will a 26 x 18 return air grill be enough for my central a/c system ?
i had a complete 4 ton system replaced by a 4 ton condenser, and 5 ton furnace and coil. the existing return grill is 26x18, regular stamped style grill. i am going to install a 50% higher air flow grill the same size, due to noise factor and wanting better air flow coming through the vents, will this be enough air flow for a 5 ton blower, or do i need tp install a second return? i have a 1750 sq foot, 2 story house, with the return grill on the bottom floor in the hallway. and if i have to install a second return , what size, and where should it be installed ?
Update:ive had a couple techs that say i need an additional return
Comments
Without an ON-SITE airflow survey, it is IMPOSSIBLE to answer. You select the HVAC components to fit the home, not the other way around.
All the previous responses have valid points. I'll only add this. As far as I'm concerned, there's really no way to oversize return air.... The more open grille is a fine idea, but the rest of the return air opening needs to match that feed.
A second return cannot possibly hurt anything as long as it is not on a reflection wall that will only suck up directly cooled or heated air, lowering efficiency.
thats my 2 cents
Heat rises so in the summer time you want to get the hot air off the ceiling (your attic is insulated to R13 rating, right? If not, why not.....) which means the vent should be up near the ceiling and have a means to shut if off come winter. Winter time you want the lower unit to return the cold air that is at the low point in the room. (first floor....)
Measure the size of the main duct coming off the furnace and convert it to square inches. Do the same for your grill, if the grill is larger AND the area behind it is larger than the main duct then it should be okay. Otherwise, install another grill in the line.
the size of the duct and how its attached to the furnace has more to do with perfomance than the grill size. that grill is more than enough for 2000 cfm at residential pressures and velocities. but if its screwed to the wall and the 3 1/2 inch space inside of the wall is acting as the duct transporting the air, then it doesnt matter how big the grill is. you are only getting 26X3 1/2 worth of air, not 26x18 worth of air.
If there is room at the intake side of your unit;that's where you want to size in a larger return;adding a second will be more of a benefit to heat removal /air changes but get the return sized in correctly with respect to what static is required for that unit and that duct system;too much missing info for anyone to give you exact answers on here;rely on the techs who advised it.