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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 awindow 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 apermanent 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 ahome 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 amuch 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 acoating of frost form. The c05densation problem
increases as the outside temperature decreases.
A high humidity level usually result sfr0i: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 afew minutes to
bring in cool dryer air.
3. Cook with pans covered.
4. Take shorter baths or showers with cooler water.
5. Install afresh 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 aheat 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%
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