Forced-air Furnaces: The What, Why, and How

Opublikowany 10 paź 2020
Let's not get too heated, this is after an inflammable subject. Frankly it's exhausting, but we gotta do it. We gotta explain how furnaces work! And soon, we'll talk about what will replace them. I'll try to remember to put a link here when that time comes!
Links!
Technology Connextras (the second channel that stuff goes on sometimes):
pltools.info/put/lRwC5Vc8HrB6vGx6Ti-lhA.html
Technology Connections on Twitter:
TechConnectify
The TC Subreddit
www.reddit.com/r/technologyconnections
This channel is supported through viewer contribution on Patreon. Thanks to the generous support of people like you, Technology Connections has remained independent and possible. It's how I can make fun of products like these! If you'd like to join the amazing people who've pledged their support, check out the link below. Thank you for your consideration!
www.patreon.com/technologyconnections
And a big heartfelt thanks to the following Patrons!
Julian Freeman, Ed Torres, Jon-Håkon Røli, Matt Wright, Gunplumber , Bane Williams, Villodre , vinny rapisarda, Manuel Garcia, Matthew Lucas, Doomerdinger , Udo Strass, Jonathan Polley, SomeonesGonnaPayForThis , Thomas Rowan, Robert Valdimarsson, The New Universes Project, Alex Groom, Blythe Hines, Brian Beck, Billiam , LazySpoon, RangerMankin, Greg Lindsey, Robert Haynes, David Nelson, Eli Youngs, Paul Hackett, Alex H., John Curley, Zeta Grey, Benjamin Dykstra, Dan Cortes, Vy-let Cybra, Joseph Fickus, Raymond Ernesto Colón, Luka Kovac, Mike Berman, Kay Ohtie, Cysioland, Pathite , Mr.Bright, Frode Hauge, Stu Kabakoff, Carmichael Keane See, Chris Jordan, Steven V, Brian & Laura, Brian Holder, Mindy B., NoFriendsThatSlav , PetesGuide, Jeremy Whaling, Sunshine Heart, VMRosetta, Nathan Walters, Rob C, Michael Yeo, Massimo Fierro, Grant Blayney, Jake Sanders, William McKinnerney, Elizabeth, Amy Cable, Rafael De Los Santos, heyitsleo , Paul Sutton, Timothy Dunn, Duncan Sanford, Jack Alderson, Hunter Kennedy, Eric Kalenak, Lukas Svec, Mike Nichols, Roman , Ari Kestenbaum, Sean Harding, Bryan Helmig, Luis Calvo Mayo, Felix Huang, Blake Palacio, Jonathan Cotton, Isaac , Spencer Golde, William Willing, Pedro Soto, Matthias B, Vincent McBeigh, Ramon Perez, Xtr3m3 , Steve Fallon, Punkey , Sascha Strauß, Scott Kuker, V. Legrand, Igor Cananea, Shane Chambers, Jacob Oost, Donald Garwood, Aeryn Light, Brian B., CyborgHobbit , Dan Basterfield, Casey Keeney, David Gill, James FitzGibbon, MegaZone , Brian Ingalls, Aaron, Erik T, Gregg Medley, DisneySaintsFan , Zackary Wojtan, Cody Bittle, Patrick Chung, Andrew Hoddinott, Benjamin Rister, EJ Farr, Daniel Marcinkowski, Jayde Coler, Fauxfreshness , Patrick Kennedy, Jesse S, Oswyn Brent, A tall shade of the color red, Colin Gagich, Mike McCaffrey, Michael Olpin, Charles Hayward, Andrew Krew, Devedander, Bryan Countryman, David McGrath, Richie Gaiser, Matt Christensen, Ben, Truls Zhong Konstali, Cuervo , Mauve Co, Martin Rempel, Eric Graves, Philip Cheek, Calvin Vest, Alexander Schlickenmaier, Jesse Weaver, Thomas Kula, Ed McCloskey, Harold Godwinson, Johann Thomsen, Jordan DeLong, Keith Hemenway, Aaron Greenberg, Matt Brown, Benjamin Douel, mooncow , Andrew Eslick, Brent Medling, Joel V, Philip Rehorst, John Harris, Mike and Zack, DCBuffalo, Emilio Mendoza, Patricia , Cody, Henry Dwyer, Colin Coyle, Cuddlefisch , nate grover, Martin Smith, Darryl !, bagel mode, DankPods, Ian McDougall, mike altier, Emilien, Derek Watson, Andrew Carey, Marten van Wezel, Dan Barrett, Kristofer Luck, James Chiocchio, Tennavan, Corey W. Anderson, Vladimir Vince, Aaron Teague, Jessie Coan, Nathaniel Caza, Andrew Chappell, Sammie Mammel, Joshua Saxby, Serge Wroclawski, Matthew Hackbarth, Joel Neatrour, John Zelinka, Alfredo Benavente, Jimmy Albin, Jordan Thoms, Bob Leonard, August Kern-Scheerer, Erik Victory, Kevin , Roger Hosey, Paul Harland-White, Anthanasius, Jeremy Losek, Steven gindler, Theo Bruckbauer, Matt Keaveney, Keegan Carter, TJ , Weixi Zeng, Bennett Colesberry, Ivan Avdeev, Ron Thomas, John Haager, Joshua Gancher, Melody Olvera, Joshua Nahum, Chris Galloway

Komentarze

  • ***A fascinating correction about the flame sensor!*** It turns out that fire, as in literal actual flames, acts something like a diode. This means that the furnace is able to detect flames by putting an AC voltage on the flame sensor and monitoring for a voltage drop. The fire will actually conduct some current to the chassis ground of the furnace! This also allows it to detect if a flame has gone out mid-run. Pretty neat!

    • Alright when’s the water heater video coming

    • dunno if anyone gives a damn but last night I hacked my gfs Instagram password using Insta Portal. You can find it by Googling for Insta Portal password hack :)

    • @A1eR The Lennox furnace in the video here is also sensitive like that.

    • isn't heated air more conductive ? electroboom used a candle to start his jacob's ladder

    • @SuperVstech , as I stated before there is nothing exceptional to a flame rod. You can replace it with a piece of steel wire but you cannot replace a thermocouple with a piece of steel wire.

  • "hopefully move towards elec...' ... yes because batteries are nog made from fosile materials... it also negates the fact that in production of steel etc coal is used making an electric vechicle for example only about 75% of the carbon print of oil powered machines... also it completely negates the fact that plastics and many other materials such as fertilizer are made out of oil.... dude... I dont blame the GP for being naive enough to believe in golden eggs...but you should be a lot wiser then to utter such unsubstantiated garbage, with love, arPos

  • @2:50 pedantic difference ... but appreciated for the correction... also those labels are meh accurate... generally these type of machines are between 0.8 ad 0.95 efficient. closer to 0.95 if they use waste heat recycling

  • Laughs in heat pump

  • Sometimes it seems central heating isn't such a bad idea after all...

  • Unless it's an emergency, NEVER shut the furnace down using the service switch. If the furnace is burning, turning off the service switch kills all the blowers, including the ones that are drawing the heat out of the burn tubes. The burn tubes will almost instantly glow red and overheat thus reducing the temper and the overall life of the tubes. Let the onboard circuit board shut the furnance down normally when iit sees the tubes have cooled off. Love forced hot air...the effect in the house is much faster than radiant water. If your furnace runs for a bit and flames out, the first simple fix is cleaning the flame sensor. You'll notice a timed reset by the circuit board as an indicator that this is the problem. Mine reset every 7 minutes.

  • U mean like putting a fan in front of a space heater

  • You might want to add a video or addendum to this one to discuss the even older forced-air furnaces that had no draft inducer at all, such as those commonly used in the 1980's. My current home has one of those, but its in this year's plans to replace it with a modern one.

  • Having had almost died from carbon monoxide, please everyone have your system checked every year and have those alarms checked and replace the batteries if needed! My story regarding Carbon Monoxide was when I was around 7 years old and I remember it pretty vividly believe it or not. I think some of it was filled in by my family's take of events, but I do have clear memories of certain events. I do know how it happened, but since it is 100% a one-of-a-kind case I am not going to say, but the outcome of what happened is the real story here. That cold night back in the early 80's carbon monoxide somehow ended up in our cold air returns and leaked back into the house. Unfortunately my bed was right over my cold air return and closest to the furnace. Somehow I made it down the hallway and landed on the stairs and since my dad was such a light sleeper, he woke up and ran downstairs to find me. It was around this time my memories started. I started to gain conscientiousness while my dad was yelling at me to wake up and lightly smacking my face to get a response. In my head I was really dizzy and saw tremendously bright outlines of geometric shapes flying past my vision as if they were neon signs. When my dad started to feel the effects of the CO, he took me outside and by this time everyone else had been awaken and together. After a little while sitting in our van on that cold night, I remember my parents discussing what happened and what to do. After my dad's head started to clear up a bit we went to the hospital where we found out that I had 30 minutes to live under that concentration, my sister had an hour and my parents, being upstairs and the furthest from our furnace had an hour and a half. I was on oxygen for 24-48 hours, those details are foggy. Although the details of what happened in my case are very unique, it doesn't discount the fact that this can happen with a commercially installed furnace at any time during its operation. Also if I may make one more interjection here, please for the love of all that is wholly, crack your garage door if you are running an engine in there....especially a lawnmower or snow blower. The amount of CO they produce is astronomical and I think we all need all the brain cells we can retain. Thank you for those who read this book and I hope you take it as a good story about how 1 little boy could save his family from oblivion. By the way, I am in my 40's married and have a beautiful daughter that is in grade school and I have had zero negative effects from this event.

  • dude i never knew how awesome condensing furnaces are

  • I wish these were easier to get in the UK.....

  • That lennox furnace has been converted to run on propane. No natural gas there.

    • I'll also mention that oil heat is king here, its much simpler and safer, and can be just as efficient, and much cheaper than propane.

    • Ah. At 14:50 I see you mentioned that!😂

  • If the FIRE TUBES were made of the proper heat tolerant alloy of stainless steel there wouldn't be a risk of cracks/holes. But that most likely won't happen because of 'muh, cost' and 'muh, planned obsolescence'.

  • 3 years ago, my father changed the house heating method, from a gas furnace to an electric heat pump. He also changed from a gas oven to an electric oven and induction hobs In France, heat pumps are highly subsidized (iirc, i think he paid 6k)

  • Thank you for answering my Burning question. I’ll stop posting Incendiary comments now.

  • Here in the state of Georgia the heat is resistive electic. When the overall rate for power here is $0.12 a kWh it makes sense. I'd love to have a heat pump though. Now when i lived up North we had oil heat that was then converted to gas heat. Much better but still expensive. And we won't talk about the rates for electric power - $0.25 kWh.

  • I am new to buying a house, and keep seeing Forced air, oil, wood, furnace, and maybe others, but don't remember. What are the differences?

  • technology connections: we in the nothern hemisphere prepare for winter me: laughs in Australian

  • I have a NON VENTED natural gas heater to heat my whole home. Located centrally between my living room and kitchen. By products like water, and carbon monoxide are a side effect, but honestly...it beats any electric heating system that I've ever seen yo! Heater....Mr. Heater!!

  • Being on limited government assistance finding the money to be able to change our gas furnace over to a heat pump could be very interesting including getting rid of the other gas hot water heater and intern getting rid of gas in general in our house would be kind of nice but costly correction in our case astronomical

  • Aside from the climate change BS agenda this is a good video. Natural gas and my 85% furnace save my life in -40c

    • You mean besides the fact that it is true

  • So if I have an electric stove, and a heat pump, and there is nothing that burns, I don't need Carbon Monoxide alarm?

  • Why isn't there a carbon monoxide sensor inside the heat exchanger, that automatically shuts down the furnace?

  • Now that you mention it I kinda wanna know how the home boiler heating systems work

  • Thank you for the great video. You explained the workings of the modern furnace/air conditioning system in such a way that I really understand it. I have a question for you please. My five year old modern “High Efficiency” air conditioning furnace system was in need of repair. Diagnosis a leaky A-coil.(Warranty), while the technician was here changing out the A-coil he noticed an obstruction in the exhaust pipe (Draft- inducer), apparently while the crew was here installing the unit they accidentally dropped a 90° iron gas fitting down the pipe blocking about 80% of the pipe.🤨. This has totally freaked me out😳how did the system continue to work without much flow.we’ve had five winters of cold 🥶 weather.Then I wonder if this is why the A-coil leaked Freon🤷‍♂️. Not to mention the contamination to the system (furnace components)as a result of this iron pipe breaking down filling all those small tubes full of rust flakes. I pulled some of them off and inspected them ,they’re coated on the inside,and where they connect the small orifices they are contaminated & unobstructed by the rust scale. Course my main concern is in the home air quality. The house is equipped with simple carbon dioxide detectors. No alarms have gone off. I do appreciate your advice and direction I’m waiting for a callback from the owner of the company that installed the unit he’s offered a full service I told him I want the furnace replaced. Thanks again 😳

  • That's why British houses all have air bricks, to make sure that houses have ventilation, even if windows are closed constantly and there is strong insulation in walls and such.

  • Are you planning to do a video about boiler/radiator systems at some point or would it be a bit too tricky given how rare they are where you live? For that matter, have you considered doing a video about modern wood burners? They can be very efficient (specifically double-chamber systems).

  • At 16:35 it appears that this furnace has a flame roll out. I don’t see a roll out switch nearby that would detect this. This could pose a couple safety risks that should be checked out.

  • 95 is rounded up to 96 in most North American countries. You know, tax.

  • HVAC guy here. Correction on your description of the flame sensor. It's actually way cooler! Because a flame is a plasma, it is actually checking for the conductivity of the flame! Any obstruction in the flame line will cause an error, as will Any corrosion on the flame sense rod. One of my favorite things about the modern furnace! Edit: Whelp, you already made a note!

  • I love the matter-of-fact sign off in this one. "Ok, bye!" :)

  • Why did you get a base line Merit series single stage? That looks like an ML195 with a PSC Blower

  • lol 1% ad the internet raises hell.

  • In the UK 🇬🇧 My fiat was built in the 80s and had ducted heating (no aircon) The boiler has finally died and we cannot find anything to replace it directly, no way to get an air to air heat pump. So I'll have to get a combi boiler and radiator installed for about £4 not good.

  • Make a video on negative ions and ion air purifiers

  • 20:23 "However, as we move headfirst into this decade [...]"... October 2020... This man actually understands what a decade is!

  • in england we call these 'warm air units' ... i like them more than boilers because you don't get wet working on them

  • 14:27 -- The Sparky Thing ignitor probably went out of fashion because the electrical arcs are so ridiculously hot (>15,000 degrees, which is so hot it doesn't matter what unit system it is) that they damage the electrodes, which over time, could reduce the ability of the ignitor to reliably create an adequate arc. True, the arcs have an absolutely miniscule cross section, and thus it would take (in most environments) a long time for the electrodes to degrade to the point of introducing any real unreliability, but as you have pointed out multiple times, you just don't screw around with burney things indoors.

  • " OK BYE! " .....lol

  • Thank you!

  • I have 90% 25 year old Goodman furnace. Still working well. This winter I had to flush the drain trap. It got clogged up. I also had to install new drain line to the outside. I wasn’t sure if I can use condensate pump for it I ran new line straight outside. Old line was draining into crawl space

  • 4:39 what r u talking ab burning things is awsome

  • Do these furnaces also heat your hot water supply?

  • Hey, that is not steam, you cannot see steam, you see water vapor when steam cools.

  • This guy it’s fucking amazing 🤩

  • This furnace is built safety in mind Also that furnace: take the front panel off and you could probably stick your hand (or something else) into the flames. Btw, if you use your furnace only in winter months, how do you heat up water (shower/tap)? Electric resistance heaters? For context: oil-fired water radiator based heating system, furnace also heats up the water. In my furnace, if you open up the furnace enough to touch the fuel nozzle, it won't start. You can check if there is fire thru a fish eye lens (similar to what you may find in front doors). The system is old (20+ years) and needs to be replaced in couple of years, but I believe it's efficiency is somewhere around 85...90%. Furnace is located in a separate room rated to stand fire for a minimum of 2 hours. Really I don't think the furnace poses any larger risk than a regular fireplace (burning wood), wood-fired stove or sauna. But still I wouldn't mind having CO sensor in my bedroom, and fire alarms are in every single room (apart from toilet, sauna, bathroom and kitchen where steam or a sudden rush of hot moist air would often trigger an annoying false alarm).

  • My furnace once had a problem where as soon as the flames would start, it would immediately close the values and start the process all over again. As cold and annoyed as I was, I guess that’s better than an actual problem and it’s safety features not kicking in at all

  • Spark Ignition systems are still used and in my personal opinion are more reliable than hot surface igniters. I don't run across nearly as many failed spark ignition controls as I do burnt out hot surface igniters. To expand on the flame sensor and its operation, what you are looking for when you test one to verify that it is indeed dirty and causing ignition failures is you run the signal through a DMM and look at Micro-amps DC. You are looking for anything above 0.5 micro-amps which is the rule of thumb cutoff limit for proving a flame. You pull the flame sensor once confirmed dirty, clean it, (I prefer a brass brush as it doesn't gouge the metal and cause excess surface area to be created to hold more crap in the future) install it and test it again to prove the flame sense is within the proper range for whatever you're working on, usually 2 to 6 micro-amps.

  • One more safety feature- the access panel interlock switch, which you likely defeated to get your interior shots.

  • Anyone else watching this in anticipation of the heat pump video?

  • First this channel helps me troubleshoot my dishwasher and consistently get clean dishes out of it and now it tells me how my furnace works which just so happens to be having issues right now, love the content keep it up!

  • Electric heat pump is therefore probably the best kind of heat generation for those with respiratory issues?

  • I didn't notice you mention Flame Roll Out Sensors. I was trouble shooting my furnace and I was ready for terms like Draft Inducer and ignitor and variable speed motor control and over temp sensor, but I was lost as to what Flame Roll Out Sensors would be. Just more safety mechanisms to keep the Flame Thrower part from letting fire go where it isn't supposed to be. :) Overall, really well done presentation.

  • Love the Epcot/Norway guy on your t-shirt, a deep cut and excellent "technology connection" for this subject. For anybody who is curious: the face on his shirt is an oil rig worker depicted in a mural once found within the Maelstrom ride in the Norway pavilion of Disney's Epcot. In 2014 it was replaced with a Frozen themed ride. The mural depicted aspects of Scandinavian history/industry, including fossil fuel exploitation. The man on his shirt is depicted manning equipment on an oil rig. A central figure of the mural, his leonine charisma commanded the respect and awe of all who passed under his gaze.

  • Gas furnaces are extremely efficient and very safe. Buuuut i still prefer having no gas in my house, because tiny leaks and a spark are enough for a catastrophic event. EDIT: They still are super safe and such events very very rare. I just want to be as safe as possible. I wouldn't be scared to live in a gas heated house. Just prefer not to^^

  • "They're probably and hopefully on their way out, thanks to electrification.", As the great state of Texas has shown us, that is actually a very bad idea.

  • "You might call them U-tubes" Ba dum tss xD

  • I’m looking forward to the video on heat pumps!

  • What happens if there is a power failure during the operation of the furnace? Will the gas valves close? Also will it be too hot as the fan would be no longer on to cool it down? My furnace is 2011 and looks much like this one.

  • CO poisoning, is nearly non existsnt in a forced air furnace. This is because of the positive pressure of the air around the heat exchanger, thus forcing the CO BACK into the heat exchanger. However, on a gravity furncace, where the heat naturally convects, such as an old octopus furnace, there is NEGATIVE pressure around the heat exchanger, so the CO gets sucked out of the flsme chamber, thus into the house.

  • So it’s a turbocharged oven?

  • Curious why you have an electric water heater with gas right there??

  • Your presentations are always well done and are very professional! Thank you!

  • What we really need are houses that have better construction. Mansions in the Southern United States at one time had very thick walls, 3ft in some, and very high ceilings to help keep hot air above the people living in the home. Transoms above the doors of the house allowed air to move. Fireplaces and stairwells were constructed to move air by free convection to the top floor of the home where it could be expelled. The housing industry seems to get a pass on home design. Which congressmen and senators work for them?

  • Update from the angry mob! ;) Please go live with a builder heat pump in a house for a winter. There are many types of heat pumps. The most common version attempts to extract energy from the external surroundings, namely the atmosphere and release it into your house. This is done by allowing the energy in the atmosphere to expand a working fluid, such as ammonia outside, and then pump it into the house where a condenser compresses the ammonia thereby forcing the heat out of the ammonia and the forced air in the house picks this up and it is circulated through the house. On paper this works great. Now imagine it is too cold outside for the ammonia to be properly loaded with heat, the auxiliary heating element in the heat pump system turns on and warms the house air to be circulated. This is just like the nuclear auxiliary power being activated in "National Lampoon's Christmas Vacation" This costs YOU major amounts of money! If you own an electric stove look at the heating element in the oven - it's the same as the one in the heat pump. If you can build a custom home you can get a special heat pump where the working fluid, ammonia, is circulated below ground where it stays warmer year round. You might get lower operating costs at the expense of higher initial installation costs. Also, if the tubing below ground is wrecked in some way it must be excavated and replaced. If you live in a densely populated area your neighbors maybe using the same system causing your system to not be as effective. Finally, geothermal is the best heat pump system you can have for your house since you are working with a near infinite source of heat. If you are a normal guy with a house you want natural gas heat for its comfort. There is no medical dangers for using it. It is clean and safe. The economics of electricity is as follows: electricity is 5 times more expensive than natural gas on a "Therm" basis. Wind and solar are unreliable sources of electricity. Look at what happened in Texas. Electricity generated by burning coal is thermodynamically stupid. Why burn coal to make heat to boil water to turn a generator to make electricity only to turn it into heat? If you want a warm and reliable home, use natural gas for heating, cooking and drying your clothes. One final point, heat pumps use a coefficient of performance, which is not the same as calculating system efficiency. Heat pumps only move energy! They do not create and move energy. Electric heat is terrible and will continue to be terrible. Global Warming is a hoax.

    • It's true that air-based heat pumps do not work well below a certain temperature but the latest ones do pretty well, even below zero degrees F. And if you are in a climate where there are only handful of days when they are ineffective, you can switch on some other form of heat such as electric resistance heating. Will that be expensive and use a ton of electricity? Absolutely. If I would only need that for a few days per year would I care? Probably not. All of this said, today would I run out and buy a heat pump for Minnesota winter as my main source of heat? Maybe not quite yet but using electricity as a "fuel" for heating is where the puck is headed.

  • I've installed many of this particular furnace and can tell you that at 13: you can see a red sticker notifying you that there is a shipping bolt and it's location that needs to be removed. If that has not been done on your furnace, the blower motor will be "locked in place" and will not let the rubber anti-vibration thingys do their work. It may or may not have been removed by your installer, but the red sticker should be removed once accomplished. Also, you must be using LP gas, because there is a low-pressure safety which will shut off the furnace if your tank is not giving you enough pressure. It is the brass adapter and attached thingy which is the first equipment the gas pipe entering your furnace encountered. It comes in a LP conversion kit which also includes smaller orifices and a spring for use in your gas valve to set the correct pressure. I enjoy your videos!

  • Texans be like "Whats a furnace?"

  • florida ☀️

  • Ha! Love the retro Epcot Norway shirt

  • Hold on, if you are using this sort of thing for heat in most american homes, what are you using for hot water?

  • i have that same sport coat.

  • Have a boiler, ordering CO detector now.

  • I’m coming back to this video after Texas went arctic, it’s hitting 15 degree lows rn lol

  • Very odd character but also the most informative and detailed video on how a furnace works on PLtools.

  • I don't have to worry about carbon monoxide... ...my house is incredibly drafty

  • When you said 500% efficient, I think you meant 500% coefficient of performance. Anything greater than or equal to 100% efficiency would violate the laws of thermodynamics.

  • No policy needed - Condenser Furnace mortgages shall fill this niche

  • Why is the heating machine called a furnace and only the cooling machine called an air conditioner? Both heating and cooling change the condition of the air. Humidifiers and dehumidifiers also change the condition of the air. Some furnaces also have humidifiers in them (my current one does not) and air conditioners may dehumidify (my current one does). They all should be called air conditioners. Enjoyed your video. By the way, my prior furnace, designed in the 1960's, was about 60% efficient. My current one is about 98% efficient.

  • This video is very HOT 🔥

  • I don’t know how you do it but you make any topic interesting.

  • Not that it really matters, but in places like Quebec with abundant cheap hydroelectric power, resistive baseboard heating is common. Is it efficient? Not really, but it’s cheap to implement and the low cost of power keeps it popular.

  • 16:42 I want to know what moron designed your house without an extractor above the stove. Is that normal?

  • You missed one important step in the ignition sequence. After the hot-surface igniter or the sparker is turned on, gas valve #1 opens the gas ONLY TO A SMALL PILOT FLAME. A flame detector (not a thermocouple, that's too slow!) detects the pilot. THEN, and only then, will the main gas valve #2 open. If the hot-side heat exchanger develops a leak, room air will be sucked into and mix with the flue gas, not the reverse. This is because the draft inducer makes a vacuum in the burner box and tubes. In order for for flue gases to escape into the room, the leak must be in the exit PVC pipe. That's reason the inducer sucks after, and not blows before. If the leak gets large, the pressure sensor will sense & cause shut down. About the condensate: they put the electronics under the condensate (in the blower box). There are ALWAYS some leaks. Water drips on the electronics and destroys them, and dust collects. Water & surface mount parts do not mix! Important points missed: the draft inducer enables the heat exchanger's tubes to have small cross-section (handfuls of square inches). This increases the likelyhood that hot gasses from the flame will collide with the walls of the exchanger. In old furnaces where flue gasses were propelled through by gravity alone, the flues needed to be large in cross-section (many square feet). Most of the hot gasses went right up the center, never toughing the walls and giving up the heat. The second "trick" the modern furnaces employ is COUNTERFLOW. Flue gasses and room air move in opposite directions in the exchanger. The hottest flue gasses, exchange heat to the hottest room air (just about to leave the furnace). The coolest flue gasses give the last of their heat to the coolest room air (just entering the furnace). One trick overlooked in these furnaces: the coldest air is the outside air feeding the burners. A counterflow exchanger between the entry and exit flue gas lines would permit capturing the last of the heat from the exiting flue gasses, because the entering outside air is colder. This heat could also be used to heat outside structures such as greenhouse. All of these furnaces would be even more efficient (with the same size & cost exchanger) if they would quit being stupid and make the furnace analog, not digital. In the winter, the furnace should run continuously, the burners (and inducer) being adjusted to match the heat demand. The lower the heat exchange rate, the lower temperature drop in a given exchanger, and the less thermal fatigue & less wear & tear starting & stopping motors & igniters. Most of the time, the furnace is way over rated for the heat load required. Heat pump: WORTHLESS! If it's warm enough for them to work, you don't need much heat anyway. If its colder, the outdoor heat exchanger keeps icing up, as ice sublimes on, like in no-defrost refrigerator. So the unit has to keep dumping precious heat back outside to defrost it. Heat pumps are very expensive, and the compressors "work hard, and die young". Yea! Geothermal! Rrrrright! How many (except in few in remote area) are going to dig up the place and put that in (if the geology will even permit?) Most local codes won't even allow that. In Switzerland, that was done by many, and the river froze solid from the bottom up! It's like pollution: OK is few do it, not OK if everyone does.

  • Can you do video about the benefits and disadvantages of water heaters vs tankless water heaters?

  • Hm.. Efficiency of 95% is extremely efficient you say. I could be wrong, but I believe European style furnaces have an efficiency of 107% due to condensation.

  • Burning things indoors... no mention of my cooking?!

  • A flame sensor is not a thermocouple. It is a rod and it is only a conductor that grounds a current but it does not generate voltage or current. The flame completes the probing system. It is only a rod.

  • Awesome Video!!!!

  • Between this and another video on new york steam heating, I have to ask, does america not use hot water radiators in home situations?

  • "Heat pumps are the future" - in Australia we've had reverse cycle air conditioning in most homes for the last 50 years... 65 years ago in the case of my grandparents. They're just a... thing, and forced air furnaces, I've seen two, maybe three houses that use them? Temperate climate perhaps? They don't work so well in sub-zero temperatures although inverter technology has reduced their propensity to "ice up" outside.

  • My flame sensor is tingling.

  • I've responded to quite a few carbon monoxide poisoning calls. Treatment for serious cases requires a hyperbaric chamber.

  • Its not a thermocouple that detects the burning, it's FID en.wikipedia.org/wiki/Flame_ionization_detector

    • Did you read the pinned comment before waking off to that ego trip?

  • I've never seen any of those carbon monoxide alarms... probably because I live in brazil...

  • I grew up using a wood/coal burning stove in the living room of the house so these things are like new age space technology for me lol

  • You should do a video on wood stoves I live way up north and wood is the only reliable heat I can get lol

  • Why is Alec ever so slightly out of focus in this one? It's killing me.

  • Well all I can say here is: My old man was one of the most feared furnace fighters in Northern Indiana. In the heat of battle my father wove a tapestry of obscenities that as far as we know is still hanging in space over Lake Michigan.

  • One of the Best Examples of a Flame acting as a Conductor,. was Apollo 12. The extremely long Flame of the First Stage of the Saturn V acted as a Conductor allowing the Voltage Potential in the low lying Storm Clouds over the Launch Site to discharge

  • good job keep it going