7000 sq/ft home with HVAC concerns

I’m did an 11th month inspection and the homeowners have concerns that rooms aren’t cooling and heating properly. The master bedroom closest to the outdoor units were freezing cold (90degree day in Nashville, TN) while many of the other rooms were much warmer. Homeowners told me the opposite is true in the winter with the heating. All of the outdoor units (3 by Carrier, 14 SEER) appeared to be 1.5 ton units. I know this is mostly outside of our scope, but can I say anything in the report that the system may be undersized for their home? Do I simply recommend an energy audit to re-figure Manual J etc etc?

I would report what I observed.


You can say anything you want in your report it’s yours and your arse on the line. I would hope you performed some type of testing/measurement to verify the significant imbalance in the home to verify the client concerns. If they are 1.5 ton units I would suspect the Builder did a major FOOPAH on that one!

I would not recommend an energy audit for what you believe are seriously undersized units. If you performed measurements at the supply registers I would certainly note what was found and indicate significant issues that do require further evaluation by the Builder. This is a potential build discrepancy and warranty issue the Builder needs to be involved in.

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I’m with Larry. Don’t try to report/guess why, just report what is happening.

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Honestly, I’m not sure you really even have a significant issue.
90f degree day in TN?
No factual details? Temp? RH? Differentials? Distances from Units?
You gave us nothing, and you expect an honest, factual reply?

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Thanks for the advice- I included the temperature differentials and what I observed with poor ducting in the report and recommended further review by an HVAC specialist.

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I am a little confused. But that never stopped me, Lol.

What style of home? 1 or 2 story? I presume slab on grade ranch if its Nashville.

You mention (3) Three separate 18,000 BTU condenser units and ductwork. Hmm?
Where they, the compressors, all the same age?
Was there HRV/or ERV ventilation? If so. Did it share ducts?

Where/Are all 3 evaporators in 3 separate plenums connected to the same ductwork OR is the home’s HVAC split into 3 zones?
What was next to the master bedroom closet? Santa’s workshop?
I heard Trump threatened sanctions, and worse, if he kept on manufacturing in China. You know, You never know.

To myself, someone a little confused, Lol, it’s hard to give advice without being able to explain how the HVAC system is set up in the home.
I personally don’t care about exact measurements in this case, for now. Having a reasonable explanation about the ductwork and how the 3 separate condensers tie into the duct work may unconfuse me enough for a reasonable recommendation BUT that would be trumped by, “Refer to a licensed HVAC contractor” anyway.

I suspect, the system was under rated or mismanaged from the get-go. Additions have been made along the way by prior owners.

You set up a complicate HVAC hypothese from what I see. Refer to Licensed HVAC contractor.
Best of luck with all your endeavors. Keep us posted.

I am in Nashville and deal with HVAC system design all the time.
I have never seen 1.5 ton units used on a 7k/sf house anywhere here. I hope your right about this.

If you just did this inspection, 90 degrees plus the outrageous humidity this month has HVAC equipment operating above max design. “Temperature” readings are not sufficient, as enthalpy (a thermodynamic quantity equivalent to the total heat content of a system. It is equal to the internal energy of the system plus the product of pressure and volume) can not be determined with a thermometer. Design temperatures for HVAC Cooling equipment in Nashville is 97F Dry Bulb, 77F Wet Bulb (ASHRAE). Anything above this and the systems are under size for current ambient conditions and can not be evaluated.

Obviously, the “cooling load” of a closet is nowhere close to an adjacent room. The temperature difference you recorded is just a relative differential. It has no basis to indicate a problem. Basically it’s normal.

You have nothing on which to base this claim.

Call me when you come across these issues (they are common). They are very complicated to assess and you don’t need to be one in a string of people who who the client calls and can’t fix their issues.


Only detail that should be reported is the inlet/outlet temperature differential measured at the return and supply ducts and name and model of the condensers and air handlers. Size of the units and design details (other than forced air) are beyond the scope of the report.

Want to explain what can be determined from this information, and how it is determined?
Also, where in Home Inspection Standards this is required reporting?

David, that’s standard information provided in an inspection. Whether it’s sized correctly, however the duct work is setup, that’s not my area to address. I list the installed equipment , whether it was operating and temperature differential while operating. Warm and cold spots in the home, that’s a design or operational issue beyond the scope of my inspection. I don’t understand your question. Every report I’ve seen or received lists the equipment unless the ID tag is completely missing. At the very least the equipment manufacturer name is listed as a picture of the ID tag is included.

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What is standard information?

I realize that you can put anything additional into a home inspection that you find necessary, so long as you are qualified to do so. “Qualified” is the key element here.

I have been writing home inspection reports since 1995 and I have never identified any appliance in my home inspection report unless it was to identify where the deficiency was located. State law dictates to me what will be included in a home inspection report and this is not on the list. If it is a requirement elsewhere, I would like to know the reasoning behind it as it may be a significant consideration for inclusion.

You (and others) indicate that HVAC diagnostic is not in your area of expertise to address, yet many of you stand behind taking temperature differential measurements with a thermometer. I would like to understand why this is, and what the science is behind it.

I have been designing and diagnosing HVAC/R equipment for decades and have never been able to determine performance of any equipment based upon a temperature differential taken with a thermometer except to determine the temperature rise of a furnace/heater in the heating mode (which is a sensible heat process). But even here these temperature readings are not taken at the supply and return register they are taken 3-4 duct diameters downstream and upstream of the appliance.

If you are inclined to use a hygrometer and a psychrometric chart, with some long mathematical equations, you can provide some useful information. Other than that you are providing useless information to your client which can be misconstrued and create liability. It is about as accurate as determining the tonnage of air conditioning per square foot of a house. Simply a wild ass guess.

It is my recommendation to those reading this thread that making temperature differentials as a standard reporting requirement is not accurate enough to find a permanent home in a home inspection report template. Scientific fact; using the back of your hand is a more accurate measurement tool than any thermometer in your tool bag!

Again, no one says what you can/cannot put in your inspection report but it is not prudent to be utilizing inaccurate or false information.

For your additional information; the process of taking sensible heat temperature differentials is a tactic used by HVAC equipment installers as a shortcut to determine operating parameters of equipment they installed, knowing what the parameters are for that and similar installation applications. When you put in 25 units a month in the same type of house, built by the same contractor, you can get an indication if significant deficiencies exists in the installation. It won’t tell you what the significant deficiencies are but they will let you know that there is a deficiency somewhere (and there are a large number of causes for consideration). Hardly a procedure that should be required in all inspections, performed by an individual who disclaims all liability for performance evaluation of any component being inspected.

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Not worth the play on words. I was the industrial supply business for over 30 years. One of the first questions always asked, what is the temperature differential. Doesn’t matter if it’s a small HVAC system or a large cooling tower in a power plant. No one doing home inspections is breaking out the pressure gauges or checking draw on startup. Checking supply vs return ducts is just a first flag and not an indication that further evaluation is or is not required. Like everything else in an inspection, it is a report on how the system was functioning the day of the inspection. If the air coming out of the supply ducts is not cooler than the air being returned and I did not report it as such, you damn well better believe the complaints would be endless that I screwed the client over on the inspection and in their mind never even checked the system. Welcome to doing business in the Northeast.


It’s adequate just to report that heating/cooling was uneven throughout the home and recommend evaluation by a qualified contractor. The temperature splits are not as simple an indicator as is commonly thought. Indications by the same split differentials typically considered outside the norm can vary in different climate zones.


Most states don’t require you to confirm capacity or balance. There should be a comment about this in your report.

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I just completed a 7,000 square foot home. 3 4 ton AHJ. That’s 12 thousand BTU.

If you have the label from the condenser/compressor or Evaporator cabinet post the MN/Model Number and SN/Serial Numbers please.

12000 BTU = 1 Ton last time I looked

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Yup, Scott, you have it correct, as a rule of thumb. :smile:

Not in Robert’s world.

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Must be the Canadian Metric conversion thing! :wink:

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