F.

I bought four 300 watt heaters for my 350 gallon tank, but only installed two of them at first to see what would happen and with one at its lowest setting and the other set at 78F, they maintained 86 degrees Fahrenheit. This was during the summer with the room temperature at 75F, and the water used to fill the aquarium was 82F. Both heaters still came on (why?) and then went off 15 seconds or so later. That is what cemented the idea in my mind that they actually work on timers and not thermostats. So, I unplugged the heater set at the lowest setting.

When the heater was the only one enabled in the tank, it was set at 78F, but failed to maintain the desired water temperature. If it had a functioning thermostat, it should have been on constantly. But, it would come on and go off about 15-20 seconds later just as if it was on a timer.

Every heater I've ever had has come on when it shouldn't and has gone off when it shouldn't. The good news is I am able to maintain a relatively constant temperature even though I do have to adjust the temperature setting.

 

[PaPeRo]

one at its lowest setting and the other set at 78F, they maintained 86 degrees Fahrenheit.

Huh? Sounds like crappy heaters if you ask me. My heaters NEVER go higher than what they're set at. When I do water changes the heater turns on because of the cold water and when it reaches the preset temp it turns off never does it go higher.

Both heaters still came on (why?) and then went off 15 seconds or so later.

If it comes on for only 15 seconds then it's obviously doing some sort of self calibration/resetting. If it comes on and stays on for a long time then that's when you have a malfunction or a crappy heater.

What brand/model heater are you using?

What I've noticed on my heater when the water is colder than the set temperature is that sometimes during the heating phase it stops for a minute then restarts again. This tells me that it's doing this to retake temperature readings from the water since you cannot accurately take temp readings from inside the heater if the heating element is hot. In other words it needs to let the heating element cool down before the thermostat can stabalize to get an accurate water temp reading.

Even the cheap heaters from over a decade ago have thermostats. Back then you would turn the dial a little bit at a time until you reach the desired temp then you would back the dail a bit until the light turned off.

 

[OohFeeshy]

I think most people are missing the point that it doesn't really matter. A few degrees either way isn't going to do any damage, temperature isn't overly constant in the wild.