Do You Have A "Cold Storage" Room In Your House:
There are rooms all over town that would be
great for fur storage, or make good meat
lockers, and which are inhabitable only by
Siberian Huskies or Polar Bears. Many people are
frustrated with rooms in their homes which just
never get warm enough and sometimes are down
right cold. They usually try to add insulation
or storm windows or both. These measures
normally fail to cure the problem because they
don't really address the cause. The cause is
almost always insufficient heat entering the
room. Increasing heat to a single room from a
central ducted system however is often quite
difficult.
Most cold rooms are associated with forced air
heating systems.
Forced Air Systems:
Forced air systems work by blowing air from the
furnace to the rooms through supply ducting and
pulling it back via return ducting. It is no
easy trick to deliver a balanced amount of warm
air to the many different rooms within a house.
The main duct or ducts (extended plenums) that
carry air away from the furnace must generally
be systematically downsized as run-outs to
registers tap air from them. Usually the plenum
should be downsized after three or four taps.
This is to maintain a consistent air pressure
inside the plenum to ensure delivery through the
entire system.
Balance:
For an individual room to heat properly it must
receive enough heated air to keep up with the
losses through windows, and wall, floor, and
ceiling surfaces. When it gets colder outside,
the heating system runs longer to keep up with
the increased losses. Larger rooms with more
window surface and greater exposure require more
incoming heated air. The air volume to a
particular room (assuming a uniform plenum
pressure) is controlled by the size and number
of the runout ducts to the room. Systems must be
flexible enough to work adequately with both
heat and air conditioning. The typical two story
house requires 2/3 of the total air volume to
reach the second floor during air conditioning
season (the cold air tends to fall back to the
first level) and 2/3 of the heated air on the
first floor during the heating season (heated
air tends to rise to the second floor).
Balancing The System:
To balance a system to accommodate the seasons,
individual room register dampers are adjusted to
lessen or increase the air volume entering the
rooms. Some systems have dampers built into
extended plenums or main ducts serving
individual levels of the house. Cold rooms may
simply be out of balance with the rest of the
house. Make sure that the registers are fully
open and that no plenum damper is shut. If there
is very little air coming out of a register,
unscrew it and put your hand into the duct to
see if there is a blockage. (Rags, pop bottles,
and sheet metal pieces are often found.) If
there is no blockage and you still get little
air, try closing other registers to see if that
increases the air flow. Occasionally ducts are
not connected or just barely so. Look down the
duct run-out with a strong flashlight and a
mirror.
Typical Balance Problems:
Frequently too much air enters the room
containing the thermostat and not enough reaches
the cold room. The thermostat responds to its
room temperature and turns the furnace off
before the cold room can be adequately heated.
Adjust the registers in the room with the
thermostat to restrict the flow. A thermostat in
the air path may also respond this way.
Sometimes thermostats have to be shielded or
moved.
More Significant Problems
Slab Houses:
Houses built on concrete slabs (no basement or
crawlspace) often have furnaces which push air
down and through ducts within the slab. If the
furnace is located in the center of the house
there is usually no readily noticed problem; but
houses with the furnace at one end will often
have a cold room at the opposite end. Usually
insufficient air reaches the room and the air
that does is often quite a bit cooler. The best
solution in such a case often is to add an
electric baseboard heater to boost the heat. If
the room is poorly air conditioned as well,
consider a through-the-wall heatpump.
Renovations: Renovated three story townhouses
with heating and cooling equipment located on
the roof almost always have cold first floors.
It is very difficult to force warm air (it just
loves to rise) down three stories. If the first
floor registers are located in the ceiling, the
warmed air never reaches the floor. The small
amount of warm air that reaches the first floor
registers travels along the ceiling back to the
return. The result is often a very cold floor.
Strategically placed electric baseboards are
often a practical answer here too. You will find
the first floor quite cool in the summer. (The
colder AC air just loves to fall.)
Finished Basements:
Some finished basements never seem to get
adequately warm. The usual reason is that the
original ducting was designed to heat the upper
levels of the house only. Heat registers to the
basement were probably cut into the extended
plenum for the first floor and empty to the
ceiling. This lowers the pressure within the
entire system disrupting the
flow of air throughout the entire house.
Recognize that heating the basement is at the
expense of the upper level heating. Close the
basement registers when you are not using the
basement.
Additions:
Some poorly planned additions utilize the
original registers where the addition meets the
old exterior of the house. The results are
usually quite poor. Heat from original registers
usually responds to inner returns and won't
travel to the outer walls of the new addition.
It is usually better to extend register ducts
directly from the plenum to the outer wall of
the new addition or install a separate
through-the-wall heatpump. Tapping existing duct
systems to heat and cool additions is almost
always a bad idea.
Hot Water Systems:
Cold rooms with radiators or baseboards are
usually easily cured. The reason there is no
heat is that water is not moving through the
radiator or baseboard. This is almost always due
to an air blockage, a faulty inlet valve, or a
badly adjusted balance valve. Sometimes there
just isn't enough water in the system.
Check the system by running the thermostat up
and pinpointing which radiators or baseboards
are not heating. If there are multiple
thermostats make sure they are all turned up and
that the corresponding circulators or zone
valves are working. Touch the circulators and
feel for the vibration. Put your hands on the
pipes on both sides of zone valves (little boxes
with thin wires leading from them mounted across
pipes above the boiler) to see if the hot water
is flowing through them. (There is usually a
little slide on zone valves which allows for
manual operation.) If the only radiators or
baseboards are on upper levels, check the boiler
pressure gauge. It should typically show 12 to
14 pounds of pressure since that is usually what
the feed valve is set at. If there is less than
this the feed valve may not be operating and the
heating system may not be filled with water.
Check individual radiators or baseboards by
first making sure that inlet valves are open and
that the radiator or baseboard is adequately
bled. Locate the bleed valve on one end and open
it. Allow all air to hiss out and wait for water
to flow. (Have a coffee can or cup ready to
catch the water.) If air hisses out and then
stops and no water flows, the system is probably
low on water. Tighten the bleed valve and wait
(with the system operating) for about a half
hour and then try it again. Bleed it until you
get water. If you can't get water, the system
feed valve is probably faulty. Call a plumber.
Adding an Air Bleed Valve:
Long runs of copper baseboards sometimes have
air blockages which are very difficult to bleed
off. Consider tapping the baseboard with a
"saddle valve" at the opposite end from the
existing bleed valve. Saddle valves clamp around
the pipe and pierce the tubing by tightening
them down. They cost less than three dollars and
anybody can install them.
Cool Rooms:
Occasionally baseboard systems (crawl space
houses) have a cool room on the end of the run
of baseboard. This is usually due to excessive
temperature loss and is often cured by
insulating connecting pipes beneath the floor.
Use 3 1/2 inch fiberglass insulation with a foil
backing (foil to the outside) wrapped and taped
around the pipes with duct tape.
Sometimes the boiler water temperature is simply
too low. Radiator systems usually run at 140
degrees F. while baseboard systems usually run
at 160 to 180 degrees F. There is usually an
adjustment on the front of the boiler.