I've been reading this forum for several weeks before I finally registered. I have gained a lot of knowledge that I did not previously have.
There are some things however that I'm not too certain about and hoping that I can be pointed in the right direction.
First, a bit of history about my setup:
I live in a 1956 ranch style block home in the deep south. No insulation in the walls (plaster), oak wood floors, double pane windows, black roof, southern exposure. Return ducts: 1 in the living room that was 14x23 and in the hallway about 10 feet away was 14x14. I always had to get custom-cut filter media for the filters as they were not a normal size. The media I used had an orange tacky-like coating on the front to help control the excessive dust problem we had (More on that later)
The old system was a 2.5 ton Lennox B25 outdoor unit matched with a Lennox 3-ton air handler (in the attic). The unit was 16 years old and worked ie: it blew cool air. The house would never get below 79 in the summer, and would barely keep it 72 in the winter. That's with it running 15-20hrs a day, everyday. I always had yearly checkup's and cleaning done. The duct work had no leaks in the attic that I knew of for the past 10 years.
I did however get insulation blown in the attic (about 9" worth) and that reduced the run time on the a/c from a 24/7 to 15-20hrs per day. Humidity inside was 65-70%.
I did not know any better and figured that's just the way it is.
Fast forward to about 2-3 weeks ago:
The blower motor woke us up late one night making a hell of a noise. That morning I was going to simply swap the blower motor out, or so I thought. I opened up the portion of the air handler that housed the blower and discovered it was absolutely slam full of mold. That explains why we have all been sick off and on for months, and kept seeing small black balls of "stuff" coming out of the vents. At this point I decided to start getting estimates on replacing this thing.
Many estimates later and contractors I settled on a local contractor that has been around for just over 40 years and has great reviews. Everyone seemed to want to do a hack job but this guy. I sign the contract and they were out in two days.
The new unit is an Amana 3-ton ASZ-14 with a ASPF31376 air handler.
They removed the old air handler with no problem and began to remove the old air intake that was in the living room. It basically was a 3-sided plywood box with no duct inside. No joke. It had been pulling outside air from a large hole in the floor (old chimney) behind a false wall in the broom closet where the "duct" was ran. That explains the excessive dust (7 HEPA filters running 24/7 to help control it) and the inability to cool the house.
I wanted the new air handler in the broom closet and not back in the attic to increase efficiency. The contractor sealed the closet, the hole in the floor and put the air handler in the closet. The hallway return duct (14x14) was eliminated and the living room return grill (14x23) was opened up to accommodate a 18x30 filter.
The filter is in the 18x30 intake in the living room the hole runs directly into the closet that houses the air handler. Under teh closet door I have added a rubber sweep to "seal" the bottom of the door from getting unfiltered air into the unit. The problem however is that the unit seems to struggle with the 18x30 filter. When I close the closet door you can hear the fan motor sound as if it speeds up some when it is pulling through the filter.
I can't get a 22x22 filter in (filter rack size on the bottom of the unit) because the door opening is only 20". I removed the door and jamb to get the air handler into the closet and have everything back together now. I did however manage to get a pleated filter into the filter rack with a bit of "help". I removed the 18x30 filter and it seems to not struggle as bad.
I'm guessing that it wouldn't hurt to add another return grill & 18x30 filter in the master bedroom (other side of the broom closet) ....
Or could I simply put a piece of 22x22 gutter guard material in the filter rack and simply buy 22x22+ filter media for the bottom of the air handler?
I am very limited on space so not sure what to do. The contractor feels that the single 18x30 intake in the living room should be ok....
It may be worth mentioning the fan speed is set on Med-High (T-4) tap.
I will provide pictures as soon as I get back home.
thanks for any suggestions.