What if Your System Only Moves 280 CFM Per Ton?

Cooling Example:

  • Three-ton condensing unit, indoor fan moving 840 cfm x 16° ∆T x 1.08=14,515 SBTUH
  • 840 CFM x 5.36 ∆H x 4.5= 20,260 TBTUH
  • 20,260 TBTUH – 14,515 SBTUH = 5,745 Latent BTU removal per hour.

Heating Example:

60,000 BTU Output. 660 CFM x 44° ∆T x 1.08= 31,363 BTUH.

Cooling Example:

Three-ton unit: 36,000 TBTUH. 20,260 ÷ 36,000 = 56%.

Heating Example:

31,363 ÷ 60,000=52%.

Scoring Your HVAC System

The calculations above show the HVAC system score. In these two scenarios, the scores are as follows:

Cooling System Performance Score (CSPS) = 59%
Heating System Performance Score (HSPS) = 52%.

In today’s market, do you think your clients would like to improve the performance of their system and upgrade? What if this is how some of your systems function? If you don’t measure, how would you know your systems have a degree of separation?

Would your refrigerant charge correct at 280 CFM per ton?

Image from the Graphic Conservation Website.

Don’t assume what most contractors assume: 400 CFM per ton is a rule of thumb. Before deciding you need to adjust the refrigerant, you must verify airflow! It is paramount to charge the system based on manufacturer requirements accurately.

Going up Against Well-Trained Competitors

What if your competition is trained/certified and better at diagnosing these problems? What do you do if that is true?

My uncle, Charlie Fusari, a professional prizefighter, faced Sugar Ray Robinson for the Welterweight Championship in August 1950. He lost a decision. When I was 15, I saw a video of the fight and had one question: Uncle Charlie, how come you didn’t block Ray Robinson’s punches?

My uncle’s response was difficult to swallow. “Alfonse, I blocked the punches that I could see,” he explained.

I laugh at that now, but it’s the same in our industry.

How do you identify HVAC system issues if you can’t see them? How can you fight the HVAC System Performance battle if you have not trained to do that?

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