I am at a loss on this one. I recently bought a new house with a Ruud Silhouette furnace in it and the filter was simply laid in the return box opening. It didn't look as if it fit at all. Can anyone tell me what filter size I should look for when making my run to the local hardware store?
the size of the return duct going into the furnace,if you have no track top/bottom to hold it in place..might consider the return grill in the hallway for it.remove the grill and measure the opening that is the only return and is the same as the one down on the furnace.if you have a ranch type with 2 seperate returns grills 1st and 2nd floors.... then it would be 2 filters....20X20X1.....16X20X1......20X25X1 are typical at the HD or Lowes(cut them to fit).if you go with it down on the furnace return make sure it has a cover over the filter access so you don't suck in basement return(if it is not heated by that furnace)