What Causes Low Airflow in a Heating System?

Posted: September 23, 2019

Air duct

If you have forced air heating (a system with a furnace and ducts, as opposed to a boiler with radiators or baseboards) in your Central Maine home, then one of the most common problems you will encounter is low airflow.

Some of the classic signs of low airflow include having hot and cold spots in your home, experiencing air pressure problems (ever have a door close itself in your home? It’s not haunted – it’s your HVAC!), and of course not enough air coming from your vents.

The good news is that many of the root causes of airflow problems are curable with a minimal investment of time or money. Here are some of the most common causes of flow issues in your forced air system, and what to do to fix them.

  1. Blocked vents/registers – Furniture, drapery, and other obstructions can block vents, disrupting airflow, decreasing the efficiency of your heating system, and causing your furnace to overwork to keep you warm. Keep vents clear whenever possible.
  2. A clogged air filter – The filter in your forced air system removes dust and debris to keep your indoor air as clean as possible – but it does its job so well that it will eventually get overloaded. When it does, airflow suffers, resulting in hot and cold spots, lower efficiency, and premature wear down of key heating system parts. Aim to check your furnace air filter about once a month during heating season, changing when needed.
  3. Leaky / poorly installed / undersized ductwork – Your ducts deliver heated air from your furnace to your living space – but they never do it with 100 percent efficiency. In fact, as much as 30 percent of the air you paid to heat could be getting lost along the way as a result of leaky, undersized, or poorly installed ductwork. Consider having a professional ductwork inspection to assess how significant the problem is in your home; you should be able to get one for free, or for a minimal investment.
  4. A faulty thermostat – Like any home comfort equipment, a thermostat can malfunction or even break down, and one potential consequence of that is poor airflow. Check the battery on your thermostat and replace it if needed. If you think you might have a problem thermostat, contact an home heating expert.
  5. A problem blower fan – Blower fans force air through your ductwork to deliver heat to your space. But blower fans have motors, and motors can slow or break down. If your blower fan is sluggish, poor airflow can result; you’ll need to call in a pro to replace the blower fan.
  6. Poor size matching – When it comes to choosing a furnace for your home, bigger isn’t always better. Unfortunately, many contractors don’t know this (and some do, but sell you a larger system anyway…but that’s a topic for another blog). If your furnace is too large for your living space, it will do its job too quickly, then shut off before repeating the process. This “cycling” can wear out parts prematurely and accelerate the need for heating repairs; it can also make it more difficult to clear humidity from your living space, since the air won’t flow for long enough to clear moisture from the air.
  7. An old or inadequately maintained heating system – Heating systems don’t last forever, and as they start to go, performance can drop off dramatically. That’s why it’s so important to get professional heating maintenance throughout your equipment’s lifespan – and to replace it when you notice signs of old age (consistently poor air flow, for example).

Experiencing problems with your forced air heating system, or looking for a heating system upgrade this fall? We can help! Contact the pros at Murray-Heutz Oil and Propane today to learn more about the propane- and oil-fired furnaces and boilers we sell, install, and maintain!

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