Sonoran Property Inspections

Home Inspections Prescott, Prescott Valley, Cottonwood, Scottsdale, Arizona

Defrost Cycle of a Heat Pump

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Baby, it’s cold outside! So today’s blog from your hometown Home Inspector is all about heat pumps. Whether you are in the Phoenix area, or in Prescott and quad cities area, learning how your heat pump operates may help you. Here, we cover some fundamentals of a particular heating system called a heat pump using non-invasive, visual-only inspection techniques. We also discuss its defrost cycle.  Yes, more than you may want to know, but… here you go. As always, feel free to contact me with any of your home inspection questions.

How it Operates
When a heat pump is operating in the heating mode or heat cycle, the outdoor air is relatively cool and the outdoor coil acts as an evaporator.  Under certain conditions of temperature and relative humidity, frost might form on the surface of the outdoor coil.  The layer of frost will interfere with the operation of the heat pump by making the pump work harder and, therefore, inefficiently.  The frost must be removed.  A heat pump has a cycle called a defrost cycle, which removes the frost from the outdoor coil.
A heat pump unit will defrost regularly when frost conditions occur.  The defrost cycle should be long enough to melt the ice, and short enough to be energy-efficient.
In the defrost cycle, the heat pump is automatically operated in reverse, for a moment, in the cooling cycle.  This action temporarily warms up the outdoor coil and melts the frost from the coil.  In this defrost cycle, the outdoor fan is prevented from turning on when the heat pump switches over, and the temperature rise of the outdoor coil is accelerated and increased.
The heat pump will operate in the defrost cycle until the outdoor coil temperature reaches around 57° F.  The time it takes to melt and remove accumulated frost from an outdoor coil will vary, depending on the amount of frost and the internal timing device of the system.
Interior Heating Element
During this defrost cycle with older heat pumps, the indoor unit might be operating with the fan blowing cool air.  To prevent cool air from being produced and distributed inside the house, an electric heating element can be installed and engaged at the same time as the defrost cycle.  In defrost mode, this heating element will automatically turn on, or the interior blower fan will turn off.  The heating component is wired up to the second stage of a two-stage thermostat.
The Typical Cycle
The components that make up the defrost cycle system includes a thermostat, timer and a relay.  There is a special thermostat or sensor of the defrost cycle system, often referred to as the frost thermostat.  It is located on the bottom of the outdoor coil where it can detect the temperature of the coil.
When the outdoor coil temperature drops to around 32° F, the thermostat closes the circuit and makes the system respond.  This causes an internal timer to start.  Many heat pumps have a generic timer that energizes the defrost relays at certain intervals of time. Some generic timers will energize the defrost cycle every 30, 60 and 90 minutes.
The defrost relays turn on the compressor, switch the reversing valve of the heat pump, turn on the interior electric heating element, and stop the fan at the outdoor coil from spinning.  The unit is now in the defrost cycle.
The unit remains in the defrost cycle (or cooling cycle) until the thermostat on the bottom of the outdoor coil senses that the outdoor coil temperature has reached about 57° F. At that temperature, the outdoor coil should be free of frost.  The frost thermostat opens the circuit, stops the timer, then the defrost cycle stops, the internal heater turns off, the valve reverses, and the unit returns to the heating cycle. A typical defrost cycle might run from 30 seconds to a few minutes.  The defrost cycles should repeat regularly at timed intervals.  An inspector should not observe a rapid cycling of the defrost operation.
In summary, certain conditions can force a heat pump into a defrost cycle (or cooling cycle) where the fan in the outdoor coil is stopped, the indoor fan is stopped or electric heat is turned on, the frost melts and is removed from the outdoor coils.  When the frost thermostat is satisfied or a certain pre-set time period elapses, the outdoor fan comes back on, and the heat pump goes back into the heating cycle.
One problem of many older heat pump systems is that the unit will operate in the defrost cycle regardless of whether ice is present.  On these systems, if it’s cold outside, the defrost cycle might turn on when it is not needed.
If the defrost cycle is not functioning properly, the outdoor coil will appear like a big block of ice, making the unit non-functional.  Damage could result if the heat pump operates without a functional, normal-operating defrost cycle.
Causes of Frost
There are many reasons why an inspector might find frost and ice stuck on an outdoor coil of a heat pump that is not properly defrosting.
The cause of the frost and ice problem may include:
  • a bad reversing valve;
  • a damaged outdoor coil;
  • a wiring problem;
  • a bad thermostat;
  • a leak in the refrigerant;
  • a dirty outdoor coil covered with grass, dirt, debris and/or pet hair;
  • a fan that won’t turn on;
  • a fan installed backwards with the blades running in the wrong direction;
  • a motor operating in the incorrect direction; and/or
  • a replacement fan motor spinning at a very low rpm.
Diagnosing apparent problems with the defrost cycle of a heat pump is beyond the scope of a home inspection.

Home Roof Inspections

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Unprofessional Roofing

As we approach our summer monsoon season here in Arizona, it’s time to inspect your roof -or have a home inspector inspect it for you- to make sure you are ready for the storms and the extreme heat.  In the Prescott area the rains are more prevalent (and steady) than in the Phoenix area (where there can be lots of dust storms and winds, followed by a little or a lot of rain). In either case you want your roof to do what it is designed to do, and we want to give you a few tips to help.

Whether your roof is tile, asphalt shingles, or metal there are things to look for and repair or replace as needed:

  • Broken tiles
  • Missing, broken or buckling shingles
  • Peeling paint under the overhangs
  • Rusty flashing on the roof
  • Trees or shrubs hitting the roof – clear all branches away from roof
  • Clogged gutters
  • Evidence of dampness inside the house around windows or fireplace
  • Dark patches (moisture) on the ceilings
  • Water stains on ceiling or walls

If you notice any of these things you may want to hire a roofing company to come take a closer look to determine if a quick repair is all that is needed to protect your home from future damage. Contrary to what some people believe, your roof will not last forever. While the tiles on the roof may last a long time, the underlayments still needs to be replaced every 15 years or so. Annual inspections will certainly help you maintain your existing roof in our harsh Arizona summers.

Central Air-Conditioning System Inspection

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It is heating up out here in Arizona – even here in Prescott, but especially in the Phoenix area. Now is the time to make sure your air conditioning is ready to handle the heat!  As part of a home inspection (in the Phoenix and Prescott areas) we do take a close look at the HVAC units, and if in doubt we will suggest an HVAC company come take a closer look. We also have routine maintenance done on our own home’s unit since a building’s central air-conditioning system must be periodically inspected and maintained in order to function properly. While an annual inspection performed by a trained professional is recommended, homeowners can do a lot of the work themselves by following the tips offered in this guide.Exterior Condenser Unit

Clean the Exterior Condenser Unit and Components
The exterior condenser unit is the large box located on the side of the building that is designed to push heat from the inside of the building to the outdoors. Inside of the box are coils of pipe that are surrounded by thousands of thin metal “fins” that allow the coils more surface area to exchange heat. Follow these tips when cleaning the exterior condenser unit and its inner components — after turning off power to the unit!
  • Remove any leaves, spider webs and other debris from the unit’s exterior. Trim foliage back several feet from the unit to ensure proper air flow.
  • Remove the cover grille to clean any debris from the unit’s interior. A garden hose can be helpful for this task.
  • Straighten any bent fins with a tool called a fin comb.
  • Add lubricating oil to the motor. Check your owner’s manual for specific instructions.
  • Clean the evaporator coil and condenser coil at least once a year.  When they collect dirt, they may not function properly.
Inspect the Condensate Drain Line
Condensate drain lines collect condensed water and drain it away from the unit.  They are located on the side of the inside fan unit. Sometimes there are two drain lines—a primary drain line that’s built into the unit, and a secondary drain line that can drain if the first line becomes blocked. Homeowners can inspect the drain line by using the following tips, which take very little time and require no specialized tools:
  • Inspect the drain line for obstructions, such as algae and debris. If the line becomes blocked, water will back up into the drain pan and overflow, potentially causing a safety hazard or water damage to your home.
  • Make sure the hoses are secured and fit properly.
Clean the Air Filter
The air filter slides out for easy replacement
Air filters remove pollen, dust and other particles that would otherwise circulate indoors. Most filters are typically rectangular in shape and about 20 inches by 16 inches, and about 1 inch thick. They slide into the main ductwork near the inside fan unit. The filter should be periodically washed or replaced, depending on the manufacturer’s instructions. A dirty air filter will not only degrade indoor air quality, but it will also strain the motor to work harder to move air through it, increasing energy costs and reducing energy efficiency. The filter should be replaced monthly during heavy use during the cooling seasons. You may need to change the filter more often if the air conditioner is in constant use, if building occupants have respiratory problems,if  you have pets with fur, or if dusty conditions are present.
 
Cover the Exterior Unit

When the cooling season is over, you should cover the exterior condenser unit in preparation for winter. If it isn’t being used, why expose it to the elements? This measure will prevent ice, leaves and dirt from entering the unit, which can harm components and require additional maintenance in the spring. A cover can be purchased, or you can make one yourself by taping together plastic trash bags. Be sure to turn the unit off before covering it.

Close the Air-Distribution Registers
Air-distribution registers are duct openings in ceilings, walls and floors where cold air enters the room. They should be closed after the cooling season ends in order to keep warm air from back-flowing out of the room during the warming season. Pests and dust will also be unable to enter the ducts during the winter if the registers are closed. These vents typically can be opened or closed with an adjacent lever or wheel.  Remember to open the registers in the spring before the cooling season starts.  Also, make sure they are not blocked by drapes, carpeting or furniture.
In addition, homeowners should practice the following strategies in order to keep their central air conditioning systems running properly:
  • Have the air-conditioning system inspected by a professional each year before the start of the cooling season.
  • Reduce stress on the air conditioning system by enhancing your home’s energy efficiency. Switch from incandescent lights to compact fluorescents, for instance, which produce less heat.
In summary, any homeowner can perform periodic inspections and maintenance to their home’s central air-conditioning system.

Understanding the Electric Panel Box on your Home

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One item I usually try to go over with a home buyer after a home inspection is the electric panel.  Many homeowners who are unfamiliar with construction and wiring are timid when it comes to electrical work. It makes perfect sense to have a healthy respect for electricity—it can be dangerous if you don’t understand it.

To give you confidence and a little knowledge to help you discuss electrical problems with an electrician, let’s explore how the service panel (or panel box) controls your home’s electrical system.

 

The Service Panel

After passing through the electric meter, the local electrical utility provides electricity to your house through the service panel (also called the distribution center). The panel, which is usually located in a garage, basement or utility room, distributes electricity through individual circuits that run throughout your house.

The service panel in most homes contains circuit breakers, which look like little switches. Older homes may contain fuses, but they serve the same purpose as circuit breakers—to stop the flow of electricity when there is a problem.

As a homeowner, you need access to the panel for three tasks:

  • to shut off power to the whole house if needed (you do this by switching off the large breaker);
  • to reset a circuit breaker that trips; and
  • to turn off power to individual circuits when you are doing electrical work somewhere in the house.

You can also add new circuits to the panel box if there is room, but this is usually a job for a licensed electrician.

Why Do Circuit Breakers Trip?

If you plug too many appliances into a circuit, the system senses that they require more power than the circuit can accommodate and the circuit breaker trips, shutting off power completely. It’s a safety measure designed to protect the wiring in the circuit, as too great a demand can cause the wires to overheat.

Each circuit has a limit of how much power it can handle. You will find that limit printed on each breaker. The number represents the ampere, or amps, which measure the rate or quantity of electrical flow. The number printed on the main breaker is the upper limit your house’s service can accommodate.

For example, a 15-amp circuit is a light-duty circuit that may power something like living room and bedroom lights and electrical outlets, and there are usually several outlets on one circuit.  A 30- or 50-amp circuit is for appliances that use a lot of energy, such as an electric clothes dryer or an electric range. These kinds of appliances are usually the only thing hooked up to the circuit—called a dedicated circuit—and their wiring will have a larger diameter.

Stopping Circuit Breakers from Tripping

Reducing demand on the circuit is the best way to prevent breakers from tripping. Appliances list their energy demands on an identification label on the unit. Most services experience tripping when juggling power demands. For example, if the breaker trips when you use the microwave and the toaster oven at the same time, you will have to move one of those appliances to another circuit. However, if a circuit trips frequently, contact an electrician because there may be a problem in the wiring or a short circuit.

Reset a breaker in the service panel by first pushing it to the “OFF” position and then pushing it back to the “ON” position. Fuses in older panels can’t be reset but must be replaced. Always replace a fuse with another of the same amperage. Don’t be tempted to install a higher-amp fuse because wiring size corresponds to amps. Wiring that is too small for the new fuse could overheat.

Types of Circuit Breakers

Your home is connected to the electric utility by three wires. Two of the wires are charged with a nominal 120 volts each, and the third wire is neutral. Volts or voltage is the force with which electricity flows. Each of the two “hot” wires is attached to the power bus in the service panel. You can’t see the power bus because the panel box should have an inside cover that allows only the circuit breaker switches to be accessible inside the door or cover. As the name implies, the power bus energizes the circuits with either 120 or 240 volts.

The way the circuit is used determines the amount of voltage needed. A 15-amp circuit requires one hot wire or 120 volts. This type of circuit breaker is called a single-pole breaker. An electric range on a 50-amp circuit may need 240 volts, so it has two hot wires. This type of breaker is called a double-pole breaker.

Other circuit breakers include:

  • ground-fault circuit interrupters (GFCIs). These breakers can sense the slightest imbalance in the flow of electrical current when a hot wire touches a ground, such as the metal cabinet of an appliance. Any type of abnormal current flow is called a fault. GFCI breakers trip much more quickly than standard breakers. GFCI protection is required by the National Electrical Code (NEC) in wet areas, such as kitchens and bathrooms, as well as in attached garages. GFCI outlets—the outlets with the “Test” and “Reset” buttons on them—offer the same protection.

  • arc-fault circuit interrupters (AFCIs).  A disconnected hot wire can produce a small arc of electrical current. AFCIs are designed to shut down the circuit before the arc can cause a fire.

Don’t be alarmed if your panel box does not contain GFCI breakers. GFCI electrical outlets provide the same protection. The use of AFCI breakers is relatively new, and not every municipality includes their use in local codes. If you are concerned about arc faults, consult a licensed electrician.

Map the Circuits

Make sure that the inside of the panel door has a legend that clearly indicates which rooms and/or appliances are powered by which breakers.  Many service panels’ legends are missing, illegible or inaccurate.  Make sure that yours is up to date. Work with a helper and methodically go through the house testing the circuits. Don’t assume that all of the outlets in a room are on one circuit. Kitchen lighting and outlets, for example, should be serviced by two circuits. A simple rule of thumb is to check all electrical outlets.

Be Responsible and Safe!

Unless a breaker trips or you want to shut off power to do some electrical work, there’s no need to deal with your service panel.  But it’s important to know where it’s located and to keep the area around it clear so that it’s accessible in an emergency.  It’s also a good idea to store a working flashlight nearby in the event of a power outage.

If the door to your home’s electrical service panel has scorch marks, that could indicate dangerous arcing.  If it’s rusted, there may be a hidden water leak.  It’s best to call a licensed electrician to investigate such issues further.

If your home’s electrical service uses fuses, be sure to keep compatible replacements available.

And never insert any metal object (such as a screwdriver) into the panel or attempt to remove the dead front or cover behind the breakers.  One wrong move could prove fatal.

Do NOT attempt to perform electrical work yourself if you lack the proper experience and training.

Home Inspection – Windows

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One part of any Phoenix or Prescott area home inspection we do is to look at, and operate, all of the accessible windows. This includes the inspector looking for signs of window seal failure. If multiple-pane windows appear misty or foggy, it means that the seal protecting the window assembly has failed. Let’s take a closer look at how window condensation happens, and what it may mean on a home inspection report.
First of all, Condensation is the accumulation of liquid water on relatively cold surfaces.  Almost all air contains water vapor, the gas phase of water composed of tiny water droplets. The molecules in warm air are far apart from one another and allow the containment of a relatively large quantity of water vapor. As air cools, its molecules get closer together and squeeze the tiny vapor droplets closer together, as well. A critical temperature, known as the dew point, exists where these water droplets will be forced so close together that they merge into visible liquid in a process called condensation.

Double-pane windows have a layer of gas (usually argon or air) trapped between two panes of glass that acts as insulation to reduce heat loss through the window. Other types of gas used in this space have various effects on heat gain or loss through the window. Some windows also have a thin film installed between panes that separates the space between the panes into two spaces, further reducing heat loss and heat gain through the window.

Silica Desiccant
A desiccant is an absorbent material designed to maintain dryness in the space it protects. In a double-paned window, silica pellets inside the aluminum perimeter strip absorb moisture from any incoming air that enters the space between the panes. If not for the silica desiccant, any moisture in the space between the panes would condense on the glass as the glass cools below the dew point temperature.

Silica gel has an immense surface area, approximately 7,200 square feet per gram, which allows it to absorb large amounts of water vapor. As the sealant protecting this space fails over time, increasing amounts of moisture-containing air will enter the space between the panes, and the silica pellets will eventually become saturated and will no longer be able to prevent condensation from forming.

Why Double-Paned Windows Fail:  Solar (Thermal) Pumping
Although double-paned windows appear to be stable, they actually experience a daily cycle of expansion and contraction caused by thermal pumping. Sunlight heats the airspace between the panes and causes the gas there to heat up and expand, pressurizing the space between the panes. At night, the window cools and the space between the panes contracts. This motion acts like the bellows of a forge and is called thermal pumping.
Over time, the constant pressure fluctuations caused by thermal pumping will stress the seal. Eventually, the seal will develop small fractures that will slowly grow in size, allowing increasing amounts of infiltration and exfiltration of air from the space between the panes.

Failure Factors

Windows on the sunny side of a home will experience larger temperature swings, resulting in greater amounts of thermal pumping, seal stress and failure rates.

Vinyl window frames have a higher coefficient of expansion resulting in greater long-term stress on the double-pane assembly, and a higher failure rate. Windows also experience batch failure, which describes production runs of windows, especially vinyl windows, that are defective, meaning that the pane assemblies have been manufactured with seals that have small defects that will cause the window to fail prematurely.

The Nature of Damage

If it’s allowed to continue, window condensation will inevitably lead to irreversible physical window damage. This damage can appear in the following two ways:

  • riverbedding.  Condensed vapor between the glass panes will form droplets that run down the length of the window. Water that descends in this fashion has the tendency to follow narrow paths and carve grooves into the glass surface. These grooves are formed in a process similar to canyon formation.
  • silica haze.  Once the silica gel has been saturated, it will be eroded by passing air currents and accumulate as white “snowflakes” on the window surface. It is believed that if this damage is present, the window must be replaced.

Detecting Failure

Condensation is not always visible. If the failure is recent, a failed window may not be obvious, since condensation doesn’t usually form until the window is heated by direct sunlight. Windows in the shade may show no evidence of failure, so your inspector will disclaim responsibility for discovering failed double-paned windows.

 

Recommendations for Failed Windows

According to industry experts, the glazing assembly can be replaced  approximately 75% of the time.  Occasionally, the sashes must be replaced, and only about 5% of those cases require that the entire window be replaced.

Be aware that there are companies that claim to be able to repair misty windows through a process known as “defogging.”

This repair method proceeds in the following order:

  1. A hole is drilled into the window, usually from the outside, and a cleaning solution is sprayed into the air chamber.
  2. The solution and any other moisture are sucked out through a vacuum.
  3. A defogger device is permanently inserted into the hole that will allow the release of moisture during thermal pumping.

There is currently a debate as to whether this process is a suitable repair for windows that have failed, or if it merely removes the symptom of this failure. Condensation appears between double-paned windows when the window is compromised, and removal of this water will not fix the seal itself. A window “repaired” in this manner, although absent of condensation, might not provide any additional insulation. This method is still fairly new and opinions about its effectiveness range widely. Regardless, “defogging” certainly allows for cosmetic improvement, which is of some value to homeowners. It may also reduce the potential for damage caused by condensation in the form of mold or rot.  Some skepticism exists about the effectiveness and cost effectiveness of this method of repair.

In summary, condensation in double-paned windows indicates that the glazing assembly has failed and needs repair or replacement. Visible condensation can damage glazing and is the main indication of sealant failure.

Annual Home Inspections

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The concept of an annual home inspection has been around for a long time, but it may just now be catching on that this is a good idea. Why wait until you plan to sell your home and then get overwhelmed with all the small items that you have not stayed on top of.  As a home inspector in the Prescott area, as well as the Phoenix metro area, we have seen houses that have so much going for them when they hit the market, but then once all the items from a home inspection come up the buyers get concerned with the potential added cost of fixing them, and it sometimes causes them to look elsewhere.

It is easy to stay on top of the maintenance items, and sometimes delay the more costly repairs that all homes need over time, by getting a “home health checkup” on a regular basis – just like going to the doctor for your wellness exams, or taking your car to the shop for routine maintenance. Your home is perhaps your largest asset, so maximize your investment and consider a regular home inspection to provide you with an easy to understand to-do list.

After the inspection you will have a clear idea of the items that need attention so that you may decide what you can do on your own, and what you may need a professional contractor to complete. Then you can enjoy your home more while you live there, and can have fewer surprises when you go to sell it.

Call us today to talk about what we can do for you when it comes to annual (or even semi-annual) “health” checkups for your home!

Paying a Little Extra for a Home Inspection Could Pay Off

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Buying a home in Prescott or the Phoenix area? It is probably the most expensive purchase you will ever make. This is no time to shop for a cheap home inspection. The cost of a home inspection is very small relative to the value of the home being inspected. The additional cost of hiring an InterNACHI-certified inspector (like Jerry at Sonoran Property Inspections) is almost insignificant by comparison.

You have recently been crunching the numbers — negotiating offers, adding up closing costs, shopping for mortgages — and trying to get the best deals. Don’t stop now. Don’t let anyone talk you into skimping on the home inspection. A certified professional home inspector will earn their fee many times over. With over 30 years of home building and inspecting experience, we are able to provide clients with more knowledge that can help them in the sale or purchase of a home, and — yes — I may charge a little more than a less experienced inspector.

So do yourself a favor and pay a little more for the quality home inspection you deserve!