Crazy, but that's the weather we have here in NC. Other space/design issues include an air handler installed just behind a bedroom wall or a furnace that wasn't installed on rubber pads. Here's another situation where system infrastructure makes it hard to cut down on noise: Homes with a single, central return. However, when running just the blower in med-lo and hi, I can honestly not even tell the difference in airflow at a vent on the first floor; and the air-flow is really quite high even at med-lo (ie. Airflow is also the key to a comfortable home. You're worried that you might not hear the doorbell if it rings. That's not to say hard pipe ducts are always loud. We just took up a lot of space discussing static pressure, HVAC equipment sizes, and ductwork installation quality - all in an article about airflow noise! Basically, flex ducts = less noise and possible airflow issues while hard pipe ducts = more noise and fewer airflow issues. Everything was fine until the air conditioner came on. They're way too high (or low, rather, since they're negative), indicating that the blower is pulling as hard as it can but isn't getting enough air. Turning the blower too high makes the furnace noisy when it turns on. If the air moving through your system makes a lot of noise, the first things to check on are: If you've checked on all of these things and addressed the problems, your ducts might not seem so noisy. You're going to put on some tunes - something mellow - and relax. After checking for closed vents and fixing kinked or sagging flex duct, your best move is to have an HVAC professional measure the static pressure in your system. Here is a link to the fan curve for the furnace. Keep your coil clean. Even with variable speed equipment, it can be hard to quiet these systems since the blower motor is right there and there's minimal space for additional ductwork. Participate in over 40 different forums and search/browse from nearly 3 million posts. In theory, your HVAC installer configured it properly during installation. Switch the Jumper On most control boards there will be a jumper that is marked to show that it controls the speed. Most brands required a 15 minute operation for a defrost cycle to kick in. Locate the fan relay electrical terminal and remove the current fan speed wire (normally "high") from it. You can also forget about those pesky HVAC and air duct problems. Furnace blower manufacturers recommend contacting a certified furnace blower technician to change the blower speed or try to fix the furnace. 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Cut the wire's terminal connector off with wire cutters. In reality, Hope you all had a good weekend. Does This Air Cleaning System Stop COVID-19? Because of this, I noticed something rather interesting/odd - whatever you want to call it. • The furnace will run on low stage for a fixed period of time before stepping up to high stage to satisfy the thermostat’s call for heat. The air moving through them makes noise, and a variety of factors can make air movement more (or less) audible. The HVAC Blower Motor Fan runs on high Speed all the time. The #1 question asked by NEW MEMBERS. Hello : How do you know the best fan speed for A.C . (ie. I have a Carrier furnace/heat pump with an expensive control thermostat that talks directly to the heat pump. Thermostat - controls the HVAC system and can affect performance. You'll still know your system is working. Or your phone if it vibrates on the counter. When we lower the blower speed to remove more moisture, we also lower the system efficiency. If the blower remains at the lower speed, then the efficiency is lowered under all conditions, even when humidity removal is not needed. The boss lady over the lab found a website that said if you slow down the fan speed on the blower and turn the fan on continuously it will be more comfortable and use less power. But as soon as you tap the play button and open your book - whoosh! The car has automatic temperature control. We’re exceeding the CFM’s we need by 1,235-875 = 360 CFM, and we’re running at 494 CFM/ton. That's because the noise itself isn't usually the problem. Without a PID loop, the fan will slow too much, begin to speed up, over-shoot the mark and slow down again. Sometimes, it's possible to fix these problems. Energy Recovery Ventilator (ERV) Services, COVID-19: Learn How We're Helping to Keep You Safe. Depending on a few factors, that could be the setting from the factory or it could be a different setting such as medium speed (similar to a temperature drop for the air conditioner). The air conditioner roars to life. If you have a natural gas furnace, you can also clock the gas meter to eliminate low input as a potential problem. I think you are on the right track by lowering the fan speed. The key is to set the fan so it meets the manufacturer required temperature rise (which is located on the furnace). As an Example: When building pressure drops, the motor/fan slows. Secure the old speed wire by twisting a wire nut over the end. This constant fluctuation between fast and slow motor/fan speed in an attempt to obtain the necessary speed and is called hysteresis. It looks like the lowest curve there ranges from 700 to 850 CFM, which seems too high for a 1.5 ton condenser, even though the … Signs That a High Limit Switch Needs to Be Replaced Like any other part in your HVAC system, the high limit switch can wear out over time. After all, it's pretty obvious whether you're comfortable or not! Privacy Policy. Dirty coils. Maybe you'll finally open that new book you've been meaning to read. Now you can barely hear your music. Here's What to Do. Hard pipe ductwork is less prone to kinks and bends, so it's usually better for airflow. If you've got a variable speed blower, that's definitely the case. When humidity is high, set the fan speed on low for more comfort. Good morning everyone. In heating, higher speed = (usually)more flow/lower temperature; lower speed = less flow, higher temperature. Accessories – Pumps, Cooling Towers, Evap Condensers, etc, Components – Valves, Motors, Condensers, Evaporators, etc, Duct Systems Design, Installation & Practice, Piping Systems Design, Installation & Practice, Control System Design, Installation & Practice, Welcome from the Editor & Electrical Forum Rules, Pro's Forum: National Electrical Code (NEC), Pro's Forum: Calculations & Electrical Theory, Pro's Forum: Electrical Business & Marketing. Adjust the fan speed to get close to your target airflow. Before You Buy a Better Air Filter, Read This, These Are the Most Common Furnace Problems, No Heat From Furnace? If these components are dirty, they should be corrected before you can expect to achieve the desired amount of airflow. Too low a speed will cause freezing (no good)in a/c. That's because variable speed blower or furnace fans usually run at a low speed, circulating air throughout your home more consistently than the old school, on/off systems you're probably used to. The problem has to do with space and design. Not always, but usually. In the fan curves, for a 60kBTU furnace, in high (black) running at 0.9 iwc; this blower motor should be delivering 1,235 CFM. An air conditioner that’s only capable of running at one speed— basically, on or off—can have the same problems as one that’s too large when it comes to HVAC humidity control. Many furnace blower motors are designed for a fixed speed during a heating operation, but this does not mean it can not be safely increased.. Pre-set Speed. She said it would also help with dust problems, which they have. The fan speed varies depending on the cooling or heating load, but the fan operates at lower speeds most of the time. Too high of a CFM will decrease the amount of time air crosses the A-coils, decreasing de-humidification and the overall cooling effect of the system. Assuming you select a new system with a variable speed blower, it's almost certain to be quieter than the standard blower you're replacing. You need to fix the thing causing the noise. And since less air is moving through your ducts, noise levels are lower - sometimes dramatically so. It's a tradeoff. Assuming they're properly sized for your home and your system, you'll probably hear minimal noise from all-hard pipe ducts. And while you'd like to concentrate on your book, you can't. You slump down into the sofa. will deflect a piece of paper 90 degree straight at 3-4 ft above the vent). As you document the fan speed settings that are being used, inspect the cleanliness of the equipment. But if they do - and you're keen on making your system quieter - there are some additional steps you can take. Yes... we are 20 years old. These taps just add additional winding resistance between run and common to increase the motor slip and slow the motor. While every home is different and requires a unique fix, here are some of the most common solutions to air noise resulting from "high static:". Then you can finally enjoy those tunes, dive into that book, and take a load off. Flexible ductwork is prone to kinks and bends, so it presents more points of failure for airflow. Changing fan speed My 2-story house gets very hot upstairs in our bedroom during the summer months. We've written about static pressure before. Last summer, I tried to dampen the vents as much as possible on the main floor to force the a/c upstairs, but it was still always 3-4 degrees celcius warmer upstairs than the main floor where the thermostat is. There is a price to pay for humidity control. All else being equal, hard pipe ducts are noisier than flexible ducts. That’s because it’s very important for the performance and longevity of your furnace or your air handler. • A single-stage thermostat with only one heating stage may be used to control this furnace. Ideas people , and thanks . Fan speed too high: at the end of heat cycle during purge cycle so much air moves through the heat exchanger and supply plenum that the air therein is cooled enough to turn off the blower; but residual heat in the heat exchanger re-heats the plenum air and turns the fan back on So - Friday was one of those odd days where I needed to have the heat on at night, but the AC on during the day. During the awake hours I Hold the fan speed at either low or medium. Gain access to our free AOP (Ask a Professional) Section to get real answers for your questions. I can adjust the d.c. fan motor from 1392 -573 CFM . Watch out: do NOT try to follow example fan speed setting instructions unless they match your particular brand and model air handler. Fix these obvious defects before attempting to set the fan speed. Set the fan speed on high, except on very humid days. If your filter is clean then there's not much more you can do. Don’t turn it too high if you’re worried about excess noise or if you live in a small home. When static pressure is too high, it means your ducts can't adequately accommodate the volume of air that your equipment is trying to move through them. If the MERV rating on your furnace is too high, it may force your furnace to work too hard and leave it vulnerable to damages. I know that if I lower the blower speed too much I risk freezing the evap coil. Could it be the Blower Motor Control module which I under stand provide electronic residence to the circuit to slow the speed down when controlled by the wheel on the dash control module. One of the most common issues that happens when a high limit switch goes bad is that it fails to signal the blower fan to turn off. Air moving over metal is just… louder. The blower has 4 speeds: low, medium low, medium high, and high. Ask Our Pros-Owner Assistance - NO DIY advice will be given. Every system has some, but many systems have too much. High static pressure is a common problem. Then switch the jumper to your desired speed. Your blower or furnace fan should be set to deliver the proper airflow per ton. If you're hearing a lot of noise, static pressure is probably high. In these homes, builders sometimes install a furnace or air handler right on the return plenum, which is ducted to the central return or, occasionally, a hole in the wall with a grille on the other side. I have a 2.5 ton ac unit connected to a hile 45,000 - 70000 btu 2 stage furnace . Warning. It will take a while for the temp to recover if you have a big overnight/away set back on a programmable thermostat particlarly if it's real cold outside. The fan speed changed when you switched the leads. But not always. When researching HVAC systems, airflow will come up a lot. Ducts don't make much noise on their own. This brings us to humidity controls. Depending on your local conditions, it is possible that heating and a/c can utilize the same blower speed. If there's enough space to add ductwork or rearrange the system components, that can help with noise. This setup is likely causing all sorts of problems, not the least of which is higher humidity. When the unit is in heat mode (gas furnace), the … • The application of a single-stage thermostat offers a timed transition from low to high fire. After checking things out, the contractor will likely propose one or more of the solutions we just discussed. I told her that I could change the speed. Our 20th year anniversary is May 21, 2020. In some systems, variable speed blowers really are that quiet! The low speed on humid days will cool your home more effectively and remove more moisture from the air because of slower air … © 2021 PV Heating & Air All rights reserved It allows three constant fan speeds as well as an automatic fan speed and a variable burn rate and compressor and fan speed. I opened it up and it has a four speed fan motor, 3/4 HP. You'll have to turn up the volume. If it's time to replace your HVAC system, you're in luck! A multi-tap / multi-speed single phase motor may have three or more “speed taps” on the motor. This means a 1075, 6 pole motor will run at 1075 RPM under rated load at high speed. What Ken found is that the static pressures on the return side of the duct system seem to be the main problem. You see these in smaller homes, like condos. Imagine it's a quiet afternoon and you've got the house to yourself. To remove humidity a lower speed will work better so I have read , presently I have the cooling speed to be around 924 CFM . This includes the condition of the fan, filter, and coil. If defrost cycles do not occur then there is an increase risk of your outdoor unit freezing up out doors. Do This Before Calling an HVAC Company, Hear an Air Duct Popping Noise? HVAC humidity control problem #2: Your AC is limited to a single speed. When your evaporator coil (indoor) is covered in dust and dirt, it can't … It may not make a huge difference but if the speed is too high it will be noisy. Before getting into the nuts and bolts of ductwork and noise levels, let's consider a few noise reduction basics. Post photos, respond to polls and access other special features. Now those noisy air ducts are intruding on your solitude. Components – Coils, Heaters, Motors, etc. 3593 Clearview Pkwy Atlanta, GA 30340 Most of these are on the bottom left of the control board. Running the fan too high can mean your heat pump will not run long enough in order to kick into a defrost cycle. A furnace blower motor does have to have a certain airflow through the heat exchanger when flame is present in order to prevent the heat exchanger from overheating. Compared with flexible ductwork that contains no obstructions, kinks, or bends, you'll probably hear more noise with hard pipe ducts. If you measured high airflow with a low temperature rise, there’s a good chance the temperature rise will improve once you change the airflow. Watch out: running the blower speed too fast during air conditioning may result in inadequate dehumidification, while running the fan at too-slow a speed may result in ice blockage on the cooling coil. Adjust the fan speed. Fix the bigger problem, and the noise usually goes away. And when the volume of air exceeds what your ducts are intended to handle, you get noise. Just be aware that hard pipe ducts tend to be noisier than their flexible counterparts.