Why is My Electricity Bill So High? Part 1 – Understanding Your HVAC Unit

By Vernon Trollinger, May 31, 2016, Energy Efficiency, Save Money

Though we hate to admit it, we’re more frustrated with our monthly electricity bills arrive than we’d like to admit. Besides – it’s easy to forget about your energy usage when you’re busy, and by the time your bill arrives, you’ve either forgotten what you did or you don’t really understand what happened. With our Energy Fails series, we will identify common energy usage concerns to help you prevent them from happening again – saving money on your electricity bills.

Why is My Electricity Bill So High? Part 1 - Understanding Your HVAC Unit

“What happened last month? This is a large bill!”

Understanding Your HVAC Unit

Do you ever inspect your HVAC duct work for leaks or loose connections? If not, why?

No, all the duct work is in the attic. I don’t go into the attic.

Well, sometimes, vibration from your HVAC system can shake the duct work connections loose. That’s why you need to go and check it over once in a while.

But, I wouldn’t know what to look for. Besides, I don’t like going into the attic.

Why is My Electricity Bill So High? Part 1 - Understanding Your HVAC Unit

Seriously – would YOU want to crawl around up here?

Well, it’s just an attic.

No one goes up there. It’s got … things in it.


Look, I hate my attic. There are bees … and spiders … and other bugs up there. **Shivers uncontrollably**

Really? They’re just bugs, and it’s just an attic.

Hey! I’m just afraid of my attic! OK?!

The Energy Fail

Why is My Electricity Bill So High? Part 1 - Understanding Your HVAC Unit

It’s not surprising that some homeowners are afraid of their attic (or their basement). And why not? They are to a degree hidden or secret spaces cut off from the regular living space because “No one goes there.” Even more, the creepy attic is a horror staple going all the way back to the Victorian classic Jane Eyre.

So maybe you’re not like everyone else who hides their mad spouse in the attic of their Gothic ancestral estate. And (unlike my attic) perhaps your attic does not hold your grandfather’s trunk filled with those things your mother forbade you to touch or even discuss — especially on the night of the full moon. Fear is perfectly understandable.

Look, I’ll level with you. Most attics in modern homes are sheer torture for anyone with a touch of claustrophobia. They are not at all pleasant places to spend an afternoon. They’re cramped, stuffy spaces with nails poking down from the roof decking that stab you in the head. And yes, this has happened to me, and yes, it hurts.

Why is My Electricity Bill So High? Part 1 - Understanding Your HVAC Unit

Learning even the rudiments of how your attic and HVAC unit work together can help change your energy usage habits for the better.

However, attics do an important job for your home — especially when the HVAC and ductwork are located here. Like it or not, they do require periodic preventative maintenance, even if it’s just an inspection.

Even though your home might have recently been built in the past two years, your HVAC ducts can still develop problems. Leaky ductwork reduces your HVAC system’s efficiency by 20% — making you use more energy. That can add up to $500 a year for some homeowners.

How Can I Fix the Energy Fail?

Most newer homes have insulated ductwork called “flex duct”. The flex duct is made of plastic, resembling a bigger version of dryer hose and encased in an insulating sleeve. This kind of ducting can have three problems resulting from how it was installed:

Why is My Electricity Bill So High? Part 1 - Understanding Your HVAC Unit

You don’t have to be a home builder or HVAC repair expert to grasp the important aspects of proper HVAC operation.

  1. Flex ducting supported by belts or loops can pinch the duct and restrict air flow. This can also happen if the flex duct is bent too hard to make a connection.
  2. Flex ducting is most effective when fully stretched and used for short runs. This is because the helical construction of the flex duct increases drag on air moving through it. The longer the duct run, the lower the air flow, and the higher your energy usage. Some less than careful installers do not cut the flew duct to the right size.
  3. Flex duct should be secured to sheet metal connection so that it doesn’t move. Blowers make HVAC systems vibrate and this, along with the expanding/contracting from heating and cooling, can pull duct connections apart over time. Some installers put on only a zip tie and over time the connection can come apart.

To fix this situation:

Gently tug the flex duct connections in your attic. Also look for signs of disturbed dust at these connections as these may show air leaking. Connections should be sealed with aluminum duct tape or mastic.

If your home has metal or “hard” ductwork, you’ll want to look out for and address the following:

Why is My Electricity Bill So High? Part 1 - Understanding Your HVAC Unit

A classic example of “hard” metal duct work, commonly found in commercial buildings.

  • Holes or gaps in the ductwork at seams or bends. These should be sealed with aluminum tape, mastic, or for smaller-pencil-sized holes use silicon caulk.
  • Loose connections or gaps between connections. Metal ductwork should be joined with sheet metal screws and then sealed with mastic or aluminum tape.

You can also purchase duct insulation kits for rectangular sheet metal ducts that ensures more heated or cooled air reaches your living areas instead of losing that energy along the way. Insulation specifically for duct work is rated between R6 and R8. Round metal ductwork is easier to insulate and only requires slipping on insulating sleeves.

And if you aren’t confident in your home improvement skills, PLEASE contact a licensed professional to address your HVAC concerns. The little bit of money you pay now can help reduce your electricity bills in the future.

Stay tuned for Part 2 of our Energy Fails series where we’ll show you the benefits of actually programming that fancy thermostat you own.

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A native of Wyomissing Hills, PA, Vernon Trollinger studied writing and film at the University of Iowa, later earning his MA in writing there as well. Following a decade of digging in CRM archaeology, he now writes about green energy technology, home energy efficiency, DIY projects, the natural gas industry, and the electrical grid.

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