Short #37 – The Trade Skills Gap: A Manifesto (Podcast)

By Bryan Orr

This is a voice-over audio presentation of the article of the same title on the HVACRschool.com website (“The Trade Skills Gap: A Manifesto).

The manifesto discusses the value of technicians and the trades in modern society. It also covers the plague of snobbery that we are all too familiar with in the world.

You can read “The Trade Skills Gap: A Manifesto” HERE.

Learn more about Refrigeration Technologies HERE.

If you have an iPhone, subscribe to the podcast HERE, and if you have an Android phone, subscribe HERE.

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Author:

Bryan Orr

Company: HVAC School

Position: Founder

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Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

Jim takes us all the way through the history of furnaces, from the Stone Age when he was a child to modern modulating condensing types.

The goal of a furnace is to move heat, so a furnace uses heat exchangers to facilitate heat transfer. Furnaces have primary and secondary air. The primary air goes through the burner, and the secondary air goes around the flame and is pulled in around the heat exchanger inlet. So, the flame’s heat creates a draft that pulls air in.

Natural gas and oil (LP/propane) furnaces are common nowadays, but we initially burned wood and coal in furnaces. The first gas furnaces came into existence by modifying coal, not from the gas lines we see nowadays. Long ago, the flue gases were also exhausted to the basement; CO poisoning was less of a concern back then, as combustion was usually complete. Burning the building was a much more severe risk.

The first “gas crisis” in the 1970s forced us to focus on gas furnace efficiency. In that time, we developed spill switches and retrofit kits that converted furnaces over to spark ignition. In the 1980s, we came out with the draft-induced 80% furnaces we see nowadays. We also eliminated standing pilots and draft diverters. Even though the appliances became more efficient, we didn’t actually burn the gas any more efficiently.

So, despite the technological advancements we’ve made over the years, we don’t actually burn gas any more efficiently than we did in the 1930s. However, our modern furnace technology has eliminated standby losses, controlled ignition, and focused on the role of latent heat in combustion.

Jim also discusses:

Flame color and types
Draft hoods and diverters
Products of complete combustion
Excess air: a double-edged sword
Natural ventilation
Efficiency percentages
Furnace testing and ratings
Turbulators
Modulation

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