Greenway

  This is a 2 port flap valve allowing proportional control of the exhaust stale air extraction side of the system. We have chose two exhaust locations Bathroom and a new vent in the living room. This design allows us to have two climate zones one for the living room and one for the bedrooms and the rest of the house. Its designated Turbo because it has 60 Watt fan embedded in it to boost the air flow to help match the input flow from the inlet and booster fans.

  After a few experiments I decided I wanted the following options for the input air source. 1) Fresh air from roof top. Function as a vanilla balanced ERV ventilation system, all exhaust air passes through the heat exchanger, all incoming air is warmed by the heat exchanger. 2) Loft air, typically warmer if the Sun is out even on a cold day. Reduce need for heating during the day. 3) Fresh Air bypassing the heat exchanger to reduce the need fore running the heat pump on sunny days when the air temperature is still quite low. 4) Block all four ports to prevent air moving from convection or an open window raising or reducing air pressure in the room. So the four port valve was born. ts got a dual drive now which works really well. The wooden gear was inspired by the Marble Machine i have toughened the teeth with Epoxy now which make it quite substantial.

 Looking at the specifications of propitiatory systems it seems that the fans are nothing special. They typically use Axial flow fans with AC voltage motors around 60 Watts seems suitable for our house. In order to allow me to do this without an electrical certificate my system is entirely 12 volt.  The fans I have are pretty quiet to so it seems like win win to me less that US$30 each for the 60 W devices and US$16 for the boost fans. Computer fans are a good low cost option. Quiet long lived and they have built in speed controllers too. I am using two fan types in the system. I bought them cheapef than this Specifications : -- Size: approx. 120*120*38 mm -- Voltage: 12(V) -- Blast Capacity: 280.38CFM -- Current: 5.0A -- Rotate Speed: 7500CPM(r/min) -- Noise Level: 64DBA -- Wind Pressure: 24.60 mmH2O -- Bearing: High precision double ball bearing -- Operating Temperature: -10℃ ~ + 70℃ -- Storage Temperature: -40℃~+70℃ -- Power range: Plus or minus 15% of rated power supply -- Insulati

 So I decided to use 6 mm Coroplast and build a 4 X 40 X 35 cm Core basically because it would fit in a 60 litre plastic box I bought for the ERV enclosure. Found this design in an old popular mechanics article from 1984 Took about 6 hours to complete the core The enclosure with 4 ports mounted

First things first an experiment. I had been looking around at various homemade ERV core designs and eventually decided to try a Coroplast design. The experimental core was tiny 12 X 12 X 12 cm  using 3 mm Coroplast Nice isn't it :) 20 80 mm PC cooling fans at a fixed speed four temperature probes. Here is the full scale one around 40 X 40 X 35 cm using 6 mm Coroplast A Wemos D1/R2 for instrumentation sending temperatures via MQTT to Node-Red. I'm was not totally convinced by the numbers but it did definitely exchange significant amounts of heat. I checked the calibration and it was good compared to my multi-meter TC probe. In any case it seems to work even at such a small scale. Never did understand why it seems to gain more heat that it lost from the exhaust steam, checked for leaks there were none. Any way  a hairdryer experiment showed it worked and heat was transferred too so I was happy that it would probably work at a larger scale.