The Budget

This is a rough break down of materials costs

NZ$28 1 X 60 litre Sistema box

NZ$30 3 X 7500CPM main fans

NZ$20 4 X 6500RPM booster fans

NZ$3.50 4 X Fan speed controllers

NZ$30 1 X 30 Amp PSU

NZ$104 5 X diffusers with 3M of duct and Y junction

NZ$21 4 X 150mm 3M ducts

NZ$14 2 X 150mm 1M ducts

NZ$1.00 12 X 150mm PVC flower pots

NZ$15 6 X 6mm Corroplast sheet 900 X 1200

NZ$ 50 Arduinos and breakouts for project

NZ$!00 Wire plugs sockets misc electrical

NZ$60 New tools

NZ$150 Tape screws wood sundry hardware Hot glue sticks

NZ$30 2 X Sitema filer boxes

NZ$12 2 X Foam exercise mats

NZ$30 PC Servos

NZ$100 Experiments breakages re-work

Total NZ$1,510

The Heat Exchanger

Under construction It took around 6 hours to layer the core Based on a 60 Litre Sistema box with a 400 X 400 X 350 6 mm Coroplast core. The fan speed controller is mounted on the end so it takes a 12V 10 Amp supply from the power system and 2 analogue 0 to 5 V signals for speed demand. The pink foam is a NZ$12 exercise matt which insulates it for both sound and heat quite nicely. 60 Litre Plenum on the vent side See https://greenwayerv.blogspot.com/2020/10/we-added-60-litre-plenum-on-vent-side.html

Home Ventilation Heat Exchanger

The Experiment

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.

Heat Exchanger Low Ambient 86% Heat Recovery

Drop on exiting air 2.9C Heating of incoming air 2.5C So 86% of the heat recovered

The ERV Data Acquisition System

Progress over the weekend with the ERV DAS The 999's are me testing the sensor disconnected response. I have a Pitot tube left over from an RC plane I think I might put it in the inlet air stream Pin assignment in the Arduino sketch DHT dht[ 4 ] = {DHT( 4 , DHTTYPE),DHT( 0 , DHTTYPE),DHT( 2 , DHTTYPE),DHT( 14 , DHTTYPE)}; There are 4 DHT22's inside heat exchanger lid, shown below. Sensor locations Arduino code #include < Arduino_JSON . h > #include < ESP8266WiFi . h > #include < MQTT . h > #define LED_PIN LED_BUILTIN //LED_BUILTIN is built in LED #include "DHT.h" // Uncomment whatever type you're using! #define DHTTYPE DHT11 // DHT 11 //#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321 //#define DHTTYPE DHT21 // DHT 21 (AM2301) WiFiClient net ; MQTTClient MQTTclient ; const char ssid [ ] = "Network" ; const char pass [ ] = "DF@#$%" ; // the IP address for the MQTT server char MQTTip [ ...

Drivers and Arduino Sketches for ERV Fans Control Testing

The Hookup For proof of concept seems to run reliably in the lab. I don't want to be up and down ladders to make update I intend keeping the control system in Hubitat so I can tinker to my Hearts content. Boost fan PWM control as well as start relays. The valve position is a separate driver and device in Hubitat, This will use one of the PWM Four boost fans in the ducts for each room inlet. One fan in the two way turbo exhaust valve. The valve position is a separate driver and device in Hubitat, This will use one of the PWM pins on the Wemos and its analogue input for the position pot Hubitat Valve Position Driver import groovy.json.JsonSlurper metadata { definition(name: "Greenway ERV Turbo Valve", namespace: "Greenway", author: "Nick Goodey") { capability "Initialize" capability "Switch" capability "Switch Level" command "on" command "off" } preferences { section("Device...

Greenway

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