Only one central return? If so that filter is all you need..

TD

https://www.ductless-mini-split-air-co

If you’ve ever experienced problems with your heating and cooling system and scheduled a service call, you may have noticed that one of the very first things the HVAC technician did was inspect the air filter. The list of malfunctions, major and minor, that can originate from a dirty or clogged filter is surprisingly long.

This is particularly true with heat pumps. Although heat pump technology is straightforward and reliable, a heat pump requires a consistently higher volume of airflow to effectively heat or cool your home. Shortfalls in the air volume conveyed through the ducts caused by a dirty filter have a great impact on home comfort and system efficiency. Here are some basics of heat pump air filter:

A heat pump air filter protects your breathing air and the heat pump components, too. Inorganic dust as well as airborne microorganisms like mold spores and pollen circulate in your household air. These sources of allergies and respiratory discomfort can be partially controlled by a clean filter. The filter also keeps the heat pump’s indoor coil clean, a vital element in the unit’s performance and efficiency.

Filters are rated by the MERV (minimum efficiency reporting value) system that assigns filters a number between 1 and 16. The higher the MERV rating, the more efficient the filter is at removing smaller airborne particulates. Higher efficiency filters generally utilize pleated fabric media. In most residential heat pump systems a filter with a MERV rating between 8 and 12 is a good balance between filter efficiency and adequate airflow.

During peak heating and cooling season, a 1″ heat pump filter should be changed monthly. It’s inexpensive insurance to make sure you’re getting the performance and energy-efficiency promised by the manufacturer’s specifications. A filter change is an easy DIY procedure. If you don’t know how, your HVAC contractor will be glad to show you. There are high efficiency air filters available today from your HVAC contractor that can last as long as one full year before they require changing.

So, your answer to the question is?

I agree with tigerdunes.