How A Rooftop HVAC Unit Works

How A Rooftop HVAC Unit Works

A rooftop HVAC unit, or RTU, works very similarly to most indoor systems: They provide heating or cooling to an area by treating the air that passes through it and then circulating that air.

In particular, a rooftop unit is an air handler – the part of the system that conditions the air and circulates it. From there, the air typically travels through ductwork and vents to the space you’re treating.

Commercial Heating and Cooling
What’s specific about rooftop air handlers versus indoor ones is their location. And, they’re designed a little differently to account for their being outdoors.

RTU’s are more robust and weather-proof. They’re made to prevent rain, snow, debris, and even animals from getting in, while still allowing air to pass through.

And, they’re self-contained: There’s a chiller or heating device built into it. That way, the air doesn’t have to pass further into the system to get treated.

There are also a few benefits to these over indoor units. We’ll cover those a little further down.

In any case, it’s common to see more than one RTU on a larger building. Each air handler treats a specific area within the building.

Parts of a rooftop HVAC unit

Most RTUs are rectangular, with the parts inside assembled next to each other.

What you’ll see from the outside is the casing. It’s made of metal, but much sturdier than indoor unit. That’s because it’ll have to withstand the elements.

Air Hood

Next, you’ll notice an air hood on one side of the unit. It allows air from outside to enter. That’s what will get warmed or cooled, and distributed inside the building.

As the name suggests, there’s an awning on top of it, so the air enters underneath. This way, precipitation and debris don’t get in.

Similarly, there’s a netting to block any critters or birds from entering, either.

Dampers, Filters, and Coils

The air then passes through dampers, which are rotating metal sheets. These prevent air from escaping. And, they can run at different speeds to regulate how much air gets in.

After that are the filters, which work like those on any HVAC unit. A tech can get to them through an access panel.

After passing through the filters, the air reaches the coils, which transfer thermal energy.

In the case of air conditioning, they remove heat from the air. In heating mode, the coils add warmth.

Behind that is the fan. It’s the part that’s actually pulling that air into the unit in the first place. From there, it pushes the now-treated air into the ductwork

Typically, behind that are the compressors and condensers – the parts responsible for heating or cooling the air.

RTU vs. An Indoor Unit

What makes a rooftop unit attractive to a building owner? After all, it’s an important part of the building that you won’t be able to access easily.

However, there are some significant advantages to an RTU.

The two big factors are space and noise. More than anything, these are why property owners consider these models.

Placing your HVAC equipment on the roof means you don’t hear them working. In general, commercial units are noisier than residential ones. They’re often covering more space and working harder.

In smaller areas or places where sound is especially an issue, this makes a big difference.

Zoned HVAC

When you have a large building, you’ll get better results by zoning your HVAC. That’s having more than one unit, with each one handling a different area of the building.

But, that means taking up a lot of valuable real estate for air conditioners or heaters. The solution is to put them where people aren’t: the roof.

This way, you get the advantages of multiple units treating different areas. But, you don’t take up room where people are working.

After that, you end up with some more benefits.

Security and Efficiency

RTUs are secure. Without easy access, they’re less prone to vandalism or accidents. No truck will back up into your expensive HVAC unit way up there.

And, when they’re used properly, RTU’s are more efficient than indoor models. That’s got to do with zoning versus one large unit handling the entire area.

Also, most models come with additional temperature and humidity control to help you zero in using less energy.

How Long Does an RTU Last?

It’s tricky, but not impossible, to predict how long a rooftop HVAC unit will last. A good span is between 10 and 20 years. That accounts for constant exposure to wind, rain, snow, ice, and sunshine with no shade.

Like any outdoor unit, these won’t last as long as a furnace or other indoor appliance.

Then, there’s the big caveat: maintenance.

There’s a term used in a few industries: Run-to-failure. In the HVAC world, it’s when you install an AC or heater and use it until it breaks down.

In that case, you’ll be lucky if your RTU makes it a decade. Preventative maintenance makes all the difference.

That’s especially so for a commercial unit. Most buildings, especially in office parks, don’t have windows that open.

So, you’re relying on the heating and cooling system all year. It maintains the temperature and circulates the air.

Therefore, you want your unit running in great shape all the time.

Regular Maintenance

The best way to extend the life of your RTU is preventative maintenance with a good service plan.

If your rooftop unit provides both heating and air conditioning, then you’ll want it inspected and cleaned by a professional twice a year.

Even though it’s out of the way up on the roof, a tech will have no problem reaching it. At the least, they’ll need to get up there to change out the air filters.

While they’re at it, part of maintenance includes routine cleaning and inspection. This way, you avoid unexpected breakdowns.

Service Plans

Cleaning and inspections keep everything running smoothly. And, you’ll avoid sudden, costly breakdowns when a tech replaces a worn-out part before it breaks.

This process does more than save you money on a replacement. It also ensures the system is working at its best all the time. That means lower energy bills.

Service Plans From Bovio

Finally, you’ll get fewer complaints about it being too cold in the winter, or too hot or sticky in the summer.

And, with a service plan, this is as out-of-sight and out-of-mind as the unit itself. If you sign up for two inspections a year, you’re set. Your HVAC company should get ahold of you when it’s time to come out, not the other way around.

Of course, there’s a small upfront cost that comes with these services. But, you more than make up for it when you’re not suddenly replacing HVAC systems every few years.

Are you interested in a rooftop HVAC unit for your South Jersey business or commercial property? Contact Bovio to see if your building is right for a system such as this, and what the best setup would be for you.

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