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The Right HVAC Unit for Your Home

A couple of months ago, the HVAC unit in my home started malfunctioning. The temperature inside my home soared to over eighty degrees Fahrenheit, even though my air conditioning system ran nonstop. After inspecting my air conditioning unit, my knowledgeable HVAC contractor recommended I purchase a new system. He discussed the pros and cons of installing different sizes of HVAC units with me. After considering my HVAC contractor’s advice, I decided to purchase a three and a half ton HVAC unit. Shortly after my HVAC contractor installed my new air conditioning unit, my house started feeling more comfortable. On this blog, I hope you will discover how an HVAC contractor can help you select the right air conditioning unit for your home. Enjoy!


The Right HVAC Unit for Your Home

Is Your Furnace Shutting Off Prematurely? Here's Why!

by Jamie Shaw

A typical residential furnace runs until it can meet the thermostat setpoint, at which point it will shut down and wait for the temperatures to drop before doing it all over again. If you have a modulating or multi-stage furnace, the process will work a little differently, but the fundamental idea will remain the same. 

In other words, you can be sure that something is wrong if your furnace routinely shuts down before reaching your target temperature. The time it takes to hit your setpoint can vary, but the furnace shouldn't shut off before you're warm and toasty. If it does, there's likely to be an underlying issue that you'll need to address.

Why Do Furnaces Shut Off Early?

You might be surprised at the simplicity of a typical residential heating setup. In most cases, your thermostat (or thermostats) uses a single control signal to call for heat. The thermostat will monitor your home's temperature, call for heat when it drops too low, and stop calling for heat once it's just right.

In general, this means there are only two fundamental reasons why your furnace will stop heating your home before reaching its setpoint:

  • The thermostat stops calling for heat prematurely
  • Safety switches trigger a furnace shutdown

While there are many potential reasons for these two scenarios, almost all furnace short cycling will boil down to one of these causes.

What Should You Do With a Short Cycling Furnace?

It's always a good idea to start by checking your thermostat settings. Ensure your thermostat is on heating mode and at an appropriate setpoint. If you're using a smart thermostat, try disabling any energy-saving or learning features, as these may change your setpoint automatically. These steps won't rule out problems with your thermostat or wiring, but they will rule out simple issues with settings.

You can also check the control board for error codes if you have a relatively modern furnace. Your furnace may display error codes by flashing an LED light or by displaying an alphanumeric code on a small display. In either case, you'll need to cross-reference these codes with your manual. If a safety switch is to blame, you'll likely find an error code alerting you to the problem.

However, it's important to remember that these error codes are similar to the fault codes you can read from a modern car. They provide a good starting point but won't necessarily point you to the problem. Instead, it's important to have a professional HVAC technician investigate any issues with a short-cycling furnace, especially if your control board indicates a potential safety issue.

To learn more, reach out to a furnace repair technician.