A whole house fan pushes hot air out through the attic vents and brings cool, fresh air in through open windows. Benefits Of A Centric Air and QA-Deluxe Whole House Fans. Why People Love Whole House Fans. Whole house fans offer a variety of benefits that can enhance comfort, health, and financial savings. Simply open your windows and let the fan do its job! Within 5 minutes, the fan will completely replace the air in your home. To quickly cool your home down in the morning, use the whole house fan before outside temperatures warm up. After the house has cooled, turn off the fan and shut windows. This will reduce usage of your air conditioning ...Description. The Original Quiet Cool CL-2250 whole house fan moves 2,465 cubic feet of air per minute on high, giving you superior, cool airflow without air conditioning, and dramatically cutting your electric bills. Ideal for master bedrooms or larger rooms where additional fans may be present, this whole house exhaust fan offers convenient ...Our QuietCool Whole House Fans save customers up to 50-90% off A/C related electricity costs. QuietCool house fans are a ventilation system that is whisper quiet compared to old, traditional whole house fans. Because it is quiet, homeowners will run it for hours at a time allowing it to cool the entire mass of the home. The Whole house fan will ...A whole house fan works on an air change rate which is a measure of the air volume that’s being added or removed from a house, then divided by the …The amazing Whole House Fan with our exclusive Zephyr... Whole House Fan Company, Sacramento, California. 312 likes · 1 talking about this · 17 were here. The amazing Whole House Fan with our exclusive Zephyr Blade is the most effective way to cut your enThe HV1000 R38 Whole House Fan easily mounts in the attic on 16 or 24 inch on center joists. The fan can be installed vertically or horizontally. This 1000 CFM* fan quickly circulates air and cools your home whenever the outdoor air is cooler than the indoor air. The HV1000 R38 Whole House Fan operates at one speed to exhaust hot air, indoor ...Aug 4, 2022 ... In the US a whole house fan (or sometimes referred to as an attic fan) refers to a fan that exhausts the air in the house to the outside.A whole house fan is a ventilation system that helps cool your home by drawing in fresh air from outside and pushing out the hot, stale air from inside. It is typically …Top 10 Best Whole House Fan in San Francisco Bay Area, CA - December 2023 - Yelp - Element Home Solutions, Bay Area Whole House Fans, The QuietCool Guys, Northern California Whole House Fans, Jazz Heating, Air Conditioning & Plumbing, Atlas Heating, Air Flow Pros Heating And Air Conditioning, Hassler Heating & Air Conditioning, Bay City …When a radiator fan belt breaks, the entire car engine can cease to work. A dead battery is a high possibility. In addition, the break may cause serious damage to the alternator, r...When it comes to constructing a new house or undertaking a renovation project, accurate house plan drawings are crucial. These drawings serve as the blueprint for the entire constr...Check Price & Details. QuietCool comes with a high-quality whole house fan that can satisfy a lot of buyers’ needs. With 1472 CFM, this fan can be duct in the attic in order to reduce any unnecessary noise. While using this fan you can be sure that there will be no heat or cooling waste between the house and the attic.1-800-818-4298. Perks. Benefits of a Whole House Fan. Cools Quickly. Bring outdoor fresh air into your home & push out hot attic air making your home up to 10° cooler or more. Lower A/C & Operating Costs. Save up to 90% on your cooling costs using a whole house fan instead of your air conditioning.The HV1000 R38 Whole House Fan easily mounts in the attic on 16 or 24 inch on center joists. The fan can be installed vertically or horizontally. This 1000 CFM* fan quickly circulates air and cools your home whenever the outdoor air is cooler than the indoor air. The HV1000 R38 Whole House Fan operates at one speed to exhaust hot air, indoor ...Aug 24, 2020 ... sound familiar? A whole house fan is using the same principles as bathroom exhaust fan induced ventilation but with a larger fan. The benefit of ...With the active ventilation of a whole house fan, the powerful breeze coming through the windows in the home allow homeowner’s to feel 5 to 10º cooler within seconds of turning the whole house fan on. Save up-to 50-90% on A/C costs. Homeowners are saving tons of money on their A/C usage due to the energy efficiency the whole house fan brings.Whole-House fans can be effective in any climate, but they are more appropriate for dry climates than humid ones. As a general rule, climates that have nighttime lows below about 67°F during the cooling season (or shoulder seasons, if operated only then) and day-to-night temperature swings of about 25°F or greater are ideal for whole-house fans (Givoni 1991).The most common time to operate your Whole House Fan is when the outside temperature is 10-15 degrees cooler than inside your home. These fans are an alternative to air conditioning. Whole House Fans can also be used to exchange the air in the home, helping to remove indoor pollutants, odors. moisture and VOC's.This whole house fan is in my home. I have used it since it was installed in 2016. For every website that says whole house fans waste money instead of saving it, there is a study that shows the opposite. Take for example this report from the National Renewable Energy Laboratory, a laboratory of the U.S. Department of Energy.Whole house fans come with numerous benefits: The most significant advantage of a whole-house fan, is its reduced energy consumption compared to an AC. This leads to lower energy bills which prove especially useful in hot summer months. Besides, these fans quickly cool your home. They take only a few minutes to cool your …Hvac. How Much Does a Whole-House Fan Cost? [2024 Data] Normal range: $800 - $2,400. A whole-house fan costs between $800 and $2,400, with a national average of $1,700, …Feb 23, 2023 ... Despite what some people think, QuietCool whole house fans were not created to eliminate your air conditioning, but with QuietCool you can ...Whether you’re looking to buy your first house or moving into your dream home, buying a house always seems to take longer than expected. It usually takes a few weeks just to look a...The average price for Whole House Fans ranges from $100 to $3,000. What are the shipping options for Whole House Fans? All Whole House Fans can be shipped to you at home. Is there a 6878 product available in Whole House Fans? Yes, we carry a 6878 product in Whole House Fans. Check out the 6878 CFM Energy Saver Advanced …1. QuietCool QC ES-5400 Energy Saver Whole House Fan. 2. Cool Attic CX24DDWT Whole House Fan. 3. Tamarack Technologies HV1000 R38 … A whole house fan pushes hot air out through the attic vents and brings cool, fresh air in through open windows. Benefits Of A Centric Air and QA-Deluxe Whole House Fans. Why People Love Whole House Fans. Whole house fans offer a variety of benefits that can enhance comfort, health, and financial savings. 5 Best Whole House Fans. April 3, 2022 by Roy Cohen. It’s understandable that you may be wanting to look at alternative options to air conditioning your home. With the best whole house fan, you’ll be able to save up to 90% on your energy bill. After searching through many whole house fans, we found the best one to be the QuietCool QC CL-4700.5 Best Whole House Fans. April 3, 2022 by Roy Cohen. It’s understandable that you may be wanting to look at alternative options to air conditioning your home. With the best whole house fan, you’ll be able to save up to 90% on your energy bill. After searching through many whole house fans, we found the best one to be the QuietCool QC CL-4700.The QuietCool QC CL-6000 5665 CFM House Fan is an advanced whole house fan that improves ventilation cooling and reduces cooling costs by up to 50-90% compared to traditional cooling methods like air conditioning. With its durable construction, this fan provides reliable cooling for your entire house.The whole house fan works by moving hot air from the living areas to the attic thus creating a negative pressure inside the house. This negative pressure will draw the cool air from outside through the open windows which in effect will lower the temperature of the house. The hot air moved to the attic will be vented through the soffit and ridge ...When a radiator fan belt breaks, the entire car engine can cease to work. A dead battery is a high possibility. In addition, the break may cause serious damage to the alternator, r...The QuietCool brand of whole house fans has taken America by storm. The QC CL-2250 advanced whole house fan is a new take on the idea of whole house ventilation. Whole house ventilation allows you to bring the cooler outdoor air through your windows, home and attic space to thoroughly cool and ventilate both the home and attic.Comprehensive whole-house fan installation and repair across Greater Merced. Consult our experts. Skip to content. 209-723-0062. Emergency Services. Home; Heating. Furnace Repair; ... Whole-house fans can be an extremely efficient way of providing indoor air quality by ventilating your entire home with fresh air circulation.Whole House Fan - recommendations. I've put a few whole house fans in like this one. Although they work and are great for cooling the house with out using the AC, When set to high, it sounds like there is a P-51 in your house. I found this company and read a few reviews that seem like it is a good alternative (same air flow with a dramatically ...Quiet Cool Whole House Fan Explained in 3 Minutes. Watch on. A whole house fan works on an air change rate which is a measure of the air volume that’s being added or removed from a house, then divided by the volume of the actual space. When it comes to these specific types of fans, they should be operating at 30 to 60 changes per …HV3400 2 Speed Whole House Fan With Remote Control $ 1,685.00 – $ 1,765.00 Select options; LIFTLOCK 2500 Whole House Fan – no duct $ 1,429.00 Add to cart; As Featured On. Contact Us. 1 800 222 5932. Tamarack Technologies, Inc. 20 Patterson Brook Road – Suite #7 West Wareham, MA. 02576. Send us a message. Quick Links. Home; Fan Finder;Whole-House fans can be effective in any climate, but they are more appropriate for dry climates than humid ones. As a general rule, climates that have nighttime lows below about 67°F during the cooling season (or shoulder seasons, if operated only then) and day-to-night temperature swings of about 25°F or greater are ideal for whole-house fans (Givoni 1991).May 1, 2019 ... In that article, I wrote, "Because they depressurize a home, whole-house fans can cause atmospherically vented appliances located inside a home ...Rattling and banging most likely means the fan blades are banging against the housing as they turn. It sounds like a helicopter with bad blades is sitting on ...When it comes to ensuring uninterrupted power supply for your home, whole house generators are a reliable solution. These powerful units can provide electricity to your entire hous...With sizes as small as 80 square feet, tiny homes are any dwelling under 400 square feet. The small-house movement embraces homes under 1,000 square feet in size. Take a peek into ... 42 in. The QuietCool brand of whole house fans has taken America by storm. The QC CL-2250 advanced whole house fan is a new take on the idea of whole house ventilation. Whole house ventilation allows you to bring the cooler outdoor air through your windows, home and attic space to thoroughly cool and ventilate both the home and attic. Jul 18, 2023 · This rapid air exchange—large fans can purge a house of hot air in two to three minutes—not only removes built-up heat but also creates a pleasant breeze. A whole house fan can turn over the air in a home up as much as six times an hour, depending on the size of the house. When you use a whole-house fan, it’s important to open doors and ... Whole House Fan vs Attic Fan. Whole house fans and attic fans are often confused. However, they are not the same thing. Attic Fans – ventilate only the attic to reduce heat buildup and operate year-round ; Whole House Fans – ventilate the whole house, including the attic and living space by bringing cool air from outside into the house to cool it and …Top 10 Best Whole House Fan in San Francisco Bay Area, CA - December 2023 - Yelp - Element Home Solutions, Bay Area Whole House Fans, The QuietCool Guys, Northern California Whole House Fans, Jazz Heating, Air Conditioning & Plumbing, Atlas Heating, Air Flow Pros Heating And Air Conditioning, Hassler Heating & Air Conditioning, Bay City …Rather than directing all of that hot air out of vents throughout your home, whole house fans pull air in through open windows and allow the incoming air to ...Whole house fans are well known for being more energy-efficient. Overall, whole house fans cost about $0.01 – $0.05 per hour of use while an air conditioning system may cost about $0.20 per hour of use.. That’s enough to really add up over time! Does a Whole House Fan Save Money vs. Air Conditioning?Cleaning your whole-house fan is easy and should be done regularly to maintain efficiency. If you’re looking for a contractor in Atwater, CA, for help, the experts at Cosmic Comfort are here to help! Our team of professionals can inspect and service your fan to ensure it runs optimally. Contact us today, and let us help you! Renting a room can be a cost-effective alternative to renting an entire apartment or house. If you’re on a tight budget or just looking to save money, cheap rooms to rent monthly c...Actually, it is recommended to run a whole house exhaust fans overnight. This way, you are cooling more than just the air, you are reducing the temperature of your home's entire structure. It takes time to cool off your home's shell which includes the siding or sheetrock, and the underside of the roof or the roofing membrane.A whole house fan is a cooling system that circulates air throughout a home and offers enough attic ventilation and cooling. Whole house fans are … TTi HV1600 R38 Whole House Fan (2 Speeds), Insulated Quiet Cool Attic Fan with Remote and Self-Sealing Doors, Duct Free Whole House Attic Fan Improves Air Quality. 24. $1,02500. FREE delivery Feb 28 - Mar 5. Or fastest delivery Tue, Feb 27. For homes or buildings with a whole house fan, the hot air is pulled into the attic. Due to positive pressure, air in the attic is pushed out through the vents or gables. Simultaneously, negative pressure is created in the living area, which helps to draw cooler air in through the windows. On the other hand, attic fans simply force hot air out ... Whole house fans are great alternatives to central air conditioning to cool your home. Check out our comprehensive guide and top reviews! Skip to content. Menu. Home; Learn; ... Looking for a whole house fan to supplement (or replace altogether) central air conditioning for your house? Perfect! In this proHVACinfo guide, you’ll learn:The Trident Pro Series 6.5 is an installer exclusive QuietCool whole house fan and is a great option for homes around 3,000 square feet. The TRI PRO 6.5 is the most powerful whole house fan in the our Trident Pro Series. Capable of a whopping 6,123 CFM this 4 speed whole house fan is also the most versatile of the series with a wide CFM range ...Northern California Whole House Fans, Sacramento, California. 182 likes · 5 were here. We carry the Quiet Cool Whole House Fans. 15yr warranty on parts and labor. Call or visit qcwhf.com A whole house fan is a powerful and energy-efficient way to cool your home, improve your indoor air quality, and save money on your energy bills. These innovative systems use the natural cooling power of outdoor air to rapidly cool your home and provide instant relief on hot days. With a whole house fan, you can enjoy a more comfortable and ... Dec 31, 2023 · The Tamarack is a unique whole house fan that features self-sealing insulated doors with an R38 rating. Unlike other whole house fans that leak air into and out of the attic, the Tamarack unit creates an air-tight seal. The dampers automatically open when the fan is in use, and they close when the fan is shutoff. So, if 1) you are buying a home with an old whole house fan that is still functional and, 2) you enjoy opening up the house during cool and moderately warm weather, then definitely keep it and use it until the high humidity days arrive. But a whole house fan turns from energy-saver to an energy-waster during heating and air …When you’re a general contractor, you’re responsible for the construction taking place at someone’s home or business. The task could be as simple as installing new doors in someone...Apr 8, 2020 · Quiet Cool Whole House Fan Explained in 3 Minutes. Watch on. A whole house fan works on an air change rate which is a measure of the air volume that’s being added or removed from a house, then divided by the volume of the actual space. When it comes to these specific types of fans, they should be operating at 30 to 60 changes per hour to be ... November 19, 2020. Expert, unbiased advice on how to buy a whole-house fan, including options, sizing, when and how to use them, and manufacturers. In This Article: Whole House Fans vs. … QuietCool has been one of the fastest growing companies in the United States for the past 7 years thanks to our extensive expertise in the residential ventilation world. We have the ultimate line up of residential fans including whole house fans, smart attic fans, solar attic fans and garage fans. At QuietCool, integrity, diligence, and ... More often than not, the malfunction is due to some loose wires or an insufficiently oiled bearing, both of which can be addressed in the blink of an eye. Here are 6 reasons why your whole house fan is not working: A broken motor. Overheating. An insufficiently oiled bearing. Loose wires.However, on average, running a whole house fan for 1 to 2 hours is sufficient to circulate fresh air and cool down the house. 4. In addition to cooling, whole house fans also contribute to improving indoor air quality by expelling stale air, pollutants, and odors from the house, allowing for a healthier living environment. 5.Simple, step by step instructions to guide you through the installation of a Centric Air Whole House Fan.Video Transcription: Thank you for your interest in ... A whole house fan is a type of fan, commonly venting into a building's attic, designed to circulate air in an entire home or building. The fan removes hot air from the building and draws in cooler outdoor air through windows and other openings. While sometimes referred to as an "attic fan", this term properly refers to a powered attic ... Whole House Fan - recommendations. I've put a few whole house fans in like this one. Although they work and are great for cooling the house with out using the AC, When set to high, it sounds like there is a P-51 in your house. I found this company and read a few reviews that seem like it is a good alternative (same air flow with a dramatically ...Mar 2, 2023 ... The capture hood must fully cover the inlet grille and the equipment should measure the amount of airflow for which the WHF is rated. For ...Our Classic Series is the powerful Whole House Fan that started us on our journey of accomplishing energy-efficient whole-home cooling. With our classic design, patented technology, and reliable production, you can start your low cost journey exactly where ours did. Permanent Split Capacitor Motor (PSC) 117 watts to 1,147 watts depending on model.A whole house fan works through suction by pulling in the cooler outdoor air into the home’s interior. In order for this to happen, you will have to either…. Fully open a few windows. Slightly open (a few inches) several windows. Fully open 2-3 doors. You will have these three options, or maybe a mix of each. Our Classic Series is the powerful Whole House Fan that started us on our journey of accomplishing energy-efficient whole-home cooling. With our classic design, patented technology, and reliable production, you can start your low cost journey exactly where ours did. Permanent Split Capacitor Motor (PSC) 117 watts to 1,147 watts depending on model. TTi HV1600 R38 Whole House Fan (2 Speeds), Insulated Quiet Cool Attic Fan with Remote and Self-Sealing Doors, Duct Free Whole House Attic Fan Improves Air Quality. 24. $1,02500. FREE delivery Feb 28 - Mar 5. Or fastest delivery Tue, Feb 27. SAVE UP-TO 50-90% ON A/C COSTS. Homeowners are saving tons of money on their A/C usage due to the energy efficiency the whole house fan brings. With a whole house fan, A/C usage can be cut dramatically, or even eliminated completely in certain climate zones.For a fan used to cool an attic, see Attic fan. A whole house fan is a type of fan, commonly venting into a building's attic, designed to circulate air in an entire home or building. The fan removes hot air from the building and draws in cooler outdoor air through windows and other openings. While sometimes referred to as an "attic fan", this ...What's the difference? And which is right for your home? Definitions of whole house fan vs. attic fan vary by region, causing some confusion.Energy Savings with a Whole House Fan . Fans are simple motors with blades attached. They don’t cost much to operate. The QC Guys estimate that a modern whole house fan in California at a rate of 16.7 cents per kWh (I pay 14.3 cents per kWh in MI) will cost 6.5 cents per hour on high and 1.8 cents per hour on low.. By comparison, a …Mar 8, 2024 · Type 1: “Standard” Whole-House Exhaust Fan. If you’re considering an exhaust fan for your house, the standard whole-house fan option is The least expensive and most powerful whole-house fan. Standard exhaust fans are large (up to 30″) and can produce as much as 4,000 – 6,000 cubic feet of air exchange per minute. 5500 CFM Energy Efficient Whole House Fan Includes 2-Speed Wall Switch with Timer. Add to Cart. Compare. Top Rated $ 284. 99 (435) Model# 24SF6D240C. Hessaire. Tamarack TTi HV1600 R38 Whole House Fan (2 Speeds), Insulated Quiet Cool Attic Fan with Remote and Self-Sealing Doors, Duct Free Whole House Attic Fan Improves Air Quality. 24. $1,02500. FREE delivery Jan 19 - 25. Or fastest delivery Thu, Jan 18. Whole house fans work best when the outside temperatures are more relaxed, which is in the morning and evening. Whereas Attic fans are highly active during the day when the temperatures are very high. A whole house fan has more than a goal because they keep both the building and the entire house cool. Compared to the attic …Mar 8, 2024 · Type 1: “Standard” Whole-House Exhaust Fan. If you’re considering an exhaust fan for your house, the standard whole-house fan option is The least expensive and most powerful whole-house fan. Standard exhaust fans are large (up to 30″) and can produce as much as 4,000 – 6,000 cubic feet of air exchange per minute. Discover the natural cooling potential of a whole house fan in Florida's hot and humid climate. Explore the benefits of enhanced natural ventilation and potential energy savings. A Whole House Fan Company. Modern, Quiet & Energy Efficient Whole House Fans Call Today (877) 267-3205. Rate Us on Yelp. Loading. Shop.
Fresno Whole House Fan Co. 124 likes · 1 talking about this. The Central Valley’s #1 most trusted whole house fan dealer/installer. The 100 girlfriends who really love you.
Item: Whole House Fan Premium Ceiling Shutter / Ceiling Shutter Fits Fan Dia.: 48" Shutter Overall Size: 50" x 50" Shutter Construction Material: Extruded Aluminum Frame and G-90 Galvanized Tie Rods Shutter Opening Required: 48" x 48" Shutter Free Area: 13.224 sq. ft. Shutter Mounting Position: Horizontal Shutter Mounting …In the debate of whole house fan vs. attic fan, if you live in a region with hot summers and your primary concern is reducing attic temperatures, an attic fan would be more appropriate If you live in an area with cool evenings and nights and want a more comprehensive cooling solution for your entire home, a whole house fan would likely be …1. QuietCool QC ES-5400 Energy Saver Whole House Fan. 2. Cool Attic CX24DDWT Whole House Fan. 3. Tamarack Technologies HV1000 R38 …Top 10 Best Whole House Fans in Corona, CA - February 2024 - Yelp - Whole House Fan Company, Whole House Fans Orange County, Whole House Fan Installers, Friends & Family Heating And Air Conditioning, J Martin Indoor Air Quality, The QuietCool Guys, Eco Air Solutions - A Whole House Fan Company, Comfort Cool Fans - A Whole House …Jul 10, 2022 ... Operate your fan for a minimum of 10 minutes first thing in the morning for the best results. This will allow the cool outdoor breeze to run ...Ductless mini-splits can provide HVAC for an entire house. Mini-splits are more efficient than central AC because air is dispersed via refrigerant lines instead of ducts. Further increasing the efficiency of mini-splits, zones can be created to maintain different temperatures in various parts of the home.Browse photos of whole house fan on Houzz and find the best whole house fan > pictures & ideas. skip to main content. Get Ideas. Photos. Kitchen & Dining ... $500,000-$750,000 NARI Capital CotY Award- Green Entire House NARI Regional CotY Award- Whole House Remodel: $500,000-$750,000 NARI Regional CotY Award- Green Entire House NARI …Ductless mini-splits can provide HVAC for an entire house. Mini-splits are more efficient than central AC because air is dispersed via refrigerant lines instead of ducts. Further increasing the efficiency of mini-splits, zones can be created to maintain different temperatures in various parts of the home.When you need electrical services for Whole House Fan Installation in Greenwich, Darien, Stamford, etc, Safe and Sound Electric is your first choice. Call Us Today! 203-536-0021 |Whole House Fan - recommendations. I've put a few whole house fans in like this one. Although they work and are great for cooling the house with out using the AC, When set to high, it sounds like there is a P-51 in your house. I found this company and read a few reviews that seem like it is a good alternative (same air flow with a dramatically ...Apr 20, 2020 · A whole house attic fan designed to cool and ventilate entire homes by exhausting hot air from indoor spaces. Smart digital controller with temperature and humidity trigger programming, fan speed control, timers, and alarms. Utilizes a PWM-controlled EC motor that results in quieter and more energy-efficient fans than most others. Mar 2, 2023 ... The capture hood must fully cover the inlet grille and the equipment should measure the amount of airflow for which the WHF is rated. For ...The DAYTON economy ceiling shutter fits flush in ceiling opening below whole-house fans. Tie rods at each end side of shutter assure uniform opening when fan is operating. White extruded aluminum frame with 1-1/2" flange and 3/16"-dia. mounting holes. White louvers with felted edges. Nylon fasteners for quiet operation. 42 in. The QuietCool brand of whole house fans has taken America by storm. The QC CL-2250 advanced whole house fan is a new take on the idea of whole house ventilation. Whole house ventilation allows you to bring the cooler outdoor air through your windows, home and attic space to thoroughly cool and ventilate both the home and attic. A whole house attic fan designed to cool and ventilate entire homes by exhausting hot air from indoor spaces. Smart digital controller with temperature and humidity trigger programming, fan speed control, timers, and alarms. Utilizes a PWM-controlled EC motor that results in quieter and more energy-efficient fans than most others. Rattling and banging most likely means the fan blades are banging against the housing as they turn. It sounds like a helicopter with bad blades is sitting on ...We all had our favorite teachers when we were in school. They gave us great advice, encouraged us when we were down, and shaped the things we care about. You might still be friends...The QuietCool QC CL-6000 5665 CFM House Fan is an advanced whole house fan that improves ventilation cooling and reduces cooling costs by up to 50-90% compared to traditional cooling methods like air conditioning. With its durable construction, this fan provides reliable cooling for your entire house.Apr 8, 2020 · Quiet Cool Whole House Fan Explained in 3 Minutes. Watch on. A whole house fan works on an air change rate which is a measure of the air volume that’s being added or removed from a house, then divided by the volume of the actual space. When it comes to these specific types of fans, they should be operating at 30 to 60 changes per hour to be ... .