"RP" wrote in message
...


PrecisionMachinisT wrote:
"Colbyt" wrote in message
...

There are a couple of nice HVAC guys in this group and several who are

not.

I am not one of either group.



So Im ****ing chopped liver then, no ???


It may be possible if you have a multi-speed motor. For anyone to help

you

is going to require more information. I suggest you post again with the
brand name and model number of the furnace. A guy with the nick of
Turtle

is

one of the nice guys.



You can only pull in whatever airflow your existing return ducts will
allow....ya ever wonder why it is when you stick your hand on the
vaccuum
cleaner nozzle the motor actually speeds UP ????

Regardless, increase all airflow across your evaporater coils and then
the
moisture that was SUPPOSED to drop out...doesent....now consider that
moist
air holds a HELL of a lot more heat than does dry air.........

I could have let it go, but you made two incorrect points here, and
these were the only two points that you made.
Your first statement, taken at face value, says that increasing blower
rpm will not increase cfm. This is incorrect. The cfm won't increase
proportionally to blower speed, but it will increase.
Your second statement is also incorrect. Moist air, per unit volume has
a greater specific heat than dry air, and thus holds more sensible heat
energy at a given temp, OTOH, it isn't a HELL of a lot more. The
advantage of dryer air is that you can set your t-stat to a higher temp
and still be comfortable. The load on the system is reduced, not because
of the lower specific heat of the air, but because the rate of heat
infiltration into the space is proportional to the temperature
difference across the outside surfaces of the structure. With a higher
external surface TD the net load on the system will be higher,
independently of moisture content of the indoor air. In medium to low
humidity areas this isn't a big factor since indoor RH won't vary as
much with changes in blower speed as it will in high humidity areas.

In high humidity areas you can lose efficiency by reducing blower speed
or indoor coil size if there is very much air infiltration, since the
latent load will be higher, thus offsetting any gain provided by running
a higher indoor temp. Given a tight structure, the higher latent
capacity system may be more energy efficient or it may not be. There
are too many factors to establish a rule of thumb; each structure is
unique, as are the preferences and habits of its occupants. You should
target RH, and let efficiency run a close second.

Where RH isn't a factor, then increasing blower speed should be
considered, but again there are many other factors involved, one of
which is the additional energy draw of the motor at higher speeds,
another being the increase in high side pressure produced by the extra
load on the system. In most every case, what is done on the one hand to
increase efficiency is offset by some other factor to some degree, so
that small changes won't in general have a significant effect on overall
efficiency. Changing blower speed is not however a small change and
should be done only when indoor comfort is noticeably lacking, and only
after the real problem has been repaired, that is, if incorrect blower
speed wasn't the real problem.

The OP's question is essentially equivalent to asking "should I increase
the air/fuel ratio in my vehicle's carburetor?"


'Usenet troll' is a tough job--but SOMEBODY has to do it...

G

Once your full shaft horsepower is being consumed, any further gains to be
had in air volume lie in increasing your duct size.

As to the any specifics quantifying hell...probly best to leave that up to
speculation.

BTW, your post above was good and quite informative.

--

SVL