In these cases, you’d need something more powerful in order to properly exhaust the warm air. A working fan will grasp it t ightly. Of course, a tiny undercut would be a problem when the HVAC system is running, the exhaust vent is off and the door is closed. Is it normal or do I need to get the contractor back in? Danko: Ha!Danko: Ha! (But, hey, they have a radiant barrier!) The makeup air would come from the path of least resistance, and that could be it. Wonder if anyone can help with a problem I’m having: I’m replacing a small bathroom fan which didn’t work well with a higher cfm version. If you plug the vent it's going build pressure and blow back into the home. Scroll down to the table that shows the ratio of cfm to area for different configurations to find the numbers. The air doesn’t go where you’d like it to, but it flows easily. The fan and light operate separately or together and are housed in a classic white design that complements any decor. Great info. But quite a number of houses are in a humid climate where outdoor dew point is higher than the indoor dew point. Thus prevent the fan from sucking air. Except when it doesn’t, of course, as in in this case. When I put new fans in I of course redid the ductwork. Run new 4 inch duct and a newRun new 4 inch duct and a new 4 inch vent. Seen that happen a lot. Is your vent pipe large enough for the larger fan? As a property manager, I have seen several fires due to overheating motors in exhaust fans. (Remove all dust and dirt so the air can flow properly) Use a canister vacuum and remove ALL dirt and dust that is in the vent housing and and on the fan blades or blower wheel. Looks like i'll be in the attic making fiberglass snow angels. Code Compliance A bathroom exhaust fan works by pulling moisture out of the air before it can cause harm. Don’t Confuse Design Temperature With Degree Days. Check out these 8 spaces with tubs in the shower, Small wonders are challenging to pull off in bathroom design, but these 8 complete baths do it with as much grace as practicality, Mein Benutzererlebnis mit Cookies anpassen, World of Design: Where Color Trends Begin. Obviously ceiling-mounted bath fans can have problems with crazy flex ducts. Here, instead of blowing into an open duct or open space, the air hits compressed fiberglass insulation. Usually, no duct means better air flow. Despite all my research it was a mistake. First, it goes over a ceiling joist in the attic. There was 40 years of accumulated dust, like in a dryer filter. I guess they are supposed to have flaps in them too. Masha: No,Masha: No, bath fans should NOT be blowing air into the bathroom. The crack under the door is large enough for a toddler's hand (according to my wife) and the vent in the bathroom serves two rooms so that should provide additional air to pull. Indem Sie weiterhin auf der Website surfen bzw. I'd love to see what you're inspired by. Replace it if you have a bad switch. They’ll be lucky to get half the rated flow out of that fan. What have you seen? So a 50 CFM fan requires a 3/4″ to 1″ undercut, depending on door width. Duct too long. This decorative exhaust fan looks more like a conventional flush-mounted light fixture, but inside is a motor capable of moving 110 CFM. You can see from the dark spot on the fiberglass that some air does escape, but it won’t be much here. That cheap little plastic damper on the discharge of the fan has been stuck closed from installation due to drywall texture or paint overspray. Because of this, I installed a larger exhaust fan that was plenty more than our small bath needed and have begun to realize that it is not pulling air, condensation literally drips down the walls while she showers. Exhausting a bath fan through a soffit as you describe may be OK as long as there’s no possibility of feedback. The duct is clear, no obstructions.. What could the problem be? Remove the grille and try to find and clear the clog with a brush, preferably one that’s specifically for cleaning ducts. Right? If the duct is supposed to be going one way, the installer needs to install the fan housing with the duct opening facing that way. Walt S.: That really long run in #3 above does exactly that – dumps what little air makes it there into the soffit. Green Curmudgeons, Architects, and Outlawing Batt Insulation Barbara W.: You’ll have to have someone determine why they’re not pulling air out of those rooms. I am also glad to see that E.T. The vent pipe could be blocked, or it might just be snagged. I figured is was less back pressure than 15′ of 4″ duct with a 90 elbow and a roof cap. The hose is buried under attic insulation however so I can not say for sure. Every cubic foot (or cubic meter for those of you outside the US) of air that the fan removes from the bathroom must be made up by a cubic foot (or cubic meter) of air coming in. Hi there, Dee Dee! My bath fans were installedMy bath fans were installed as picture #1 above. Great post and excellent blog. Don’t just turn the fan off when you leave because it probably hasn’t done enough yet. Bath fans are great at exhausting humid or smelly air, so (in spite of the code loophole) every bathroom should have one. This is yet another very quiet bathroom exhaust … That duct needs to go all the way to the outside to do its job. Some of the fancy fans have lights in them and I am told that the fans vary in quality. You can revoke your consent to receive emails at any time by using the SafeUnsubscribe® link, found at the bottom of every email. I pulled my fan off from the bathroom ceiling and reached into the exhaust hose. And one thing not to forget. and one in the laungry rm. Bathroom exhaust fan not pulling air. Thanks. The fan blades spin the wrong direction and no air is pulled out of the bathroom. Is this a reason possibly to go with a simple wall-mounted fan (on an exterior wall, of course), like the Panasonic WhisperWall? Insulating bath fan ducts is a great idea, too, to prevent condensation inside the duct in cooler weather. The biggest problem Ii se isThe biggest problem Ii se is the use of flexible duct. This will disturb the airflow more than anything. Once the fog is gone from the bathroom in periods of high dew point, turn off the fan. Thanks. Isn’t having a bath fan going directly into the attic doing the same thing, putting humid air into the attic? These five problems aren’t the only ways that your bath fan’s air flow might be compromised, of course. The next time someone starts to takes a shower, leave the door open, but also open a few windows a bit around the house, not the bathroom window. The larger fan had the same size as the original. We did a master bath remodel and I got a multi-function fixture that was a vent fan, heater, light and night light. Maybe the bathroom is too big for it or your family is a huge fan of hot showers. The NuTone White 50 CFM Exhaust Bath Fan The NuTone White 50 CFM Exhaust Bath Fan with Light combines efficient air circulation and up to 100 watts of illumination in one easy installation. Great stuff! My guess is the bathroom fan exhaust pipe is located in a cold attic space. If your bathroom fan is not able to pull in air, it could be the fan is not clean and air gaps are blocked by dirt. In addition to being more energy efficient, they exceed the current minimum code-required air flow and are generally very quiet. We've moved and are doing another remodel, this time I'm installing one of those heat lamps - yep, may not be "modern and stylish" but they are effective! By removing moisture from the air before it's allowed to collect, bathroom exhaust fans help prevent this from happening in the first place. You will need about 300 square inches of opening all together. If the bathroom exhaust is not removing the moist air then you should get it fixed before you have mould problems. Not much comes through. Did you see it? I just got a new fanI just got a new fan installed and it seems that it is blowing air out as well as sucking it in. Mehr erfahren. Pull the grille down and pinch the springs to release them from the housing. Gordon T.:Gordon T.: I seem to recall responding to your question about wall-mounted fans somewhere (LinkedIn) and probably said they’re OK if they don’t go through a building envelope wall. There are numerous homes that are the same in our neighborhood and I have noticed they all have the master bath exhaust exiting through a side vent, where our home exits into the soffit. the reason you got mold on it is because the bathroom fan got it wet with moisture and you may also need some better ventilation for the attic and need some local advice on the amount and best methods for your area. As you can see in the photo above, there’s no duct attached to this fan. My favorite is the magicMy favorite is the magic connection. Mike E.:Mike E.: That’s another good one. Maybe you bought a small exhaust fan in order to save money. Not only does it have to make that turn, which reduces air flow, but the duct isn’t pulled tight, which reduces it even further. A typical bath fan is rated to move 50 cubic feet per minute of air when it’s operating, but most actually move about half of their rated air flow. Emails are serviced by Constant Contact, © 2020, Energy Vanguard | 533 West Howard Avenue, Suite E, Decatur, GA 30030, HVAC Design for Code Compliance | Energy Vanguard, HVAC Design Data Collection Forms | Energy Vanguard, Sample HVAC Design Reports | Energy Vanguard. Any advice or ideas would be appreciated. I like your bathtub though. As a general rule, a bathroom should have an exhaust fan that pulls out a minimum of 50 CFM or greater. If the bathroom fan motor won't run run, either the motor is burned out or there may be no power to bathroom fan, says Family Handyman. Colors go in and out of vogue. The usual culprit here is that the house is built too well without adding the necessary counter measures. That’s a bit unusual and could cause problems, depending on what else is in there. What an amazing resource. Because of this, I installed a larger exhaust fan that was plenty more than our small bath needed and have begun to realize that it is not pulling air, condensation literally drips down the walls while she showers. I realize this question is over a month old but wanted to share my experience. If the fan is not turning the wrong way I suspect your exhaust ducting or outdoor vent is blocked. The rule of thumb for sizing bath fans is 8 ACH (actual flow)of the bathroom volume. As for the humidity outside being greater, that is the reason for installing fresh air ventilation directly into the return side of the AC, bringing in clean, dehumidified air. Whenever you look for the flow rating of bathroom fans, do not forget to look at what pressure conditions they were rated for. Great stuff! Or does that carry energy problems of its own? What can be done to fix this problem. Then it goes into a piece of rigid duct that goes right up to another ceiling joist. I originally only asked about the exhaust exiting the soffit thinking this would be the only issue causing the lack of air pull but suspect now there are many more variables involved I have not thought of. Just some more info. If you have an older fan, check to see if it is thermal-overload protected. Use a 5-6″ duct, preferably insulated and run it “straight” up through the roof if possible. The humid air is sucked back in to the attic. Here’s another fan with a duct that starts off OK. …just as we get tired trying to find out how far this thing goes, the air inside gets too tired to make it all the way to the end. Akicon Ultra Quiet 90CFM Ventilation Fan. Where the contractor extends the flexible duct 15+ feet straight up and obviously over time it tears. There are several reasons why your exhaust fan might have stopped working. Here are 5 reasons why this happens. Went up into Attic and the Exh. Or, even if the bath fan was vented through a soffit, that is separated by 5 feet on either side away from other soffits, shouldn’t this solve bath fan air going into the attic? Here’s how they make their way into our home decor, Learn what features to expect for $3,000 to $100,000-plus, to help you plan your bathroom remodel, A designer and his team hit the industry’s biggest show to spot bathroom ideas with lasting appeal, Learn how to balance your budget and set priorities to get the home features you want with the least compromise. Clean the vent cover under hot water in the sink. It was very stylish and not cheap. The electrician is more concerned with the mounting fins than efficient duct flow. @Allison: it’s helpful to know how much undercut is needed so we don’t go too crazy with this — 1/2 square inch per CFM. The master bath has a 4″ to 3″ reducer then 5′ of 3″ ductwork with a long 45 degree elbow. Air flow can be restricted on the front end of the fan, too. What this means is that you need to run the bath fan with the door open for a while to get a decent amount of air exchange. Bob: Sounds like you’ve got your fans done right now. I have a 1″ undercut at the bottom of the bathroom door and the duct has one elbow at at the ceiling vent housing and then runs about 9′ straight out the back of the house. A stiff vent pipe is better because it does not snag. Insulate the duct. A fan will expel air, but only when there is makeup air to replace it. The fan pushes the moist air you create from taking a shower outside, so you don’t rot everything in your bathroom. Thanks! Here's how to do it best, Not a fan of shower-tub combos or of ditching the tub altogether? We have had luck in solvingWe have had luck in solving problem # 4 by having the HVAC contractor install the fan housing rather than the electrician which is customary. This isn’t a very logical ventilation method, especially when temperatures are below zero, or when the weather is 90°F and humid. Keep your ducts and grilles clean to have a good runnig power of your fan (the same as with your car). M. Johnson: Yes, that’s absolutely true. They work But they do not pull the air out the rm so they are not functional. Chris C.: Using metal elbows at turns is a great idea in any duct system. Great big undercuts in theGreat big undercuts in the bathroom? Thank you so much for posting photos - they are so helpful when trying to get an idea of what you're working with. Good topic. Use a metal elbow as is takes off out of the fan. Supposing there were both an HRV and a dedicated exhaust fan in a bathroom, and the exhaust fan happened to run when the HRV was not running, would that tend to draw makeup air from the HRV duct (i.e. One more scenario to considerOne more scenario to consider: ducts could be perfect to outdoors with no obstructions, plenty of makeup air is available, and the poor fan still not move much air. I love your analogy of soldiers crawling through the ducts. may not need to replace all of it just the obvious part but what a pain in the buttski that is going to be. I always like to tell people when laying out the ducts in craziest possible manner to imagine that they were soldiers who need to crawl throug these ducts to the end, and figure out which layout will exhaust them more. Why Do We Need Exhaust Fans? Get it checked out. Would this small difference be the reason for poor air pull or do I have a blockage somewhere. I’m sure the installer just took his lunch break and will be back any minute to finish this up. Don’t forget privacy concerns. System Replacement Generally, fans manufactured before the ’90s were not protected. Nice big outdated bathroom that is not very functional. Bathroom Specialist. Vent was never vented out side. The wire spiral that gives flex duct its round shape also gives it extra friction, especially when it’s not pulled tight, as you see here, so the air flow just peters out. Yeah, I caught that alien lurking in an attic about 3 years ago. The vent outside could be blocked. Having the fan exhaust intoHaving the fan exhaust into the soffit doesn’t help much, as the ventilated soffit is the intake for the ventilated attic system. Can i drop down a foot toCan i drop down a foot to exit the room to outside,I am in the basement and do not want to drill through the header. Data Collection Thanks! Check the fan switch with a voltage tester. To take full advantage of your fan's cubic foot per minute capability, it helps to supply enough intake, or makeup, air by leaving the bathroom door slightly open while the fan is … If so, the pipe gets very cold when the fan is not in use. You could be overworking it and it’s failing to keep it. Air King Ltd BFQ70 Snap-In Bath Fan - ENERGY STAR® This high performance ENERGY STAR exhaust fan features our unique Snap-In Installation System. If your duct gets too curvy your pressure losses will definitely overcome the rated pressure for the fan (might be good to post some article about fan system curves in a future to explain this concept in more details). Why do you have a fan in the laundry room, though? Thought you would like to know since no one mentioned these items. I wish you the best of luck with the sweepstakes - your bathroom definitely has potential! Given where I determined it exits in the soffit and the location of the fan I would say there are minimal turns if any as it is a straight shot. HVAC Load Calculations Is your furnace a high efficiency type that has a PVC flue and another PVC combustion air intake? What solutions are folks using for the bathroom return path problem? I wrote a couple of articles about this last year: An Easy to Fix Air Flow Problem That Can Save Energy – and Your Life 4 Products for Enhancing Air Flow in Dryer Vents. This cold pipe can cause the air inside the pipe to go from warm to cold. See if this helps, and report back. Replace a dead motor. 3. Or so they say. For an incognito bathroom exhaust fan, consider the Hunter Sona Bath Fan with Light. What about when the moistureWhat about when the moisture is high in the air outside anyway, such as on a rainy day the moisture levels outside could be at 96% humidity +. Not sure if this is the right forum for this, but I was wondering if someone could help. I tested the suction by using a Kleenex and the fan would not pull the Air out. :). BTW, yes, it is vented. 10 Bathroom Trends From the Kitchen and Bathroom Industry Show, Where to Splurge, Where to Save in Your Remodel, Where to Store the Towels When You Don’t Have a Linen Closet, How to Choose the Right Hood Fan for Your Kitchen, Green and Clean: Ventilate for a Healthy Bathroom, 8 Narrow Bathrooms That Rock Tubs in the Shower, how do i figure out the amount of tiles i need toile the bathroom. Open each a little bit so it doesn't get too cold in one room. A quick way to catch a blocked duct w/o going into the attic is put a piece of paper over the running fan and see it it can hold it. Letting the fan exhaust into an open attic will cause moisture buildup on the underside of the roof. The problem is when wood surfaces in the attic are colder than the exhaust air dew point… you get condensation. The baffle just inside the exhaust vent had about 1/4-1/2 inch of heavy compacted dust on the outside that was weighing it down and the force of the fan was not enough to efficiently lift it. These were both residential grade just more CFM on the new fan. Maybe he’s not coming back. not only majorly disgusting but also potentially dangerous. ACCA Manual D (3rd edition),Appendix 1, para. A1-2 and table A1-2 show a prety nifty table for sizing undercuts at a 300 fpm velocity. Now what? And yes, positive pressure ventilation systems can help with the dew point issue. 05)requires one square inch of free area opening per 1 cfm of supply air. The intention is to discourage the practice. The fan has failed the TP test as well as a small trash can bag test, it cannot pull either of these items. Your source of knowledge about the world of building science, home energy efficiency, green jobs and more. It is AMAZING how quiet they run when installed like that and they perform as expected. Shouldn’t a modest undercut along with the HVAC supply vent in bathrooms supply sufficient exhaust vent makeup air? Basically, a bathroom exhaust fan is simply a fan attached to a hose that leads outside. It’s a top choice if you’re designing a bathroom that is beautiful and functional. It sounds like maybe the fan flow is hitting an obstruction that’s deflecting part of the air back into the bathroom. I've checked the damper and located where it exits the home in the soffit and am ready to check the line for a blockage but wanted to ask before burying myself in lovely pink insulation. Can we look forward to something about mineral wool? Airflow at exit outside is strong. After removing all the dirt and dust, test the vent by turning it back ON. Here's another fan with a duct that starts off OK. Reset the circuit breaker if necessary. Turn on the exhaust fan and hold a thin piece of paper, such as toilet paper, over the grille. There's a 4" Exhaust vent going out Roof about 10' away, can I add the unvented Fan to the existing one or do I have to vent separately? Bathroom Workbook: How Much Does a Bathroom Remodel Cost? The old ductwork is about 5′ and straight, but it’s only 3″ around while the new fan has a 6″ opening with a 6″ to 4″ adapter. Putting in a bigger fan can overcome duct problems if it’s too difficult or expensive to fix the duct, but fixing the duct is always where I’d start. Here are my “Keys”Here are my “Keys” to get them to pass: Use next highest rated airflow for the rate you are trying to achieve. People who work on houses are a creative lot. All fans now are required to be. Do you have a heat recovery device to bring fresh air into the building? took a position of ductwork inspector on the first picture above. Even on a muggy day in Houston, though, bathrooms can have a higher dew point than outside – at first. Yet this time-honored method of bathroom ventilation is still enshrined in our … Realistically though, undercutting bathroom doors is probably the only viable option for these typically small rooms that have the doors open most of the time anyway. I’ve also seen why so many bathroom ventilation fans don’t move much air. Of course, the root of theOf course, the root of the problem is that the folks supervising the workers often don’t know what they’re doing. It is often considered aIt is often considered a gospel that these exhaust fans remove moisture from the house. How? To determine this, a few more questions....
Did they put plastic on the ceiling before the drywall? Sample Reports. Even when looking at the air that fan removes. I assume that is not going to lose a lot of its cfm rating. Do you have makeup air coming into the cold air return of the central air from outside? The way it’s hooked up the vent is pointing DOWNWARDS so condensation doesn’t fill up in the vent. Exhaust fans are used to pull air particles from your rooms and out into the atmosphere and can help remove heat during the summer. Allison, Allison, A thousand thanks for doing this blog. In the old days, if the bathroom was smelly or steamy, you were supposed to open a window to air it out. Let's all be honest - bathrooms are very rarely the nicest smelling rooms in your home for a myriad of different reasons. If you can locate the model number of the fan, and the manufacturer’s name, you can look for its manual online. Avoid venting through a soffit vent or ridge vent. Just wanted to question that conventional wisdom. Wonder if anyoneGreat info. According to code, a bathroom without a window must have an exhaust fan with a ventilation rate of 50 cfm for intermittent operation or 20 cfm for continuous operation.
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