Are High Merv Filters Worth It

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When browsing for air filters, you should just go for the filter with the highest rating, right? Not ever. Many people don't consider how a filter with a high MERV rating will touch other parts of the HVAC arrangement.

The main concern when upgrading to a higher MERV rated filter is the reduction in airflow in the system. The reduction in airflow can have far-reaching implications in terms of performance and efficiency on your entire HVAC system.

Does a higher MERV rating affect airflow?

Generally, a filter with a higher MERV rating volition reduce airflow. However, there are many other factors at play such as the size of the filter and the type of blower motor in your HVAC system.

Filters for key HVAC systems are usually the master form of particle removal for residential and commercial buildings.

Much attention is giving to the filter's efficiency at removing particles and cleaning the air. Merely using a filter also introduces a barrier that can crusade reductions in airflow.

Could using stronger filters lead to inadequate airflow? Information technology seems obvious that a stronger air filter will reduce the airflow in your HVAC arrangement. However, because the airflow reduction caused by a high MERV filter is commonly an afterthought for well-nigh homeowners.

Even if loftier MERV filters are used, will information technology substantially affect your organization? One study found that while there is a link betwixt using loftier-efficiency filters and increased energy use, for well-nigh residential systems the bear on is not significant.

Quick Pick

When it comes to air filters affecting airflow, there are iii factors at play:

The size of the air filter. The size of the air filter has a huge impact on how much airflow goes through your HVAC system. This is mainly because a filter with a large face surface area will minimize force per unit area drops.
The efficiency of the air filter. The MERV rating has an indirect impact on airflow. Generally, filters with higher MERV values will have less airflow.
Blower motor blazon. Whether yous take a PSC or ECM blower motor has implications on airflow.
When faced with filter pressure drops PSC motors will maintain less airflow simply utilise the same amount of energy.

ECMs will maintain the aforementioned airflow but use more energy.

This is very important considering if your arrangement has an ECM blower motor, then you volition come across probable meet minimal airflow impact when using a high MERV rated filter. Instead, your blower motor will apply more energy to maintain airflow.

How filter size affects airflow

The size of your air filter has a huge effect on the airflow through your HVAC organisation. Assuming all else is equal, the larger the filter, the more airflow through your HVAC system.

This applies to both the length, width, too as depth of the filter.

In a pleated filter, the deeper the filter, the longer its pleats. The expanse of the filter that is used for filtering air is called the face surface area.

A filter with more confront expanse is effectively a larger filter size. So this means that the filter will produce less pressure driblet.

Filter pressure drop and MERV rating

The pressure drop across an air filter will decide how negatively the filter affects airflow. Higher pressure drop = less airflow.

The Air Conditioning Contractors of America assumes that the pressure drop beyond a filter is 0.10 in. westward.c. Withal, one study plant that bodily pressure level drops in habitation installations were on average 0.28 in. w.c.

Even though stronger filters produce higher pressure drops, in that location are some ways that airflow can be maximized while using high MERV-rated filters.

In fact, even filters with high MERV ratings can be used in some systems with a minimal pressure drop. The trick is that the filter'south face area needs to be maximized in order to obtain the lowest filter force per unit area drop as possible.

There are a couple of unlike means to maximize your air filters' face area:

Increase the size (width) of your air filters. This includes maximizing the cross-sectional area of the slot that you put your air filter in.
For instance, if an air filter's slot is in the render register of an HVAC system, some homeowners might elect to modify the return register to a larger size to arrange a larger filter.
Utilise an air filter with a larger depth. For instance, a 2-in. pleated air filter will take a larger face expanse than a 1-in. pleated air filter.
The air filter slot on your home's HVAC system determines the depth of the air filter that you lot tin can use. In order to use a deeper air filter, your air filter'southward slot will demand to be large enough to accommodate the filter.

How Total External Static Pressure (TESP) affects airflow

The full external static pressure or TESP is the pressure difference across your entire HVAC system. The full external static pressure level is measured by taking the difference of the pressure between the supply and return registers.

Why is TESP important? It is an indicator of how much airflow is going through your organization. Generally, higher TESP = more airflow.

How do air filters contribute to total external static pressure?

Air filters contribute to TESP by reducing the total external static pressure in the arrangement. This means that using an air filter will reduce the amount of airflow in your HVAC organization.

Nearly residential homes are designed to take no less than 0.5 in. w.c. of TESP. Since the air filters in many residential homes contribute to more than half of that pressure, information technology is clear that air filters are responsible for a large part of the pressure driblet in an HVAC system.

Since using an air filter is not optional, you'll demand to find a filter that meets both your air filtration needs and airflow requirements.

The diagram below shows a typical pressure distribution of a residential HVAC system.

Pressure distribution of residential HVAC system.

In the diagram, the full external static pressure level is represented by ΔP _render and ΔP _supply. Yous can clearly see how the air filter reduces the total external static pressure level by adding to pressure drop.

How unlike types of blower motors affect airflow

The type of blower that you take in your furnace or air conditioner will largely make up one's mind if in that location volition be a reduction of airflow in the organisation.

Permanent Separate Capacitor (PSC) Motor

Permanent split capacitor (PSC) motors are used in virtually standard, economic system-priced furnaces. In the presence of airflow restriction, PSC motors volition swallow relatively the aforementioned amount of power but provide less airflow.

Even though the amount of power that a PSC consumes remains unaffected, the reduction in airflow can cause an overall increase in energy use. This is due to increased runtimes from the reduction of heating/cooling capacity.

When using a loftier MERV rated filter, you volition likely meet a slight reduction of airflow when using a PSC motor. As the filter gets muddy and more than airflow is restricted, the PSC motor will deliver even less airflow.

Electrically Commutated Motor (ECM)

Electrically Commutated Motors (ECM) are newer and more than energy-efficient than PSC motors. ECMs consist of a brushless DC motor combined with a microprocessor to control its speed.

The result is that when airflow restriction is introduced, the ECM will speed up to maintain the same amount of airflow. Doing and then increases the energy utilisation of an ECM.

However, ECMs are already very energy-efficient, and then they volition on average employ less free energy than a PSC, fifty-fifty with a dingy filter.

The impact of dirty air filters on airflow

When your air filter gets dirty, the pressure drop across the filter will increase. This volition crusade a reduction in airflow in your system.

Did you know that a dirty filter really filters out more than particles? The implications of having a dingy air filter are like to using a high MERV filter. As the air filter clogs, it is able to trap smaller particles in its muddied membrane.

I recommend changing your air filters every 1-ii months to maintain peak functioning and energy efficiency levels.