How to Balance a Forced Hot-Air System | This Old House

Thank you to Richard for explaining what balancing the system entails

Wow that was awesome thanks for sharing

Thank you, this video solves my issue.

Great video! What is the actual name of that 'adjustable start piece'?

You guys have great content and you guys entertain me for a long time

I want this man as my neighbor.

Best channel ever

Dampers are a pain. Removed all of mine. They create resistance and they were all in unaccessible locations. Completely redid duct work and sealed with shurtape and insulated with foam aluminum wrap on outgoing ducts from trunk. Registers have dampers so thats sufficient. Also 2 dampers one on each side of trunk about a foot off plenum division. Well made video as always from toh.

I cant find that adjustable start piece anywhere. Does anyone have a link?

Theoretically, after all the balancing dampers have been installed you need to adjust them according to the heating layout that determines how many cfm of air is required at each outlet. A flow hood or hot wire anemometer is needed for this measurement. You can also get vane anemometers that work in conjunction with a smart phone and app. Some of the measure velocity only so you need to convert fpm to cfm. If you don’t have a proper layout, you can make educated guesses based on pipe size, for example, a 6” pipe typically has a designed flow rate around 80 to 100 cfm. Balancing takes time - every adjustment you make could affect others. Put your furnace fan on high speed and take the filter out while balancing. Also, make sure the blower wheel and cooling evaporator coil are spotlessly clean before doing any balancing.

Coming from the east coast to the west coast and only able to have forced air kinda sucks. I grew up with baseboard heating that kept the room warm for a long time. With forced air you feel the difference immediately. My new home's probably has the same size supply trunks for every room. Downstairs (separate zone) is freezing with a 6-8 degree difference to the main floor where the two bedrooms overheat with the doors closed. The developer set the downstairs zone system to blow at least 20% air into the main floor....which is a separate zone. Is that a standard thing? It gets too hot on the main floor. We all know heat rises so why is there air blowing in the other zone when you don't need it. I can't close the dampers because I need them open on the main floor. We were told by the developers heating company we would need to basically heat the house from the downstairs zone due to the 20% being blown into the other zones. Also, we were told we needed to keep the bedroom doors open downstairs to keep an even flow of heat so the bedrooms wouldn't overheat. We've never slept with the doors open ever. This makes no sense.

My very old house has slits in the pipe and a piece of metal is slid into the slot (perpendicular to pipe length) to partitially block airflow.

The problem with these dampers is you need access to your duct work. If you have your ducts running in a finished basement, these options won't work for you. They are great though if they're accessible.

Doesn't adding dampers make your system less efficient unless they are at the start of the run making alot of back pressure unless you have a variable speed system? For you AC it would push more cold air back toward the condenser making it less efficient too.

What about SQUARE [] ducts?

my house has 2 zones and an electric motor damper in each run, but one zone is always loud when the air is rushing through it. Can't I adjust the stops on the other zone damper motor, so it always has a little air flow through it and thus the loudness will be decreased.? Thanks in advance. Dennis the inept HVAC man.

Request for help for forced hot air ducting.I have an England's Stove Works 3000 Sq Ft wood stove in my basement.Using 30 Gauge Galvanized piping you can connect this to a forced hot air system as a supplemental heating source.   The warm air supply-duct system should be constructed of materials with a minimum temperature rating of 250 deg. F.....etc.... I do not have a forced hot air heating furnace or any duct work.Currently it just vents the hot air into the basement which is the other option. I have to say the stove works awesome.It would be great if I could install some duct work to a register in the floor and let the hot air flow into the house, it has a blower, but I wouldn't even need to use it.I have access above the stove to the first floor of my house where I can install a register with 30 gauge duct work.It would be about a 4 foot run from the stove to the floor above.Is the air going to be too hot with the 30 gauge duct touching the wood floor/register at a 4 foot run?Thank you in advance for your reply.Pat

Totally missed constant airflow regulators

So how do you determine if the system is in balance, is there a way to check the system to know when a balance is reached?

At 2:50 how do you know if the damper is closed or open? It doesn't look like there's a directional connection.