How to Zone a Forced-Air Furnace and Air Conditioner | Ask This Old House
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- čas přidán 8. 05. 2016
- Plumbing and heating expert Richard Trethewey shows how to divide a home's heating and air-conditioning system into different zones. (See steps below.)
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Richard adds motorized zone dampers to a forced-air heating & cooling system.
Steps for How to Zone a Forced-Air Furnace and Air Conditioner:
1. Cut into each flexible branch duct and install a motorized zone damper. Secure the damper to the duct with nylon cable ties.
2. Make the wire connections at each motorized damper and run all the wires back to the control panel at the furnace.
3. Remove the control panel's cover and plug in the telephone-jack connections for each zone.
4. To maintain the proper pressure within the system, install a weighted bypass damper between the supply trunk and return trunk.
5. Seal all the duct joints with mastic or foil-faced duct tape.
6. Adjust the weights on the bypass damper to ensure proper airflow to all registers.
7. Find a suitable spot in the house to install a wireless thermostat to control the new zones. To ensure accurate readings, place the thermostat away from direct sunlight and heating registers.
Expert assistance with this project was provided by Northeast Heating and Cooling [www.northeasthc.com/].
The motorized zone dampers are manufactured by ZoneFirst [www.zonefirst.com/].
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How to Zone a Forced-Air Furnace and Air Conditioner | Ask This Old House
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The look on that guys face is like he is doing a hostage video
Thanks Richard. I always learn something when I watch your videos!
Excellent info!
what a nice video!
good job rich
Good vid
having some issues with my unit, no heat, cool or fan.
Noticed one of my ducts fell down from the rack and i was ignoring it.
Noticed it had a "handle" just sitting there. Turns out it is that bypass thing valve.... that would explain why my airflow as sucked for 2 years....
Still have my main issue but i thought that was funning :D
You installed the bypass damper, however, did not install a discharge air temperature sensor (DATS).
This is interesting i have a split level house . The upstairs is above the garage. Duct works runs in the garage finish ceiling for the upstairs. Always freezing cold in winter. I Had hvac company looking into the problem. They said my only real option was adding electric baseboard heating for the upstairs.
Would love it if he slowly explained the how a room is configured with the vent and return.
Right
How about a link to this company's system so that we can look for installers and providers in our area?
Oil Furnace
The Forced-Air Furnace system is controlled by an electronics board only work good in lower lighting areas. In Florida, I would not use them because there are many lighting.
That’s right bypass hot air right back into the intake of the furnace. This will cause the furnace to cycle on the limit, or lock out completely. Every zoning system needs a discharge air temperature controller that will cycle the furnace off before the limit trips. Most of these zoning systems make the equipment cycle on and off excessively. This is like trying to make a variable air volume system, work with constant volume heating and cooling equipment. You can get by with a few dampers, if the ductwork is a little oversize, but 23? I didn’t know the zone control boards could handle that many, unless they used DDC type communication.
There's two zones. Each damper is daisy chained to the next one in that zone. You have the same bypass with a whole home humidifier and that works just fine.
so when I bring wire in the wires on the smoke detector will be like pigtails.? @ThisOldHouse
Should do a vid on the call back when it freezes up or cuts out on high limit should have used an ECM variable speed
Charles Bryant that’s what the bypass damper does. It mitigates that
@@BillyN31 No Charles is correct. The air coming out of the air handler has been cooled about 20 degrees from what it returned at so lets say the 2nd floor stat is set at 70 degrees. and the room is 73 degrees. The thermostat on the first floor is most likely satisfied thus closing the first floor dampers. That means air returning at 73 degrees from the second floor is being cooled to 53 degrees after it passes through the evaporator and heads out the plenum. So as soon as the air heads out of the plenum it will get redirected through the bypass because the first floor t-stat is satisfied. That means the air that has just been cooled 20 degrees is being sent right back a second time through the evaporator coil and cooling it an additional 20 degrees. I realize the air is going to be mixed with some return air from the second floor but lets say it is lowered 10 degrees instead of 20 degrees. That would calculate to 43 degree air entering the evaporator. The refrigerant temperature would be about 10 degrees lower which would make for a 33 degree coil. If it ran very long like that it would start to ice up. If the system was undersized like mine it would definitely start icing up. Not tryin to be dis agreeable but it could develop problems and lead to early compressor failure from liquid slugging back to the compressor due to low superheat.
victory21222 ok. I love your logical thinking! Thanks for being one of the few comments that is actually intelligent!
I really this video.
I want to know more about air distribution and duck system.
I have RMO license.
Do you know any training i could take ?
I live in Brooklyn,Ny.
You can find out more about ducks at your local pond.
I have a central heat and a/c with 3 zones, one of the dampers has power but 0 volts. I would like to know where is the problem, is damper or the electrical box that control the whole system. I changed all 3 thermostat and did not fixed the problem. Thank you for your help.
Juan Carlos -sounds like you need to call a qualified hvac contractor
Help me out.. what's the tool called that he use to cut out a perfect circle on the return box?
Malco HC1 i think
How big (sqft) is the house?
yee haw, this old house coming to oahu! they can do a filming on jalousie windows, how to plant a papaya tree, and install a washer machine plumbing outside on back patio, oh yeah, and what is this gadget??
+refrigeration tech Hi there, submit your requests here for a chance to land on Ask TOH! asktoh.thisoldhouse.com/toh/asktoh/question.jsp
Hi Richard Can the zone air conditioning ( heating or cooling)system be added to any heating or cooling unit or does it have to be a special type ?. I was consulting a local HVAC company representative to have zoning done for my house and was told that the zoning can not done on a single stage unit and it has to be variable stage or two stage unit. This amounts to changing my existing unit that is still in very good condition and probably has another 10 years of life. Also I was told that it is illegal to place a bypass duct in California because of health concerns. I am not sure if that is true or if there are any real health concerns and if so what kind of health concerns?. Appreciate your expert advice.
I need to do exactly the same thing for my house for 2 levels of controls - one for upper floors and another for basement. Can anyone help?
Ashoke Roy what state?
A cheaper thing to do would be to open the dampers manually in the rooms on the upper floor and close the dampers in the basement rooms during the summer. Do the reverse in the winter. This keeps the cooIer air upstairs and cool air sinks so the air will move down to the basement. Usually the basement stays cool during the summer anyway. I'd also buy fans (or ceiling fans if you can afford it) for the summer, and space heaters in the winter. Just run them when someone is in that particular room. You can get space heaters with thermostats for $40, floor fans are cheaper. Buying about 4 of each is around $250. Using them isn't going to raise your electric cost that much. In fact, you may be able to turn the thermostat down in the winter and up in the summer to offset costs. A new system will cost thousands of dollars, which you won't recoup in savings until probably 20 years, at best.
How did it all work? I was waiting and no finale? What happened. This all sounds good but I'm a little skeptical about how it all works out. I've been waiting for this for years. I seems too complicated for residential use. Only time will tell. Thanks.
How is this complicated. I followed this video , got a little help and installed it at my place. Saves bill by directing most of the heating / cooling to the upper floor when no one is in the lower floor ( read night time )
23 dampers at what? 75$ each? ouch
I looked up the company... Currently $238/ea for 8" dampers, and minimum $350 for the control board makes it $5,812
@@elooney85, I just looked up that company. Website is partially hacked.
All for a bit of tin with a servo on it. I wonder how much the control board is by itself.
E.Looney 😂😂😂
Where do we buy this ???
That is what i would like to know. I live in a one story home and the front of my house is always cooler then the back half. id love to zone my bed and bath room off from the kitchen, office, and livingroom.
pretty sure this is a repost. watched this clip on CZcams a while ago
Can you please provide the damper/ control brand name? Thanks in advance.
3:40 will give you the damper brand and model. Controller should be found via a quick google search for the brand.
I am also interested in modifying HVAC system in this way. What is the brand of your choice for damper and controller? Thanks
go with honeywell zone pro
How much should it cost to install the Zone Dampening system, on 2 story Townhome when building one. The builder is asking for $7.7k and I don't see it costing that much in addition to what you already showed. 3 floors 3 thermostat, 3 zones. shouldn't cost 7.7k
I assume that includes the cost of the furnace and A/C unit since that seems fair. Not sure how they designed it, but if there is extra ductwork plus the cost of the equipment, it will be a couple thousand dollars for sure.
shop around, you'd be surprised what the difference in cost is. The bigger guys have to charge a lot, and if you get someone that they hired, he may not be good. A small business owner/installer guy will give you a better job at less cost.
The cheese is strong in this one!
where do you get this system
What's available out there for zoning a boiler system?
Zone valves or separate circultors with anti convection valves and control board
@5:35 whole reason i came to this video... and they blow right over it :(
and what about half closing your registers on the first floor and fully open the ones on the second floor...? I thought that was the purpose of being able to adjust the register...???
DoMorin very noisy and can lead to condensation on grills which contributes to mold
It does work, I just put an extra couple runs in the basement to prevent too much pressure and noise.
I have a zoned system and it sucks upstairs as it does not maintain the set temp. May need to have a load calculation done to see if system needs to be re-sized $$$ had to replace all of my damper motors cost more than 75.00 🤑
If you are going to zone a system do it right and not like this. Go for 2 stage equipment with variable ECM motor and 2 stage AC. Or else you can run into high limit and freeze ups. This is a hack way to do it.
2 STAGE WONT GUARANTE ANYTHING.. A lot of time 2 stage kicks in High too quick and still have high static and oversize complete Variable system is best but who can afford them
A proper zone system designed to work with the equipmemt will allow full system control. Lennox harmoney systems have their own limits and safetys to prevent freeze ups and staging control. Do some research.
Title 24 says you need tape
That wasn’t cheap !
his comm closet is killing me
Maybe not such a good idea to put a bypass in so close to the return...can superheat the return air in the winter (and cause the furnace to shut down prematurely) or supercool it in the summer (and freeze the evap coil). Put in bypass dampers on some/all the branches. Same $ and prevents accelerated wear & tear on the expensive furnace and evap components.
I'm no professional by any stretch of the means, but this was the first thing I thought when he described what that did.
Personally, they should have just used the basement as a dump zone for all that extra air. There, solved.
@@cadets3 I dump most of my air in the basement, then it works it's way up to the first floor through convection, as well as the ducts. The furnace runs longer so the upstairs gets more heat. I just did that without any dampers, but will just shut ones off to one area if another area is cold. I really like having a warm basement, and the heat is much more even on the first floor. In the winter I shut off most of the runs in the basement and let most of it go to the upper floors.
Hackery at its finest...
What would be the solution aside from having a separate A/C compressor and furnace for each floor? Like everyone can shell out 15-20k in parts and labor to add that, right?
What a pain in the neck!
terrible way to zone. and bypasses are a really bad idea. if you have a single stage system deal with the extra noise or risk overheating/freezing your coil, along with killing your systems efficiency. Best advice is to have registers with big spaces that don't restrict airflow. Also extra velocity can be a good thing if you're properly directing airflow based on the location of your registers. It will get the hot/cold air to where it needs to be verses going where it wants based on convection, and will help mix the air creating a more uniform temperature in your home. At the end of the day there are better solutions but if you're retrofitting a single stage system, there are no guarantees zoning will be a great solution, but it can work just do not make more than 2 zones, and monitor your system to make sure the decreased air flow doesn't cause overheating or freezing of your coil. NEVER DO A BYPASS!
talljohn5350 - I agree with your comments. Have to make sure the minimum airflow requirements for heating and cooling are met when the smallest zone is calling otherwise will have issues with high limits in heating and ac freezing in cooling mode. But hey what do I know, I’m just a Carrier factory trained technical support specialist.
@@MarkMark-kq6mc , I couldn't agree with you more. I am amazed at some of the contractors that install these things and don't have a clue about temperature rise or how to take it or even how to locate it on the manufacturers plate. I yet to see one of these videos where the installer took the temperature rise after the installation was completed. But hey what do I know, I am just a first responder / HVAC technician for a gas utility with 35 years of experience.
@@boby115 I'm guessing this is an older episode, judging from Richard''s youthful appearance. Really, they are trying to retrofit an existing old system at low cost with the tools they had at the time, maybe. Even with the bypass, what hits me is that you have an HVAC system that is either over-sized or under-sized given how many dampers are open or closed. Plus, we've all read about proper sizing to avoid excessive on/off cycles. So, what is the solution for an existing home? And what is the solution for a new home?
Waaaaaaay too many moving parts. I have a similar system in my house and it’s 100 percent Garbage . If a company tells you that this an option and they want to install Ruuuuuun away as fast as you can
True. I've installed lennox xc20s and xc25s on peoples home and just the amount for a 5ton zoned system was over 20k and they are a piece of crap, yes I'll admit it does what you want to do but for that amount your better off getting 2 basic system for a less and lasts longer then those xc series
Well there are better systems why you have to do homework.. my boss does a system that uses air bladders to block the flow withpneumatics. The system actually works great.. did you buy the house eith the system already there or did you have it done..
The home is a new build and it was finished in early 2020, another problem I found with these systems is that if for some reason the upstairs gets hotter than the lower level and you need the heat on downstairs and the ac on upstairs you can’t do it. That alone is a reason not to use it. As strange as that sounds I’ve actually ran into that problem a few times .
Plastic zip ties? Really? Those things will last less than a year before they are so brittle every last one will have snapped in half.
What a jerk, the next person gets lacerations when working on the ducts. Cut the zip ties flush.
Every time he talks about HVAC I cringe, he is what we call a hack
Ask how to hack this old house