"HOME TECH": The Inner Workings



The Toilet

Yes...those tales you've heard are true. The toilet was first
patented in England in 1775, invented by one Thomas Crapper,
but the extraordinary automatic device called the flush toilet
has been around for a long time. Leonardo Da Vinci in the 1400's
designed one that worked, at least on paper, and Queen Elizabeth
I reputably had one in her palace in Richmond in 1556, complete
with flushing and overflow pipes, a bowl valve and a drain trap.
In all versions, ancient and modern, the working principle is the
same.

Tripping a single lever (the handle) sets in motion a series of
actions. The trip handle lifts the seal, usually a rubber
flapper, allowing water to flow into the bowl. When the tank
is nearly empty, the flap falls back in place over the water
outlet. A floating ball falls with the water level, opening
the water supply inlet valve just as the outlet is being closed.
Water flows through the bowl refill tube into the overflow pipe
to replenish the trap sealing water. As the water level in the
tank nears the top of the overflow pipe, the float closes the
inlet valve, completing the cycle.

From the oldest of gadgets in the bathroom, let's turn to one of
the newest, the toothpaste pump. Sick and tired of toothpaste
squeezed all over your sink and faucets? Does your spouse never
ever roll down the tube and continually squeezes it in the
middle? Then the toothpaste pump is for you!

When you press the button it pushes an internal, grooved rod down
the tube. Near the bottom of the rod is a piston, supported by
little metal flanges called "dogs", which seat themselves in the
grooves on the rod. As the rod moves down, the dogs slide out of
the groove they're in and click into the one above it. When you
release the button, the spring brings the rod back up carrying
the piston with it, now seated one notch higher. This pushes
one-notch's-worth of toothpaste out of the nozzle. A measured
amount of toothpaste every time and no more goo on the sink.

Refrigerators

Over 90 percent of all North American homes with electricity have
refrigerators. It seems to be the one appliance that North
Americans can just not do without. The machine's popularity as a
food preserver is a relatively recent phenomenon, considering
that the principles were known as early as 1748. A liquid
absorbs heat from its surroundings when it evaporates into a gas;
a gas releases heat when it condenses into a liquid.

The heart of a refrigerator cooling system is the compressor,
which squeezes refrigerant gas (usually freon) and pumps it to
the condenser, where it becomes a liquid, giving up heat in the
process. The condenser fan helps cool it. The refrigerant is
then forced through a thin tube, or capillary tube, and as it
escapes this restraint and is sucked back into a gas again,
absorbing some heat from the food storage compartment while it
does so. The evaporator fan distributes the chilled air.

In a self-defrosting refrigerator/freezer model, moisture
condenses into frost on the cold evaporator coils. The frost
melts and drains away when the coils are warmed during the
defrost cycle which is initiated by a timer, and ended by the
defrost limiter, before the frozen food melts. A small heater
prevents condensation between the compartments, the freezer
thermostat turns the compressor on and off, and the temp control
limits cold air entering the fridge, by means of an adjustable
baffle.

Smoke Detectors

Is your smoke detector good at scaring to death spiders who
carelessly tiptoe inside it? Have you ever leapt out of the
shower, clad only in you-know-what, to the piercing tones of your
alarm, triggered merely by your forgetting the close the bathroom
door? Is it supposed to do this?

There are two types of smoke detectors on the market; the
photoelectric smoke detector and ionization chamber smoke
detector. The photoelectric type uses a photoelectric bulb
that shines a beam of light through a plastic maze, called a
catacomb. The light is deflected to the other end of the maze
where it hits a photoelectric cell. Any smoke impinging on this
light triggers the alarm (as