Temperature and humidity control for an incubator using Reef-Pi

Litserv

Community Member
Review score
+0 /0 /-0
View Badges
Joined
May 3, 2020
Messages
26
Reaction score
26
Review score
+0 /0 /-0
I have an incubator that I use to incubate Testudo Hermanni eggs. For this I use a RPI with Reef-Pi.

While the temperature control works great for my aquarium, I have major problems with the incubator:
The temperature in the aquarium runs within the set hysteresis around the set point.
But the temperature in the incubator shows a fluctuation range of 2 - 3 degrees Celsius, although I have set 0.1 degrees Celsius as hysteresis.
A DS18B20 serves as temperature sensor.

I assume that the 'inertial mass' - air instead of water - is much too low and that is why the overshoots occur.

Therefore, I imagine a proportional control instead of a 2-point control for the temperature as a solution: The heating power adapts to the difference between the set temperature and the actual temperature. This can be done very well via PWM.

In Reef-Pi, a PWM connection should also be selectable under temperature control. Two parameters would be useful: offset and slope.

Can this be implemented in Reef-Pi?
Or is there another solution or a work-around?

I am grateful for any suggestion for a solution.
 

Sral

Active Member
Review score
+0 /0 /-0
View Badges
Joined
May 2, 2022
Messages
230
Reaction score
260
Review score
+0 /0 /-0
Location
Germany
I think your analysis is correct: the thermal capacity of your air is much lower and the heater is therefore too powerful and/or has too much thermal capacity (so it heats far after it has been turned off).

Another possibility is that your sensor isn’t coupled well. If it’s designed for water, which has higher thermal conductivity if I’m not mistaken, it might heat up much slower than the air around it, switching off your heater much later. You could either try to remove the sensor’s shielding or improve its coupling with a kind of heatsink with fins and/or put it into the airflow of a fan.
 
Upvote 0

Ranjib

7500 Club Member
Review score
+0 /0 /-0
View Badges
Joined
Apr 16, 2016
Messages
9,542
Reaction score
16,531
Review score
+0 /0 /-0
Location
Pleasant Hill, Concord
This will require some development work (coding) but I am happy to incorporate such feature if its of common use. I had thought of this (variable control based on analog input, instead of just digital on/off) while building the control logic, but i could not find any such output equipment (e.g. heater or ato) where it will be useful. Do you have any heater in mind that can take pwm input?
 
Upvote 0
OP
L

Litserv

Community Member
Review score
+0 /0 /-0
View Badges
Joined
May 3, 2020
Messages
26
Reaction score
26
Review score
+0 /0 /-0
analysis is correct
Thanks!

a kind of heatsink with fins and/or put it into the airflow of a fan
Good idea: "... heatsink with fins..." I'll try it, because a fan is not enough.

Do you have any heater in mind that can take pwm input?
Yes, using a module between Reef-Pi (PWM) and any Heater:
Unfortunately this module will not be sold resp. shipped to Germany. I found similar modules, but out of stock for now.

Next solution: DIY with MOSFET: https://www.instructables.com/AC-PWM-Dimmer-for-Arduino/

This is what I go for. I don't recommend it everybody, but I'm familiar with AC 230V.
 
Upvote 0

Sral

Active Member
Review score
+0 /0 /-0
View Badges
Joined
May 2, 2022
Messages
230
Reaction score
260
Review score
+0 /0 /-0
Location
Germany
I found others, available in Germany; e.g.:
I ordered 3 and will test the functionality over the weekend and report.
Nice ! I might actually use that too ramp up my flow pump, or dimm it, if it is too strong.

When you have set them up, can you write whether that circuit will still output AC or if it reduces it to pulsed DC ? Not sure if the latter works with typical Aquarium pumps.
 
Upvote 0

What are all the ways you "filter" your reef aquarium?

  • Chemical Filter Media

    Votes: 184 46.9%
  • Skimmer

    Votes: 323 82.4%
  • Natural Methods (rock, sand etc)

    Votes: 338 86.2%
  • Algae Scrubber/Reactor

    Votes: 52 13.3%
  • Rollermats

    Votes: 64 16.3%
  • Filter Socks/Pads

    Votes: 216 55.1%
  • UV Sterilizer

    Votes: 119 30.4%
  • HOB or Canister

    Votes: 56 14.3%
  • Ozone Generator

    Votes: 15 3.8%
  • Coral

    Votes: 200 51.0%
  • Other (please explain)

    Votes: 7 1.8%
  • Refugium

    Votes: 152 38.8%
  • Water Changes

    Votes: 276 70.4%
AquaCave Logo Banner
Top