I have to install a new furnace (oil) with an A-Coil for Cooling. Due
to height requirments I am putting in a low boy that is 37" tall.
Again, due to existing duct work issues, I would like to place the
coil on the return side of the unit (negative pressure). The unit is
a Concord. My supply house tells me this is not recommended and may
cause corrosion of the heat exchanger. I was wondering if anyone had
experience with this our thoughts?
My thoughts??? Ok, but its not what you want to hear. Concord is cheap shit
for a reason. Other manufacturers make furnaces that are only 34 inches
tall, but they will only sell to bonified contractors. There is also a
reason that manufactures tell you in the installation instructions NOT to
put the evap coil on the RA side of a gas furnace. Also *most* manufacturers
have put out changes to their warranties that state any of their equipment
that is *NOT* purchased from a legitmate dealer or distributor are null and
void....this includes *ANY* of their equipment that is purchased off the
Call a pro, because its painfully obvious that you not one.
I appreciate your email, and I think I appreciate the responses posted
by the other members. I used to be a refrigeration technician years
ago after I got out of the "Voc" after high school. I got pretty good
with that. I used to also do installations during college when I
changed fields and got into law enforcement. I know I am not even
close to a professional, but I can hold my own. I am doing this for a
widowed woman whos son is my best friend and I'm trying to help. I
have a "professional" tin man, also a high school friend, that is
doing the duct work. The system I am replacing is forty years old and
the duct work is existing. We are trying to accomadate a supply and
return run that feeds half of the home (split level ranch). This is
why I am using a low boy furnace and want to place the a coil on the
return. We are going to cap the existing return and make up for it
with a new higher one that will pull from a spot higher up and also is
common to the old returns area of work. My tin guy is the one who
first suggested this and told me he sees this done on lots of jobs
(professional). He called his supplier and was told it was okay to
do, just usually not recommended due to corrosion potential. Are you
confident this is a bad move, and if so, do you have any other
suggestions. I really do appreciate the groups comments.
my only response is if your replacing the furnace why go with oil?
its nasty. its expensive, and parts are getting harder and harder to find
oil furnaces are a dying breed,
most 80 and 90 % furnaces these days are only 40 inches tall or less
55 dF air across the heat exchanger will condense a lot more water vapor
than 72-75dF air.
That's why they recommend the coil be after the heat exchanger rather than
Being an oil burner I presume it's not a draft induced flue. If it is there
is less chance for the warm outside air to settle in the heat exchanger, but
even so there will be outdoor air in the exchanger & it'll condense & rust
from the inside out.
What are you thinking? If you're thinking what we're thinking, then I
think that what you're thinking, isn't what you should be thinking. You
But I think if they find out what you think you think. Then they'll
realize they'll have to think about suing you for what you are thinking
about doing if you do it.
I'd think again about even thinking of thinking to do what you're
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