What happens if your furnace is oversized?

Author: Noel Lynch PhD  |  Last update: Saturday, April 26, 2025

Irregular Temperatures. You'd expect an oversized furnace to produce an excellent heat output. However, when a furnace is too big for a building, it will struggle to maintain the thermostat's settings. Its inefficiency and short cycling will cause the unit to heat the property unevenly.

Is it okay to oversize a furnace?

This is not a good thing and will lead to premature failure of the furnace. Besides premature failure, an oversized furnace will be prone to short-cycling, which is a term that refers to a furnace shutting down before the thermostat has been satisfied.

What happens if your HVAC system is too big?

Too Hot or Too Cold Air

An oversized HVAC unit can make your home's inside temperature uncomfortable. An HVAC system with excess capacity can heat or cool your home faster, but that speed often results in a couple of other issues. First, your home won't benefit from gradual, even heating and cooling.

What would likely be the result of an oversized mid efficiency furnace?

What would likely be the result of an oversized mid-efficiency furnace? The furnace would operate at a low temperature split.

Can a furnace have too many BTUs?

The more BTUs a furnace has, the larger the area it can heat. However, bigger isn't always better. If your furnace has insufficient BTUs, it'll work non-stop and never keep your home at a comfortable temperature. Alternatively, a furnace with too many BTUs will frequently cycle and be inefficient.

What happens when your furnace is oversized or undersized?

What happens if BTU is too high?

An air conditioner with BTUs that exceed the recommended square footage in your home may also take on more wear and tear over time because it will initiate its on/off cycle more frequently. It could also create a subpar cooling experience because your AC's compressor may turn off much sooner than it should.

How to fix an oversized furnace?

Oversized furnaces are very common unfortunately. Not much you can do about it without replacing with a smaller furnace. You can choose your thermostat though, either a bunch of short cycles or have it wait and do one big heat blast every so often.

Does a high efficiency furnace dry out the air?

Because the furnace constantly uses air to burn, it will also draw in cold, dry air from outdoors, which in turn affects your residence's humidity. High-efficiency furnaces, also referred to as a sealed combustion furnace, are better at keeping your humidity even.

What is one disadvantage of over sizing a furnace?

An oversized furnace can cause a number of problems, including increased energy costs, shortened furnace life, and uneven heating. If you're not sure what size furnace you need, talk to a heating and cooling professional.

Is it better to oversize or undersize HVAC?

Neither oversizing nor undersizing your AC unit is ideal. Both scenarios can lead to issues with efficiency, comfort, and longevity of the system.

How do you fix an oversized HVAC system?

Jump into these seven tips for how to correct an oversized air conditioner and get your house cooled down properly.
  1. Switch to a Smart Thermostat. ...
  2. Install a Dehumidifier. ...
  3. Add Warm Air Into the HVAC System. ...
  4. Reduce Fan Speed. ...
  5. Increase Minimum Run Time to the Maximum. ...
  6. Add Ductwork. ...
  7. Replace Your AC Unit.

What is the most expensive part in an HVAC unit?

Usually, it is a quick fix, but sometimes the failure can be caused by a much bigger problem. The most expensive part of an AC unit to replace and repair is the air compressor.

What happens if an HVAC unit is oversized?

If your AC is too big, it will cool down your home too quickly, and the cycle will shut off before the drip pan is full. A less than full drip pan will not drain, which will cause that water to evaporate and recirculate inside your house, making it feel humid.

Can I put a bigger blower on my furnace?

No, you should not put a bigger blower motor in your furnace.

Do high efficiency furnaces need venting?

No matter where you go, you'll hear homeowners raving about their high-efficiency gas furnaces. If you're thinking about replacing your current heating system with a high-efficiency condensing furnace, you'll also need high-efficiency furnace venting.

Why is my furnace sweating so much?

While it may seem unusual, it's actually quite normal for most furnaces to create some amount of condensation while they are running. If this condensation appears to be more than what you'd consider normal, it could be a simple fix. First, check your condensation drains to make sure they are not blocked.

Is a furnace ruined if it gets wet?

Furnaces and Boilers

Natural gas furnaces, space heaters and boilers all have gas valves and controls that are especially vulnerable to water damage from floods. Corrosion begins inside the valves and controls, and damage may not be readily visible, even if the outside of the device is clean and dry.

What size furnace for a 2000 sq ft house?

This size of home still needs a large furnace. If you want to evenly heat a 2,000 sq. ft. home, you'll need to look for furnaces rated between 60,000 and 125,000 BTUs, depending on the factors we discussed earlier.

Can a furnace get too much air?

Understanding Excess Air in Furnaces and the Potential Problems It Causes. Too much excess air can reduce your furnace's energy efficiency and introduce more carbon monoxide into the air. Why? When there's too much excess air in the system, it dilutes the water and carbon dioxide during the combustion process.

Why is my furnace blowing out cool air?

A furnace blowing cold air could be the result of a leak in your ducting. Over time, the changing temperatures wear on all sorts of things, including your ductwork. In fact, it's rather normal for ductwork to develop leaks over time. When ductwork has a leak, cold air will enter a duct and blow into your home.

Is it better to undersize or oversize a furnace?

Even a slightly undersized furnace will accomplish the job the majority of the time. Taking things down a few sizes will more than likely solve some of your common heating problems like too high of a utility bill while half of your house is blazing and the other half is an icebox.

How many BTUs to heat a 40x60 shop?

To heat a 40×60 shop, which is 2400 square feet, you'll typically need between 108,000 and 132,000 BTUs.

What is the most reliable gas furnace brand?

The 5 Best Furnace Brands
  • Carrier Furnace: Best Warranty.
  • Lennox Furnace: Best Company Reputation.
  • Bryant Furnace: Best for Durability.
  • Trane Furnace: Most Years of Experience.
  • Amana Furnace: Best for Efficiency.

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