The information I gave you was not "wrong", it was just incomplete. There's
a big difference. I did not think it was important to go into all the
details with the first message, so I left somethings out. They were
obviously of use to some people, while it may have been useless to others.

Back in 1951 when this house was built, they used 2x4 construction with rock
wool bats in the roof. The basements and 2nd floors (actually attics) were
unfinished. The original homeowner finished the 2nd floor but did so as
inexpensively as possible; this included no additional insulation and used
doors. Apparently some ethnic groups are just plain cheap. When I added A/C
in the late 1980s the contractor did the best he could given the situation
in the house, stating it would not be effective on the 2nd floor. Fine. I've
lived with it that way and am happy the main floor was comfortable.

When the furnace was replaced, none of us expected there to be any
difference in operation besides going from oil to natural gas heat, and
reclaiming several square feet of basement floor space.

Whether the system (heating and cooling) was working properly or at its most
efficient settings is really immaterial if the house is comfortable and the
homeowner is not complaining. Well, now I'm thinking of complaining and
decided to pose the question here. I had no problem adjusting the pulley
size on my old furnace, and I have no problem playing with the fan speed on
my new system. If the ducts are inadequate for the air volume at the highest
speed, then slowing it down is my only option besides ripping everything out
and starting all over again. It was easiest with the old furnace to find one
fan speed that was a compromise and leave it alone. May not have been the
best setting, but it did the job. Kind of like driving a car in 2nd gear all
the time. It may be a bit hard to leave a stop sign, and it may wind the
engine up kinda fast on the highway, but at least you don't have to worry
about shifting.

So, if you are stating (not recommending) that the lowest speed is usually
for heat, and higher speeds for cooling, I can go with that. I'll see what I
can do to take the fan speed down one or two notches for cooling and see if
that helps with the humidity extraction at all. I'm not going to fry the
system or cause anything else to go wrong. As it is, the air temperature
coming off the fan on the compressor unit outside has never been more than a
few degrees above ambient temp anyway, so I've known all along that it's not
pulling out as much heat as it could from inside the house. Maybe that's why
it's been working as well/poorly as it has all these years.

You've given me food for thought. It's my choice whether to cook it and eat
it, or throw it away. I thank you for all the advice, suggestions, warnings,
caveats, etc.

Bob M.
======
"CBHvac" wrote in message
...

"Bob M." wrote in message
...
I live in southern CT. The house also has a poorly insulated 2nd floor.
When
the first system was installed, there was NO insulation in the walls and
the
house was painted brown. Sucked up a lot of solar heat. There's also a
half-finished basement, but the HVAC system attempts to heat and cool
the
entire house. So in actuality, the house is much bigger than the 800 sq
ft
would imply.

Then....the information we had, that you gave was wrong...another reason
why
we always tell people that we cant see it from here...


When the temp is in the 90s outside, the unit does run for hours at a
time.
During those periods the condensate pump will come on once in a while
(maybe
every 15 minutes). The system will bring the house down from 78 (daytime
setback) to 74 regardless of outside temp in about 2 hours.

I have news for you....at 90F or higher in your area, you can expect it to
run all the time, since the design ttemp in your area is less than
that...and the TD during design is 20F.....so..so far, it all sounds like
it
was sized correctly, and perhaps better than you expect..but again...we
cant
tell from here.


On the previous system, the fan speed was adjustable by changing the
pulley
size on the motor. I had fooled with it at one point and it was set to
work
very nicely in both winter and summer seasons without change.



The new system has four fan speeds but uses a direct drive AC motor on
the
blower. The lowest speed is used when the thermostat's FAN ON/AUTO
switch
is
set to ON and the system is not calling for heating or cooling. Just
moves
a
little air around so you don't get that stuffy feeling. The highest
speed
is
for cooling, and one of the other two is used for heating.


Depending on the setup and original design from factory of the unit, low
speed is ALWAYS for heating, and higher speed is for cooling...however,
with
a 4 speed motor, you have more options and the highest speed may not be
needed....


The contractor who replaced the system did nothing but that,
manufacturing
new plenum pieces where necessary. As long as it heated and cooled, his
job
was done. He didn't install the original system, and when a friend with
a
similar house called these same people in to add AC to his system, they
refused, saying they'd need a lot more return ducts to the 2nd floor
(which
they could not add), and other problems. Would have cost him like
$10,000
to
do it "right" so he just bought a few window units and saved a lot of
money.
I had a similar experience when I added AC to my old system, but the
contractor wasn't as insistent and was able to install one return duct
to
the 2nd floor in my house. I don't think it does much good, but it's
there
anyway. I will get much more cooling when I replace my roof and add
insulation to the 2nd floor walls and ceiling. As it stands now,
upstairs
reaches 90F in the summer and goes down to 50 in the winter, so you can
imagine how little insulation there really is up there.

Umm..kinda vaugue there....we are building homes with R40 in the walls and
ceilings, and they can drop to freezing if the temps outside are low
enough,
and there is no heat in the place...
I dont really understand what you are trying to get at here, but the R and
U
values are important, but they play a huge part in the Manual J and D
calcs...
something it sounds like has not been properly done.


I will try changing the fan speed to see if that helps at all. One thing
that seems unfortunate with this unit is that they give you four speed
wires
from the motor, and only three active terminals and one "place holder"
to
connect them to, so you can't have one speed for both heating and
cooling,
or the same speed for FAN ON and heating and cooling.

Unless its a heat pump, you dont want that...low for heat, and a higher
speed for cooling...

I am going to check
the possibility of making some form of jumper that will allow me to have
one
wire go to multiple terminals while leaving the others disconnected. I'm
good with electronic and electrical stuff so I'll take precautions first
and
measure twice before blowing something up. If I were designing this
controller I would give the system more flexibility than it seems to
have
right now.

I suggest that unless you understand thermal dynamics, how this will
affect
your comfort and your systems performance and life, and things like temp
rise, superheat, subcool, and the like, you leave it alone, and get a
company out that can set up the unit properly, and not hack it in..
What you are talking about doing, sounds great in theory, but in actual
use,
can create even more issues..


Thanks for all the comments, suggestions, and agreement (in part) with
my
analysis.

Bob M.
======
"jim" wrote in message ...
Bob M. wrote:

About 800 sq ft Cape Cod style house with forced warm air heat.
Added
2-ton
York central A/C in 1989. Due to plenum shape, they put in a
horizontal
coil
rather than an A-shaped coil. Worked well once I blew insulation
into
the
house. Always felt very comfortable.

Replaced the furnace in 2000 with a Lennox gas unit, and they
installed
a
new Lennox A-shaped coil in the output plenum. Same 2-ton capacity.
Same
York compressor unit. The system will cool the house down quite
nicely,
but
the humidity seems uncomfortably high at times, like over 50% even
with
the
temp down to 74F. On days when it's in the mid 90s the system will
bring
the
house down to the mid 70s and keep it there, cycling on and off as
need
be.
The condensation pump runs, but not nearly as often as it did with
the
old
setup. Cold air comes out of the ducts at about 58 degrees, so the
system
seems adequate for "cooling" purposes.

The fan speed was factory set to the highest speed. I'm wondering:
could
such a fast fan speed be literally blowing the air and moisture
right
off
the coolihg coil, and not giving it a chance to condense the
moisture
so
it
drains out? I can lower the fan speed (I have 4 to choose from) but
before I
get into that, I wanted to at least see if my theory made sense. I
figure if
the air moves slower across the coil, the moisture will condense and
drip
down and out. Never had this problem with the old horizontal coil.

Also, one of my upstairs rooms has its own 5000 BTU window A/C. When
I
run
that unit to cool the room down to 74, then leave it to go back into
the
main floor, there's a noticeable increase in humidity and the room
feels
clammy and uncomfortable. It's this comparison that's got me
thinking
the
central system isn't removing the humidity like it used to.

Any thoughts or suggestions? Is my analysis sound? I don't see any
moisture
around the furnace, so I'm fairly sure the condensed water is going
where
it's supposed to. When the thermostat shuts the system off, the
condensate
pump usually comes on a few seconds later to pump the water out.
That's
why
I almost think it's saving it until the fan slows down or stops.

Thanks.
Bob M.
800 sq. feet and 2 tons seems like too much a/c for the
building.......
if you dont want to turn the fan speed down then call out a tech and
get
him to check it out and see whats wrong with it.. not the same guy who
put in the second unit for you... he will never find his own
mistake...