How to Retrofit a Gas Furnace

Natural Gas Furnace Retrofit

An old gas furnace that has poor efficiency ratings can cost you a bundle. While it’s possible to simply replace the gas furnace, you can also retrofit it with some of the following upgrades that will save you money and improve its efficiency without costing you a fortune.

  • Vent Dampers, When the furnace isn’t firing, a vent damper will close off the vent to stop excess chimney losses. These are most effective with older furnaces and boilers. Newer models don’t benefit much from this upgrade as they may already have features installed that provide the same basic benefit.
  • Derating Gas Burners, The vast majority of older furnaces and boilers are oversized, resulting in too much gas being burned. It is possible, through retrofitting, to actually reduce the heating capacity of your gas boiler to the point that it only produces what your home needs based on an accurate load calculation. This is done by reducing the size of things like the baffles, the burner orifice and other components in your furnace. Beware that this is not allowed in all municipalities and must be performed by a professional due to local building codes.
  • Intermittent Ignition, Instead of a continuous pilot light that burns all year round, you can have an intermittent ignition installed that will click on only when you need the furnace to operate. These are electric and quite complex so they should be installed only by a trained professional, but they are relatively low cost and they pay for themselves in 5-10 years. Keep in mind that the cost savings are more for devices that are not too old, older devices that can just be turned off entirely (pilot and switches) when not in use won’t gain much from this upgrade.

Retrofitting or Replacing a Gas Furnace

To decide whether retrofitting is worthwhile for your gas furnace, you must first determine the savings you stand to gain from doing so. If you feel like you’re going to gain a significant amount of money from retrofitting your gas furnace, you should contact a technician to go over your options. If some upgrades are not possible or you simply have a very old furnace, replacement may be your best bet.

This information is provided by Air National AC & Heating Of Houston, Inc., a Houston air conditioning and heating contractor offering HVAC installation, maintenance and repair.

The Importance of Purging Air from a Hydronic System

Hydronic System Maintenance

Hydronic heating and cooling systems, which use water as a material for heat transfer to regulate air temperature in a building, provide excellent HVAC capabilities for homes and large buildings alike.  Hydronic systems make use of water pipes plus manual or automatic balancing valves, and it’s important to eliminate air from the pipes and valves constantly to keep it working properly.

The principal result of air trapped in the system is a loud and irritating banging noise as the water and air travel through the balancing valves.  Air can also disrupt the heat transfer process, as heat can escape from the water into the trapped air and make the system significantly less efficient.  Oxygen that enters the system via the trapped air can also speed up the corrosion process and rust out the inside of the pipes as well as damaging the seals.  Control valves, which use mechanisms to open the valve automatically to respond to changes in the water system, are also an excellent way to keep an HVAC system air-free without maintenance.

Air should be purged from the system after installation, and if done properly the pipes and balancing valves will remain air-free for years.  To begin, locate the ports on either side of the mid-plate (in the center of the valve).  On a small valve measuring less than 2″, air can be purged using only the upstream port.  A larger valve will require purging from both the upstream and downstream ports.  Pipe and valve manufacturers often provide a variety of products to help remove air.

In a water-loop hydronic system, there are several different ways by which air can become trapped in the system, and these different products may be recommended based on the type of trapped air.  Air may be entrained, or contained in bubbles traveling through the pipes with the water; it could also be dissolved into the water if the temperature and system pressure are right.  Entrained and dissolved air can be drained with tools like an “air scoop.”  Free air also sometimes floats upward to the highest point in the system and becomes trapped.  Free air is easily vented automatically on automatic balancing valves.  If the system begins to make more noise than usual, consider purging excess air to return it to normal functioning.

*This post is courtesy of Flow-Pac LLC. Our sincere gratitude goes out to them. Please contact Mr. HVAC if you would like to be a guest writer.

Why You Should Have Your Furnace Inspection Early

HVAC (heating and air conditioning) Furnace Inspections

Have you had your furnace inspection yet? While it may seem like it’s too early, now is the perfect time to have a furnace inspection in time for winter! Let’ face it, cold weather is on its way, and having a furnace inspection is the only way you can be absolutely sure that your furnace will be able to carry you through the winter months comfortably!

The best thing you can do for your furnace every year is to have it inspected early on, we’re talking late September early October. Why? Think about it, would you rather have an HVAC tech come out and spot any problems with your furnace now, or in the dead of winter when it breaks down and the streets are blocked with snow?

Not having a furnace tune up at the beginning of the heating season can cause a number of problems. Not only do you risk your furnace breaking down at the worst possible time, but you also potentially compromise your own personal safety by causing dangerously high levels of carbon monoxide to escape into your home.

A typical furnace tune up and inspection consists of the following:

  • Safety test for carbon monoxide (CO)
  • Check for hazardous debris in the chimney and flue
  • Clean air filters and re-install
  • Check operation of thermostat and safety controls
  • Check gas pilot safety system and clean as required
  • Clean motor and fan
  • Check blower operation
  • Check condition, tension and alignment of fan belt, and perform required adjustments
  • Clean burners and set for proper combustion & ignition
  • Check gas piping to furnace

What can you do in lieu of furnace inspection?

There are many things you can do on your own (in addition to having a furnace inspection) that will help keep your furnace in tip-top shape. Some of these things include:

Testing your CO detector, test your CO detector (by hitting the test button) to make sure it works. Replace the battery at this time as well. Don’t have a CO detector? Get one! They are extremely important, particularly during the winter when your furnace is constantly running.

Keeping your furnace clear, make sure there are no clothes, lint or furniture blocking airflow to your furnace. Also make sure there is nothing flammable stored near the furnace that could explode given the chance.

Changing your air filter, this one is extremely important! Clogged filters can significantly restrict airflow to your furnace and seriously hurt its performance. Disposable air filters are pretty cheap, so stock up before you turn your furnace on and change them once a month.


Editor’ Note: This excellent article was provided by Nick Massa of Magnolia Heating and Air Conditioning. Their website is We welcome other technicians and managers to write for our website. You will be doing the industry a favor while promting you and your company.

Why Use a Supply Ball Valve?

Supply ball valves are one of the most durable styles of valve available, and their design means they retain their ability to shut off water applications for years with little maintenance.  There are many reasons to choose a SB valves over traditional balancing valves.

What is a Supply Ball Valve?
A supply ball valve, or SB valve, is a valve designed with a ball-shaped device to control flow.  The valve consists of a simple opening with a round metal ball inside.  The metal ball contains a hole called a port running directly through it, like a bead on a necklace, and when the valve is open, water runs in one side of the valve, through the port and out the other side.  To close the valve, the user turns a handle to rotate the ball so that the port runs perpendicular to the pipe.  This cuts off the flow of water.

Advantages of SB Valves
SB valves are very versatile and can support very high water pressures, making them a top choice in industrial applications.  They’re available in several variations suitable for a range of projects.  A ball valve’s durability means that it won’t need to be replaced as frequently as other types of valves in high-pressure applications, and they continue to work without maintenance even after being set in the same open or closed position for years.  This can save money on a construction project over time.

Supply ball valves also feature handles directly over the valve which clearly display the valve’s position, if the handle runs parallel to the pipe, it’s open; if it runs perpendicular, the valve is closed.  Valves can be closed or opened quickly and without tools.  Though SB valves can’t restrict water flow the way a throttling valve can (restricting the flow incrementally by closing the valve to certain degrees), the supply ball system offers an excellent solution for contractors looking for a durable and economical valve choice.


*This post is courtesy of Flow-Pac LLC. Our sincere gratitude goes out to them. Please contact Mr. HVAC if you would like to be a guest writer.

Maintaining Balanced: Equilibrium in the Flow of Water

The hydronic system is to heating and cooling as the circulation system is to the body.  Our heart valves control the pressure and flow of the body as balancing valves control the flow and pressure of water in an HVAC system; any kind of imbalance will create problems which will eventually result in an entire system malfunction.

It has been shown that most heating and cooling efficiency problems are not from faulty equipment, but from an imbalanced hydronic system.  Quite often in an imbalanced system, one part of the circuitry will get favored over the other and the stronger side will steal the weaker side’s water flow.  So in essence, one part of the building will be the desired temperature and the other will either be freezing cold in the winter or roasting hot in the summer.  Not only is this uncomfortable, it’s also a waste of energy and very costly.

In order to achieve water flow balance, the system needs to have a design flow balancing valve at each terminal.  Depending on what size system you have, you could need an SB valve, an automatic or a manual balance valve.  The balancing valves are automation tools to measure and regulate the flow pressure and temperature at each terminal.  By keeping the flow metered and regulated, water gets forced back through the weaker side of the circuitry and the whole building’ temperature becomes stabilized again.  To find out which type of balancing valve your hydronic system requires, it is best to contact your local control valve suppliers.


*This post is courtesy of Flow-Pac LLC. Our sincere gratitude goes out to them. Please contact Mr. HVAC if you would like to be a guest writer.

Weak AC Airflow – Improve Air Conditioner Air Flow

Find out what’ causing weak AC airflow in your home and how you can fix it to significantly improve your home’s comfort.

5 Effortless Ways to Improve Your Air Conditioner’ Operation

We’re officially entering the dog days of summer, and already we’ve seen it all: unbearable humidity, crazy freak thunderstorms and, of course, sweltering 90+ degree temperatures. It’ times like these when people everywhere are either thankful for their air conditioners or are sweating and sleeping in the basement because their air conditioners don’t work! Weak airflow is one of the most annoying air conditioner problems there is, not only because it’s uncomfortable but also because you can’t immediately be sure of what’ wrong with it. There are a number of reasons why you might be experiencing weak air conditioner airflow, some are easy fixes, some require the help of a professional.

Ways to Improve AC Airflow

Replace your filters monthly – you’ve probably heard this one so many times that it seems cliché, but it bears mentioning because it’s so important! As air passes through your home, air conditioner system and ductwork, it picks up all kinds of junk. The purpose of the filters is to catch this dust and debris so you’re not breathing it in every day.

Now, no matter how clean you keep your house, you’re always going to have dust and debris moving through your ducts, your air filters are going be catching a lot of it, and as they do, it’s all going to start slowing the airflow. This is why it’s so important to change your filters every month, if you don’t, eventually they will become so clogged that air is simply not going to be able to get through.

Changing your filters every month is important for another reason as well, if weak airflow persists in your AC, it can actually cause your air conditioner to freeze, potentially resulting in serious damage. Changing your filters is an easy way to prevent this from happening.

Make sure your AC dampers are open – if you have weak AC airflow in only one or two rooms in your home, you might not have an air conditioner problem at all, you might just have thrown off dampers. AC dampers are essentially valves in your ducts, when they are open, air moves easily. When they’re closed, either part of the way or all the way, you’ll have weak, if any, airflow from your air conditioner. To check your dampers, go into your utility room and look for your HVAC plenum (it’ll be the big, plain metal box). You should see a bunch of ducts coming out of it, all with levers that should be in the ON position, these levers are called dampers.

If any of the dampers are in the OFF position, turn them back ON, your weak AC airflow problems should go away immediately.

Change your air filters, and we’re not talking about monthly replacements this time. When you go to the hardware store you’ll see about 10 million different types of air filters, and you’re supposed to just know which is which. All of these air filters have different MERV ratings that indicate the effectiveness of the filtration. You might think more filtration from your air filters is better, after all, it means less dust in your home, right? Well with air filters, bigger is not necessarily better. In fact, if the filtration is too powerful it could block airflow!

Air filters are rated as follows:

  • MERV 1, 4: this is the standard rating for most residential air conditioners. Filters at this level do a decent job of filtering particles out of the air and can trap dust and debris as small as 10 microns.
  • MERV 5, 8: these filters are commonly used in offices or light commercial buildings, and are sometimes found in homes, especially if the homeowners want extra clean air (because of respiratory problems, etc). Filters at this rating can trap particles as small as 3 microns in size, but this filtration comes at a cost, since air has to work harder to move through the filter, homes with these filters may start to see problems related to weak AC airflow.
  • MERV 9, 12: very uncommon in residential settings, filters of this rating are usually found in much larger buildings with powerful HVAC systems. Filters that are this strong need to be replaced frequently because they will get filled up very quickly.
  • MERV 13, 16: air filters this powerful are pretty much only used in sterile environments like hospitals. Since they stop such small particles (as small as .3 microns in size) they tend to cause weak airflow with all but the strongest HVAC systems.

Seal up leaking ducts, this may surprise you, but leaking air ducts are more common than you might think, in fact, they’re among the leading causes of weak AC airflow! If you think you have leaky ducts, shine a flashlight in one of your vents and see if you can see any light coming through. If you can, call an HVAC contractor to come out and seal them up, duct sealing will improve your air conditioner airflow, making you more comfortable and saving you up to 30% on your heating and cooling bills!

Resize your ducts: if you’ve tried improving your weak AC airflow and nothing is working, the problem might be simply that your ducts are too small for the amount of air coming from your AC. Call an HVAC contractor to inspect your ducts and assess if they are the proper size, if they are not, installing new ductwork will go a long way toward improving weak AC airflow.


Editor’s Note: This excellent article was provided by Nick Massa of Magnolia Heating and Air Conditioning. Their website is We welcome other technicians and managers to write for our website. You will be doing the industry a favor while promting you and your company.

The Advantage of Two-Pipe Direct Return Systems

In heating, there are two categories of hydronic pipe systems: the single-pipe and two-pipe direct return.  The single-pipe system conjures up images of those steam radiators seen in old apartment buildings.  They are commonly used small residential, commercial and industrial buildings and are based on a gravity circulation system.  Two-pipe direct return systems on the other hand, can be both pump and gravity based and are suitable for buildings of all sizes.

The two-pipe direct return hydronic system has its advantages over the single-pipe system in significant ways.  The single pipe system has one pipe running from one radiator to the next and then back to the boiler, flowing in circular motion.  Being gravity based, the hot water circulation has a tendency to lose heat momentum as it moves further through the circuit.  Essentially, the first apartment on the circuit will be toasty warm whereas the last apartment on the way back to the boiler will be freezing cold because of the water temperature drop.

Two-pipe direct return hydronic systems have a pipe circuit for the supply and the return.  The advantage it has over the single-pipe system is that the hot water directly routes to each radiator terminal at the same time.  The return circuit carries the cooled water that has been circulated from the terminal back to the pump and boiler to get reheated.  This type of circuitry can cause an imbalance in differential pressure due to the fact that length of the pipe is shorter between the terminals closest to the pump and longer at the opposite side of the circuit.  Therefore, manual balancing valves with a venturi flow meter are required to maintain an even pressured flow.   Two-pipe direct return systems take less time to heat up than single-pipe systems and provide an equal distribution throughout the building.

This post is courtesy of Flow-Pac LLC. Our sincere gratitude goes out to them. Please contact Mr. HVAC if you would like to be a guest writer.

When to Choose a Manual Balancing Valve over a Circuit Setter

Take a moment to consider the positive and negative connotations associated with the words “manual” and “automatic.”  Thanks largely to modern technological developments, we’ve come to look down on manual equipment options as old-fashioned or even obsolete, but the truth is that even experienced plumbers and pipe experts know that a manual balancing valve is often a better choice than an automatic balancing valve or circuit setter.

Though water heating and cooling system installers saw a revolutionary way to hook up a larger building project with the advent of the circuit setter, it’s not always the best choice (even setting pricing aside).  Circuit setters feature a built-in balancing valve system and monitoring and measuring points allowing for automatic calibration of the water system.  Because there’s no need to readjust valves by hand or mess with the existing system, circuit setters allow for easy expansion of the water system into other parts of the building project (such as an addition).

The main selling factor is the shutoff valve capability, which allows users to shut off water to an entire part of the system to save water and energy when part of the building is not in use.   Being able to shut off water to a particular area of the building is an excellent feature for large construction projects which may undergo renovations or need additions, but circuit setters simply come with too many expensive features for smaller buildings and homes.  Manual balancing valves may require installation at more junctions of the piping system and hand-calibration, but they offer a time-tested and much less costly method of keeping a water system in balance.

Manual balancing valves come with a wide range of benefits, including the capability to read low rates of flow very accurately while saving energy.  In a smaller home water heating or cooling system, hand adjustment of manual balancing valves does not pose a problem and costs are generally much lower than the cost of installing fancier valves.  Choosing the right system for your building project can make a world of difference in your client’ energy bills and satisfaction with the final product.

This post is courtesy of Flow-Pac LLC. Our sincere gratitude goes out to them. Please contact Mr. HVAC if you would like to be a guest writer.


5 Ways Automatic Balancing Valves Can Improve Your Water System

This post is courtesy of Flow-Pac LLC. Our sincere gratitude goes out to them. Please contact Mr. HVAC if you would like to be a guest writer.

When planning or installing your system, the choice between automatic balancing valves or manual balancing valves is not always clear.  While each device offers specific benefits, some are a better choice than others given the circumstances; even when multiple options exist, an automatic balancing valve is often the best choice.

In a water flow system, it’s important for the system to be “in balance” so that water flows evenly through all terminals in the system.  Balance occurs when the flow through the entire system corresponds to the flow rates designed for it, and if balance is not achieved then the heating or cooling effect intended by the system may not be achieved.  Balancing valves are the only way to achieve this – there is no way to adjust flow through the terminals by manipulating pipes alone.

While manual valves may be the right choice for many projects, here are the top five ways that choosing automatic balancing valves can improve your water system:

  1. Manual balancing valves require system-wide calibration of the flow pressure in order to achieve balance. This means that the installer must calculate the exact pressure needed at each unit and set the valve, an extremely time-consuming process and often surprisingly expensive if the system requires a large number of valves.  An automatic balancing valve, however, automatically adjust to changing flow rates to provide the perfect balance for the system even under changing pressure.
  2. Simplicity and costs. Automatic balancing valves are easier to install and require less maintenance to keep the system running effectively.  This means lower installation and operating costs.
  3. Sensible distribution of units across the system. While a system employing manual balancing valves will require a valve unit at each terminal, brancher, pump, and riser, the same system would require an automatic balancing valve only at each terminal.  This both decreases costs and simplifies maintenance by eliminating the need to re-do calculations and readjust the entire water system when needed.
  4. Greater flexibility. A system using automatic balancing valves can be adjusted easily and can even be expanded or completed in segments.
  5. Energy costs plus rising and falling room temperatures. The amount of energy wasted by a water chilling or heating system whose valves are not perfectly adjusted to put the system in balance can be enormous.  When a system with a temperature-sensitive sensor controlling water flow experiences an excess of flow due to poor valve calibration, the temperature in the room may become colder or warmer than what was set on the thermostat.  The system will respond by sharply decreasing flow, causing the temperature in the room to rise and fall suddenly.

Using automatic balancing valves eliminates a range of problems, satisfying the installer, homeowner, maintenance staff, and environment.  Installing water heating or cooling systems is certainly a challenging task, but selecting automatic balancing valves will surely reduce costs and keep customers happy.

Automatic Control Valve

Automatic Valve from Flo-Pac

About Flo-Pac
Flo-Pac LLC is a premier provider of automatic and manual balancing valves, venturi flow meters, hookup components, calibration equipment, and more.  For more information, visit



Manual Valve

Manual Valve from Flo-Pac

Heat Gain and Loss Explained

How to Size a Heating and Air Conditioning (HVAC) System

An Explanation of Heat Gain and Loss as well as load calculation.


According to a scientist by the name of Sir Isaac Newton (he’s they guy who had the apple fall on his head), “all matter seeks equilibrium”. Cold air and warm air seek each other out and mix together. This is why your home or office often feels drafty.

This is the same situation as if you were to combine two glasses of water, each with a different temperature. The water would “mix” together forming a consistent temperature.

Hot and cold air are always trying to get together and equal things out. All buildings lose heat to the outside or gain heat from the outside. That is the reason why structures need to make up for heat loss and gain. That’ why we make a living installing and maintaining HVAC (heating and air conditioning) systems.

Heat Loss

Temperature Differential is the difference between the outside temperature (ambient temperature) and the inside temperature (mean temperature). When it is 72° F inside your house, and 5 degrees outside your house; you have a temperature differential of 67° F. With a differential, the cold will suck the heat out of your house through the exposed walls and ceilings, and through the windows and floors. This is known as heat transfer.

Cold air is also trying to infiltrate the building through any opening including the smallest cracks. This is known as infiltration. Your heat, on the other hand, is trying to escape through every nook and cranny. This is known as exhalation. Cold air is always working to get into the structure and warm air is always trying to leave the structure. The rate of this exchange depends on many factors including the temperature differential.

The total of all this leaking and losing at a specific low temperature for your region is known as the heat loss. This total will be calculated in BTU’s per hour, and the heating system will need to produce and distribute this same amount of BTU’s per hour to maintain your 68° F room temperature. As most rooms differ from one another, each room’s heat loss must be determined. The total loss of all rooms added together will determine the size and design of the heating system.

In simple structures, the mere replacement of this lost heat is sufficient; but in complex houses with open floor plans and multiple levels, the flow of heat within the building becomes a factor. Heat rising from the first floor to the second, increases the demand on the first floor while decreasing the demand on the second.

In the typical heat loss calculation (like more heat gain software), all windows are created equal, no matter which direction they face. Disallowing for wind factors, similar types of glazing lose heat at the same rate. On the other hand, when calculating heat gain, windows facing east and west gain more heat than those facing north and south. This results in larger quantities of air being distributed to rooms with east and west facing windows.

This air is necessary for cooling but not for heating. In the more northern climates, where heating is a priority, enter all window areas as east and west shaded, regardless of which direction they face. This will restore the emphasis on a balanced distribution system rather than on weighted toward solar radiation.

Heat Gain

Cold is actually the absence of heat. In other words, cold can be described as “empty”. There is no such thing as cold; only the absence of heat.

The coldest it can ever get is about -460° F. This temperature is referred to as absolute zero. It is only theoretical because no one has ever recorded it; but scientists have gotten extremely close in a laboratory setting.

Conversely, temperatures can reach into the billions. Earth actually maintains itself at the bottom of the thermometer with average temperatures in the neighborhood of 70° F.


Heat gain and loss can be predicted using generally accepted engineering principles. Heat gain and loss is generally measured in BTU’ or British Thermal Units per hour.

It is the function of a cooling system to remove unwanted heat from a structure and relocate it to the outside. This heat exchange is accomplished by the use of the refrigeration cycle as performed by your air-conditioning system. Since it is the job of the cooling system to remove heat, a cooling system’ capacity can be measured in BTU’ per hour. In other words, how many British Thermal Units of heat can be moved from one place to another in one hour.

The function of the heating system is to replace heat lost through the heat transfer process. Since it is the job of the heating system to add heat, a heating system’ capacity can be measured in BTU’ per hour. In other words, how many British Thermal Units of heat can be added to a structure in one hour.

Both systems combined should be referred to as a comfort system. However, a comfort system is made up of more than just properly sized equipment. It includes proper supply air ducting to deliver the proper amount of warm or cool air. It also includes a return air system that helps produce adequate circulation. There are other functions that this comfort system should serve. They include air circulation, air filtration, and humidity control.

Heat Gain and Loss Related Definitions

Absolute Zero: The theoretical temperature at which all mater stops moving (-460° F and -273° C). This temperature has never actually been achieved.

Ambient Temperature: Outside air temperature. More specifically, the temperature of fluid (usually air) which surrounds objects on all sides.

British Thermal Units: The quantity of heat required to raise the temperature of one pound of water one degree Fahrenheit.

Celsius: The temperature scale used in the metric system. The freezing point of water is 0° C and the boiling point is 100° C.

Cold: The absence of heat. There is no such thing as “cold”.

Comfort System: The combination of a heating and/or cooling system as well as other necessary components capable of delivering comfortable living conditions with regard to temperature, humidity, air filtration, and air circulation.

Exhalation: The passage of mean air (inside air) from inside a structure to the outside of a structure through openings such as doors, cracks, windows, etc.

Heat: A form of energy, which acts on substances to raise its temperature: energy associated with random motion of molecules.

Infiltration: The passage of ambient air into a structure through openings such as windows, doors, cracks, vents, etc.

Mean Temperature: The temperature inside a structure.

Temperature Differential: The difference between the mean temperature and the ambient temperature.

Heat Gain and Loss Software

There are several software prgrams on the market designed to allow heating and air conditioning technicians to quickly and accuratly calculate the correct size of heating and air conditioning (HVAC) equipment. Software such as Easy Load Calc, uses the simple and quick “whole house” concept. This method is appropriate for most normal residential HVAC sizing scenarios.

Other heat gain and loss calculation software programs, such as WrightSoft’s Right-J® software, use a more complicated method known as “room-to-room. Their calculations are based on the Manual J calculation concepts developed and owned by ACCA ® (Air Conditioning Contractors of America®). Please check their website for more information.

Heat gain or loss comments?