Concrete Vs Plastic AC Pad: What Works Best?

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An AC or heat pump's outdoor unit is responsible for releasing the extracted heat from your room and outside of your home. For these outdoor units to do their job consistently, it needs to sit on an AC pad that commonly comes in concrete and plastic. But how do you know which one works best? We researched it, and here's what we found.

The AC pad that will work best for you depends on the size of your outdoor unit. If your outdoor unit is large, you may want to go with concrete. If it's just a medium or small-sized outdoor unit, you can go with a plastic AC pad instead.

Knowing what kind of AC pad you should get for your outdoor unit can help maintain it in the long run. In this guide, we go through the kinds of AC pads out there and more to help you in your decision-making.

Collaged photo of two air conditioning units, Concrete Vs Plastic AC Pad: What Works Best?

Picking The Best AC Pad

The AC pad is important to mount the outdoor unit on a level surface that can handle the vibrations from it. Without an AC pad, the outdoor unit might end up digging itself into the ground due to the vibrations from operating and tilting to the point of damaging the internal parts. Apart from that, the elevation can keep off any immediate dirt or bug off the outdoor unit that may come in and get into your air conditioning unit.

A heat pump and air conditioning unit on concrete pads

Since your outdoor unit will be sitting on top of the AC pad, you'll need to set it up first. The most common types are concrete and plastic, and each is good to use, depending on the size of your outdoor unit.

Concrete

Gray concrete air conditioning units on concrete slabs

Concrete AC pads have been used for the longest time due to their lifespan. They can also support the weight of a large outdoor unit, making them the obvious choice for larger air conditioners. Aesthetically speaking, they aren't as pleasing to the eyes, but what makes up for it is their functionality.

While they are durable, concrete AC pads can also sink to the ground over time, which is why some would put in gravel to support the pad as it carries the weight of the outdoor unit. Cracks may also form over time due to rain.

Plastic

Hvac system on a plastic AC pad

Plastic or rubber AC pads are ideal for medium-sized or small units. Some are made with recycled materials, but plastic or rubber AC pads are highly durable, depending on the make. They can be water-resistant and UV-resistant, making them resilient to different environmental elements and won't crack as easily. They can also be eco-friendly as well which is why this is becoming a popular option to choose amongst homeowners.

Check out this plastic AC pad on Amazon.

How To Install AC Pad

Now that you know the kinds of AC pads that are out on the market and what works best in what scenario, you'll want to know how to install an AC pad properly. It's not as simple as placing the AC on an area; you'll need prepare the ground for it and more to avoid your outdoor unit from tilting.

Gray air conditioning unit on plastic AC pads

Deciding If You Need An AC Pad

It's been mentioned that an AC pad is important to keep your outdoor unit from becoming damaged over time. However, the reason why this is the first step is to look at whether you have an AC or heat pump already in place. If yes, consider its lifespan and its condition.

For a unit that's almost at its end, you may want to wait it out instead of buying a new AC pad for it. This is also in consideration of the fact that the size of your replacement AC may differ from your previous model. If your AC is still new, then you should go ahead and get it an AC pad.

Purchasing The AC Pad

Keeping the size of your outdoor unit in mind is important when picking out an AC pad. Aside from that, you also have to make sure that the AC pad will provide a 1-foot distance between the support feet of the unit and the perimeter. AC pads are available in most hardware stores and can cost about $100.

Preparing The Ground

Before placing in your AC pad, it's important to level the ground first. The outdoor unit will tilt if you don't level it properly. Over time, this can cause damage to your outdoor unit leading to a shortened lifespan of the unit and higher costs on your part.

To do this, you'll need to select the area where your outdoor unit will be placed. From the, compress the ground and top it with sand to level the ground. Use a leveling tool to check if the ground is even before moving to the next step.

Try out this 9-inch level on Amazon.

Adding A Base

Some people don't necessarily follow this next step and just place their AC pad on top of the leveled sand. However, it is recommended to add a solid base to make it more permanent instead of you periodically having to dig under the AC pad to add more sand underneath when it sinks.

You can put a layer of gravel on top of the sand as a solid base for this. Another way to go about it is by pouring concrete on top of the sand. While this may be a more permanent solution, you may need to call an expert to do it for you. Remember to always check if your ground is level when doing this step.

Installing The AC Pad And Unit

Gray air conditioning unit placed on top of a plastic AC pad

Once you're done adding your base, you can simply install the AC pad on top of it. You can check with the level if your AC pad is stable before placing your outdoor unit on top of it. It won't hurt to double-check if the outdoor unit is leveled with the leveling tool as well.

In case the outdoor unit is not leveled, you can install leveling pads under the unit. Lift the unit and slide the pads under the feet of the unit until it is leveled properly.

What Happens If The Unit Is Not Leveled?

Old white heat pump for a small residential house

It's crucial that the outdoor unit is leveled to make sure that it keeps working as intended for a longer time. But to understand its importance, you should know what kind of problems you may encounter if your unit is not leveled properly.

Internal Damage

As mentioned, the internal aspect of your unit might get damaged if the unit stays tilted for a long period of time. The part that is most affected by this would be the compressor which is responsible for compressing the liquid refrigerant of the unit to gas while absorbing the heat from the room.

If the unit stays tilted, the oil from the unit that powers the compressor will be distributed unevenly. This may lead to the compressor experiencing damage and overheating. The unit may also exert more effort and use more electric power to do its job, which means that the electric bill for it may cost more.

Water Accumulation

When you turn your AC on, it extracts the air's moisture which eventually gets expelled out. If the outdoor unit is tilted, this might cause the water to remain within the unit. Mold can accumulate and rust can form.

It can also damage the coils of your unit, making it harder for it to get rid of heat from the room as normal. If this happens, your unit will exert more effort just to keep your room cool and add unnecessary costs to your electric bill.

Excess Vibrations

Vibrations from your outdoor unit aren't only problematic due to the noise. Excess vibrations due to your outdoor unit being tilted can strain the internal parts of your unit. Apart from that, the vibrations can cause the unit to sink down. It can also cause a refrigerant leak due to the vibrations shaking its lines loose.

Final Thoughts

Collaged photo of two air conditioning units

Concrete and plastic AC pads are both good for your outdoor unit, but considering which one is the best depends on the size of your unit. If you have a large outdoor unit, it is best to use a concrete AC pad. If your unit is medium or small-sized, you can opt for a plastic AC pad instead.

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