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Carbon Monoxide: What Do You Know? Four Package Unit Inspections That Expose CO Safety Issues

Most HVAC technicians don’t think about CO (carbon monoxide) while they’re working on a package unit in 90°F heat. They know that getting the cooling back on is the top priority. However, as a professional technician, don’t forget that health and safety are also top priorities. Here are some quick checks you can do with your summer service procedures that could expose potential CO safety issues. Let’s look at four inspections that may reveal hidden… Read More

Carbon Monoxide: What Do You Know? Duct Connections that Kill Airflow and Heat Exchangers

In the middle of the summer heat, you probably aren’t thinking much about cracked heat exchangers. However, airflow is essential year-round in our industry. If you encounter systems with low cooling airflow, chances are high you also have messed up heating airflow. David Richardson, NCI Trainer Low airflow through a furnace forces it to operate outside of manufacturer specifications. The heat exchanger overheats and may lead to premature equipment failure. Let’s look at some issues… Read More

Inverter Driven – Voltages, Part 1

Diagnosing inverter drive systems in many cases is easier than diagnosing electro-mechanical/analog systems. The inverter drive will report error codes both external to the device (temperatures at compressor discharge, evaporator, etc) and internal faults (IPM, EEPROM) but the error cause may be ambiguous. An IPM failure could mean more than simply an IPM (inverter power module) failure; it could be that the converter has failed or that one or more IGBTs (switching transistors) have failed. Read More

One Engineer’s Opinion: Why You Should Use Product-Integrated Direct Digital Controls

The product integrated controls that I am speaking of are Direct Digital Controls that are factory-installed in HVAC equipment. One of the major benefits of DDC Controls is that they can be monitored from computers or smart phones. Bruce Longino, PE, LEED AP Many years ago, building owners hesitated to specify product integrated controls because they were proprietary. The manufacturer of the HVAC equipment could charge what they wanted and the owner was stuck. However,… Read More

Carbon Monoxide: What do you know? – One Reason Heat Exchangers Rust

By David Richardson David Richardson, NCI Trainer Have you ever wondered why some heat exchangers rust while others remain spotless year after year? One overlooked reason could be flue gas. Let’s look at what heat exchanger rusting can reveal and why it’s happening. Visual Signs of a Bigger Problem Our industry has blamed heat exchanger rusting on everything from contaminated combustion air to high humidity levels. While these issues must be addressed, they aren’t… Read More

Inverter Driven: Signal Wire

By Dan Applegate Though at first quickly evolving, the DFS/mini-split equipment has settled into a near-standardization: many of the systems work very much (and look very much) like the other. Of course there are variations amongst products, so always consult with your manufacturer (i.e. read the installation and service manuals) but there are some areas that have become common ground. Wiring from the outdoor unit to the indoor unit, for example, has become rather standard… Read More
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