Our planet, for example, can usefully be understood as a single organism. Its many interconnections are complicated, yet the better we understand them, the more likely we are to be able to keep it a safe home for all of us.
SCIENCE TRIES TO EXPLAIN SYSTEMS
The better we understand how systems in a home work, the safer we can keep the home and the better inspectors we will be. One example of science confusion is “filtration lines,” those dark stripes along the walls of carpets. The presumption is that fine particles get sucked into the walls by the negative pressure provided by your forced air system. Some sources say it’s even due to holes in the ductwork.
Questions to ask include:
- How much pressure is needed to pull dust along a wall?
- Why are the lines so uniform? Certainly, some areas of the wall would be more permeable than others?
- What about lines on concrete floors?
Occam’s Razor is a standard for testing hypotheses, and it proposes that simple solutions are more likely to be correct than complex ones: surely the tack strips make it more difficult to clean next to the wall. Carpet cleaners who say they can’t be cleaned are not pretreating with a brush and using a small enough vacuum head to get them up. It seems to make the most sense that these stripes are primarily just dirt that is not easy to vacuum up.
Maybe, in some cases, dust comes out of the ducts. This would certainly be cause for comment. It’s important to stay humble and keep trying to get a bigger picture, say, from multiple causes.
Occam’s Razor can help us come up with simple solutions for homeowners and protect them from less knowledgeable or unscrupulous contractors:
“Please just get the gutter cleaned before you have the basement waterproofed!” is something I’ve said many times.
Cleaning the gutters and adding downspout extenders are a simple surface solution to wet basements. Even adding expensive foundation floor drains means the water still must pass over the whole basement wall before it gets removed. How about this drainage solution that saved a house from the waterproofing expense?
SCIENCE CAN SEE INTO THE FUTURE
Scientists can predict when the sun will expand and melt the Earth because of how other stars like ours have behaved. Because of our experiences in older homes, we can predict what will happen to a poorly supported expansion tank, for example.
Here’s one on CPVC looking like a catapult. On new homes, they are still installing them straight up on 18 inches of ¾ inch copper pipe. Water is supposed to cycle in and out, but if the internal bladder fails, the tank remains filled with water. I have seen 2-year-old tanks full of water bending the lower joints. One plumber told me when a tank torqued off it did $75,000 worth of damage to the basement. Therefore, these need shelves under them or straps to support them so they stay upright.
Expansion tanks are installed because water takes up more space when it’s heated. The pressure causes weeping valves and joints nearby, and in one of my houses, a CPVC joint popped out in the bathroom just above the water heater. These effects happen regardless of the absence of backflow preventers.
Utility Has to Be Balanced with Safety in Science
There are always trade-offs between function and safety; think of the moon mission. The astronauts must stay alive while riding inside a spacecraft. The more complicated the system, the harder it might be to understand safety concerns. Take water heaters and electric panels, for example. Realtors will say they “work,” yet they contain safety devices that can’t be tested until they’re needed, and that could be too late. Circuit breakers are supposed to trip before the wires melt. Thermostats on water heaters are supposed to turn off before super-heated water comes shooting out of the TPR valve, which is not desirable, but better than the tank exploding. If the TPR valve doesn’t work, then it’s astronaut time. Gas furnaces eventually get holes in the heat exchanger. Death is unlikely in any of these circumstances, but why take the chance with a Federal Pacific or Zinsco panel, a water heater more than 15 years old, or a gas furnace over 25?
As teachers of house science, we need to do our best to understand how the different parts of a house work together, link our recommendations to observable facts as we discuss them with home buyers, be humble (we might not have the whole picture), and look out for the future of our clients by making sure their new house is safe.
SOME USEFUL SCIENCE TERMS:
Condensation: Condensation is a process. It’s the opposite of evaporation. That stuff on your iced tea glass in August is condensate.
Galvanic Corrosion: When different metals contact each other, an electric current forms, which can lead to degradation of the materials. Volta used this property to invent the battery. One of the oddest occurrences of this in homes is those green spots all along the bottom of copper pipes.
These are caused by steel flakes from old water heaters settling along the pipes, eventually causing pinhole leaks.
Efflorescence: When water passes through a substance, or, like on metal ducts, simply touches it, salts are drawn out.
THREE WAYS HEAT MOVES: Conduction is through touching. Convection is through air movement. Radiation is invisible infrared electromagnetic radiation. Insulation with a foil face prevents all three kinds of heat movement.
Adiabatic Cooling: Is part of why air conditioners work.
Have you ever cleaned your keyboard with a can of compressed air? A volatile fluid (meaning it has a low boiling point) is compressed in a can. It has a certain amount of heat in a small space and when you reduce the pressure by opening the valve, it has the same amount of heat in a larger space, so it gets cold.
Also, the change of state from a liquid to a gas absorbs heat from the surroundings (in the same way sweat from your body takes the heat with it as it changes into a gas).
This all happens when the high-pressure line shoots coolant into the interior coil. Well, the low-pressure line (the big line-set pipe) then takes it out to the compressor/condenser to get pressed into a liquid again so the cycle can repeat itself. No net heat is lost, it’s just transferred outside.
The only energy added is by the work the compressor does (and the exterior fan).
Adiabatic cooling is also how water vapor leaves the ground and turns into water droplets in the clouds because the air pressure decreases with altitude. The air literally weighs less as you go up. The weight of air pressing on us at sea level is like being under 10 meters of water. nosurpriseshomeinspection.com
