So you don't have several return ducts in different rooms? I have 3 in
my house?

Robert Gammon wrote:

wayne wrote:
One other thing you could do is to put a filter on the return ducts?
How many do you have would that work? You could also see how dirty
the filters were. As for the 2" filters where I am they make them
all to order as there are so many odd sizes. You could just have
them make the filter out of whatever paper you want. If you have
room for the V idea that would be a good solution also. You could
even go with a 4" filter


I have ONE return duct. It sits right under the furnace. I put the
filter here, there is no other place for it.

2" and 4" filters, even MERV 8 versions, put a serious burden on the
air handler

I have seen the specs for Filtrete, PrecisionAire, Purolator,
Accumulair and several others in a 2" deep size. They all put too
much pressure on the fan.

I change the filters on a regular basis, usually about every two
months with a pleated MERV 8 filter.

The message from the furnace manufacturers is CLEAR, we care about
the equipment, we don't give a damn about you.
Except for some ground source heat pump manufacturers,who now include
very large 28x30 (and larger) MERV11 2 inch filters with the unit,
AND they have increased the fan HP from 1/3 to 1/2 HP AND they offer
a fan upgrade to 1 HP on the most popular 3 ton and 4 ton models.
These units come with a 2 inch filter rack installed and there is an
option to install a 4 inch filter rack.

My fan is a 1/3 HP fan like almost everyone has in a 3 ton unit these
days.