The best rule of thumb I have found is:
Length X Width / 144 * 288 = Max. CFM
I have used this formula to size many HVAC systems. It has always worked. For example, a 5 ton unit should have a 30x36 grille(2-18X30 filters). (30x36)/144*288=2160 max cfm.
Return Air should be sized at 200 square inches per ton according to AirMate and other filter grille manufacturers to achieve 2.0 static pressure. The Return Air Duct should have an unobstructed 6 square inches per 1000 BTU of cooling.
Your ac contractor or engineer will determine the correct size.
What you are refering to is called a return filter grill and there are tons to chose from, ( from ) tons of places. Home Depot, Lowes, and the likes of these places or your Heating Air/Conditioner Wholesaler close to your area. Also try typing in Central Air Return Air Filter Grills in your search bar. The Bigger the better is the rule of thumb with return air filter grills to a reasonable point . 600 cubic feet a minute is what I design air flow quantity for on my basic stuff. It is my opinion you are better off with a less expensive filter and a slower flow rate design through your return air filter grill than to use a expensive but usually highly restrictive filter in a smaller return air filter grill that is already restrictive in itself. Don't take me wrong here!!!!! ( Those Super High Quality Return Air Filters are Wonderful , usually ), Just make sure you have plenty big enough filter grill return area size to accomadate them in your system. Hope this helps: Jimiwane
Air return duct and filter grille size is dictated by the size of the unit (CFM) not the size of the house.
The size of the return air grill depends on the size of the forced air fan. The return air grid to reduce noise should be 5 to 8 times the size of the fan outlet. A 36000 btu heating system often has between a 500 to 1500 CFM fan the outlets on these fans are often between 30 and 80 square inches so the grid should be between 150 and 600 square inches (depending on the fan), the bigger you can fit the better. If you can fit it I'd put in a 12 x36 grill (432 sq in) but a 12 x 24" (288 sq inch)grill should work well too.
the filter is easy to change. it should be in one or two places, the return grill which will be in a hallway near the thermostat. this is the most common location if your furnace is located someplace not easily gotten to. the return grill should have a small latch(es) or screws/nuts keeping it closed, the grill is hinged to allow it to swing open for easy filter changes. simply remove old filter check the size that's written on it and replace with same size assuming it fit right. lil trick if it's high up turn on the fan this will hold the filter when you have your hands full balancing on a ladder/chair. replace it every 2 to 3 months depending how it looks. If your furnace is in the garage or a closet and you only have a flat return grill the filter will be in the bottom of the furnace, just open the bottom door and you will see it, pull it out and replace. the filter needs to have some kind of support in it, checkerboarded thread at least to keep it from being sucked into the blower motor when it starts collecting dust. they only cost a couple of bucks at walmart or a do it yourself store. pleated ones have more surface area and work great. hope i helped. viking40
The size is determined by the ac contractor or engineer.
48,000 btus is equal to 4 tons of air flow, 12,000 btus per ton. You need 144 sq in per ton. Return grill should be 24x24. 48,000 btus is equal to 4 tons of air flow, 12,000 btus per ton. You need 144 sq in per ton. Return grill should be 24x24. 48,000 btus is equal to 4 tons of air flow, 12,000 btus per ton. You need 144 sq in per ton. Return grill should be 24x24.
What size supply register are you using? The return register should match the supply. If the return is too small you will have positive air pressure in the room, and if too large you will negative air pressure.
The label on the Filter or the Manual should tell you. Otherwise you should be able to contact the manufacturer, perhaps via their website, to find out. It can vary depending on make and model, not just size.
really depends on the size of the unit but if your not sure i would go with a 20x20 or a 20x25 filterback grill..
Each air conditioner take a different size of filter. The air filter should be checked routinely and changed as needed.
The average size of a Cadillac Deville Grill is listed on the site Auto Anything as being roughly 1.3 meters by 0.6 meters, though the size of a grill of course depends on the car.