HVAC Zoning Basics - Bypass Dampers and Dump Zones

HVAC zoning basics is about bypass dampers and dump zones used to bleed off extra air from the unused zone. HVAC zoning problems exist in forced air furnaces. how to install HVAC systems can be complicated if you're not an hvac technician. youtube has several home repair videos from this old and fox family heating and air. honeywell and jackson systems both make a board to control install HVAC ducting.
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[@JandC007]

Good video - I have a three-zone system, and the "dump" is in the bonus room/office right over my desk. This video has provided me an education on ow my system really works.

[@shadricosuave]

Great instruction and video. Now if I could only find an hvac pro that actually is educated to this level in Fayetteville, Georgia area.

[@TexasEngineer]

When I purchased my two story house I ripped out all the ducts and repaced the 3.5 ton with a zoned 4 ton heat pump because I got a very good deal on the scratch and dent units. The ducts were oversized for the 1860 sq ft house in Texas. Two theromostats worked as designed, No dump zones or bleeding ducts. The upstairs was a bit noisy in one room. The unit aged out and I replaced it piece by piece. The outside condeser with another 4 ton heat pump. After the thrid indoor fan and the synchronizers I replaced the air handler with a 5 ton two speed RUUD and converted it froma 410A to a R22 for the condeser. Resently I came into a RUUD 20 SEER variable speed 5 ton condenser. I replaced the condenser and changed to 410A refrigerant. Now this was a challenge to set up the zoneing with a two speed air handler, a variable speed condenser, single stage thermostats and a Honeywell zone board. With trial and error my best settings are: Run the system on low as much as possible and let the dampers do the work. This means that after 40 minutes of running on low the zone controller will go to high. Typically it will run 2 to 5 minutes on high and then shut off. The high speed helps with humidity control. The variable speed likes long runtimes to achieve super high efficiency and very low noise on low speed. My power bill has been cut dramatically by running on low. The return airs are on both floors so floors are not separated and the returns airs will mix floors. I have also found that bleeding 1/4 open on the downstair damper keeps the downsatirs theromstat from cycling while the upstairs is calling. For heating, it is electric and in Texas we don’t use much heat. My intent is to keep the heat on low unless the temperature gets really cold in which case the electric grid will fail first. My heater can pull 82 amps on high, enough to drain my wallet very fast. Low and slow works and only go to high if you can maintain temperature.

[@kforeal2226]

This explains it well. My house has its own thermostat on every floor and I recently had to change my own filter and thought it was a dual furnace. Don't judge me.

[@johnwhite2576]

What a great through but accessible treatment of this subject.

[@MrMcurtis08]

One of our new salesman just installed a 2 zone system on a gas fau that had a 50 delt T before adding dampers and now its over heating obviously. I am thinking we need to go from a 16 inch return duct to a 20 inch and also add possibly a few dump zones. Thank you for your help I love watching these intelligent HVAC service tech videos

[@MrCorydog]

Thank you for your informative video. I have a raised ranch home. The HVAC without any controls on it causes the lower floor to freeze while the living room, dining room and kitchen, all with cathedral ceilings stay very warm. Additionally, on the living floor, the bedrooms (3), stay very cool. As of now, I have magnetic covers on 66% of the downstairs registars to force more air upstairs. It has made a difference, but on a 95 degree day, the living room and kitchen still reach 80 degrees and my wife has issues with heat due to heart problems. I would think a three zone system would work well, by dialing down the downstairs and bedroom air flows during the day, and then opening up the bedrooms for nighttime. I do have fixed speed blower in my HVAC system. I tried to damper off with a manual damper on the entire downstairs duct. I ended up stressing all of the rivets holding the fan together and it started to come apart! Obviously, the answer is to not entirely cut air to other zones, but partially restrict it. Thanks again. I will probably be installing the Honeywell system in August. Ron

[@foxfamilyhvac]

Great info Ron. Good luck with that 👍

[@Ggg77777]

Great video! I had a service call working with a Honeywell HZ322 , it kept tripping on low temp ( discharge air temp ) the supply temp was correct. It’ll trip at 45 then reset sorta like short cycling, I checked dampers all were operating normal? It did have a by pass damper it was maybe 1/4 open. But still will trip

[@markbowman4426]

When Honeywell Truezone damper came out with Adjustable Range Stops I never looked back.

[@Pennconst101]

That is one of the smartest things they have ever done. And that in itself is a bold statement

[@BrianDebbieShannon]

liked your video, but it confirmed as I have always known, zone systems are not effective for a home unless there is variable speed used to to drive the air, and the coolant. The only reason zones became of use , in my opinion was to get by with a smaller system. Even with variable speed systems, and EEV's additional systems like mini splits make much better sense. I recently redid my home built in 1966 from a package unit and crawl space ducting to a smaller variable gas over electric 20 SEER split heat pump, and furnace combo (dual fuel). I then added mini's for the bedrooms not used much. The master bed, kitchen, living room, and dining area are covered by the split. I chose 2 separate mini's for the additional bedrooms because one could switch from heat to cool from the other. Also there is a slight increase in energy savings with multiple mini's versus a multi head system.

[@virgil3241]

This was an awesome video to discover. We recently moved into a house with a dual zone system and noticed shortly after we moved in December, the house would take a very long time to heat up. What they did was the bypass duct, so the return air was being heated up just like you explained. And I assume if we left it the coil would of frozen up with the ac in the summer. We took out the elbow from the bypass duct and capped off each end, and problem was solved. But now we have a whistle when one of the dampers close. I have adjusted the electronic damper so it doesn't whistle, but now a lot of air goes through that damper, which defeats the purpose of having that zone shut. I have tweaked it to the sweet spot of no whistle, but want the air blocked more. I have tried the dump method as the video suggested, and it works, but the utility room the furnace it in, gets very hot in the winter, and very cold in the summer, so I recapped it off. What are some suggested to use this redirected air more efficiently for my basement. Problem is its completely finished so I don't have much access to the duct work besides my utility room. Also, is it better to have the zones close as tight as possible, or should some air be allowed through? Can adjusting the zones help with low air flow at vents the furthest away from the furnace

[@SalvadorHVAC]

I replaced a Power open zone damper last week, we installed a new Honeywell Damper that still bleeds air into the closed zone, you can set it up to like 30% leak rate or smaller. When I saw my first zoned system I was immediate thrown for a doozy because of the by pass.

[@SalvadorHVAC]

6:40 exactly what I am talking about

[@SalvadorHVAC]

Another fun thing I had to do on this job was number the correct zones for the customer & rewire the zone board. Someone before us took off the 24v from Zone 1/2 and I’m guessing tried to give it 24v all the time or something because both sets of wires were on different tab. He had a single-story home zone 1 for the living room, dining , kitchen area. Zone 2 for the bedrooms. So it was easy to figure out. The attic was just getting to me

[@foxfamilyhvac]

Wow great feedback. Sounds like you guys know what you're doing. Keep it up!

[@foxfamilyhvac]

@@SalvadorHVAC yeah I had a zone system where the stats were wired to the wrong zone! Upstairs was feeding downstairs. There were some other issues going on too. But wow, the installers really blew it with that system.

[@mataiaren6917]

I work on new homes in OH and I know for a certain that a zone system should be an option. Nope, builders don't offer it or lie, even if homeowners inquire about it.

[@LRBennettInc]

You never mentioned how to properly size the bypass in either the dump or return? 75% of the largest zone? What's the rule? We ran across one today and had a 14" bypass on a 3 ton system? It barely brought the barometric weight off of zero with either zone open or closed? I like the 24V return dampers with the static sensors. Thanks for the info.

[@lucassfernando7536]

The question i have is Instead of By pass damper wouldnt it be better to put modulating furnaces with variable speed ECM motors which will automatically slow down after sensing high static pressure building up in duct

[@media2763]

If you have an air handler with a variable speed fan, can it be programmed to use the lower / slower speeds when sending air to the smaller zones, thus creating less cfm, less pressure, and reducing the need to bleed off excess pressure.

[@HoldYourSeahorses]

My exact question.

[@MrMcurtis08]

I think that due to the amperage draw the ecm auto corrects its speed to run efficiently

[@billiekweiss7772]

A tech today left my damper to zone 2 stay open! Is this a risk factor?

[@831363]

I have a similar house to your example in this video (smaller scale). My small area is upstairs where I sleep. My downstairs damper has gone bad for the second time after I replaced it. (the larger area/downstairs damper will close permanently) No bypass or dump zone in my system. Is this because it has constant air blowing on that larger damper most of the time? It’s the damper that’s always closed so maybe it’s the constant pressure overtime causing it to stick in the closed position. That’s a theory one tech had

[@NLopezzz]

Thanks for the info - I'm sure there is a reason this is a bad idea but when using bypass connected to the return, could you use a limit switch with a lower temperature so the burners shut off earlier? That way you are still re-using the heated air, conserving energy, and eliminating the "super-heated" situation? Also, do they make variable speed blowers that increase/decrease based on the number of open zones?

[@staticpressurenerd5182]

Where I come from, Bypass is a bad bad word. I would always use a dump zone before ever installing a bypass damper. My favorite zoning system is the HeatPumPro by Arzel Zoning System (not just for heat pumps.) If you have 2 stage equipment, you can control the fan speed depending on the amount of available duct work to control objectionable air noise. The fan is staged independently from the outdoor unit. If you do not have 2 stage equipment you can use the Evergreen zoning system by Arzel which utilizes the evergreen motor for staging the fan. If you have never heard of it you should check it out!

[@realisticjman]

Ive been doing this a long time and where I live in Florida the but all the dampers and actuators in the attic which means they all seize up and storm working within 10 years in experience its garage and I avoid it

[@yourmomma3132]

Good video Greg

[@alexschwallenberg9540]

It's a shame but sometimes you have to use a barometric bypass damper because of the set up and age of the system you're zoning. It's not cutting corners but it's the best you can do without replacing equipment or modifying the ductwork. Which is sometimes impossible without tearing parts of the house up. I'm on one right now just like that and I have to make it work. Is what it is sometimes.

[@soccerdancedad]

Does the fan run continuously? We just moved into a home with this system. After watching this, I understand it much better but the fan box in the attic is always running. Is this normal? The condenser outside only comes on when the thermostat calls for cooling.

[@OldePhart]

I'm a fairly advanced DIY guy and found this while looking for zone info to replace the awful Beutler system the house came with. The Honeywell dampers have caught my eye. But something else I see in my own home is that the master gets pressurized so doesn't have good flow and thats not a zone problem . How would one fix that? install a return duct that is piped to the return plenum?

[@lapk78]

We have a 12"x12" return in our upstairs master be just for this reason.

[@yourmomma3132]

Any beutler system is crap. The zone box dampers are too small and they put zone systems on single stage equipment with undersized return air intake. These units short cycle, overheat, hi limit. Add a return air intake to the master. Put it in the closet. That way you won’t see it or hear it. Then when that system does, get a 2 stage system with properly sized dampers.

[@OldePhart]

@@yourmomma3132 I also found just last week that the damper doors interfere with each other . Upstairs blend door can land against the downstairs door and then they just sit there half way between. I had to cut the edge of one so they could pass each other. Pure junk.

[@tonyh4033]

We never dy bypass dumps. Only install 2 stage or variable capacity with zone dampers.

[@josephcastaldo4881]

Great video! Thank you!

[@foxfamilyhvac]

Glad you liked it!

[@georgemendez777]

I just moved in a house with this new system I was really confused but understood as I researched it. Now I have a question I have a single condenser 5 ton carrier cooling 2950 sqft home and everytime one thermostat calls for cooling while the other is already calling for cooling I noticed the condenser shuts down for 30 seconds and starts back up to cool the second floor and then first floor calls again and does the same thing and this is continuous throughout the day I live in buckeye arizona where temps exceed 110 degrees frequently my concern is the amount of cycling this is doing roughly 30 to 40 times in an 8 hour day and obviously continues through the night as well but just giving an example as to how many times in a 8 hour period this thing cycles I'm not over exaggerating either ok maybe a little bit. Either way the cycling is very annoying and I'm sure it's not good for the system either. The thermostats seem to be playing tug of war all day long... what's your input on this and is there a way to keep the system running and allow dampers to do their thing without the system cycling with very short resting periods.

[@av1204]

I have a question when it comes to this. Could you not have two branches for each zone, one damper that only opens if the other zones are satisfied? This would dump that extra air only into the zone that you are trying to manage. I might be crazy, just a thought.

[@av1204]

second thought too. You said you have dampers that can partially open. Could you not program those to be in a normal partial close state and then when the others fully close the zone that needs satisfied will fully open?

[@mmsondsy97]

Hello good info.. thank you.. I know I’m not imagining that one room is getting hot air where the other area is cooling.. Our system “smart home” has 3 zones.. drives me crazy.. we’re in AZ I hate walking through our 2200 house in areas that are 83 to 78 because the guy said we need to keep the thermostat 2 degrees different from others.. we’ll this is why I’m hating this system.. Can I keep the house at an even temp..say 78 all over the house.. what will happen to the zones/damper.. our house is 2 years old and still not happy with house temperature to make it comfortable year round.. PLEASE advise thank you in advance

[@JoelSuppa]

I have no idea why someone told you that you cannot keep all your thermostats at the same temp. Either you misunderstood him or he is just an idiot. You can absolutely do that (I'm an HVAC professional)

[@imrankittur8654]

Can you pls comment on electricity consumption ? If air is getting bumped all the time , is it not wastage of electricity to unnecessary run the High tonnage single unit and dump the air ? Makes no sense to me , how is this type to design approved ?

[@michaelnichols2192]

So if you have a ture vs speed unit none of this is really required. Vs speed meaning inverter or 2 stage . If this is still a issues use 2 systems. The other options are very large un insulated turn around loops in ot attics to increase return Temps. Cols Evans get colder and colder and freeze

[@OYET-te2jn]

So what zoning control will allow control of staging? I am zoning my single zone house into 3 zones. 5 4x9 registers each. 2100 sf total. 7500 ft elevation in Colorado. Have ecm variable speed furnace/ac coil. Replacing single stage condenser with two stage. I want to control staging when only using 1 or 2 zones to reduce airflow ect. Thanks!!

[@Autsom57]

Thanks!

[@thatoneguy1277]

I have a question. I just started HVAC school and am in basic electricity and magnetism. My question is how much of that will I use in the field. Im having a hard time understanding it and I'm starting to question if I'm smart enough for HVAC.

[@realisticjman]

Ive been doing this since 2005 I have my own business now , you dont have to be smart to do hvac you have to have common sence and understanding in electrical and what powers what and how relays work and understanding how refrigerant should act and how super heat sub cool is measured as for that stuff in school I never went if you really want to learn this stuff go work for someone or a company start as a helper and see if you can hang hvac is hot and it sucks sometime your in attics on a roof and get dirty once you learn something move on dont stay for one company forever you'll learn more that way

[@mandir0909]

Great video! I learned a lot, just wish I knew where those pesky dampers were located so I could attempt to.. yeah.. nevermind..lol! I do have a quick question though.. I believe they set the bypass to be distributed through multiple vents on the main floor when the upstairs has reached its max, however, as of late the upstairs is barely pushing out any air and instead it is pushing hard throughout the main floor, even with the main control completely off.... This is a new issue that happened during winter last year, do you think a duct is blocked? a damper in need of replacing? should I just call a pro and move on with my life??

[@foxfamilyhvac]

How did this turn out for you? I'm curious. Was it a damper that was stuck open?

[@alexschwallenberg9540]

Sounds like the upstairs damper is defective to me. HVAC tech here.

[@TimujinWorld]

Is using a barometric damper dumping to an attic space a good idea? I had a HVAC company say we will install a register in the attic to dump when one zone is calling. I didn’t think it was a good idea in my two zoned single stage air handler system. I have my 2 zone dampers set to not close fully as in your 3rd example. The idea of wasting energy to the attic space is crazy to me. Problem is 33 code and 3 minute heat cycles with jet engine register noise when one zone is fully closed when heating or cooling.

[@foxfamilyhvac]

Really seems like a huge waste of energy. I would rather see them use dampers that can be set to not close all the way. It's actually less work for the installers to do this. Using dampers like the Honeywell ARD's is super easy to set that. This way the excess air dumps into the unused (zone not calling for air) zone SO THAT UNUSED ZONE DOESN'T HAVE TO RUN AS OFTEN WHEN IT IS READY TO CALL FOR AIR!!! It's not like that unused zone is going to overheat the excess bleed off air being dumped into it. So, no I would not let them do it. Also dumping that zone into an unconditioned area is just irresponsible. Every single cfm of air should enter the living areas of your home. Not the attic. And really do you want a company that is even offering this waste of energy installing your new system? I wouldn't. I would want a company that is going to save me as much money as possible for the life of the system. Get another estimate. It's always good to get at least three and decide who you trust the most. It's such a big investment on your part.

[@foxfamilyhvac]

Open the other Ard bleed off some more and measure static pressure if it's just a service problem. Relieving that air is soooo important to your furnace not overheating.

[@TimujinWorld]

Thank you very much. If you all were in SoCal I would have you do the work.

[@rossfarina6334]

TimujinWorld I also live in SoCal. Did you find a company to go with? Trying to figure out who to use is daunting

[@TimujinWorld]

Ross Farina not yet.

[@davidrowlett2896]

Zones drive me bat shit crazy in Texas.. Most wont cool correct. undersized for 104 degree days we may have 30 to 45 days of over 97 so its a issue.. I hate bypass because its a waste

[@aa-ron1596]

I have a question and hope some kind soul can help! In a 1 Compressor setup with 2 zones, should the dampers in each zone open and close when on/off? Example: 1. Zone 1 is turned on the damper is open 2. Zone 2 is turned on and Damper is open (both zones on and both dampers open) Shut off Zone 2 and the Damper closes, Shut off Zone 1 and the Damper closes or vise/versa. My setup (I can give specifics but not sure it matters) Its not working this way which seems pretty logical to me..instead one zone may close when it should be open....no matter what I do on the Honeywell control board I can not get both zones to open at the same time or close just one while leaving one open if that makes sense...thanks if you made it this far!

[@zachosborne6577]

Garages are a good dump zone. Gives heated and cooled garage.

[@CCCC-tq8yo]

3 yrs later and the prices have doubled lol

[@Ian-ei1ce]

I have a question. I just bought a house 3 years ago(2 story home with 2 zones 1806 sqft)and I’ve been having many issues with my air conditioner at least every year. First year, my compressor went bad, and now, my air conditioner was froze up. I had a company come out(not the ones who did the original in stallion when the home was being built) and say that my coil was leaking. He also said that when they installed my HVAC system, they did not install a “bypass” or “trap” for all of the excess air and should’ve never passed inspection. He went on to say that I’ll need a whole brand new system estimated around $10,000+. If I don’t get the system, I’ll continue to face issues like this time and time again. Am I getting shammed or is that a legit statement? Thank you.

[@foxfamilyhvac]

Tough to say. I wouldn't just rely on the one company's opinion. I would call around to two or three other companies and see what they say and for God sakes don't call any of the big companies in your area. Only smaller to mid size companies. Your bound to get a straight shooter there. It's all about sales in the big companies.

[@joeglenn8955]

anyone ever dump the extra air into the garage?

[@foxfamilyhvac]

I actually have had a third zone that went to the garage, aka the poker room, lol.

[@joeglenn8955]

if it's just a garage they will still use to park cars do you see anything wrong with dumping the supply in a garage back and side walls unfinished . house shared wall and ceiling sheetrocked.

[@foxfamilyhvac]

@@joeglenn8955 I was just a helper back when we did this job. Personally I think it's a waste of energy pumping ac into an un-insulated garage. Not sure if he improved the garage after we left. I didn't think I understand your question though. Autocorrect may have changed a word for you. 😊 Can you re word it?

[@foxfamilyhvac]

@@joeglenn8955 I have seen people hooking a ductless system up in their garage though. Still a waste of energy on an un-insulated garage but to each their own. It works if you oversize the air entering the room. 😊

[@joeglenn8955]

what I meant was while installing a zone system, instead of using a bypass and dumping the air back in the return or in a common area. has any one dumped the air in the garage? not to really condition the garage . so you don't have to much heat on a heat exchanger or to much AC on the coil

[@juanitabridges3728]

M

[@robertj.2319]

IF YOU PROPERLY INSTALL THE REQUIRED DAT SENSOR ON THE SUPPLY PLENUM AND SET THE CORRECT HIGH AND LOW TEMP LIMITS WILL ALLOW THE ZONE PANEL TO CYCLE THE HEAT AND COOLING OFF UNTIL THE SUPPLY TEMP REACHES AN ACCEPTABLE TEMP. WHICH WILL PREVENT THE SYSTEM FROM LOCKING OUT. LOW LIMIT DROPS Y TO THE AC UNIT AND HIGH DROPS W TO THE FURNACE. I DO NOT LIKE ZONING. ONE UNIT TWO TSTATS. PREMATURE WEAR AND TEAR ON A SYSTEM. THE COMPANY I WORK FOR IS A TRANE DEALER AND INSTALLS ABOUT 40 OF THE XV VARIABLE SPEED SYSTEMS EACH YEAR IN THE NC MARKET. GREAT EQUIPMENT. THE COMMUNICATING ZONING THAT TRANE PRODUCES FOR THE EQUIPMENT IS TRASH.

[@foxfamilyhvac]

I've heard the same

[@chrisday6117]

SO MANY CAPITALIZED WORDS 👀😐

[@newkidontheblockism]

Just don’t do zoning lol