Atlanta Inspection News! Consumer information: November 2007

Most heating systems in atlanta and across the nation use forced hot air in today residential homes.Because most air conditioning systems require forced air, the air handler can be used for both heating and cooling.It is more economical to install a single air delivery system than two.Hot air systems area availiable in a wide range of systems styles and capcities.

Most forced hot air systems are fossil fueled.Most common used in residential homes are hot air forced system as a cabinet mounted furnace installed in attic,or basements,or crawlspace.Proper venting is very important in the fuels combustion process the by products are removed from the heat exchange area and in to the venting flue and out of the building enevolope.Furnances are availiable for horizontal,vertical upflow,and vertical downflow applications.The central forced air heating used to heat a flow of air is the furnace.Most furnances are controlled by space thermostat.When heat is needed the burner starts immediately,but the fan does not start to distribute the air until the heat exchange temperture rises to around 110*F.

The blower starts when an internal thermastat(called a limit control)senses the heat exchanger is properly heated.When the space reaches temperture setting unit will cut-off.The fan is installed upstream of the exchanger for an important reason.Air pressure just past the fan is the highest than any where else in the system.

Today homes use indoor air for combustion and to help the flue draft.Under some conditions the fan can draw air down the chimney (if one is in the home) and into nearby return inlet registers.This can cause improper combustion and venting and allow these gases enter into home.Constant improvments have been made through the years in the heat exchange area.I would always recommend a inspection if a new unit has been installed to assure the contractor followed all the standard building installation code.If not when or if you go to sell your home you will be stuck with correcting the mistakes.I'm not trying to bad mouth good companys,but there empolyees will rush a job or take a short cut because they know you will never no the differance.

The split system air condition is the most widely used in residential applications.This includes central split direct expansion units and modular systems,split systems have their compressor,and usually condenser ,seperate from the evaporator.They work with a air handler and duct system.Central systems are used in residential and commercial buildings.These systems integrate well with forced air heating.Common controls make them eassier to operate.

Air to Air Heat pumps

A special form of electric heater is the heat pump.There are two types of heat pumpms:air to air and water source.Air to air are widely used in residential homes..Heat pumps are specialized air conditioners that move heat energy into or away from a space.The system can be reversed to cause heat to flow from spaces to the outside(like a regular A/C) or from the outside to the inside.This is considered its heat pump mode.

Air to Air heat pumps have two refrigeant coils and reversing valve.When cooling is needed,the indoor coil functions as the evaporator and heat is removed from the inside space.The outdoor coils functions as the condenser and the heat removed inside is discharged outside.

Reversing the flow of refrigerant swaps the coil's functions.The outdoor coil becomes the evaporator and absorbs heat from the outside air.

Forced Warm-Air Heat
Caring for the Forced Warm-Air Heating System
Balancing the Heat
Setting the Fan Control

Low installation cost, fast heat delivery, and reliability make forced warm-air systems a popular heating choice. The system is versatile and lends itself to the addition of central air conditioning. In this system, a blower pulls air from the rooms into the cold-air return and return duct, through a filter, and into the furnace. There the air is heated. It then flows back to the rooms through the warm-air ducts and registers.

Caring For the Forced Warm-Air Heating System
To ensure trouble-free operation, service the system as follows:

Clean or replace the filter monthly during the heating season.

Brush and vacuum heat exchanger surfaces annually (see owner's manual for instructions).

Clean the blower blades at the start of each heating season. Add a few drops of motor oil to each oil cup if your blower is equipped with them.

Check and adjust the belt alignment and tension if your furnace has a belt-driven blower. To replace a worn belt, loosen the motor adjustment bolt, remove the old belt, and attach a new one.

Examine the ducts annually for leaks; seal any leaks with duct tape.
Balancing the Heat
If some rooms are too hot or cold, try adjusting the dampers in the registers and, if your system has them, the dampers in the warm-air ducts.

Leaving the thermostat at one setting, let the system run for 3 hours to stabilize the temperatures. Open the dampers wide in the coldest rooms. Then adjust the dampers room by room until temperatures are balanced. Wait half an hour after each adjustment before rechecking or readjusting.

Speeding up the blower may help heat chronically cold rooms. Adjust the motor pulley of a belt-driven blower or, for a direct-drive blower, change the electrical connections (see owner's manual).

Setting the Fan Control
If you're chilled by a blast of cool air when the blower turns on, try adjusting the fan control.

CAUTION: If your furnace has a combination fan and limit control, do not touch the pointer on the limit control side. This pointer turns off the furnace if the maximum allowable air temperature is exceeded.
As the blower turns on, hold your hand in front of the warm-air register farthest from the furnace.

Ideally, your hand should feel neither cooler nor warmer.
If it feels cooler, uncover the control and move the fan control's ON pointer a few degrees lower.

To adjust the temperature of the air coming out of the registers, move the ON pointer to set the temperature at which the blower turns on, the OFF pointer to set the temperature at which it turns off.

Many modern subdivisions are mass graded.This means an undesirable building location(lots of steep grade are uneven lots.)is transformed into individual flat or moderately sloped lots by movement of dirt.This usally includes removal of soil at hill(the cut lot),which which is them imported to other areas on site to create fill areas(the fill lot) or cut-fill areas(transitional lot).Cut lot tens to perform well since the soil is undisturbed where the hill was removed.Fill lot can compact more once the home is completed;this movement,however,is usually uniform and rarely cause distress th the home.These condition are consider when inspecting a home when built from mass graded lots.The homes soil,and foundation are in constant movement and forces fighting against one another.

A structure is expected to stand up.The force of gravity is constantly working to bring it down.A structure has to be designed to resist gravity.It must support its own weight,which is called DEADLOAD of the structure.It must also support the live load which are imposed open it,which include the people inside,the furniture,and other weight such as snow,and the materials used in the roof structure skeleton.
A structure does transfer its weight through the exterior walls,and load bearing partions to the foundation which in then transfers the weight to the soil through the footing.Not only is a structure expected to stand up, it is also expected to stand still.The structure movement is partially determined by the conditions of the soil support the structure,and proper drainage around the stucture.When the ground below the house fails,the house sinks.Soil moves.The foundation resists the pressure of the soil against the structure.Homes built on the proper site should be built strong enough to resist this natural pressure.

MOVEMENT:
The effects of settlement and movement on a home and their effects on the rest of the structure are not always obvious.While some signs are obvisous,other signs might need more in depth study to determine the cause of underlying issues.Wall cracks appear as the result of overloading or because of settlement or heaving.The location of the cracks can be a clue to what is going on to the foundation.

SOIL:
Is a dynamic system.Soil Moves.A house bult on the bottom of a hill can have soil moving toward it over time and exerting more and more pressure against the foundation.It may be pushed from its original position.

WINDS
:Place an effective upon a structure.With heavy winds theres forces of pulling,and uplifting.Structures must be strong enough to resist these forces as well.

Vertical Cracks:
 Are most often caused as a result of settlement of the structure,soilcompacting,or soil washing away under the footings.It occurs when there is an upward overload force next to a downwards overload force.They can also occur after remolding,when new dead loads are added to the structure,or by adding very heavy live loads.
 Vertical cracks that extend down to the footings may be serious and should be investigated carefully.This could be cause by uneven settlement of the building and could indicate the wall is seperating-one part settling more on one side of the crack than the other.The crack extending to the footing could also indicate a failure of material such deteriorating block,decayed mortar,or weak concrete,or improper construction standards.

Angled Cracks:
Appear when the upload and download force offset each other.They can appear when there is major difference in the soil under the home from one location to another,heaving of the soil,and resulting footing failure.Angled cracks can appear in pairs,where a load in one direction is offset by a pair of loads from other direction.When a crack is a single corner of the house,it can indicate a broken footing because of the soil underneath,expansive clay soilsor even the uplift from heavy tree roots in that location.

Horizontal Cracks:Z crack formation
On the foundation stem wall can indicate pressure being applied from the outside.The cause can be soil pressure against the wall,improper backfilling,and surface problems such as poor downspouts,Grade of lot,surface water drainage that allow water to pool around the foundation and increases the pressure pushing against the wall.When the wall is actually displaced-when the surface of the wall is out of alignment and the crack is wider on the inside face of the wall,serious problems can result.
 There are other cause for horizontal cracks in foundation walls.There could be a vertical overload on the wall.Or the crack could be caused by settlement,where the wall has dropped when the soil underneath settled.

Internal Stresses:
The integrity of a structure depends on each individual structure members.A structure is in a constant state of Stress as individual member extert forces upon each other.For example,Floor joists spanning the structure would sag without the restraints and support provided by girders,which in turn push on supporting columns.These supoort systems must work in concert with each other without excerting more load to one another and resulting in damage.Structural member have two forces working on them at all times compression,and tension.Members of the structure has forces such as shearing,and bending.Individual members may fail under these stresses.Home inspections looks for these underlying problems.