Jan 25, 2016

Simple DIY Air Heat Exchanger You Can Make With Your 3D Printer

Air heat exchanger is a useful ventilation system part that will enable you to save energy while maintaining a good air flow in your enclosed space. It uses the outgoing air form the heated space to warm the cold air that is going from outside. Heat is thereby recovered and energy consumption for heating decreased.
They are mostly used in passive or low-energy houses or buildings, but they can be used in most insulated spaces. There are also applications where you can cool the air coming in.
The entire system is also called Heat Recovery Ventilation (HRV). You maintain air flow which improves indoor air quality, reduces bacteria and mold buildup, stabilizes the moisture but you don't need to open the windows and still keep some 70-80% of heat that would normally be wasted.

Yvo de Haas developed a small DIY 3d printable version that he implemented in his house with excellent results. The heat exchanger itself is printed in PLA while tubing is standard PVC with standard 60mm fans to drive the air. The electric fans can be noisy but they can be easily replaced with quieter ones.

He developed two versions of this DIY HRV: one that is partialy 3d printed and one that is fully 3d printed.

Here is what Yvo writes about the fully 3d printed unit tech specs:
The completely 3D printed version is, as the name suggests, completely 3D printed. To make it I modified my Ultimaker with an E3D V6 with 0.25mm nozzle.
The walls of the exchanger are 0.3mm thick. The outside dimensions of the exchanger are 15x8x7cm but it has an internal surface area of around 1000cm² (1/10th of a square meter or about a square foot). It is printed in PLA and takes around 10 hours to print at 0.16mm layer thickness.
With special adapters it can fit 60mm fans and all the other adapters I have designed special adapters were printed to connect the 60mm fans to the 3D printed exchanger.

Fully 3d printed heat exchanger element. Here is where the magic happens. 

Heat exchanger installed on the window with fan ventilators attached. 

Yvo measured and logged the temperature data:
The 4 temperatures (unit does not matter):
  • Hot in (the warmer air that enters the hot side of the exchanger)
  • Hot out (the warmer air that exits the cool side of the exchanger)
  • Cool in (the cooler air that enters the cool side of the exchanger)
  • Cool out (the cooler air that exits the hot side of the exchanger)
Does it work?
The answer, YES. After running for over 8 hours while I was at work, the air was a lot fresher. Usually when I come home there is a certain staleness to the air, but now I came home to nothing. Just nice air. I had the logger running for the entire time. The test started around 8 o'clock, every number on the X is 6 seconds. There are 3 zones of interest.
0-3000: Here the air outside is slowly heating up. Temperatures around this point are: HI: 17°C, HO: 10°C, CI: 6°C, CO: 14.5°C, giving 63.6% for the hot flow and 77.3% for the cool flow, averaging 70.5%.
3000-4000: Here the sun hits the window and there is a spike in temperature. No useful data can be gathered from this time.
4000-6000: The air outside is slowly cooling. Temperatures around this point are: HI: 17°C, HO: 12°C, CI: 8°C, CO: 15°C, giving 55.6% for the hot flow and 77.8% for the cool flow, averaging 66.7%.

Full construction tutorial with heat exchange data charts can be found at:


Project homepage and all the files needed to make this heat exchanger:


Learn more about energy recovery ventilation here:


If you want to build full size DIY heat exchanger from coroplast here is a full video tutorial by YT user "Designed By Instinct":

For a page dedicated to DIY solar, heating, cooling and ventilation solutions, plans and user experiences including HRV check out: