If you’ve decided on a mini-split heat pump for your home, “what size mini-split do I need?” is an important question to ask. Inadequate heating or cooling in your home can result from the wrong sized unit. Even though ductless heat pump systems use sophisticated technology, you still need the right size in order for them to do their job. Here’s how to size a mini-split system!
How To Size a Mini-Split System
When it’s time to make a decision, knowing how to size a mini-split system can help. Note that this advice is not meant to take the place of a professional’s opinion. However, it will help you understand how experts choose the appropriate ductless system size and should give you a fair sense of the sizes you can anticipate.
Here are the best steps to take to properly size your mini-split:
- Understand the way your mini-split works and why it’s important to choose the right size
- Do some rough math using the British Thermal Unit to gauge the size you need
- Know other factors that can affect the efficiency of your unit (and the required size)
- Work with experts for their opinion and professional installation
By following these steps, you’ll save money and be comfortable each month with an effective and efficient mini-split.
Why Proper Sizing Matters
To understand why choosing the correct sized unit is crucial, it’s good to have an understanding of how it’s supposed to operate.
Mini-split heat pumps are a popular choice for those seeking the best energy efficiency. These ductless systems are top quality with SEER ratings ranging from 13 to 22. Instead of ducts, the air conditioning unit delivers cool air to your room. As a result, it doesn’t need to push as hard to keep the temperature where you want it.
Still, there are some challenges that could prevent the system from functioning as it should. In addition to a unit size that is too large or too small for your space, installation mistakes can lead to further issues in the future. You’ll be able to avoid mistakes if you know in advance what size your place might need. You’ll also be safe working with a trusted company for your installation.
What Happens When Your Unit is Too Small?
A too-little unit will run overtime attempting to cool a space that it was not designed for. Your home’s temperature will fluctuate and your energy expenses will increase as a result. In one corner, you might feel chilly, while in the other, you might be too warm. The unit is working harder than usual, which increases the likelihood that it will break or wear out early.
What Happens When Your Unit is Too Big?
On the other hand, a bigger unit has its own issues. First off, you’ll wind up paying too much for an excessively huge mini-split.
The unit will repeatedly turn on and off because the room will fully cool too fast. This is a process known as short-cycling. Your unit becomes exhausted from this short-cycling, which accelerates wear and tear. A larger unit won’t have the opportunity to manage humidity on such brief cycles, leaving your home feeling uncomfortable.
The British Thermal Unit (BTU): Your Mini-Split Sizing Guide
There is at least one inside unit and one outdoor unit in mini-split systems. The outside unit must be scaled for the entire home if you are installing multiple indoor units in different rooms. The indoor units must be sized for the area they will be heating or cooling. With the variations in room size and other factors, you may need a different-sized unit for each space.
So how do you determine “what size mini-split do I need?” The British Thermal Unit (BTU) gauges the amount of heat required to raise the temperature of a pound of water by one degree Fahrenheit.
Depending on your room size, a different amount of BTUs per hour is required. You can use this key to roughly estimate how many BTUs you’ll need per hour to efficiently keep your room comfortable. Using the square footage of your room, you can figure this out. A mini-split should be sized as follows:
BTU and Square Footage Key
- 350 square feet: 9,000 BTU per hour
- 500 square feet: 12,000 BTU per hour
- 750 square feet: 15–18,000 BTU per hour
- 1,000 square feet: 18–24,400 BTU per hour
- 1,250 square feet: 23–30,000 BTU per hour
- 1,500 square feet: 24-36,000 BTU per hour
When to Adjust Your BTU Expectations
In addition to room size, there are other variables that can make a mini split work extra hard. If any of these things apply to you, you might need to modify your BTU expectations:
- How high is the ceiling? To adequately cool a room with a ceiling higher than 8 feet, around 20% more BTUs are needed
- Sunlight and light bulbs: sunlight and light fixtures produce heat, which may require your air conditioner to operate longer. You might need a larger unit if you don’t want to block any of the light.
- Tech gadgets and appliances: other gadgets can also raise the temperature in your house. If the mini-split is near a TV, computers, or the oven, for example, it might work harder.
- Flooring type: Because carpet insulates, its presence can change a room’s temperature and, in turn, the amount of air conditioning the space requires. Conversely, a hardwood floor might make the space feel cooler.
- Housemates and Family: If the room is often crowded, body heat may raise the temperature. When thinking about mini-split sizing, keep this in mind.
- Outside air has a way of getting inside our houses. You might need to raise BTU by about 30% if you reside in a hot climate with regular highs of 90 degrees Fahrenheit.
- Old/poor insulation: Insulation in older homes is more worn. A 30% increase in BTU will be needed in poorly insulated rooms.
Still Wondering “What Size Mini-Split Do I Need?” Ask the Professionals
Although it’s wise to do some calculating ahead of time, it can be challenging to do it yourself. To get the absolute best idea of what size mini-split you’ll need, get in contact with an experienced HVAC professional. Here at Live Free Heating Cooling Electric, we offer premier mini-split services to the New Hampshire area. Get in touch with us for a free estimate today! (terms apply)