1) The first DIY PPS that I built used a small duct fan drawing air from outside and pushing it through a hepa filter to the inside. It is important to use duct fans as you need to create air pressure more than air flow and box fans are not built to create the amount of pressure required.
2) Ideally you get a PPS system with a heat recovery unit. Also important is to have the PPS demand controlled based on an indoor air quality monitor that measures PM and CO2 and then only pushing in the right amount of air to meet your target values for PM and CO2. This way you can save a lot of energy costs and temperature differentials.
3) Thanks for asking ;) We maintain popular open source air quality monitor kits that are very easy to assemble and use industry grade sensors [1]
2) Ideally you get a PPS system with a heat recovery unit. Also important is to have the PPS demand controlled based on an indoor air quality monitor that measures PM and CO2 and then only pushing in the right amount of air to meet your target values for PM and CO2. This way you can save a lot of energy costs and temperature differentials.
3) Thanks for asking ;) We maintain popular open source air quality monitor kits that are very easy to assemble and use industry grade sensors [1]
[1] https://www.airgradient.com/open-airgradient/kits/