HVAC 101 Crash Course: Bigger is not better

There was a lot of research with our “self-taught crash course” on HVAC… Bigger is NOT better!  After a dozen visits by the HVAC company over the past year, we were at our wits end dealing with the humidity in the house.  Last fall, the units had been recharged, systems balanced, new coils in the downstairs units and other details in attempt to help with the cooling and humidity.  The size of the units had been questioned and re-evaluated.  What we did not know until recently is that they were missing a key calculation in the software to determine the unit sizes.

Last month, I knew something HAD TO CHANGE!!!  I had read that well-built, energy-efficient homes which are tight can build up C02 levels, so I bought a humidity/C02 monitor.  Unfortunately, it confirmed we were not getting sufficient fresh air into the home.  Feeling more determined than before to find a resolution, I research more and it led me to learning about Manual J Load Calculations.  The “Improper Practices” section states, “Do not use “rules-fo-thumb….Floor area to tonnage ratios for the U.S. housing stock can range from less than 500 SqFt per Ton to more than 1,200 SqFt per Ton.  Efficient single family detached homes with a normal amount of well-distributed glass typically fall in the 700 to 1,200 range.”  Sure enough as the corrected calculations were 974 SqFt per Ton for our home.

With this all sounding like a foreign language I was quickly learning, we prayed to see the answer we needed and asked to meet with the owner of the HVAC company and their team. Over the next week, God gave us clarity on the situation as we were led back to paperwork which our draftsman had done and the HVAC company had dismissed.  Pieces of the puzzle were coming together, including the fact that our electric bill had been higher than anticipated — oversized units cost 26% more electric.  The State Energy Rater, who had done the original calculations for our draftsman, explained the miscalculations and it felt like a huge mountain before us had been moved.  The HVAC company willingly learned from him and we could see the light at the end of the tunnel!  They assured us they would make the situation right.

So, with the news that our upstairs bonus room calculated at 0.62 ton instead of 1.5 tons and the downstairs calculated at 3.5 tons instead of 5 tons, then the question began how to make it right?  With different sized units, all of the duct work would have had to be replaced – YIKES as the duct work above the bonus room isn’t accessible.  Thankfully, they installed top of the line variable speed units, while upgrading the thermostats.  Also, they added dehumidifiers to each unit and the attic space.  We went from a 60% humidity on a regular February day (had been higher during warmer months) to a healthy 45% humidity! Our attic space went from 80% humidity to 50%!

Dehumidifier was able to be placed directly on top of the upstairs HVAC.  Downstairs HVAC unit is higher and the dehumidifier would not fit between the trusses, so it was located nearby on a constructed plywood shelf.

February brought great air inside our home and a variety of weather outside of our home….warm high 80’s some afternoons and low 40’s other nights…..a crazy windy day (yikes on the trampoline and thankfully it did not hurt the neighbors fence and the metal bent back)…

There’s nothing like a beautiful sunset…except for when your boys are excited about the sunset and capture these pictures…

UnknownHave you checked the humidity in your house???  You can easily check the relative humidity with a $10 investment…

ThermoPro Digital Hygrometer and Thermometer

Sources vary recommending 40-60% humidity, but the more we learned the most ideal is 45 – 50% to prevent mold and other issues, with winter time humidity dipping even lower.  If you add a dehumidification system to your HVAC unit, then choose one with a built-in fan cycling so that it will improve the whole home and not just one room and run on mild days when cooling or heating are not needed.  It is recommended to buy a system which can remove up to 90 pints of moisture per day.  Investing $1K to $2K could make a difference in the air quality of your house as we can tell you that high humidity is less than ideal.

http://www.CriticalCactus.com shares the following in their 10 Reasons Why Ideal Home Humidity Levels Prevent Sickness and High Costs post…

To wrap it up, there are 10 reasons to dehumidify your damp house.

  1. less bacteria and viruses,
  2. less bugs,
  3. reduced risk on allergies caused by dust mites and other bugs,
  4. no mold and mildew,
  5. less toxins,
  6. increased overall wellbeing (a more pleasant atmosphere),
  7. fewer trips to the doctor because you are healthier,
  8. you will probably feel happier
  9. lower heating costs,
  10. no risk on damage to the house and furniture.

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