How frequently does your heater cycle on/off?

Reefs and Geeks · Feb 8, 2021

I recently upgraded my heater situation for my 380 gallon total system to a 600w BRS titanium heater. I decided to upgrade after noticing ythat one of my multiple 300w heaters was drawing either 150w or 300w of power vs a consistant 300w, and would frequently kick itself on and off due to it's internal thermostat even if the tank was cold, so it was not very efficient at warming up the tank when the weather got cold.

Now with my 600w heater I'm noticing that the tank heats up quite fast, at least for what I'm used to. I originally had my apex controlling the temp between 77.5 and 78F, and noticed it kicked the heater on/off about 9 times a day. It seemed like alot, so I changed it to control between 77 and 78 and now it kicks on/off 4 times a day.

How frequently does your heater kick on daily? does frequent on/off cycles lessen the life of the heater? I have an inkbird I plan to use for some redundancy with the heater and to reduce the switching on my EB832 soon, so am considering going to a tighter band of temperatures, but don't want to do so if it's going to cause pre mature wear on the heating element itself.

My system is a 150g display, with a 125g basement sump, an 80g basement frag tank, and a 30g basement frag tank all tied together. I went with the 600w due to my total tank size and the face that so much of my system is in a fairly cool basement. It does seem the rest of my equipment does a fair job of helping maintain tank temp, including a couple of smaller backup heaters I have in the system to help buy some time in case my main heater dies on me.

driftin · Feb 8, 2021

Interesting question, short cycling. Depending on how cold the living room is, my heater seems to raise my tank 1/2 degree in anywhere between 10 and 20 minutes. Usually closer to 10.

Philly Reefer · Feb 8, 2021

My tank is not as big as yours.(40B+20L). But temp does go up and down.

This is just the last 24h

My temp controller(bayite) is on 0.5 F swing. The eb832 outlet for the temp controller is always on for me unless it goes higher to 82F

78F On
78.5F Off

Potatohead · Feb 8, 2021

Nine times a day isn't that much.

I would guess most people's heaters cycle at least once an hour, and I would probably say twice an hour is not out of the question. It really depends on a lot of factors, mainly the relationship between the water temperature and the room temperature and if other equipment in the system is adding heat to the water. When the lights are on the heaters will be on less, etc.

A higher wattage heater shouldn't really turn on less often, it will just heat the water faster.

ca1ore · Feb 8, 2021

Agreed, 9x per day is not short cycling. A higher wattage heater will be ON for less time but OFF for the same amount of time. My system is set to a range of 0.5 degree F and the heaters cycle twice per hour.

Rubberfrog · Feb 8, 2021

ca1ore said:
Agreed, 9x per day is not short cycling. A higher wattage heater will be ON for less time but OFF for the same amount of time. My system is set to a range of 0.5 degree F and the heaters cycle twice per hour.

Exactly this. The tank cools down just as fast, regardless of how fast your heater brings it back to temp.

saltwaterjunkie12 · Feb 8, 2021

My apex turns my heater on and off about 15-18x per day depending on the temperature. I am running a 800watt titanium heater on my 500 gallon and haven't had any issues. I do however have an alert set on my apex, and keep a backup heater just in case as this has crossed my mind as well.

Pistondog · Feb 10, 2021

Reefs and Geeks said:
I recently upgraded my heater situation for my 380 gallon total system to a 600w BRS titanium heater. I decided to upgrade after noticing ythat one of my multiple 300w heaters was drawing either 150w or 300w of power vs a consistant 300w, and would frequently kick itself on and off due to it's internal thermostat even if the tank was cold, so it was not very efficient at warming up the tank when the weather got cold.

Now with my 600w heater I'm noticing that the tank heats up quite fast, at least for what I'm used to. I originally had my apex controlling the temp between 77.5 and 78F, and noticed it kicked the heater on/off about 9 times a day. It seemed like alot, so I changed it to control between 77 and 78 and now it kicks on/off 4 times a day.

How frequently does your heater kick on daily? does frequent on/off cycles lessen the life of the heater? I have an inkbird I plan to use for some redundancy with the heater and to reduce the switching on my EB832 soon, so am considering going to a tighter band of temperatures, but don't want to do so if it's going to cause pre mature wear on the heating element itself.

My system is a 150g display, with a 125g basement sump, an 80g basement frag tank, and a 30g basement frag tank all tied together. I went with the 600w due to my total tank size and the face that so much of my system is in a fairly cool basement. It does seem the rest of my equipment does a fair job of helping maintain tank temp, including a couple of smaller backup heaters I have in the system to help buy some time in case my main heater dies on me.

I bought one of these to minimize temperature sawtoothing between 2 points.
Amazon product
It cycles the heater off and on, in a time proportion of 10 seconds.
It is a PI controller that adjusts the percent of time the heater is on.
For example it might be on for 6 seconds then off for the next 4 seconds, on for 6 off etc. The control tries to maintain the set temp, rather than waiting for temp thresholds to cycle.
This is commonly used in industrial applications, the switches and heaters are designed for the switching frequency.

Rubberfrog · Feb 10, 2021

Pistondog said:
I bought one of these to minimize temperature sawtoothing between 2 points.
Amazon product
It cycles the heater off and on, in a time proportion of 10 seconds.
It is a PI controller that adjusts the percent of time the heater is on.
For example it might be on for 6 seconds then off for the next 4 seconds, on for 6 off etc. The control tries to maintain the set temp, rather than waiting for temp thresholds to cycle.
This is commonly used in industrial applications, the switches and heaters are designed for the switching frequency.

Sounds like it will fry the heater quick