I would like to improve the air flow to the master bedroom in my house.
Presently, the air is not as cool as it should be. It's about 5 degrees
warmer than the other rooms. Physically, this bedroom is the farthest
distance from the main unit which is a Day and Night, 5 ton A/C. The house
is 1700 sq ft. All the other rooms have sufficient flow and cooling. There
are about 7 vents throughout the house. I tried temporarily installing a
stove exhaust fan just outside the air duct but that didn't seem to help the
air flow or the cooling. Any ideas on how to rectify this problem?
Put in a window unit. You can get a new one for less than $150.
I did that and cut my cooling bills by 2/3rds, saving the cost of the unit
in two months.
That was three years ago.
I'm gonna buy a mongoose with the money I saved. Or maybe something else.
Insulate the plenum and trunk lines with FSKL, at least 1-1/2". Also add
another run into the bedroom. There is no way seven runs is enough for a
house that large, unless the individual runs are huge. Also, throw out that
restrictive allergy-gard filter if you are using one. You want a high
velocity throw-away if a one inch slot is all you have.
Actually, rereading your post; five tons of air through seven 6" runs equals
a no air flow ice cube anyway. You better have a pro check that system
Was it always this way? If so, chances are the duct was undersized
or poorly installed. Take a look at the duct size and run relative
to the others in your home.
If this is a new problem, maybe the duct is blocked, collapsed, or
leaking badly. Connections to registers, other ducts, etc. can come
It's also possible that you have a baffle splitting the air flow
between ducts/registers which has moved, diverting air away from
the register in your master bed.
Also consider the return path. A problem there will mean the
a/c is just trying to pressurize your bedroom and air flow
will fall badly. In that case, opening the bedroom door might
help quite a bit :-)
In any event, I'd start by making the most detailed inspection that
you can in order to figure out what is going on. 5 tons for 1700 sq
ft sounds generous but we don't know what climate you're subject to.
| Malcolm Hoar "The more I practice, the luckier I get". |
You could have a duct balancing damper closed for the duct run to the
bedroom. Go to the main Trunk Duct off of the Blower Unit and youll
see the branch ducts coming off of it ; throttle down the duct
dampers about 50 percent to the rooms closest to the blower and open
the duct dampers for the longer runs. Make sure your Blower is up on
high speed, the air filter is clean , and the a/c is fully charged on
freon. You most likely need an additional duct ran to the bedroom so
you get adequate air to the space--have an additional well sized duct
ran . Right off hand, 7 supply registers for a 2,000 cfm / 5 ton
cooling system is not enough . Im willing to bet your air
distrubition system is choked down hurting the performance .
No, you want to move the maximum cfm possible for cooling and a lower
cfm for heating . If you have a home without duct balancing dampers,
then you had a system that was cut corners on ; the rooms farthest
away from the blower will starve for air while the ones closest will
get too much .
Dave (ilbebauck's real name) is a HVAC hack.
Just ask any of the real techs in alt.hvac what they think about him
and his "advice"
Be sure to mention daveinlakevilla and daveinillinois, nics he was
using there untill he was chased off
I see two big issues:
1 - 7 vents for the entire house can't be enough.
2 - 5 tons for a 1700 sq ft house sounds over-sized, provided the
house is of reasonable insulation and the windows aren't open in
Miami I have a 3100 sq ft house in NJ and mine is that size. In new
houses here that are over 4000 sq ft they are putting in around 6
tons, split between 2 systems.
I'd get a pro in to evaluate the whole thing. It's likely you are
throwing $$$ out in energy bills that are higher than they should be.
You need to move a certain amount of air through a system based on the
size to make it operate correctly. So it's got nothing to do with how
many rooms he has, it's because of the system size he believes he
has. Even with mediocre insulation 5 ton is pretty big for a house
that small. If you don't move enough air across the coil it's
temperature could drop below freezing. When that happens the
condensation freezes on the coil instead of draining.
OMG, we have a winner ;-)
Yes, a 5-ton unit feeding only seven 6 in. ducts with the
dinky little registers would make no sense. While stupider
things have happened, I very much doubt that's the OP's
The OP certainly does need to inspect his ducts carefully
and should be building some understanding of how much air
is being moved where while also looking for leaks and
| Malcolm Hoar "The more I practice, the luckier I get". |
In a residential application, you are limited by how big the supply
registers/boots are especially if the ducts are run down a stud
space ..therefore, the quantify of ducts IS important in such
instances. If the ducts are ran in the attic into the second floor
ceiling with the airhandler located in the attic too, then you have
much more leeway on the size of ducts , etc.. His best bet is to get
a professional out to his house to look it all over , as those of us
replying here cant see the entire installation from our laptops...and
can only offer up some vital considerations in a general sense.
It still goes back to the size. If you have ten ducts of the wrong size,
cooling is is not as good as five of the correct size. Sure, you may need
two if the space for one is too small, but no matter the number, the size is
the overriding concern.
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