Teco Chiller

[Bent17]

Hi all,

Can someone please point me in the right direction here...

I am trying to configure my Teco 500 chiller so that I have a constant temp of 25c.. The chiller is going on every 2 minutes which I dont think should happen.. My heater is calibrated to go on at 24.8.

Can someone who has the same setup let me know the values I have to input in the chiller as there are around 4 different values I need to enter

 

[kingmushroom]

You should configure the central temperature and something called hysteresis. This is a margin that control systems in general use to avoid turning on in the wrong time. You can check the idea of what hysteresis is in wikipedia, but I will try to make it short.

I have a TK500 running for more than a year in a aquarium exposed to the morning sun (sunrise until 10:00AM), and will use it as an example of how you can configure your chiller.

In my setup, I had the chiller configured to chase the temperature 26.5C, with 1C hysteresis (factory default), and do not use the internal heater for more than one year.

I configured one of my external heaters to turn on at 25.5 (more or less) and the second to turn on at 25C (installed it a little later). Analog type, those glassy sticks with a resistance and a turn knob with a bimetal inside.

In this way, my aquarium temperature can fluctuate from 25.5C to 27.5C and nothing will turn on.

In the morning, usually the temperature is low, and keeps close to 25.5C thanks to the heaters.
When the sun shines directly in the aquarium, it start to heat slowly until the chiller start at 27.5C and turn off at 26.5C.

This cycle continues until the sun stop shinning, chiller start, chiler stop, water heat slowly with the sun/light/pumps.

This goes on until the sun set and the temperature starts to drop, and the only heat source is the pump and wave maker. Then it cools until reach 25.5C (not exactly because is a analog bimetal independent from the chiller) and the first heater turn on. In the coldest nights the second heater should turn on I hope.

Then the heating period starts, heating start when is too cold, heats to a little higher temperature that when started and stop. This is the heater hysteresis that I can't configure because is a mechanical bimetal, but works fine.

Yesterday I suspected that the external heaters are not configured right or are not working fine and I will take them out, clean with vinegar and test outside the aquarium.

So I turner them out and configured the TK500 to heat and cool.

Now with 1C hysteresis and central temperature of 26.5C, the chiller turn on when the water is hotter than 27.5C and the chiller heater turn on when the water is colder than 25.5C. The temperature stays always between 25.5C and 27.5C and everybody inside seems happy.

1C above/below the target temperature is a good difference in heat (water takes a lot of energy to change temperature) and reduces the number of cycles that the compressor turn on/off (it wears by the time spent on but also the number of times it turn on)

So don't try to keep a exact temperature, there is no point in doing so. Choose a range, and configure your chiller to turn on above it and the heater to turn on below it.

If you have corals from the pacific, something like 28C MAX and 25C MIN should be good right? Then you take the middle point, set is as desired temperature, and set 26.5C as desired and 1.5C as hysteresis.

Now you try to set your heater to turn ON when the chiller temperature reach 25C and it will be very hard to have both turning on. Hopefully, even if the heater starts to drift but you can keep an eye on them.

If you have an external controller, you can calibrate the chiller to follow you external controller or both to a reference thermometer buy it is hard to need it.

I could increase my hysteresis to 1.5C but the heaters turn in the night of the colder days, and the chiller every day that the sun shines without clouds or the rare days above 30C. The chiller starts, works 10 minutes and stop for almost an hour.

In short, make sure that you heater is turning on at 25C and check the temperature it turns off.
It should have a margin to the temperature that your chiller turn on (at least 1C), otherwise your heater will turn on and stay ON, your chiller will turn ON, they will fight, and your electric bill will go UP. Then the heater will go OFF before your chiller. You may have to replace them a little sooner too.

This can happen later on when the heater gets old specially if it is mechanical.

Make sure that your chiller starts and keep running for a while, stop for a good time. Long cycles mean less wear. For the heater this is not so relevant because a motor suffers to turn on, for a resistance this don't matter that much.

I told I tried to keep it short, I'm sorry for not keeping my word.
Hysteresis is your friend, use it.