From The Desk of Roberto Montiel
Alban Home Inspector
FLAGSTONE INSTALLATION
AND MAINTENANCE
Flagstone is a natural rock, formed
by sedimentation. Its color comes from the cementing materials, such
as silica, calcium or iron oxide, so colors can be red, blue, buff
or even chocolate. The most common uses of flagstone is for walks
and patios.
If installation is not proper, however, the structure can easily
deteriorate. Techniques for installation of flagstone pieces are
very simple, but each step is critical. To begin with, every
flagstone structure must have a proper slope to let rainwater drain
off the surface. If water is retained, mildew will develop over the
surface and eventually weaken the mortar joints and the cement base.
Mildew can be killed with an herbicide, which is available at any
garden shop or hardware store. If the strength of the cement mortar
joints is diminished, this will cause the flagstone pieces to become
loose.
The second result of poor drainage is that during winter weather,
freezing temperatures make the trapped water expand and break the
cement joints. There are several ways to prevent this. The first is
the slope. Civil Engineers figure a minimum 1/4 inch fall over a
12-inch distance to be acceptable. A commercial masonry sealer can
be applied every few years to protect against constant exposure to
the elements. Furthermore, mortar joints can also be resealed
periodically as needed.
Another important aspect of flagstone installations is that the
stone pieces MUST be laid over a COMPLETELY solid concrete base with
no air pockets that could trap water. Again, the freeze thaw cycle
in winter will cause the flagstone to lift and loosen.
Finally, the quality of the sand, a relatively precise 3-1 mixture
of sand to mortar and the |
Gas Furnace Efficiency by
Arthur Lazerow |
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Forced air heating is provided in homes by either gas or oil
furnaces. The great majority of homes nationwide are heated with
natural gas furnaces, although in many areas with no supply of
natural gas, heat pumps have become the choice of builders for
heating their new homes these last twenty years. Oil heating is
seldom used today.
There are two primary reasons a homeowner replaces a furnace: it has
either become so old and cranky that it is beyond repair or the cost
of natural gas has gotten so expensive that efficiency of older but
still functioning equipment is an issue.
The indoor furnace functions as a gas burner, producing heated
flue gases. These hot gases heat a metal heat exchanger to transfer
the heat to the home’s recalculating air. The spent flue gases drift
up the flue pipe into the atmosphere. The higher the efficiency, the
less heat that goes up the chimney, so to speak.
Efficiency rating is called Annual Fuel Utilization Efficiency (AFUE).
It is expressed as a percentage, and essentially indicates how much
of the energy created by burning natural gas is transferred to the
home. Many furnaces installed in homes built during the housing boom
of the 1980’s are now being replaced. The issue is what equipment
efficiency should the homeowner select?
Older furnaces operated at 50-60% efficiency. Boo! Too much money up
the chimney pipe! The federal National Appliance Energy Conservation
Act of 1987 mandated that all new furnaces should be rated at a
minimum of 78% efficiency. Thus, there is no choice for a cheaper
low efficiency 60% furnace. Today’s customer is faced with a
midefficiency furnace operating at 80% or a high efficiency furnace,
called a condensing furnace, which operates at no less than 90%.
Carrier manufactures a model SXC with a 96.7% AFUE.
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The mid-range furnace at 80% efficiency is totally
satisfactory for residential use. The mid-range efficiency comes
from the addition of a second heat exchanger located above the
primary heat exchanger. The flue gases pass over the first stage
heat exchanger at about 65% efficiency and an induction fan moves
the spent flue gases through the second stage heat exchanger, which
removes another 15%. Most of the mid-range equipment features
sophisticated burner controls that account for additional
efficiency.
The high efficiency furnaces are called condensing furnaces because
they are so efficient that the moisture created by the combustion
process of natural gas actually condenses out of the flue gases,
creating water inside the furnace flue pipes. Add the hydrocarbons
from combustion to the liquid of condensation and acid is produced.
Early machines with metal flue pipes experienced rust-through during
the first years of operations, thereby liberating carbon monoxide
and other gases. Accordingly, high efficiency furnaces are piped
with PVC plastic flues to handle the acidic flue moisture and gases.
Which to buy, you ask? As a home inspector, I believe the most
efficient system, although more costly, is most desirable. However,
several heating contractors with whom I spoke about this subject
recommended the mid- ange system. With over 80% efficiency on the
mid-range machines, as compared to the slight increase to the 90%
level, the cost surcharge for the high efficiency was not
reasonable, they claimed. The contractors also commented that the
high efficiency equipment has been found to require much more
maintenance, whereas the mid-range furnaces operate relatively
maintenance free.
From the standpoint of maintenance of all heating equipment, I
recommend an annual
continued on page 2
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