Furnace Capacity: Understanding the Heating Power of Your Furnace

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Does your furnace capacity have what it takes to keep you warm this winter? While indoor comfort in cold weather is dependent upon several factors including outdoor temperature, furnace capacity is the biggest key in determining whether your household will be warm and energy-efficient all winter long. The capacity of a furnace refers to the amount of heat it produces (measured in BTUs), varies by make and model, and, for optimal performance and efficiency, must be matched to the specific heating requirements of the house.

Furnace Capacity Is Fixed

The capacity of a particular furnace is built into the unit. It can’t be increased or decreased. You’ll be living with that fixed heat output — whether it’s too little or too much — for as long as the unit is installed. That’s why it’s so important to get a heating load calculation by a qualified HVAC technician before installing a furnace in your home.

How Much Capacity Is Enough?

Fortunately, furnace capacity isn’t an x-factor. Furnace heating power is expressed by BTU output per hour. This figure is always included in the manufacturer’s specs and also shown on the unit’s ratings plate, usually permanently affixed to the inside of the furnace door.

The right capacity for your particular home can only be determined by a heating load calculation performed by a qualified HVAC contractor. Rough guesstimates or a “one-size-fits-all” approach to furnace capacity aren’t appropriate and lead to poor heating performance, diminished indoor comfort and substantially higher energy costs.

A professional heating load calculation includes a room-by-room survey of the home utilizing software that records input about characteristics including the amount and quality of insulation, number of windows, orientation to sun exposure, and structural air leakage. The software calculates the precise BTU per hour figure required to keep the house warm in typical winter conditions in your local climate. This figure can then be matched with a furnace that provides the necessary heating power — no more, no less.

For more on determining the proper furnace capacity for your home, contact the heating pros at Apollo Home Heating, Cooling Electrical, and Plumbing.

"Ernie & Mike did a superb job on my new furnace and A/C installation. Despite having more than a day’s work to do, they came in and stayed until the job was done. They were organized, efficient, and protected the rest of the house well. Got both furnace and A/C installed the same day. Ernie was courteous, informative, and clearly knew his job better than anyone I’ve encountered before. The units look so good guests now get The Tour of our new system. Apollo is clearly not a fly-by-night company. I would recommend them to anyone in need of a new furnace and/or A/C."
- Jerry A.
"I called Apollo because of a water leak I thought I had in our upstairs shower going into the kitchen. Robbie came and assured me everything was fine & looked at all the other plumbing. He ended up changing a few pipes for our washer & clearing a drain. He was very nice & knowledgeable with all my questions. I ended up signing up for the care plan & was very happy with my service."
- Cassandra B.
"The team at Apollo exceeded my expectations. As a business owner, my attention to the details and commitment to providing excellent service is high. From the sales rep. to the installation team, everyone’s performance was outstanding. For example, the installation team went to great lengths to protect our floors, placing floor runners and across the wood floors and up the stairs. They even were spot washing walls upon their departure. I highly recommend this company."
- Randy B.
"We scheduled an estimate AND a tune-up. We knew something was wrong with our furnace, but hoped we could make it through the rest of the season. Upon telling Bill what our furnace was doing, he warned us immediately what the possible outcome was going to be; a cracked heat exchanger. He watched the flames roll backward, tested carbon monoxide levels, which were so high they meter’s last reading was 5,600 before saying “high”. He immediately shut it down, tagged it, and explained that with levels that high and children in our home he wanted off right away. He continued his inspection and showed us via a camera that not only was it cracked in multiple places, but had holes all over it. He gave us a few options for repairing it; his knowledge as well as genuine concern was beneficial and refreshing. Luckily we also scheduled an estimator, Micah, to come too and we were able to get costs between repairing and replacing (with several options). We decided to replace with a much higher efficiency furnace and one sized properly to our home. Hands down, not only did they both provide us great service and knowledge, but without sounding dramatic, they may have saved our lives. This was our first time calling Apollo, but it won’t be our last."
- Sarah B.
"Apollo is an excellent company. I always receive great service. Alex A. was professional and friendly. He kept me informed during the process of checking my furnace and heat pump to make sure they were working properly. The company makes sure you are notified who is coming and when they are on the way. All my interactions with the company have been wonderful."
- Beverly S.
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