How to Quiet a Noisy Forced-Air System | This Old House

In this how-to video, This Old House plumbing and heating contractor Richard Trethewey makes peace with a raucous heating duct. (See below for a shopping list and tools.)
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Shopping List for How to Quiet a Noisy Forced-Air System:
- bypass damper
- 7-inch start collars
- _-inch sheetmetal screws
- foil duct tape, used to seal seams in ductwork
Tools for How to Quiet a Noisy Forced-Air System:
- drill/driver
- circle-cutting jig, used to cut round hole in metal ducts
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How to Quiet a Noisy Forced-Air System | This Old House
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[@shizzlenizzle]

4:35 "... and when we do, the bypas-DUN-TI-DUN-TI-DUN-DUN-DOOOO..."

[@dgrblue4162]

That lady's ring is borderline a dangerous weapon 😂

[@junaidgt90]

The byPass damper opens up like 🎶 🎸 🎸 🎸 🎸 🎼

[@jennifercolbert6581]

This fan works very well. kzbin.infoUgkx7yWIKcrbA9KMHkGSfcgxW2lsjHT6B8Sh I replaced my old fan as our radon levels began to spike. When I remove the old fan water poured out of the fan. Must have entered in through the out spout. Replaced with this unit and levels dropped a bit but still over 4.0.Did some more digging and found that we had a small hole under our waste pipe that was allowing some water and radon in.Patched the hole and the levels dropped almost overnight.I really would recommend the radon sensor. It gives real time readings. Without it we would have never known that we had this issue.

[@freewoodencrosses]

Richard: I am not sure the media filter is a great option. It allows dirty air into your ducts to collect for years until you clean the entire duct work. Now return duct filters (although they must be changed more often) do not allow dust into the return ducts. To me this is a better option.

[@Engineer9736]

He barely got a chance to finish his sentence lol

[@UKEbikers]

Richard van Pukkem lol, and we didnt even get to see the results, probably had to cut it short as it whistled worse than before!

[@Tyler-cf8jl]

He should’ve mentioned that a 7” duct won’t work on all systems, the bypass should be sized correctly for each system. You should also have the collar on the return duct further from the furnace to prevent it from overheating and shutting down on a high limit fault.

[@myid9876543]

I was wondering how this wouldn’t just immediately high-limit. Furnaces need a delta to not bring output air above their upper limit, when you feed them hot air, how does it not immediately go past the limit?

[@mattluongo7763]

Not too mention a DAT sensor

[@legendkillla21]

Bro noone gets to tell Richard how stuff needs to be done

[@JBK63]

If the fan had a second speed available a relay arrangement could’ve been set up so that when the thermostats were not both calling for heat or cool the lower speed could’ve been used

[@kennethbubser9601]

Need to calculate total cfm. Minis the cfm of smallest duct. That determine size of bypass. Hate sending bypass back to return duct. Because it can raise temperature rise.

[@Amer-yl4gb]

No more whistle, no more annoying noise AND no more HEAT! :)

[@mikeaxiotis6830]

A furnace has a set temp rise across the heat exchanger. By putting that bypass damper going from the supply to the return, your now dumping hot air and re surculating back to the heat exchanger heating the air further and then circulating the hotter air back and continue raising the temperature of the air and more importantly the heat exchanger. When the heat exchanger gets too hot over a period of time ( and with that bypass it will over heat often) you shorten the life of the heat exchanger causing cracks and potentialy releasing CO into the air stream. You either can : -Set the same bypass damper to spill into the unfinished basement . Or If it's a finished basement ( and you really want zones) then you need a multi stage unit and control system to throttle the output (air and fire rate) based on demand. Or simple easy fix. Take the dampers out. You don't need Zoning unless you have a 4000+ sqft house.

[@askhowiknow5527]

I got itchy just watching him touching that insulation

[@Milostro]

Fascinating!

[@thisaccountsucks5556]

That thumbnail: I thought he might have been Tony Soprano.

[@r.j.mechanical3876]

Goes to show that comfort from climate control does not just come from temperature control... there are noise considerations too. A good contractor should be able to fix that.

[@boedillard8807]

Are any types of furnaces louder than others - e.g. gas or electric or geo thermal or is all the noise in the living area strictly from the air flow in the ductwork?

[@benkuxhouse787]

I'm surprised a 7 inch could work, but it would have been real tough to put in a 10 inch. At least it's 150 - 200 CFM being bypassed. Hopefully she has a good zone control panel, not an old relic. Need a dump zone and especially with a bypass it has to regulate the discharge air temp. Bypassing supply to return the furnace will have to cycle on a discharge air limit or you'll be cycling on the hi temp limit in the furnace.

[@godzilladestroyscities1757]

The age of the zone controller doesn't really matter. I work for one of the manufacturers of the controllers. We can make 40 year old controllers respond as quickly as new ones, just takes a smart person to follow our instructions. Also, you need to know how to install relays.

[@ezyjack826]

replacing blower motor on my furnace. problem is it's an old unit (pre 1988) and they have updated the motor. the new motor has 4 wires plus the 2 capacitor wires and the original motor had 5 wires plus the 2 capacitor wires. the difference according to the motor tag is the original motor had two med speeds and the new motor only has one med speed. can I wire it up with one med speed? do I use med lo wire, med hi wire or both med to the new motor? ty for any assistance you can provide. 🙂

[@fjm232300]

Richard, love the show and thank you! Been a fan of T.O.H. for years! My question is: I have a powered humidifier. I broke a blade on the motor cooling fan. The humidifier still runs but is noisy and unbalanced. I see online they sell carrier replacement blades. But I don’t see a set screw or locking device?!?! How do i change the blade? THANKS! Jay , chicago.

[@Tracker5111]

So, without make and model someone can answer this? Look up manual please.

[@Ranger5250]

Can anyone figure out how to properly drive self drilling screws? You STOP when the drill bogs

[@l.a.m7645]

I do heating late at nite this is something I would incomplete for the morning. LOL

[@juangabriele5822]

K

[@joshuaellison01]

We are searching for a solution to our in slab duct repair issue. There appears to be areas which are deteriorating and the spray encapsulation, like Duct Armor, seems like a good solution. Anyone have experience or feedback on this method? Replacing what's in the slab does not appear to be an option, neither is installing split units or overhead duct work.

[@SaltySparrow]

Oh wow, they have the same filter holder I do, lol

[@JohnHVACR]

danekarl did u get the upgrading kit yet?

[@Chronos0802]

A flex connection on the return air drop would have helped quiet the system down quite a bit also

[@michaelkeller4301]

How would a flex connector quiet the static pressure? Did you watch this video? Lol 😂

[@alamerisable]

I wonder how zone temperature control works after this modification?

[@88corinutza]

raise the temperature rise and trip the main limit lol

[@janito25]

I’m wonder , how easy will be to replace the motorized damper right above its new by pass duct ?

[@godzilladestroyscities1757]

Really easy if you read the installation instructions from the manufacturer. The motors are bolt ons. Like changing a tire on a car. It ain't rocket science. Just take pictures of the wiring before you touch it so you can match it later.

[@browniegay9130]

Can you come and fix my noisey wall vent in my living room?

[@paulmoffat9306]

Why not set the damper to have a little open space to not block completely?

[@johnmacward]

Paul Moffat it would waste heated air when the two zones are open and need as much air as possible. Why waste when it’s not necessary...

[@robthom09]

I agree. That’s what we did on commercial zones. Usually zones are not so imbalanced that some conditioned air cannot be maintained , even on a satisfied load. Sometimes had to bypass a little though.

[@dingo5208]

I'm surprised there's any pressure, that furnace is leaking like a sieve. The branches don't match and the sheet metal on the furnace is bent and separated, it's also missing any metal tape..

[@earthrat185]

How often should I oil the belt in my 30 year old but running well forced air furnace?

[@paulmoffat9306]

Never

[@Trooper85751]

oil a belt? just change it they aren't that expensive

[@cdubs1723]

Daily

[@hotwheel6663]

What kind of noise was it making?

[@copperlocks1]

Usually a high pitched whistling noise;or a low monotone hum. when you close a vent it causes pressure build up behind the closed register;the bypass,that he installed relieves pressure and dumps it back into the supply stream.

[@yournightmare9999]

If you feel you had enough furnace pipes just call 📞 "heating contractor" to install more pipes 👌😉

[@MRrwmac]

This was presented not long ago. Are you rerunning these videos on YT again?

[@Pksimages]

yes

[@CadillacM]

🤔

[@martyr857]

I have a banging noise seems to be coming from the air supply duct, only when the AC is on and cycles on and off. Here's the video - kzbin.info/www/bejne/fnLSgoWMrp6egbc

Hah, I just had the same issue. I had very restrictive system before, there was manual flap to block second floor which was permanently closed, also owners used higher MERV filters which restricted airflow even more. After removing this flap (now it's like 40% second floor, 60% first floor based on duct diameters) and replacing filter with higher airflow one (MERV 4, mostly protects from dust) it turned out that it's sucking so much air, the walls on return air ductwork were sucked in every time it started and bounced back out when shut down. The same noise you have. Obviously the solution is to increase return air diameter but it's hard to do and you can't do it on your own on rented houses etc. What I initially did is putting small blocks of wood to press against the walls - now they are always a bit caved in, so they don't bounce back. Not perfect but it works. Now I'm searching if and how I could reduce restriction on return air but it seems I can only change grille to less restrictive ones, nothing else can be done in my case.

[@alexandermolin8706]

Unintentional #asmr 😂

[@shoppersplace]

How much did the woman get paid?

[@smacleod69]

Only a 7 inch by pass on that? It should at least be a 10 inch for that system.

[@jrgarza87]

Not enough information on the size of that unit to know if it needs to be 10”

[@centrumsolutions4744]

A big problem with this solution

[@maddog12186]

You have small opening into the furnace. Not enough air flow from return. You're doing too much work.

[@maddog12186]

When you have a 1 inch pipe you don't reduce it to half inch and directly after the filter increase it to 1 inch. Its never going to work unless you have the same size capacity. Most common installers error.

[@endless1247]

POV: you are watching in 2021

[@Vision33r]

I always wonder why women don't get into HVAC jobs, they pay pretty well. It is almost 99.9% male dominated profession.

[@eddie10191]

Vision33r you said it male dominance, they'll drop kids to school laundry dinner install hvac while the guys are still on coffee break.

[@queenester2602]

When women apply, they are not even considered, because people running business assume they won't last so why waste time. I say their loss.

[@casperaudi7476]

Shit too short of a video