At Home in Texas

Are You Paying Proper Attention to Your Condenser Unit

Condenser coils play a critical role in your air conditioner’s cooling system. Yet they are fraught with risk. We need to pay attention to our condenser coils. Let’s take a closer look. Literally.

Have you seen your condenser lately? Is it sitting on a nice even concrete of stone pad? Or are bushes encroaching on it? Of course, it isn’t or you have an immediate repair task at hand. Otherwise, I hope you have an Air Conditioning and Heating Maintenance contract, and are holding a qualified HVAC service company responsible for your HVAC system. In this specific case, it revolves around keeping your air conditioning coils clean and protecting your heating and air conditioning system.

The condenser coils are where your cooling system casts off heat from your home into the outdoors. Your A/C outdoor unit is built like a tower with a powerful fan at the very top which draws air up and out of the outdoor unit. Around the edges are arrayed your condenser coils. This fan creates negative pressure in the outdoor unit that sucks in ambient air through the sides of the Air Conditioner, and across the condenser coils.

This is a typical Condensing Unit. The lawn is nicely clipped and there is a nice concrete pad. No weeds, or bushes, or vines are intertwined. But we should wonder WHAT is inside on the air conditioning condensing coils impeding air flow.

The coils dissipate the heat created in changing the state of your refrigerant back to a liquid. Therefore, condenser coils need clean surfaces and open airway passages to more easily allow the heat in the coils to radiate and conduct heat away and allow the refrigerant to return to a liquid state, where it will be returned under pressure to the air handler inside the house where the refrigerant will again be expanded into gas in the evaporator coils and effectively strip your home of the energy to do this. Any questions here? check out the notes on the thermodynamics of a heat pump just below.

Here is an easy understood diagram and a clear explanation on the heat pump cycle.
You might know it from school as the Carnot cycle, or the refrigeration cycle. But the Principles of Thermodynamics allow us to leverage the phase change of refrigerants so that we can economically extract heat from your home, and deposit it out of doors. This page details and explains how this works within the components of your Air Conditioning system.  

What is phase change and why should I care?
Phase change in the refrigerant in your AC system is what keeps you cool in summer. Yes, it is that important. Like life saving. Do you want to know more?

A key factor here is hot weather, the hotter the weather the bigger the effort needed to dissipate heat. Temperature differential aids this process, the bigger the easier. Therefore, any issue with coils dissipating heat well will be most acute on the hottest days.

Because those coils are located outside, they are susceptible to dirt and fuzz and crap buildup over time. All kinds of things can foul a condenser coil here in North Texas. Living near a major arterial can just put a lot of dirt in the air. We live in a virtual garden of Eden in North Texas, and flowering trees and bushes and wildflowers can put off pollens and blossom fragments, and the North Texas winds will carry them around our neighborhoods. If you coils aren’t kept clean, your air conditioner can encounter some very serious problems. And we understand these problems are most acute on the hottest days.


image despicts a fuzz filled, dirty condensing coil assembly.

Fuzz filled condenser coil assembly is seriously impacted. Make sure this is not happening to your outside air conditioning unit.

Dirty coils can impact you in several ways.

You might be less comfortable because dirty coils cause the system to be out of regulation and not cooling as effectively as the system can when in tolerance. If you are not as comfortable as you would like to be, dirty coils could be contributing to your misery. Longer run times, less ability to deal with humidity; several issues which directly impact your comfort could be caused by dirty coils.

Nobody likes to pay high energy bills, and a dirty coil will cause your system to work harder to make you comfortable and working hard in mechanical systems means using more electrical energy.

Dirty coils stress the compressor in the outside A/C unit and stress is what causes premature failures. But heating and cooling is all one system and one major component not performing properly can stress all other components.All components are under stress. Stress causes premature wear and early failure. Failure can leave you without cool on the hottest days. Therefore we want our coils clean and our system in top running order.

So now we know why we want our condenser coils clean. Now let’s look at two issues to resolve about keeping them clean.

The simplest way to keep your Air Conditioning condensing coils clean is to have a maintenance agreement with a reputable Heating and Air Conditioning Service Company and have them checking on and cleaning your condenser coils on a regular basis.

However, there are unusual cases where your condenser coils could use even more attention. Many of us live in tree lined neighborhoods or out in the wild with the poplars. We have so many variety of trees and flowering bushes here in North texas and this can create an unusual problem for an outside air conditioning unit.

A flourishing burst of pollen or blowing blossoms have encapsulated more than one outdoor air conditioning unit and caused a failure. You do not want to face this issue, you don’t want to experience loss of cooling. You do not want to face the smack to your wallet.

Do you live in such an area?

You might need to take special precautions on your own  to make sure an acute problem does not occur outside of the regular maintenance cycle. There are special options you can consider. There are sensor systems which can tell you when your systems are being stressed and will notify your HVAC service company of a problem. Or you can just be aware of these issues and in the spring, just have an extra eye out for problems here.

Being aware of the possibility is an important step in making sure such a dismal event does not happen to you.

Any questions or comments? Who has an experience to mention? Who has a recommendation? Add your thoughts in the comment section.

Posted in HVAC - Heating and Cooling

How long has it been since your Combustion chamber has been inspected?

The days are still warm when this was written, but what is critical is the date you read this. Do you use natural gas or propane to heat your home? Fall is coming, and this means you should be hearing from the HVAC service company you trust. You do have a HVAC maintenance agreement don’t you? Having your combustion chamber checked on a regular basis is a quite good reason to have one.

Burning fossil fuels creates carbon monoxide as a byproduct. Carbon monoxide in the air is deadly to living creatures. Burning gas means you have a combustion chamber and a heat exchanger to add heat to your air stream. This air stream is then blown out through your ducted system and out through your home to make you warm and toasty and cozy on the coldest day. You do not want carbon monoxide mixed into this air stream.

Here is a reminder that all of us using furnaces for heat, we are at risk from carbon monoxide poisoning. As long as we like living within draft-free shelters and want to use combustion to heat our homes, we are at risk.

More than one HVAC service company has been asked to verify the proper operation of an HVAC system in a home for sale by a home inspector and discovered that a combustion chamber was dangerously defective. Leaks and corrosion have been found many times, meaning the existing owner and her family had been exposed to dangerous CO.

Leaking combustion chambers need immediate replacing. Combustion gas leaks are not something you plan to deal with later. Needless to say, The home buyer would be quite relieved in this discovery situation and the homeowner should be quite appalled.  The point here is- if you have been coasting for a long period of time without careful attention to your combustion chamber, please schedule some heating and cooling system maintenance.

When furnaces are working properly, carbon monoxide bi-products go right up the chimney and out of doors where they dissipate. Problems arise when combustion chambers crack or corrode. Combustion chamber porosity allows the carbon monoxide to leak and mix into the air circulation system of your home.

The Carbon Monoxide is slightly lighter than healthy air and will thus distribute right into the life sustaining air in your home. The carbon monoxide is odorless, tasteless and not detectable by the human body. It simply enters the lungs, absorbs into the bloodstream and destroys the ability of red blood cells to absorb oxygen.

In a high enough concentration, victims die of carbon monoxide poisoning unless rescued. Vomiting and nausea and chest pains are symptoms of carbon monoxide poisoning. Low chronic levels of carbon monoxide, while not deadly, can create chronic symptoms of ill health. Elderly folks and infants are most susceptible.

Make sure you know the symptoms of carbon monoxide poisoning. Small background amounts can make people sick and sap health. I have an old friend in Arlington, Texas, who decades ago experienced a long bout of illnesses with her children. She was quite unnerved. When carbon monoxide was finally diagnosed as the culprit, she pulled out the gas furnace and went all electric.

Now, who was going to tell her that was a bit of an overreaction? Regular attention to the furnace could have made a difference. There are quite effective carbon monoxide detectors, if you know what you are looking for. The link above also talks about detection of carbon monoxide in your air. The Center for Disease Control has great info on Carbon Monoxide poisoning.

There are other potential sources of carbon monoxide in your home.

Make sure you know them and make sure you understand the concept of negative pressure inside your home.

The risk of CO from your furnace is preventable with an annual Fall Heating System inspection. A Fall inspection confirms your combustion chamber is sound.

Combustion Chambers are under severe Mechanical Stress. They do not fail at random.

There are 2 significant destructive forces acting here.

First, lets look at thermal stresses.

Fuel burns and the metal chamber expands as it is heated. The stress of expansion acts at joints and curves and connections. These stresses, acting 1000s of time in any one heating season and adding up over a period of years, can crack the combustion chamber. Units over 10 years old are even more at risk. HVAC manufacturers work very hard to make reliable combustion chambers, but maybe one in a thousand has a small undetected defect where problems can take root.

Now we need to discuss high humidity and corrosion.

As heating units have become more efficient over the years, the risk of corrosion has increased. As HVAC efficiency has increased, flue temperatures decrease. Less heat is wasted up the flue hence the system is more efficient. As exhaust gas temperatures decrease, the humidity in the system increases, and there are more encounters with condensation in the system. When condensation occurs in your flue, carbolic acid is formed from the chemical brew of combustion. Carbolic acid is very corrosive.

In conclusion, an HVAC Maintenance Plan makes sense for you, particularly if you are using natural gas or propane.  HVAC service companies  like to inspect Heating and Air Conditioning units in the Spring and the Fall. A spring maintenance inspection helps make sure the summer cooling will be done efficiently without undue wear and tear on the system.

But the Fall maintenance inspection is the most critical. Sure we want the furnace working efficiently. Sure, we want your furnace to come on when you need heat. But nothing is more critical than insuring a catastrophic combustion chamber failure has not occurred. We discuss whether an Heating and Air Conditioning Maintenance Agreement makes sense for you here.

We also recommend Carbon Monoxide Detectors. Of course, detectors are not infallible. Please keep the batteries replaced. The Center for Disease Prevention suggests changing the batteries when Daylight time changes in the Spring and Fall. Do not depend on detectors to cover for neglecting the regular inspection of your combustion chamber. Both are critical. More on carbon monoxide and CO detectors here.

Have you ever experienced a Carbon Monoxide problem in your furnace? Please add your comments below. Your experiences might help someone else better understand the risk of Carbon Monoxide.
Be safe. Get your HVAC unit inspected at least every Fall. Share this post with your friends. Lets watch out and protect each other.

Posted in HVAC - Heating and Cooling, indoor air quality

Any hints of musty odor coming from your cooling ducts?

Have you recently turned on your air conditioner in your home and noticed a musty or moldy smell?  So North Texas has a cooling season and a heating system, and these can be months apart or even in the same week. But the condition described here most often occurs when the cooling is intermittent and there are problems in your system from lack of attention and design defects. You might have the conditions right for a biological invasion of mold.

There a a couple different ways you can get mold in your duct system.

First, the filter system should keep your evaporator coils clean. Unless your system allows leakage around the filter; the filter does not fit tightly in the filter frame, or the door access leaks and the vacuum created by the blower lets ambient dust and dirt and organic matter to bypass the filters. This coupled with a wet evaporator coil, which is how your HVAC cools air can create the conditions for mold growth. A crapped up evaporator impedes your system from doing good work, and overworks your blowers and compressors. And can create conditions for mold. Wondering what an evaporator coil is? Want to know more about keeping system clean? We talk about these issues here. LINK

Now clogged and forgotten filters happen often and need immediate correction. Filters in air handlers can be forgotten, get clogged, create air blockage and upset the balance of the system and create the conditions for mold growth. Make sure you are checking the filters on a regular order. Check out the list of mandatory HVAC system checks that depend on you. 

Second, HVAC system ducts can create conditions for mold growth. Home construction in Texas saves money up front by stuffing all the duct work and often the air handler in the attic. Attics in North Texas are hostile, gaining heat in summer through which cool air in ducts runs a gauntlet. But the condition to create mold in ducts is in the heating season where a poorly insulated section of ducting allows heated air to cool and reach dew point. The cold attic at ambient temperature coupled with poorly insulated sections of ducting can create the conditions for mold. Mold growth is a complex enterprise, but mold shows perseverance, and if the conditions are right….  more on mold growth here. 

Duct systems are complex and essential to a properly working HVAC system. Yet, the ducts are often ignored and the air handler held responsible for all areas of discomfort.

Here is more information on potential duct issues.

Mold odors are a harbinger to unhealthy air. More info here.

Make sure you turn to fundamental solutions. Duct cleaning is not the answer, although it may play a role; but only if suggested by a reputable HVAC service contractor and only after fundamental issues are solved. They conditions that created the mold must be found and eradicated by proper design and workmanlike execution. Then the clean up can be discussed. Most often, duct cleaning is a profit center for grifters. More on making sure about what you are buying.

Any questions? Comments? Thoughts? Add them below.


Posted in healthy air - healthy home, link needed

Myths about HVAC You Need to Know

There are many myths about heating and cooling systems which cost homeowner’s undue discomfort and bigger bills. This is not a definitive list. If I missed one, please speak up.

Too much attribution of comfort issues is placed on the air handler or on the A/C itself.

These largest components are just part of the system which delivers properly conditioned air to you in just the right amounts.

In  fact, before you make any major purchases of new components, make sure your HVAC service company is doing proper modeling to best serve you.

Bigger is Better. NOPE

Lots of people see comfort solution through the thought, well I just need more cooling capacity. This is not true. In fact, more can often create more problems. The reasons are simple and we discuss them here.

Structural issues in the home are ignored

Too often, major decisions about the Heating and cooling system are made without any consideration of the structural shell which keeps out air leaks and insulates. The shell of the home is ignored when it plays a critical role in proper heating and cooling system design.

Attention needs to be paid to the structural elements of your home which affect air leaks and insulation levels. The structure impacts your heating and cooling load and impacts the actual size of equipment your home needs and the size of your electric bill.

Nothing is easier that some permanent solutions to defects impacting your home yet, nothing in most HVAC conversations between HVAC service company and homeowner get less attention. Oh, and this is not the time just to add more ceiling insulation

Big Old Iron is saving me money

There are a lot of people sitting around with an old antique heating and air conditioning system more than 10 years old, and thinking they are saving money.

Well you need to run the numbers. Heating and Air conditioning costs come out of your wallet every month, and add to your overall expenses. Old iron drains your wealth while giving you the feeling that you are saving money by not buying that expensive new system.

And old iron is running in ducting systems that has not been checked on over the same too long period of time. Has the home been remodeling in the intervening decades? Ducting issues can impact health of individuals when coupled with issues of air leaks and old iron past its usefulness. Just for the issues with ducts, you need to look at some new options. You can save money and be more comfortable, and feel more refreshed, and someone in the house, who has chronic conditions dealing with sinus issues and allergies jut might feel better.

There is the extra cost of repairs.

Mechanical systems were out and, yes, there is your trusted HVAC service company is your enabler because they are not going to rattle your cage and tell you, you are being silly. HVAC service people are like that. They often give you exactly what you ask for and not try to influence you as to what you need.

You need to do something different here.

You need to feel a sense of urgency.  And the day looms when your system can no longer run on a refrigerant that is no longer legal to sell, so you are being squeezed into a corner. You need to take a big breath and step out of the role of an HVAC reactionary and explore your options and the cost structure of your options. You will save money, and you will be more comfortable, and people in your home will lose symptoms of sickness and allergies and bloody noses…

Feel free to set me straight on any issue here. Also any mythology I missed, please share your thoughts. If you hear something silly about HVAC from the mouth of a human, share it. People are better off when they are dealing with reality not mythology.

Posted in home comfort, Home Structural Issues, HVAC - Heating and Cooling Tagged with:

Would You Like 3″ of Insulation with that?

I think everybody has experienced an upsell. Upselling is a time tested way to increase the size of the sale. And don’t we all love french fries. However, an upsell on insulation just might not be what you need. We are going to look at the issue of upselling insulation but first I have to make fun of companies that pitch insulation as part of some other upgrade. Get a new roof. “how about an extra layer of insulation while we are here?” Get some A/C work in the attic.  “let us add some insulation while we are here.”

Simply put, this is not a good idea, unless your attic has been retrofitted already to stop air leaks. Air leaks are a serious defect. Especially in the attic which can be cut up with lighting and plumbing chases and chimney chases. Many older homes have cut up ceilings from extensive remodeling. These add gaps through which air leaks gallop.

chimney chase diagram around block chimney

This look down vertical view  illustrates the chimney chase which provides the actual gap required between the ceiling joists and the brick fireplace chimney. This is a huge air gap and must be sealed properly to prevent air leaks of conditioned air. The actual joint configuration is trivial and not representative of actual construction. 

Adding insulation without solving the air leaks just makes it more difficult to solve the air leaks later, because insulation has to be moved to treat the areas leaking. More on air leaks here. Oh, and air leaks contribute to an unhealthy home. Like making people sick, and sick or unhealthy people sicker.


Selling up in this situation is good if there is a sound basis for implementation based in building science. Selling up for an air leakage test and sealing air leaks and adding insulation in the ceiling is good- is righteous work, helping, if administered as part of a professional energy assessment.

Home performance is a new term here – home performance relates to how much air your home leaks, how well it is actually insulated as per real measurements and building science. Seeing your home through “home performance” eyes, means understanding why your home has a problem with being too hot or too cold, or understanding your home might have a  moisture problem in summer through the principals of building science and not just time for a bigger A/C unit or a new dehumidifier. This is important… and you need to be able to separate the facts from the BS…. you have to pick out the contractor offering you home performance not “would you like some insulation with that”

That clarification made, I will go back and continue my bashing. The “add-on insulation with that” is becoming a staple in the services industry perpetrated by the big insulation companies- Owens Corning- they sell the blowing equipment to service companies and give them a deal and they can add on an easy “profit center” and you get the 3 inches of insulation and the shaft.

The proper application of insulation is important and there is an optimum level to the insulation you might need. If all these concerns are addressed, then maybe some insulation with your order of a new roof makes sense. But make sure it works for you and not just to creating a new “profit center”

Oh, and addressing the air leaks and lack of insulation at attic access door is critical move. Make sure you understand what is good for you, and not just what is good for improving profits for the service company. We will all small companies profits, but a profitable existence based on servicing customers actual needs.

Any questions, any comments, feel free to add them below.

Posted in air leak perils, energy saving strategies, Finding Quality Service People
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