How to Diagnose and Repair a Humid Air Conditioner | Ask This Old House
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- čas přidán 26. 05. 2019
- Ask This Old House plumbing and heating expert Richard Trethewey travels to Orlando to diagnose and repair an HVAC system that is creating way too much humidity
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Time: 3-4 hours
Skill Level: Expert
Steps:
1. When diagnosing a humid air conditioning system, Richard usually follows a series of steps based on the most common issue and works his way to more specific issues.
2. First, Richard checks the sizing of the equipment. Square footage alone isn’t enough to determine the appropriate size of a unit, since insulation, building materials, window openings, etc., can all also impact how much work a unit will need to do. He’s often found that units are oversized with the thought that “bigger is better”, but when that happens, the unit won’t stay on long enough to eliminate humidity. If the unit is the wrong size, it will need to be replaced.
3. The next thing Richard normally checks is thermostat setbacks. If the setback temperatures are too far apart during the day, the air conditioning system will have to work too hard to eliminate heat and humidity in the building, which would explain why the house feels humid. Keep setback temperatures to around 5 degrees difference to prevent the system from overworking.
4. If neither of these issues is causing the problem, it’s time to start digging into the specifics of the system. In this case, Richard found that a UV light was requiring a fan to be on all day. That fan was pushing the moisture collecting on the cold coil of the AC unit back into the building, causing the humidity.
5. To solve this issue, Richard removed the UV light and adjusted the fan so that it only turns on while the unit is in cooling mode.
Resources:
Richard installed the Healthy Climate Solutions MERV 16 air filter [amzn.to/2wfqX9k], manufactured by Lennox (www.lennox.com/).
Expert assistance with this project was provided by 4 Seasons Air Conditioning & Heating (www.4acnow.com/) and by Air Conditioning Contractors of Central Florida (www.accacf.com/).
About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers-and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.
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How to Diagnose and Repair a Humid Air Conditioner | Ask This Old House
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That's great you should make more HVAC videos so we can save on some energy, thank you!
Oh. My. Gosh. All this time and I thought running the fan at all times would help, but I have this exact issue.
Richard rocks! Life changing.
Amazing! This solved my problem
Glad I stumbled across this video. I kept wondering why in the afternoon my humidity level would keep rising.
When we would put the baby down for a nap, we would switch the fan to 'On' for the air conditioner and set it on 69. Usually like 2-4 hours of constant fan with the A/C cycling was the cause. Switching it to constant fan was just purely to add "white noise". I didn't do it yesterday and the humidity level never rose above 55%.
So much info that I have no where put it on thank uses guy for sharing all of your knowledge with use I watch you CZcams channel every day and am always learning something new. 👍🏻👍🏻👍🏻👍🏻
you should check out gun videos. youll learn a lot
Awesome video some really helpful stuff
Good information
Very well diagnosed.
Man the comments on these videos are disgusting. What is wrong with you people.
This was a really good segment! Thank you! Just goes to show to solve some problems you need experience and think very methodically.
1) Manual J calculation to determine if system sized correctly.
2) Keep system running at reduced level when nobody home.
3) Run fan only when compressor runs.
4) Lose UV light & upgrade to better air filter.
Wow, great info! I had no idea constantly running the fan would increase humidity. Our's is a little high and I’m running a dehumidifier to drop it.
Now you know to check for that blue light special that doesn't do what people actually need done.
i was going to suggest your condensation drainage line from a/c might be clogged. you ever notice houses have that white pipe that come off, thats where the water drains from the a/c after it naturally dehumidifies the house---- or in her case have to empty the portable dehumidifier bucket several times a day--- your line is probably clogged. maybe
I have been fighting with my air conditioner company for 22 years. When air conditioner is on the humidity goes up to 70% and when off, it’s 45%. They just tell me that’s fine and I have 5 dehumidifiers sitting around on floors just to keep high humidity from damaging house. I have always had fan set on auto although it is constantly running because the dehumidifiers add a tremendous amount of heat when running all day.
I think you need a new air conditioner company
The Filter which is MERV16 will not let a much air flow which means it will take longer to cool which means there will be more humidity removed when the A/C is operating.
I keep my fan set to auto, but the humidity level is higher than I’d like. I might try one of these 5 inch thick MERV 16 filters to see if that lowers the humidity in my house.
As you mentioned, maybe it will take longer to cool, which should allow more humidity to be removed.
I love how Richards narration during the HVAC upgrade clearly he watches a lot of How It's Made XD
Funny
Interesting
Something else that needs to be mentioned, is that the fan speed setting for the evaporator needs to be set at 400 CFM per ton of A/C. In this case, 1200 CFM. If the inside unit fan speed is set too high, there will be no way for the A/C unit to effectively remove the humidity in the house air. The inside evaporator in the basement will cool, but not dry the air if the airflow is too high, resulting in a cool, but very damp home.
Could also lower it to 350 for even better dehumidifying.
Thank you!!!
The audio is a little different lately
Yeah it's really low quality they must've changed the render settings
I don't think she expected such a HVAC Lesson! She's like umm-ok mmmm-hmmmm, Right! Ok, Yeah! I think she is over it and just wants to get it fixed! Lol!
Karra needs to call in an insulation service. She's likely spending way, way more on cooling than she needs to.
Block construction. Would have to add on outside or inside. Expensive so few do in that climate. Do wonder if attic could have some.
Somebody should have planted trees a long time ago.
but i bet shes warm in the winter. I run hot
@@Thumbhit1 rare, but still economical when there's little to no insulation. The utility will probably even subsidize it!
@@Thumbhit1 Richard seemed to imply the attic had room for insulation but there wasn't any.
*No* insulation? SMH That woman's electricity bill must be big.
That space looked like a utility room that was a converted garage. Watch at 4:06 on the right of the house. Hopefully she keeps the interior door shut to the garage.
Agreed. However the heat calc he discussed said the inside (not the utility room) had the same features.....I guess? Either way, that person should invest - as she has $$ - on some insulation. It would help with her bills and comfort.
When yo know your stuff, you know your stuff.
Going from a 1inch filter to a 4inch filter , wouldn't that causes significant air flow reduction? Isn't the evaporator fan motor designed for that one inch filter?
certain ones can accept a 4 inch one but im sure a quick blower motor change was done in the back
Because of it's larger than normal surface area, the pressure drop across this 5" thick filter is lower than a typical 1" pleated filter. So it doesn't make the fan work harder & it keeps the AC unit and the air much cleaner. No motor change necessary but it is important to check the total system static pressure in order to make sure that the duct system is not too restrictive.
My ac company said my filter merv was to high causing limited air flow. Suggested getting a lower merv.
Is that the only place that filter could be installed? I know I would not be well if I had to climb up into the attic to change the filter, even if it is only once a year. Couldn't it be installed on the return vent on the wall, in the house for easier access?
Its placed before the unit so it handles all return air. The duct tied into could be picking up returns from multiple locations.
In this case it would be a good idea to take out a maintenance contract which includes changing that filter.
Putting the filter at the return vent does not guarantee that the filter will catch all the dust in the house. I am in an apartment and the only thing they put in the furnace is an electrostatic screen which doesn't do much good.
I have filters in front of my intake vent but they don't pick up all the dust blowing through the system.
Because that screen is the only thing in the unit, it is loose and dust is pulled in from outside. They told me that they lost the key to the furnace door so I'm thinking of picking the lock so I can put an actual filter in the thing.
@@scotttovey there's a lock on the door? Lol because who needs maintenance anyways 😂
@@Ariccio123
The furnace door access is out on the balcony, patio for ground floor apartments. I'm told they lock them because they don't want renters storing things in with the furnace.
I'm like, just evict people that do! Duh!
Great show! Im wondering which app is used to calculate the decision on tonnage of AC? Thanks in advance!
If it exists, the This Old House app
@@kotk05 that's not it. Tks
They have free exel manaul J out there
It is based on a calculation called ACCA Manual J and is very scientific and takes training to do correctly. The block load calculations are easier to do but much less accurate (most app based calculations are block load).
Hi TOH , Happy Memorial Day ! 😊🇺🇸🌷🌸💐🌺🌹
WE DONT SAY ''HAPPY MEMORIAL DAY'' NOTHING HAPPY ABOUT THAT DAY
Her hair is super nice.
She's cute, the dark hair is really nice too :)
@AstronomyToday lol nice
If you wire the UV outlet off of the EAC terminal on the air handler board it will only turn on if blower is energized. That's what I do if the UV light makes ozone also
@john vonburg Some UV light brands purposely make ozone. So when the product states it makes ozone that's how i know. I understand the UV light was not the cause of the issue here...was just pointing out a solution to the issue they mentioned about leaving the fan on constantly for the ozone from the UV accessory
Richard did not go up in the attic. he would be sweating like a pregnant nun
He was being polite
@@anwarlucas he was lying
He is on TV
He makes too much money to be crawling around in the attic. That’s the job of the low ranking support tech.
Why does the audio sound off
Or sound bit deeper
Sammad yeah the sound is wrong
@@ian22222 probably optimized for laptop speakers. didnt notice
In spring and summer I have higher humidity than I like in the house. Several years ago I replaced my old Trane with what the dealer recommended - a very high-efficiency unit (even thought the old unit was very efficient and gave us no humidity problems whatsoever for almost 20 years and ran like a champ. But a freak problem NOT within the Trane unit forced us to scrap it (sadly) because the coolant needed was no longer available. So we were forced to buy a whole new system in order to comply with the new regs. Ouch! The new unit cools like gangbusters but it does it so fast there is not enough time to dehumidify the house like before. Have to have napkins under your glass of ice tea or whatever to soak up the condensation. Never had to do that before. I complained several times to the dealer/installer but to no avail.
mweb9 I would change your thermostat. If you have a high efficiency unit you should have staging meaning two stages of cooling. I know with the ecobee thermostat (what I recommend and use) it will run on a dehumidifier mode with the lower stage not to cool but to dehumidify (obviously). Often the thermostats these manufacturers push with their units are both overpriced and bad. You shouldn’t be having those issues with any sort of newer, efficient unit unless they way oversized the system.
@@Alexlfm This is good information. I have the same problem. New heating cooling unit came with condo. Its always super humid in there to the point we ache all over. Will look at size and getting a 2 stage themostat.
6:03 if they're *that* worried about allergens, they should have some better way of preventing air bypass. Gaskets, weatherstripping, or whatever.
And maybe still use the 1 inch pleated filters to protect that giant expensive thing!
They are never going to change it and after 1 year buy claritin to fix the problem
What app is he using
Your smart... U made me smart with plumbing
welcome
On that next thermostat there is an option for cool to dry. And it monitors the humidity level and turns on the ac if it is too humid.
Wow that thing was big I wonder if it works the fan harder
Because of it's larger than normal surface area, the pressure drop across it is typically lower than a 1" pleated filter. So it doesn't make the fan work harder & it keeps the AC unit and the air much cleaner.
how much does a job like this cost, on average?
How did the temp on the thermostat go from 73 to 78 so fast?
AstronomyToday that Nest ain’t cheap. 250 bucks market price. 73 could be the set temp and 78 could be the room temp.
Z. W. That market price is typically a suckers price though, at least it is with the ecobee.
In an case your right about the setting and current temperature likely being different. It is a genuine Nest as can be seen from the app.
Alexlfm I like ecobee more than Nest. I’m a HVAC tech, we just have too much problems with Nest in the field. It takes forever to get s hold of the customer service.
AstronomyToday it is a real Nest. You have to watch the video carefully again.
We recently set up our Nest to run the fan for 15 minutes each hour between 12pm-10pm. I don't think it increases the humidity at all.
Blaine Bugaski it’s mainly right after the ac turns off . Once the evaporator coil can drain the water off you’re good to go
@@christreacy4714 I suppose that can take awhile especially on a hot day where the A/C is running a lot! Or perhaps it never dries off completely. But if the pan isn't clogged and neither is the plumbing it really shouldn't be a huge problem so as long as it is draining well.
The AC coil is not cold when it is not running , so it wouldn't pick up humidity off the coil just running In fan mode. She's pulling in alot off outside air because off the lack off insulation. Might as well run the fan with the window open.
The AC coils get covered in frost when the AC is in on. Typically the fan shuts off when the AC is off and the frost melts and flows out via the condensate line. With the fan on all the time the warm air was evaporating the frost from the AC coil and putting the moisture back into the air instead of draining out via the condensate line.
@@Jacob-5949 The evap coil shouldn't have frost on it. If it's icing up thats another issue. When the compressor turns off , the evap coil doesn't stay cold for long . After a few min your coil shouldnt be cold anymore. If you're running the fan over a room temp coil , I don't see how it'll pick up moisture from it. Unless I'm wrong.
The evaporator coil should never have any ice for frost , that would indicate an issue . I have seen many cases here in VA of someone running the fan all the time and having high humidity levels and the houses were pretty tight. The air passing the coil, after it’s off of course, will pick up moisture that hasn’t drained off of the coil and humidify the air.
Have no idea what he did to make the house “less” humid. All he said was he changed the settings on the thermostat but didn’t say what he set it to.
He turned the fan setting from on to auto.
Trees should never be included in a load calculation. They could be gone tomorrow.
thats a great point. I always been a fan of warehouse homes. a home built in a warehouse
@@montanaspring7176 You mean "Pre-fab".
That filter was thick.
Extra thicc filters.
T H I C C
THICC DUCK
I had the same thing happen with my system when I ran the fan continuously. I disagree with Richard regarding the UV light, particular in the age of Covid. I am undergoing chemotherapy, and I have UV lights on my 2 systems in my house. While the light won't do anything against allergens, they certainly are effective against viruses, bacteria and mold spores. Plus, you can now get UV lights that don't generate ozone. These are relatively inexpensive insurance, and provide peace of mind. Obviously, they need to be maintained but so do the filters on the system.
so should you run the fan on all day? Or should it only turn on when the AC turns on?
It should only turn on when the AC turns on
3 yrs later where is the follow up video
I think it’s safe to say this woman didn’t care about anything Richard was saying
I think it's safe to say she didn't understand most of it. Watch her body language.
should have put it downstairs where she can get to it. that is 75.00 just to have someone come and change that filter, if not more.
Audio is still terrible
Hi, I mistakenly removed the styrofoam inside an 18000 btu air conditioner because I thought it was packing. Can this be repaired? Where do I buy the polystyrene styrofoam to repair this????
Still audio problems
How much to get that extra part installed???🙃
mold mold mold mold mold
The uv light is used for one reason.
Mold!
Are u suprised yet. People get a uv light when mold is present. In the air or in the home.
If the air is dry you shouldn't get mold anyhow.
@@peppeddu if the air is dry. Than yes but there is proven humity and alot other factors do come in to place other than wet or dry air.
If the basement is finish or unfinish.
If the foundation is letting water in.
If there is weaping around the house.
Or a french drain.
Or the health of the people living there.
The ac inside coil has insulation coating the sides. Ive always seen mold grow there and be supplied in the house from there.
Removing the uv light may help for comfort. But removing it also may have a lasting effect on the health of the occupants. Only time will tell.
We got a UV light to combat mold too. On our A coil in installed it on top of the A coil and it is prestine and clean, but underneath it is and was still moldy. I'm about to install another one under and block and protect our plastic drain pan from the UV. Not sure how to avoid the mold on the coil to begin with. We live in hot Central Florida. 😎
In general, UV light can harm the genetic material in a variety of pathogens to reduce or eliminate their chance of reproduction, essentially rendering them useless. In fungus and bacteria, this damage occurs in the DNA, while the RNA is impacted in viruses. [1]
In one promising study, far-UVC light, a powerful form of UV light, has already demonstrated an ability to “destroy the outer protein coating of the SARS-Coronavirus”-a different, yet related virus to SARS-CoV-2. [2]
This destruction effectively results in the virus’ inactivation. And due to the similarities between all human coronaviruses, it’s thought that far-UVC light would prove to have a similar inactivation effect against other related coronaviruses, including the one behind COVID-19. [3]
Why is he not putting it in? but yet he had a different technician
What’s up with the sound?
How can I get one of you out to help me
y no mastic
you couldnt put that downstairs so she could change it herself??? how is she supposed to get up there??? she is gonna have to pay to change that filter. sad. and what about old houses that leak air like a sieve? a constant fan keeps the temp constant, so what about their humidity??? good otherwise.
Clearly this problem has existed since installation. Why didn't she get it addressed by original installer earlier?
It's called This Old House, not This Old Interrogation
It is possible that she did and the original installer could not fix the problem. Sometimes, it's about experience and not book knowledge.
I had a brake problem where the brakes were sticking and wearing prematurely. The place I took it into a couple of times could not fix it. I then took it to a different shop and they suggested that it was a worn rubber break line. The line was replaced and the problem was fixed.
Sometimes, it's about experience and not book knowledge.
Because it wasn't from a company
Craiglist hacks
@@scotttovey a little book knowledge helps to know that there are brakes on our vehicles to slow them down, not breaks.
@@RoastBeefSandwich
Hey, even brakes need a break now and then.
Spell checker does not spot properly spelled but wrong word scenarios.
It gets worse. There's the triad usage confusion of Two, to and too as well as They're, there and their.
For whatever reason, I had not noticed that the breaks would not stop for lacking brakes.
It's a good thing I'm tired, otherwise this post might begin to resemble the energizer Bunny.
Did he say 3 tons on a 900sqft home?!??
No insulation, with masonry block wall construction in Florida. So it stands to reason. The number of south and west facing windows wasn't stated. That also affects the heat load calculation as well.
Flexible return..... Ok SMH😑🤦
There's a flex ductoctopus waiting to attack in that house
And yeah, they're scary common. Trying to replace mine, what a PITA... It makes 270° turns!
Sometimes you have to get creative with return air... But never use flexible duct for your return air. Build a box and connect to that 💪
The filters thickness being a 1 inch or a 5 inch is completely irrelevant to it's ability to filter larger or smaller sized particulates.The only point is that it's going from a merv 8 to a merv 16
Do you think changing to the 5 inch MERV 16 filter would actually help lower the humidity level?
@@TJ-22 No. You want to make sure your system refrigerant charge is good so that the indoor coil is getting cold enough to condense humidity. You want to make sure your coil is draining condensate properly and isnt clogged up. You want to make sure you run the fan on AUTO and not ON.
@@zesty2023 We only run the fan on auto. It’s a fairly new unit so I think the refrigerant charge is fine, and the coil is draining properly, But I’ll need to follow up on that. Thanks. I noticed that the run cycle time only lasts 7-9 minutes. Initially, I thought maybe the unit is too large, but then I thought maybe these new units are designed to run for a shorter run cycle times than the older ones. It is a single stage unit. There’s no problem with cooling, just humidity reading in the 60s according to the smart thermostat.
Did I just watch
Yes
@@Ariccio123 si
I see obesity
First
💩
1Ton of air condition covers 600sqft. She has 3 ton = 1800 sqft of cooling. She has a 900 sqft home. It's over sized. This guy has no idea what he's talking about. Imagine telling a customer you have 90% humidity because of your fan being ON. Moronic.
Too much talking....
The lady is very pretty.
this part is boring
Then don't read the comments silly!
LOL 🤣😄😎