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Combustion
Air
iAdoor
Humidity
(Cont.)
C. Drafthood
Spillage
-
_ _::_:
If there
is spillage
at a draft
hood
- (rfi_ch
goes
out
or flame
wavers
away
from
draft'Jiood):
1.
Check
for plugged
flue
connectors
and chimneys.
Check
and
repair
stoppage
and
test
again.
2.
if you have a fireplace,
open
a window
or door
near the fireplace
and then
check
for spillage.
a. If spillage
stops,
do not use the fireplace
until
you can supply
fresh air by a permanent
duct.
3.
If you have
kitchen
and bathroom
exhaust
fans
turn them
off and check
for spillage.
a. If spillage
stops,
do not use exhaust
fans until
you can supply fresh air by a permanent
duct.
Circuit
breakers
for fans should
be turned
off.
4.
Spillage
means
air starvation
and a fresh air duct
or air intakes
must
be installed
to provide
air
directly
to the
furnace
or other
gas
appliance.
These must
comply
with
local and state
building
codes or in their
absence
with
the National
Fuel
Gas Code NFPA 54/ANSI
Z223.1,
current
edition.
2. What
is Relative
Humidity
and
how
do I know
if it is tOo high
or low?
Relative
humidity
is the amount
of water
vapor
in the air
relative
to the amount
the air can hold at the same tempera-
ture.
Example:
At 40%
relative
humidity,
the air can hold
60%
more
moisture
before
it is saturated.
The colder
the air, the less moisture
it can hold.
As air is
warmed,
its ability
to hold moisture
is increased.
Example;
A
winter
day,
outdoor
temperature
10°F,
and
relative
humidity
of 70%.
If that air enters a home
and is warmed
to 72°F the relative
humidity
will drop to 6% (very
dry) if
no more moisture
is added.
Relative
humidity
is important
to your
health
and home
as
proper
humidification
helps
cut down
on incidences
of
respiratory
illness
and helps keep air cleaner
and fresher.
HAS YOUR FURNACE
BEEN REPLACED?
This furnace
is very efficient
and has a much
smaller vent
(flue)
pipe with a brower
in the venting
system.
The smalMr
vent and blower
increases the efficiency
of the
furnace
but they will also decrease
the amount
of natural
air infiltration
into the house. This is because
less air will
escape up the vent system
during the off cycle so less cold
dry air will enter the house by it_fllteration,
This in conjunc-
tion with
other items may cause the humidity
to raise to
uncomfortable
levels. This condition
can usually
be elimi-
nated
by minor
changes
in everyday
routines,
see
"If
Humidity
Is Too High".
VISUAL
METHODS
OF GAUGING
INDOOR
HUMIDITY:
•
Frequent
fogging
or excessive
condensation
on inside
windows
indicates
the indoor humidity
level is too high
for outdoor
weather
conditions.
Damage
to the buiiding
may result if the condition
persists.
(Condensation
on in-
side of storm windows
indicates
loose inside
windows.
Adding
weatherstripping
to tighten
inside
windows
usually
corrects
this problem.)
A good relative
humidity
is one just high enough
to barely
start condensation
along the lower
edges
or tower
corners
of the windows.
More than
that can be damaging°
IF HUMIDITY
IS TOOHiGH,I.
'_!'
"
Condensation
occurs
when Warm;
moist air Cdntacts
a_c6o!
surface
(window
or outside
wall, for,example),
add drops
of
water or a coating
of frost
form. The c05densation
problem
increases
as the outside
temperature
decreases.
A high humidity
level usually
result s fr0i:n bathing
or cook-
ing, etc. Suggestions
for correcting
this problem:
1.
Turn down
or discontinue
use of humidifier.
2,
Use range and bathroom
exhaust fans while
cooking and
bathing
or open a door or window
for a few minutes
to
bring
in cool
dryer air.
3.
Cook
with pans covered.
4.
Take shorter
baths
or showers
with
cooler water.
5.
Install
a fresh
air intake
duct.
Cold,
dry air brought
in
from
outside
to the furnace
area
lowers
the
indoor
humidity_level.
6.
ffthe
above measures do not correctthe
problem,
have
appliances
checked.
A rmalfunctioning
appliance
can
contribute
water
vapor
to the house,
7. -if the above items do not correct
the problem
consult
a heating
contractor
about
adding
a heat recovery
ven-
tilator
or afr to air heat
exchanger.
RECOMMENDED
INDOOR
HUMIDITY:
Use the following
table as a guide. It shows the recommend-
ed maximum
indoor humidity
in relationship
to the outdoor
temperature.
TEMPERATURE
HUMIDITY
•
Drop three
ice cubes into a glass
of water
and stir. If,
within
three
minutes,
moisture
does
not form
on the
glass,
the
air is too
dry and a humidifier
would
be
beneficial.
(Do not perform
this test
in the kitchen,
as
cooking
vapors
may produce
inaccurate
results.)
+20°E
and above
35%
+ 10"F
30%
0°F
25%
-10°F
20%
-20°F
15%
4
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