Furnace Comparison: Atmospheric Draft, Induced Draft, and Sealed Combustion (and Barometric Dampers)

There are 3 main types of furnaces, and the difference is in the venting system to exhaust the combustion gases. Here's a quick guide to how to identify one type of furnace from another, and what they do and don't do.

Natural, or Atmospheric, or Ambient Draft furnaces allow the gases to rise out the chimney powered by their own buoyancy.

Induced Draft furnaces don’t let as much heat escape in the combustion gases (83% efficient and up), and so require a small fan to ‘induce’ the gases to get started.

Sealed Combustion furnaces pull all their combustion air from outdoors, and push all the combustion gases outside with a powerful fan. The gases here are only 100-140 degrees F.

How Air Pressure Can Screw Up Your Home: the House of Pressure

Take a tour of the dynamics of home pressure with Jake Nuckolls at the Building Performance Center in Bellingham, WA. This training tool has made the invisible visible for thousands of home performance professionals, and we thought everybody else should get to see it in action too!

Thanks to Jake and the BPC- check them out at: https://buildingperformancecenter.org/

Become a member and help support our work exploring the science of homes: https://Patreon.com/HomeDiagnosisTV

Watch the first ever TV series about the science of homes: https://HomeDiagnosis.tv

Why Bleach and Sanitizer is NOT the Answer: the Human Microbiome in 1 Minute

If you only take 60 seconds of microbiology training, this should be it. Thanks to the amazing experts Marina Vance (https://www.colorado.edu/lab/vance/marina-vance) and Rob Dunn (https://robdunnlab.com), and James Weiss for the stellar microphotography (https://www.youtube.com/c/JamsGerms/featured).

See the whole 'Home Diagnosis' series at: https://HomeDiagnosis.tv

Become a member and help us go deeper exploring the science of homes: https://Patreon.com/HomeDiagnosisTV

Cleaning in America: Science and Side Effects of Vacuums and Spray Cleaners

"Cleaning" in 21st century America involves a lot of mechanics, chemistry, and microbiology- and our complex cleaning protocols have many side effects that you might not have considered before. Here's a quick demonstration of what cleaning means for your home's invisible dynamics and the health of your family.

Watch the full episode at: https://homediagnosis.tv/episode-210-headaches-of-homechem

Become a member and help us keep exploring the science of homes: https://Patreon.com/HomeDiagnosisTV

Building an Affordable Airtight Home: Sheathing Sealed (Will It Work?)

We got called in to test this before/after on one of Matt Hoots’ projects at Sawhorse in Atlanta (https://sawhorse.net/). It was an interesting blower door test series with some surprising results. Also featuring Tommy Sharp, co-inventor of ThermaCote (https://thermacote.com/). More details on Matt’s channel: https://youtube.com/c/SawHorseDesignBuild Join and help generate more education around the science of homes: https://Patreon.com/HomeDiagnosisTV

Filter Your Home’s Air: MERV 11 vs. 13 vs. 16 vs. HEPA vs. Carbon (Particles, Chemicals, & Microbes)

It can be hard to believe in things you can’t see, and everything in chemistry and microbiology is too small to see. Here’s a human-scale demonstration of the orders of magnitude of size in the world of the tiny. From episode 210 of ‘Home Diagnosis’.

To see the whole episode: https://homediagnosis.tv/episode-210-headaches-of-homechem

How to Make Enemies & Improve Gas Mileage Simply and Stressfully: HYPERMILING

Do you like games? Do you like making people angry? Welcome to Hypermiling, the most unpopular driving technique ever invented. You will get amazingly improved miles per gallon, but you might get punched too. You never know. That's what makes the game so fun.

Fire Resistant Homes: Testing Vulcan, Silica, and Baffled Intumescent Vents

We found these vents at the International Builders' Show, and were excited to test their performance (partly so that Grace could use her flamethrower). We test the three main types of fire-resistant venting for homes: an intumescent honeycomb vent, a silica vent, and an intumescent baffled vent.

Airflow testing was performed with an airtight box made of plywood and acrylic, using a DU300 fan and DM-32 and DG-8 digital pressure gauges. For the fire, we used a propane weed torch you can get at any hardware store. The chart of our airflow testing shows the square inches of opening inside the metal frames, the airflows, and the pressure drops of all three vents.

For the 'Net Free Vent Area' (NFVA), visit the manufacturers' websites. Brand names of these three vents are Vulcan Vents, Embers Out, and Brandguard. For more on the vents that performed best: https://VulcanVents.com

Watch the first-ever TV series about the science of homes: https://HomeDiagnosis.tv

Static Pressure Testing for Home HVAC: What, Why, and How in 2 Minutes

If the ductwork of an HVAC system is not designed, installed, and maintained properly, your home may start to have problems in comfort, humidity control, dust, noise, and equipment failure. Here's the basics you should understand before asking your HVAC installer or service tech to run static pressure testing. From 'Home Diagnosis' episode 209- watch the whole episode: https://homediagnosis.tv/episode-209-opening-the-ice-box-cooling-and-drying

Join our Patreon membership and get behind the scenes with us making the next season of the show! https://Patreon.com/HomeDiagnosisTV

Tools used are Retrotec DM-32 gauge and Minneapolis 300 blower door, available at: https://TruTechTools.com

Duct Leakage Test: Pass or Fail?

When you build a duct system, if you want it to work correctly you run a tightness test. See how Corbett did on his home’s first of 5 duct systems for different purposes. Using a Retrotec Duc Tester 300 with DM-32 manometer, available at: https://trutechtools.com

Watch the whole episode, and the whole season: https://HomeDiagnosis.tv

Elegant HVAC Duct Design: the Rooms are Ducts, Too

Ductwork is more than just supplies and returns- the entire home enclosure is actually part of the ductwork. Here’s a quick demonstration of how to use room arrangements to direct airflow. From Season 2 episode 9 of 'Home Diagnosis' on PBS.

Watch all the episodes for free right now: https://HomeDiagnosis.tv

Become a member and help make this show! https://Patreon.com/HomeDiagnosisTV

Best Place to Put a Bath Exhaust Fan

From 'Home Diagnosis' Season 2 Episode 9- most bathrooms are not designed for performance, let's admit it. If your mirror gets fogged up, if it takes 30 minutes to exhaust all the steam, if your ceiling drips or your walls have streaks on them, you can do better. Most of this, insanely, has to do with WHERE the bath exhaust fan is located. Here's your quick crash course to help you school all the builders, remodelers, and mechanical engineers in the world.

See the whole episode at: https://homediagnosis.tv/episode-209-opening-the-ice-box-cooling-and-drying