How can I get better HVAC airflow?


If you suspect you have HVAC airflow problems, you’re probably experiencing one or more of the following symptoms:

Hot and cold spots throughout your space. This is often one of the first signs of HVAC airflow issues.Pressure imbalance. Do you have doors slamming by themselves, strange whistling noises and drafty areas? These are symptoms of air pressure problems caused by poor HVAC airflow.Little to no air coming from your air conditioning registers. This is when you begin to realize something is wrong.Your AC system blows warm air. Now you KNOW something is wrong!

If you ignore the problem for too long, the strain on your system can lead to compressor failure. The compressor is like the heart of your air conditioner, and when it goes, there’s a good chance you’ll need a new unit.

The good news is, many of the causes behind HVAC airflow problems are easy and relatively inexpensive to fix.

Read on to learn about the most common causes, as well as one easy way to...

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A lot of things can happen in two years. As mentioned, the system could be low on refrigerant, the evaporator coil could be dirty, etc. The best thing to do right now is to turn the thermostat to "off" and set the "auto/on" switch to "on" so that just the indoor blower runs. That will help thaw out the system quicker. Let it run like this for a least an hour or two. Without being there to check the refrigerant charge or the system operation, it's really difficult to fix and A/C over the Internet. After it thaws out, run your system as you normally do. If you have an accurate thermometer, check the temperature at the return air and the temperature of the air coming out of the evaporator coil. The split should be between 16-20 degrees. If it's less than 16 degrees, chances are it's low on refrigerant. If it's more than 20 degrees, you've got airflow issues (dirty evaporator coil). Other than that, there's not much more you can do other than have the system...

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There are a number of ways to increase the overall heating, ventilation, and air conditioning (HVAC) air flow within structures, and many of them can be implemented without a major expense to the consumer. Ensuring that air ducts are clear of debris and that the vents are properly functioning is normally the first place to check, followed by ensuring that the compressor is generating enough pressure. Another common problem dealing with HVAC air flow is leaks or tears within the air ducts, and a quick repair will normally solve this problem. If none of these issues seem to be the case, it may be possible that the compressor or the actual cooling unit is too small for the dwelling they are installed on, so replacement may be the best option.

It is common for a number of issues to appear within HVAC ducts over a long period of time, and since it is near impossible to prevent, regular maintenance checks are necessary. One of the leading problems that consumers face with HVAC air...

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Ask anyone outside the enterprise IT department to identify the greatest data center cost, and they're apt to say servers. That’s true in some businesses; hardware costs are not trivial. But the truth may be that large organizations are wasting money unnecessarily by literally blowing a lot of hot air because of inefficient data center airflow.

If you're running your data center inefficiently, as many companies do, the cooling budget can be twice the cost of buying and running the hardware. That's a lot of cash wasted on heating, ventilation, and air conditioning (HVAC).

A May 2015 IDC data center survey found that up to 24 percent of a data center budget can go to cooling. With a mean data center budget of $1.2 million for IDC’s enterprise clientele, that means that cooling alone costs $300,000 a year.

In a word: Ouch!

Best of 2016: Tech & Software Conferences Guide

Companies are getting more servers for less power these days, due to the rise of...

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While industry standards specifying ventilation rates are coming out of the woodwork, a practical standard describing how to measure ventilation airflows that can be applied in the field is hard to find. Let’s take a look how you can determine residential and commercial exhaust fan airflow in the field.

Fans at Either End of the Duct

This may be obvious, but it is a good place to begin this discussion. Although in-line exhaust fans exist, most exhaust fans are found at either the start of a duct or at the end of a duct. This is a defining characteristic of some exhaust fans that affects the way we may determine fan airflow as compared to a forced air system where fans are located between the supply and return ducts.

The Dangerous Assumption

Most standards are written to persuade designers to specify the needed airflow or air change rates. These standards require a calculation, and a specification requiring that the fan should do the job. With these...

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Air distribution is the weak link in many heating and cooling systems. Here's how the industry's top pros detail their ductwork — for results you can take to the bank.

by Ted Cushman

Experts agree that sealing ducts is vital to good HVAC performance, especially in a vented crawlspace or attic, where leaky return ducts will continually draw moist unconditioned air directly into the air handler. At around $6 a bucket, high-performance duct mastic is cheap, but the labor to seal the ductwork properly is tedious and painstaking.

Good ductwork is key to HVAC performance. Yet hidden away in the dank crawlspace or the hot, humid attic, a home's ductwork goes unappreciated and underexamined. And too often, sad to say, this vital part of the HVAC system brings the energy perfor-mance of the home to surprising lows.

In one study, for example, researchers with the Florida Solar Energy Center (FSEC) replaced several oversized air conditioning units with...

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Booster fans.
We have several varieties and brands of booster fans. How do you know which one will work for you. As you would expect, there are quality and performance improvements which come with higher prices (also said as .."you get what you pay for")

Performance requirements.
Remember that you are looking for a fan to add pressure and flow to the air flowing in your duct (windmills are not considered a success). Without bringing in a team of technicians and engineers, we can still do much better than just a guess.

For the more technically minded we will talk about pressure drop (resistance to airflow). This pressure drop (measure in inches of water column) is proportional to distance and also rises with the square of the velocity. This means that if your airflow in a duct doubles the pressure drop will go up by a factor of 4.

How much airflow
The thorough and proper (and expensive) way to figure airflow is to provide an HVAC engineer with...

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Proper airflow in an HVAC system ensures conditioned air reaches every corner of a home. If airflow is disturbed for some reason, parts or all of a house may become less than comfortable due to a lack of heated or cooled air.

Conditioned air flows through ducts throughout a home. When these ducts become blocked by dust or are improperly installed, it can lead to drastically decreased air flow. This is not the only source of airflow problems, but it is the most important one.

Friction And Turbulence In Ducts

When air flows through ducts, two forces act upon it, which can reduce airflow. These forces are friction and turbulence. Too much of either one can decrease the amount of air that makes it through the duct work to reach the home, especially areas of the structure that are farther from the beginning of the duct system.

The rubbing of air against the sides of the duct causes friction. The most common type of duct used in heating and air conditioning...

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My building has operable windows and single zone split HVAC for heating and cooling. I have set up a Airflow Network in energyplus to find out how natural ventilation can contribute to lower cooling loads. (Location: mixed humid climate and mixed dry climate, ASHRAE 4A and 4B).

However, I get strange results for the winter period because natural ventilation is happening while heating is ON.

What is the right approach to avoid this? Might it be that the IdealLoadAirSystem is not interacting correctly with the AirFlowNetwork Model. Or should I set up a schedule to avoid ventilation in winter nights?

I found this information in energyplus documentation (but not sure which HVAC system does it mean): The AirflowNetwork model is currently able to model a wide range of multizone air flow scenarios. However, only a single air distribution system with a constant volume supply fan can be included as part of the airflow modeling.

@MJWitte or @Archmage, could you,...

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At National Heating & Air Conditioning, we frequently receive complaints about room to room airflow in homes. Cincinnati homeowners often associate the comfort of a room with airflow. There are many reasons why airflow can be low.

Sometimes it may seem like the airflow in a room is low, causing the room to feel uncomfortable, but testing proves that’s not the case. As discussed in the article titled “The Two Primary Causes of Reduced Airflow in Ductwork” on the Energy Vanguard blog by Dr. Allison Bailes, the two main causes of reduced airflow are friction and turbulence. Below we look at a few of the most common issues that cause these conditions to occur.

1. Dirty Furnace Filters or Excessively Efficient Furnace Filters

This is an example of friction. The thickness of the furnace filter should be taken into account when the ductwork is designed and fan speed set. If the thickness is increased because the filter is dirty, it changes the pressure of the moving...

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On the interior, warm, humid air from your home’s interior is blown through the evaporator coil. The cold coil absorbs heat from the air, cooling it, before the air is circulated back into your home. The humidity in the air condenses on the cool surface of the evaporator coil as liquid water, dripping into a pan below. From the pan, the water flows into a drain tube which is typically routed into a basement floor drain, utility sink, or outdoors.

Over time, algae and mold can build up and potentially plug the drain, so if the drain is either not flowing or flowing very slowly, it will need to be unplugged. A plugged drain can either cause damage by flooding onto the floor or, if the system is equipped with a drain float, cause the system to stop cooling in order to avoid flooding.

First, find the drain line where it leaves the evaporator coil enclosure. The drain is usually a one-inch PVC pipe (white, grey, or black). Follow it to the end where it drains. Often the...

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Research so far indicates the "garbage bag" method of measuring system airflow at registers is actually comparable to the high-tech devices that Joe HO doesn't have access to.

I'm looking for four bits of feedback:

1) Any tricks on how to implement the "garbage bag" method

2) How to know what the total CFM out of a blower should be. I have a Bryant 355AAV042060 FA5A furnace.

3) My understanding at this point: Under the ideal conditions (theoretical) if a blower is rated at 'x' CFM then if I add up all the CFM from each register when blower is at highest speed I will get 'x'.

4) With my variable speed furnace( I also have a 3Ton AC condensor/coil) and it being the Evolution Plus90I model (but with a standard single stage stat, not Evolution stat), if the control board is set up to 400CFM/Ton (for AC) and I am running a 3Ton system, then the blower speed is going to be controlled to attain 1,200 CFM. If this is correct, then my 'x' (from #3 above) is...

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Lots of Americans are switching over to heat pumps to heat their homes, because these systems are less expensive and provide a type of heat that is comfortable, reliable, and tends to cost less in terms of monthly utility bills over time. But the key to a great heat pump system that is adequate for your particular home is the installation, and that’s where expert heat pump contractors in come in handy.

The advantages of using heat pump contractors are many, but one of the big reasons is that when you get a company to do the work, you know that they are going to be there if you need a repair or have a heat pump question. Plus you can check the prior work of these local contractors, whereas if you try to hire someone from out of town you might have no way of seeing their work or talking to their satisfied customers ahead of time.

Heat pump professionals also understand our climate and local weather. That is pretty important when installing a heat pump, because these...

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The location of your heating unit affects the air distribution throughout the house. Careful sizing and installation of the duct work helps equalize the airflow, but once the experts calculate and install your equipment following the Air Conditioning Contractors of America standards, you’ll want to work with what you’ve got. As the unit gets older, the rooms far from the heating unit may feel colder than rooms close to the air handler. Inspection can determine the reason for the temperature difference; cleaning and analysis can improve the airflow in the far-away rooms.

Turn off the heating and cooling unit at the breaker. Wear work gloves and set up the ladder.

Remove the registers in the rooms farthest from the heating unit by removing the screws that hold them in place. Clean the registers with a damp cloth, and open the louvers. Set the registers aside, along with the screws.

Vacuum the inside of the duct work with a soft brush attachment, using care not to...

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There are several high-capacity variable speed/variable torque replacement blower assemblies on the market today that may provide an invaluable solution when you need to increase system airflow. Let’s take a look at replacement blower assembly basics, how to do necessary testing and diagnostics, and how to select the right blower. We’ll also consider what additional changes may be needed in the system so you don’t create a whole new set of problems as you replace a system’s blower assembly.

Blower Assembly Basics

As the practice of measuring system airflow increases, more technicians and salespeople are discovering low airflow problems in the systems they service and sell. Best industry practices require an HVAC or energy professional to provide their customer’s options to solve this problem.

One solution is to replace the equipment’s blower assembly with an increased capacity blower that’ll move the needed airflow. This will allow the operating efficiency of...

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Airflow is the lifeblood of an HVAC system. When a new system is installed, or existing ductwork repaired or replaced, an HVAC technician will make sure the airflow into rooms is balanced. The ideal is to have the return ducts running a slightly negative pressure in relation to the supply ducts. This results in a neutral pressure balance in the room, which is the optimum condition for heating and cooling. Sometimes, however -- particularly in the case of a single room that is significantly smaller than others in the home, or a room that is usually unoccupied -- minimizing airflow in the ductwork to that room is the goal.

Room Registers

Adjusting supply registers in rooms is the most accessible method of minimizing airflow into one room. Partially or completely closing supply registers reduces system airflow into that room alone, and also reduces airflow into the room return duct. However, to avoid damaging the furnace, no more than 20 percent of the supply registers...

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While there are plenty of other kinds of contractors – including HVAC professionals – in the area, you will probably find fewer contractors in who do oil furnace installations.That’s because not everyone uses oil to heat their homes, and the number of licensed oil furnace installers in any given city or town is usually relatively small.

But you can still find quite a few really experienced and reliable oil furnace installers in just by checking around and asking for some names and recommendations. If you are buying an oil furnace, the company you buy it from probably has its own team of installation experts.

Or you can phone a local company in that sells furnace fuel oil. While these companies may only do delivery of fuel and hire truck drivers – not installers of oil furnaces – you can be sure that they will be quite familiar with all of the established oil furnace installation and repair professionals throughout the area. They’ll be happy to give you names and phone...

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