At Home in Texas

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.

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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.

How do you parse your relationship between an energy auditor and a AC service company? 

This is an excellent question. This is a tumultuous time in the HVAC service industry. For decades, and in the minds of many homeowners today, a variety of traditional myths dictated suspect solutions to home comfort issues. Make sure you know these.

But the quest to save energy has given impetus to actually using building science and home performance testing to design and implement solutions to home structural and human comfort issues.

Your home is a collection of components and mechanical systems which must be analyzed as a system and you should accept no easy or glib answers. We will be constantly working on this website to clarify the issues for you of which you need to be aware.

And so progressive HVAC service companies and independent energy auditors are both plying the trade dealing with issues of building performance. There might be some difference in the conversation starting space, but you will find overlap here if the HVAC company is up to date with the recommendations of the ACCA – Air Conditioning Contractors of America, which understands the critical interlink of the existing home envelope- ability to stifle air leaks, insulation and solar loading, etc. with the critical design of the proper mechanical system for your home. If your HVAC company is not addressing these kinds of issues, well, maybe it is time to hit the pause button and reevaluate. Dealing with home performance issues are in the building code in your local area of Texas.  Let that sink in. Of course, this is Texas, and you are relying on your own wits to parse action creating value from talk. Actually testing is a great way to verify and not depend on trust.

However, the exact expert you use will be based on whom you trust for a good share of what will happen.  All issues mentioned here are important and we need to beware the man with the hammer who sees all problems as a nail.

Make sure you understand any special interests impacting your choice of professional. You need to know when your contractor or consultant has a financial connection to your potential project and how that might influence events. We talk about this issue here.

So let’s look forward at some actual roles

There are issues here that are the bailiwick of the HVAC technician. Other issues need to be dealt with by an energy assessor who might be working as a sub for a HVAC service company. It does not matter, just do not let someone glib turn you away from fundamentals and sell you something that makes a great sale but is not in your best interest as a consumer.

You need a trusted HVAC tech for regular maintenance of Mechanical Equipment.

You will need to depend on your trusted HVAC technician to help you stay abreast of how well your HVAC equipment is doing longevity and performance wise. HVAC mechanical systems are sophisticated and highly tuned pieces of machinery under constant stress of load bearing mechanical motion and the stresses of heating and cooling. They need regular attention. You need to understand the merits of a regular maintenance plan. LINK

But an energy assessment of your home is a critical part in the design of your next HVAC system.

It doesn’t matter who does it but an assessment needs to be done, and the results integrated into the design of your next HVAC system strategy. Making sure air leaks are minimized, and  insulation levels are optimized and any issues with solar heat gain are addressed. These critical  structural defects must be removed, before you invest in HVAC systems because the heat load and  cooling load directly impact the optimal design configuration for your home.  Proper design impacts the effectiveness of your system, your comfort level and the increased value of your smart investment in your HVAC system.

You must choose your expert to help with duct issues.

You also need to choose the expert, HVAC service company or energy assessment to understand how well your duct system is performing. There are lots of issues with ducts which too often get ignored.

related: Have you already taken an exploratory adventure into your attic to look at your ducting? or maybe the ducts are in the crawlspace? Crawlspaces have their own challenges for you.

You will also depend on your trusty HVAC technician to test your differential temperatures from the heating source- your air handler to the temperature of the air delivered to the vents of your home. This is a critical measure of insulation in the ducts and is also a function of the ability of air to travel effectively through the duct system.

Air balance is a big issue too. Proper air flows are essential to keep you comfortable and to properly handle moisture issues in your home. We talk about air balance issues when we talk about how experts assess the actual HVAC system.

We have not really given any definitive answers about whom to call here, but tried to outline some critical issues that need proper attention. The actual layers of expertise in these matters crosses over between technical approaches, but the fundamentals must be addressed and do not let anyone give you short shrift on topics that lay at the peripheries of their prime focus.  We discuss the issue- just whom should you call with a comfort problem here and you get to parse these issues yourself.

We talk through a useful process for deciding when to upgrade an air conditioner here. LINK

Do you have a question? Do you have an opinion? Feel free to add it below.

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You need a schematic detail and a useful work specification in your next Contract

Whenever you hire someone to work for you, you need to have a complete understanding of the work specifications. This often gets overlooked in the happy talk and the verbal promises made and you then end up with what actually what is included in the signed agreement.

Proper specifications are essential as to what quality trade practices demand; and help you make sure that is what you are getting. There are things you might feel are too trivial for this, and that is your decision; but a written spec adds clarity, alleviates unrealistic expectations, and certainly helps with verification. Of course, this is just one key step in finding the right contractor. We discuss selecting contractors here.

Even simple projects like adding a new entry door, replacing windows- there is a manufacturer’s specification that comes with it. You need to include these in the contract, you need to understand them, and you need a method of verification that the installation specs were met.

The conscientious contractor will be happy to oblige. They like it when home owners call out skill and details rather than a fixation on lowest price. They are proud of their skills and customer care. It is too bad, but caring about customers is not as commonplace as you might think- I am talking about actions here, not happy talk. Actions speak louder than words when you pay attention.

When you address work specifications, you are underlining that you care and are aware.

Keeping leaks out of windows have become such a problem in the last decade or so, that building standards have really ramped up to keep water out of walls. Engineered wood is loved by mold, and mold finds a wet leaky section of wall a lovely place to grow. We go into exceptional detail on openings in the walls here.

The water control layer in your home is a perfect example of the necessity of work specifications. There is an exact spec for sloped roofs and for every type of protrusion through your roof and a detail for every transition to siding or roof ending. You can check out roofing details here as an example.

Roofs do not leak that are built to the specifications of the National Roofing Contractors association or our own local branch- the North Texas Roofing Contractors Association or the specifications of the Asphalt Roofing Manufacturers Association. The trouble starts when the contractor you hire makes their own rules and sets their own standards. We discuss roofing in much greater detail here.

Sidewalls in Texas also have problems with leaking and creating mold in walls. The design of the water shedding layers on a wall is called the drainage plane. We discuss the drainage plane again when we are talking about the ways water gets into your home structure.  When stuff gets done for expediency and convenience and speed vs. the long term reliability of your home; problems occur.

Problems happen because someone is working without a specification or not being held to the specification. Bad stuff happens more often when people get in a hurry and are not held acountable for the quality of their work.

Your level of concern and your degree of pickiness, of course, will relate to the degree of risk involved- putting brick borders around the oak tree incorporates less risk than brick repairs in a sidewall of your home… and this matters. This is your choice, but accurate building specifications, understood by you, with a plan in place to verify; will give you fewer headaches and not hurt the feelings of the quality contractor at all. In fact, he or she will be pleased that you care and that you noticed.

The quality of the work that gets done depends on whom you hire. We discuss a to-do list before hiring a contractor or remodel here.

Have a question or a comment? Add it below.

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Some basic Roofing Mistakes to Avoid

There are several routine crimes committed against roofs out of expediency that should never be done. They do get done, because a homeowner wants to believe a fantasy, and a contractor is willing to do something mediocre just to get the job. So don’t do these.

Existing roofing should never be covered over in a reroofing situation.

You see this done with asphalt shingles to ostensibly save a few bucks now and then, but it is against code, it covers up potential problems with the decking and the roof just does not last as well.

Critical flashing areas can just be nailed over rather than properly flashed with proper flashing metals. A chimney flashing will be much worse off after a recover than with the original roof. The valley flashing on a chimney is a critical point of risk and adding a recover here is at least doubling your chances of really serious problems right from day one of a recover.

Asphalt shingles work really well when it  is well supported against a solid  flat deck.  Recovering over the existing levels the new shingles poorly supported over the roiled surface of the existing shingles.

The recover can trap moisture, cause the new materials not to lay properly and, if push comes to shove, you basically have no warranty.

We also have to be very sensitive to slope.

Any slope flatter the 3:12 which means a 3 foot elevation gain for every 12 feet of surface run… is the flattest slope that works with the standard spec for sloped roofing. You see roofers on occasion flirting with low slopes. Maybe it is s remodel, and the roofer is a roofer in name only, but you see people putting on roofing and adding an extra layer of underlayment, maybe, to help keep water out.

Once upon a time there were roofing specifications for low slope roofing that called for a double layer of underlayment.  But you don’t want this. If you get into a low slope situation, you want a waterproof specification just like for a flat roof.  With a low slope spec, you are hoping the water runs off before the water soaks through. Particularly, if you have a lot a long slope to drain, makes the situation even worse.

There are new self sticking membranes used in sensitive areas of the roofing that reseal themselves around nailheads, but this is not as good as using a roofing spec designed to keep out water.

Your good old standard roof spec can run into low slope situations as part of the roof slope configuration. Different slopes can be tricky, particularly in a situation where a roofer is moving at high speed; say, new construction. Make sure you also see the discussion on getting the roofing details right.

You might want to check out the page on the problem home.  If you have a chronic problem and the contractor is making excuses, then you might have a problem home with unique little structural traps build right in. Check out the at risk  home here.

What did I miss? 

Do you have a question or a comment; feel free to speak up. What you say might help someone make a better decision.


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