How do i know which air filter to buy?

You simply need the filter size that fits your air return. You can usually find that size on the side of the air filter you already have in use.

How do i know which air filter to buy?

You simply need the filter size that fits your air return. You can usually find that size on the side of the air filter you already have in use. This size will be the nominal size, which means that it has been rounded to its actual size. If an air filter is too small, air voids will be created and contaminants will bypass the filter material. For even greater performance, a MERV 8 filter can capture up to 70% of large airborne particles and up to 20% of medium-sized aerial particles (1.0-3.0 μm).

Air filters also help keep heat exchangers and oven coils clean, which can extend the life of the oven and keep it running efficiently. After all, the filter is what separates you and your delicate central forced air equipment from the destructive particles in your home air. The following sections explain the steps necessary to choose and install the right HVAC filter for your home. Getting an exact fit is crucial to having an effective air filter: the wrong size won't fit and will stop the filter from working properly.

Once you know the required filter dimensions and the desired MERV rating, it's time to choose the type of air filter for your home. If you are buying a replacement filter in a large store, don't fall into the arbitrary classification of filters that some companies impose on their filters. The nominal size is the 21 x 22 x 1 you mentioned, but you'll have to actually measure the filter that's currently inserted to find its real size. You should install the new filter in the direction of air flow, which makes sense, since air must flow through it to work.

I have a Trane Xb tue1c100a481ab tube, there's nothing inside it to hold the filter in place at 20×24 inches, but I'm not sure if it's right. Simply insert the filter into the slot with the arrow pointing towards the airflow (usually the fan) and make sure it fits tightly and leaves no gaps in the filter grille. The minimum efficiency information value (MERV) measures the effectiveness of a furnace air filter in capturing particles. In addition to the strength of the filter, the FPR also indicates what type of airborne contaminants each filter is ideal for capturing.

If all else fails, consult the product manual for the air conditioning system or contact the manufacturer directly for the model number of the system.