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Cheap HVAC Sensors Could Save Tons of Energy June 10, 2017

Posted by federalist in Energy, Government Regulation, Uncategorized.
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Years ago I noted that modern gasoline-powered cars operate inefficiently on gasoline with suboptimal octane, and their engine control units even detect when that is occurring. If they simply communicated this fact to their operators, they could be fueled with the right gasoline, saving money, energy, carbon, etc. But there are still no cars that do this! (I hate to invoke government, but if it took a government mandate to get automakers to put tire-pressure monitors on their cars, at a substantial cost, I wouldn’t chafe at government mandating an essentially free “low-octane” notification on the dash.)

Add to the list of things that are already measured, that affect vast amounts of consumer energy, but which are not communicated to users:

  1. HVAC filter pressure
  2. Heat-pump coil cleaning required

Central air handlers in residences have two points of maintenance that are notoriously neglected. The most common is the air filter: If it is allowed to get too clogged with dirt the energy required to run the blower will increase. In all but the most expensive systems (which can sense and adjust for airflow) the efficiency of the heating and cooling exchangers will also begin to drop. Most residents are told to change the filter at regular intervals, without regard to the dirt load on the filter. That’s unnecessarily wasteful too.

An extremely cheap sensor and controller can detect when the filter should be changed. (In fact, modern variable-speed systems already detect this, but don’t communicate it to users. And for any other system a piezo sensor on the filter flange that detects a rise in average filter pressure does the same job.)

The second fix requires the addition of a few electronic thermometers (at a cost of pennies) to the outlet of every heat pump’s heat-exchange coils: If those coils become dirty or damaged, they lose the ability to exchange heat, which again reduces efficiency, increasing energy consumption, carbon, etc. All the thermometers have to check is the temperature difference between the outgoing refrigerant and the ambient air with which it is being exchanged. If that difference begins to rise, the coils need to be cleaned. This is something that may never happen, but if it does it should be fixed right away. Hardly anybody proactively checks for this, but the HVAC systems that don’t have these sensors built-in could be retrofitted with them for a matter of a few dollars.

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