Polar Bear Air Conditioning & Heating Inc. Blog: Archive for the ‘Air Conditioning’ Category

Washington DC Air Conditioning Guide: How to Calculate Duct Size for an AC System

Monday, April 9th, 2012

Duct sizing is a complex process using one of three methodologies. The goal of duct sizing is to provide the perfect space through which heated and cooled air can travel around your home. Ducts should provide ample air flow to keep you comfortable without overworking your Washington HVAC system or costing you an arm and a leg on your energy bill.

Methods Used for Sizing

There are three methods used for most modern duct sizing. The first is the Velocity Method. The velocity method takes into account the speed at which air flows through the ducts based on their general size. A series of equations is used to determine this, including duct cross sectional area, air flow rate and air speed. A much more detailed breakdown is available on the EngineeringToolbox.com for those interested in the math behind the process.

In general though, the velocity method allows contractors to determine the appropriate size and layout of ducts based on their application (residential, commercial, industrial or high speed) and their position (main or branch ducts).

Contractors may also use the Constant Pressure Loss and Static Pressure Recovery methods to design ductwork for your HVAC system. The constant pressure loss method tends to result in more components but provides a more accurate reading of the actual pressure loss in the system based on the materials used and the layout of your ductwork.

Static pressure recovery focuses on ensuring the same pressure level is achieved at all vents and inlets for the system. It is probably the most complicated sizing method, however, so it is rarely used for residential installations.

Simplifying the Process

Were we to break down the process into its core components, this is what a Washington DC air conditioning contractor would do when sizing your duct work:

  • Determine CFM for Each Room – using the Manual J for load calculations, they would determine the CFM. This is based on the (Room Load/House Load) x Equipment CFM. The entire house must be measured and load calculations completed before this can be done.
  • Friction Loss Rate – Friction loss rate is the (Available Static Pressure x100 / Effective Length).
  • Duct Sizing – Finally, the contractor will use a chart or software to select ductwork based on the friction loss and CFM calculated in the first two steps.

The goal of all of this math is to ensure that the system installed is exactly as large as is necessary to distribute heated or cooled air to the entire house. Incorrect measurements result in improper delivery of that air and a system that doesn’t quite get the job done.

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Old Equipment You Really Shouldn’t Keep in Washington DC

Wednesday, November 30th, 2011

When you move into an existing Washington DC home, there are many pieces of equipment that you may not want to keep. Some of them are just old and poor quality, while others cost you a lot of money and others still may be dangerous to you or your children. Before you settle into your space, make sure you have every one of your systems checked thoroughly for potential problems including inefficient heating, dangerous parts or environmentally unfriendly components.

Energy Cost

Number one on your list should be the cost of the energy needed to run your HVAC equipment. Furnaces and air conditioners in particular have become much more energy efficient in the last 10 years so older systems routinely cost much more money to operate than new ones. That doesn’t mean you should immediately rush out to replace your old furnace, but if it isn’t working properly or it’s costing you more money than you’d like, the cost benefit of a new system is often worth checking into.

Other things to check include your insulation, your air quality system, your ventilation system and anything used to heat or cool food in the kitchen – all of which may be less efficient than you might like.

Ozone Depleting Refrigerants

Older appliances like air conditioners may still use ozone depleting refrigerants that are no longer considered safe (or in some cases legal) for home use. If this is the case, not only does your system probably have a very low SEER rating, it likely isn’t good for the environment or your own health. So, have your system replaced as soon as possible to avoid potentially negative side effects.

Dangerous Equipment

Finally, there are those pieces of equipment that are dangerous. If you find that your furnace has rust around the edges, your gas lines are kinked, or you have a dangerously out of date heat pump in your backyard, it may be time for some replacements. In general, these systems will last for years longer than they are considered safe and while you probably cannot buy a house without a working and safe furnace and air conditioner, you should still have them inspected carefully and replaced as soon as possible if you suspect problems.

Good HVAC equipment is hard to come by – if your home has it already, you’re in luck, but if you happen to move into a place with poor quality materials and equipment, have it replaced as soon as possible. Your health and wallet will both benefit greatly.

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2011 AC Federal Tax Credits: A Tip From Washington DC

Wednesday, September 7th, 2011

You’ve probably heard many arguments for why you should purchase an energy efficient air conditioner in Washington DC. They may cost a bit more up front, but they’ll save you money in the long run by cutting down on your monthly energy bills. They’re also better for the environment because their lower energy usage means less fossil fuels are burned to keep them running.

But there’s another reason energy efficient AC units are better buys than your standard alternative. There are Federal tax credits available to consumers who purchase them. This tax credit can more than make up for the higher purchase price of the units, allowing you to enjoy your monthly savings much sooner and know you’re doing your part to protect the environment.

How to Qualify

In order to qualify for 2011 air conditioning Federal tax credit, you need to purchase an appropriate energy efficient AC system. Your HVAC contractor or salesperson can tell you which models and units qualify for this program. Just make sure you save all documentation and proof of purchase in case you need them to validate your claim.

The AC units that qualify you for this tax credit include those with a SEER (seasonal energy efficiency ratio) of 16 or greater and an EER (energy efficiency ratio) of at least 13. These two numbers are the best and clearest indicators of the overall energy efficiency of the product and can easily be found on the packaging for any air conditioning unit. While a 16 SEER is very good, it is not the highest rating currently available, either, so you won’t be forced to buy the most expensive model available to get your credit.

Credit Details

The tax credit is good for up to 10% of the purchase price of the unit up to $300. Keep in mind, though, that you can only claim up to $500 lifetime towards this program. So if you’ve previously claimed $250, you can only claim an additional $250 for 2011. That’s still a significant savings, though, and well worth looking into if you’re in the market for a new AC unit or system.

So if you’ve been thinking about upgrading your AC system, but haven’t quiet gotten around to, now may be the time to take advantage of this great tax credit opportunity before it’s too late.

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How to Reduce the Load on Your Central Air Conditioner: A Guide From Washington

Wednesday, August 31st, 2011

The central air conditioner in your Washington house can handle a lot. It can keep your house cool and comfortable all summer long with only a minimum of maintenance. And if you have a newer, more energy efficient model, you probably are not even paying very much for this luxury. But no matter how good your air conditioning system is, it is always best if you can reduce its cooling load as much as possible.

Cutting down on the amount of work your central air conditioner has to do will save you money both in the short term and in the long term. You will be able to keep your house cool all summer while paying even less than you already do and you will help to extend the life of your system as well.

In general, reducing the cooling load that your air conditioner is responsible for involves keeping your house cooler by some other means. One great option when this is your goal is to have some ceiling fans installed. These help to circulate cool air and also create a breeze that can make it feel cooler even if the actual indoor temperature is the same.

With adequate ceiling fans in place, you will usually be able to turn up the thermostat on your central air conditioner and still be completely comfortable indoors. Turning up the temperature on the thermostat means that your air conditioning system will not have to work so hard because it will not have to get the indoor temperature down so low.

You can also reduce the indoor temperature in your house by blocking the sunlight that comes in and warms up the indoor air. Drawing the blinds, especially in those rooms that receive warmer afternoon sunlight will keep that sun from raising your indoor temperature. This, in turn, means that your air conditioning system will not have to work so hard to get the temperature back down.

You can also help to keep cool air inside and warmer air out by covering any doors and windows you are not likely to use with plastic. Also, check to make sure there are no cracks or drafts anywhere that may be letting in air from the outside or allowing cooler indoor air to escape. All of these things can make it possible for your air conditioner to keep your home cool without working so hard, and that will also mean that you will be paying less each month on your energy bills.

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What Is SEER? A Question From Washington DC

Wednesday, August 24th, 2011

If you’ve been looking at air conditioners in Washington, you’ve probably noticed that they all seem to have a SEER rating. But what does this actually mean?

The SEER, which stands for Seasonal Energy Efficiency Ratio, is a measure of how energy efficient a particular air conditioning model is. So when you’re shopping around for the best deal on an air conditioner for your home, this is something you’ll absolutely want to pay attention to.

Interpreting SEER Ratings

The SEER rating system is relatively simple – the higher the SEER, the more energy efficient the product. But because a higher price tag typically comes with a higher SEER rating, it’s important to know just how much more efficient a higher rated unit will be. It helps you decide whether paying significantly more for a higher rated unit is worth it in long term savings. Will it actually save you enough each month to make up for the difference in price?

Evaluating Your Energy Usage

A big factor here is how much you will use your air conditioner. If you live in a place with very hot and humid summers where the air conditioning runs constantly, you’re probably best off with the highest SEER you can find. When you consume that much energy to keep your home cool, you want to get as much as possible out of it, and that’s what a high SEER model can do for you.

On the other hand, if you live in an area that doesn’t have the harshest summers, you may be better off with a slightly less efficient (and therefore cheaper) model. Keep in mind, too, that the actual percentage increase in energy efficiency goes up by smaller and smaller increments the higher in SEER ratings you get. For instance, while a 10 SEER unit may be almost 20% more efficient than an 8 SEER model, a 12 SEER is only about 10% more efficient than that 10 SEER.

Finding the Right Balance

The best way to decide what SEER rating is best for you is to determine the annual cooling costs with your current unit and then calculate your savings in dollars based on the percentage each model would improve your efficiency. If you don’t currently have an air conditioner, this can be a bit tricky, but a professional contractor or air conditioning salesman can help you estimate your total monthly cooling costs with the various units.

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Cleaning Air Conditioners in Washington DC

Wednesday, August 17th, 2011

One of the best things you can do to help maintain high indoor air quality in your Washington DC home is to clean your air conditioning system on a regular basis. While these systems make it possible to endured a long, hot summer with minimal discomfort, they can also become a breeding ground for bacteria, mold and other indoor air contaminants that can make you sick or cause other types of problems.

Improving your indoor air quality isn’t the only reason you should worry about keeping your air conditioning system clean. A properly maintained air conditioner will function more efficiently for a longer period of time.

Air Filters

Changing or cleaning out your air filters regularly is one of the easiest and most important parts of air conditioner maintenance. These air filters are your number one line of defense against all manner of indoor air pollutants, but if they become saturated, they can no longer do their job. Fortunately, changing out these filters is a quick and easy job. Just mark the date on your calendar so you don’t forget.

Ducts

Without the system of air ducts that run through your home, your air conditioner wouldn’t be able to circulate all that cool air. But they’re also a very attractive place for dust, pollen, mold and other indoor air contaminants to collect. Unfortunately, the majority of your ductwork occupies space behind walls, beneath floors and in other equally inaccessible areas of your home.

For that reason, it’s generally necessary to have a professional with specialized equipment come out and clean your ducts once a year. By keeping up with maintenance, you can be sure that your air ducts aren’t harboring dangerous contaminants that your air conditioning system can then spread throughout your home.

Cooling Coils

The cooling coil is another part of your air conditioning system that needs to be cleaned on a regular basis. If your cooling coil is dirty, it won’t actually affect your indoor air quality, but it will impede your air conditioner’s ability to function effectively. The more sediment and debris allowed to build up on your air conditioner’s cooling coil, the less efficiently it will cool the air that passes over it. And if it can’t cool the air properly, your air conditioner will have to work overtime to maintain a comfortable temperature inside your home.

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Breakdowns – How to Handle an Overloaded AC in Washington DC

Wednesday, August 10th, 2011

The last thing you need on a hot summer day in Washington is for your air conditioner to suddenly cut out. Without the cooling power it provides, your house will get uncomfortable quickly. Fortunately, once you know why this happens, there are several things you can do about it.

Why Air Conditioners Cut Out

The most common reason for air conditioner failure is an overabundance of pressure in the unit. This happens because the coil gets too hot, causing the pressure to rise in the entire device. As the pressure rises past a certain point, an automatic safety shutoff system is engaged. If you can stop the coil from heating up to this point, you can keep your air conditioner running.

How to Keep Them Running

Of course, this is easier said than done. Since your condenser unit with the coil inside is located outside in the heat, it’s only natural for it to get hot during the day – especially an extra hot day when you’re using your air conditioner a lot. You also need to be careful not to put anything over or up against your outdoor condenser unit.

While this may block the sunlight, it will also keep heat in the system and prevent the air conditioner from removing exhaust naturally. So in order to keep your air conditioner as cool as possible, make sure there is nothing up against the vents or impeding air flow in any way. Once you’ve done this, try and find a way to provide shade for you air conditioner without placing objects near the device. Blocking out direct sunlight is the best way to keep your air conditioner cool as long as you can do it without interfering with the system’s natural air flow.

Getting it Back On

If your unit does cut out on you, don’t despair. The best thing to do is to wait about a half hour to give your unit a chance to cool off on its own. Then, spray the coil and other overheated areas with a fine mist of cool water. This should lower the temperature enough that the system can come back on without any further complications.

If the problem persists despite the work you’ve done to keep it cool, you may want to call in a professional to take a look and make sure nothing is broken or worn inside to cause the overloads. Most of the time a little maintenance will take care of the problem, but if not, you’ll want to get repairs done quickly to avoid a full breakdown.

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Is it Cost Effective to Use a Ceiling Fan and AC at the Same Time? A Question From Washington

Wednesday, August 3rd, 2011

There are a lot of ways to keep your Washington DC house cool in the summer, and chances are you’ve incorporated more than one of them into your home already. For instance, ceiling fans are great and can really keep you comfortable in moderately hot weather. But when the heat and humidity really start to pick up during the dog days of August, you need something a little more powerful to take the edge off, and that’s usually some type of air conditioner.

One or the Other?

If you’re like most people, you switch off your ceiling fan when the AC comes on. After all, the air conditioner is powerful enough to cool the house on its own. So is it really worth it to expend energy running another, secondary cooling device?

In fact, it is. Ceiling fans in particular use very little energy. Yet they’re quite effective at making your home feel cool and comfortable. So there’s really no reason not to take advantage of their benefits while running your AC.

Cutting Costs

You might be surprised to learn that far from being a waste of energy, using your ceiling fan and AC at the same time can actually save you money. That’s because the cooling power of the fan allows you to turn up the thermostat on your AC unit a couple of degrees without compromising your comfort levels.

And turning up the thermostat on the AC just that small amount will translate into pretty substantial savings on your monthly energy bills. That savings will more than pay for the cost of running the ceiling fan, and you save money.

Better Air Circulation

Running the ceiling fan with the AC on or off is always helpful in terms of promoting good air circulation throughout your house. And the more air circulates, the more comfortable your indoor environment will be. Good air circulation is also important because it helps to minimize the number of air contaminants that build up inside.

More Efficient Heating

The benefits of ceiling fans don’t stop with cooling either. In fact, you can run them in reverse to help maintain even heating in the winter. Essentially, there are few investments you can make that will serve you better throughout the year than a ceiling fan regardless of the other home heating and cooling systems you have in place.

If you want more information about which system is right for your home, contact your local air conditioning professional.

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Freon and Load Capacity – How Are They Linked?

Wednesday, July 27th, 2011

If you’re like most people, you probably don’t think too much about how your air conditioning system works. All you really need to know is that when you switch on the system, your house gets cooler. But if you’re looking to purchase a new air conditioner for your home, it’s a good idea to know how to select the right one to fit the space you’re trying to cool.

Air Conditioning Basics

Air conditioners use Freon as a coolant to remove heat from indoor air and transfer that heat outside. To do this, they cycle the Freon through a closed loop of coils. When the cold Freon enters the cooling coil of the air conditioner, it absorbs heat from the air passing by, thereby lowering the temperature of the air. That cooled air can then be transferred into your home and more warm air can be cycled past the cooling coils.

Air Conditioner Sizing

The more air your air conditioner can cool at once, the larger its load capacity. In order to keep a particular space cool, an AC unit has to have a large enough load capacity to accommodate that type of air volume. A unit that’s too small will obviously never be able to keep your room cool enough, but one that’s too big will have a similar problem.

The truth is that when it comes to air conditioner sizing, bigger is not better. It’s best to simply get as good an estimate as you can of what type of load capacity is ideal for the space you’re trying to cool and stick as close to that as you can.

Load Capacity and Freon

Of course, if you want your air conditioner to cool more air at a time, you’ll need more coolant. But simply increasing the amount of Freon in your air conditioner won’t make it cool any better. Freon is simply one of many elements that contribute to effective cooling. And the larger the entire system is, the more Freon is needed.

So more Freon technically contributes to greater cooling capacity, but it’s not enough to accomplish that all on its own. There is really nothing you can do to increase the load capacity of your air conditioner once it’s in place. So for best results, make sure you pick out an appropriately sized unit the first time around.

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Cooling Your House Naturally

Wednesday, June 29th, 2011

In this day and age, it seems like no matter what type of problem you have, there’s a technological solution for it. But is that solution always the best? For instance, just because you can get a high-tech air conditioning system to keep your home at the same temperature regardless of the weather outside, does that mean that you should rely solely on that system?

Of course, the choice is yours, but before you decide how best to keep your house comfortable during the warm summer months, it’s a good idea to learn a little bit more about what your other options might be.

  • Cross-Ventilation – One of the easiest ways to take the edge off when the temperature starts to rise inside is to open windows on both sides of the house. This allows the breeze to come in one side and pass out the other, taking the stale, warm indoor air with it in the process and cooling off your house naturally.
  • Stack-Ventilation – If you have a two-story home, you may want to try stack-ventilation. This variation on cross-ventilation involves opening the windows on the bottom floor on one side of your home and on the top floor on the other. The differences in pressure from one area to the next cause fresh outdoor air to be sucked in on the ground floor and pushed out on the top floor, thereby creating a strong air current throughout your home.
  • Blocking Out the Sun – The number one reason that the interior of your house gets hot in the summer is exposure to direct sunlight, so anything you can do to diminish the amount of sun that actually makes it into your home, the better off you’ll be. All you really have to do is close the blinds on those windows where sun can come in to keep the majority of that heat from impacting your indoor environment.
  • Stay Away from Dark Colors – The color of the outside of your home can also have an impact on how hot it gets indoors. Dark colors absorb the heat, while light colors reflect it. So if you want to keep the temperature down inside, stick to light colors on the exterior of your home.
  • The Importance of Shade – Any type of shade will also keep the sun’s heat out of your home. Trees are a great source of natural shade. Awnings can provide great cooling power too without blocking out your view.

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