FAQ’s for Homeowners

Hamstra Heating & Cooling

Heating, ventilation and air conditioning terminology can be confusing. To help your understanding and education, here is a list of important terms and their definitions. If you every have any questions on these terms please feel free to call us at 520-629-9833.



You should inspect your filter monthly and change if necessary. A good time to inspect your filter is when you receive your electric bill. Our motto is: to minimize your payment to Tucson Electric Power (TEP), check/replace your filter before writing check to TEP. Failing to change your filter regularly will result in higher utility bills, poor system cooling/heating, damage to your system and many other problems. CHECK YOUR FILTER MONTHLY!

Twice a year. You should have a cooling tune-up done in the spring and a heating tune-up done in the fall. Air conditioning units are like any other piece of machinery; you must have them properly maintained to maximize their performance, efficiency and life-span. Call Hal at (520) 629-9833 ex. 316 for more information on our maintenance/tune-up program.

Normal cooling settings are 75 degrees – 80 degrees

Normal heating settings are 68 degrees- 72 degrees

You should always set your thermostat to the highest possible setting that is comfortable for you in the summer, and the lowest comfortable setting in the winter. Doing this will maximize your energy savings. On average every 1 degree of temperature change is equal to about 10% energy savings. For example, changing your thermostat setting from 75 degrees to 76 degrees in the summer could result in about a 10% savings on your cooling costs.

Yes, the Department of Energy recommends a change of no more than 3 degrees for maximum possible energy savings. This 3 degrees is very important, because if you allow your home to get warmer/colder than this it will result in your unit having to work extra hard to return the home to the proper temperature when you get home. This period of extra hard work for the unit will completely eliminate all the costs you saved throughout the day and will actually now cost you more overall. This is especially true in the summer. For example, if you were to turn your unit off while you were at work, and the house temperature rose 5 degrees, when you return home and crank down the thermostat your unit now has to work very hard to remove all the extra heat in the home, and it has to do it during the hottest time of the day. This results in huge energy usage and cost.

We recommend no more than 5 degrees of change from your normal setting. More than 5 degrees of change could cause damage to the contents of the home, especially in the summer when we are dealing with extremely hot temperatures. Wood floors, cabinets, pets, electronics, etc. are all items that are sensitive to large temperature changes.

A programmable thermostat can be a great tool to maximize energy savings and is recommended by TEP. This type of thermostat can be programmed with different temperature settings for the weekends, while you are away at work and when you go to bed. It is not a necessary item to have, but is a very helpful tool to help you save on energy costs.

  • Find a thermostat setting that is comfortable for you and leave it alone. Only adjust the setting if you are away from the home for extended periods of time.
  • Always clean/replace your filter as recommended. In most situations it is once a month.
  • Have maintenance performed twice a year
  • Read all the answers in this section of our website to fully learn how to make your air conditioning system as cost efficient and comfortable as possible. If you have further questions, feel free to call us. We are always happy to help. (520) 629-9833.

There are endless reasons why your utility bills may be high. Here are some reasons why your heating and cooling is costing you a fortune:

  • Your home is not properly insulated. You may have very poor windows, minimal wall and roof insulation, etc. All these things prevent your home from blocking out the heat and cold from outside. A house that is not well insulated will always be more difficult to heat in the winter and cool in the summer.
  • Your system is not properly maintained. Poorly maintained units do not run efficiently and will cost you more to operate.
  • Your filter is dirty and is not changed often enough. A dirty filter restricts airflow and causes your unit to run harder and therefore use more energy.
  • Your system is old and inefficient. New systems are simply more efficient and use less energy to operate than old systems.
  • You have an oversized unit. Having a unit that is too big for your home will cause short cycling of the unit. The unit will come on and cool the house rapidly while drawing a lot of power. It will then shut off for a short while, turn on for a short while, shut off for a short while and so on. This short cycling process draws more energy than would be drawn under normal operation of a properly sized unit. The system start-up takes about 5 minutes of operation to achieve full capacity and efficiency. Short cycling also does not allow the system to dehumidify properly.
  • You have undersized ductwork. Undersized ductwork chokes the system and causes the unit to work harder to move air. Try blowing through a large diameter straw. Now try to blow through a small diameter straw. It takes much more effort to blow through the small diameter straw than the large one. This extra work results in more energy consumption.
  • You adjust your thermostat too often throughout the day. Yo-yoing with your thermostat (bumping it up a few degrees, then down, then up) while you are home causes a great loss in energy efficiency. Your air conditioning unit functions best when it is left at one setting. This allows it to cycle properly and run at maximum efficiency.
  • You turn off your unit while you are away at work or adjust the set point too much. (See “Can I turn my thermostat up in the summer/down in the winter while I’m away at work?”)

We recommend continuous fan operation year-round except in July and August. We do not recommend continuous fan during these months due to the high humidity at this time of year. Running a continuous fan will keep your rooms more evenly tempered throughout the day and will better keep the indoor filtered.

You should never close more than one register in your home if the air conditioning system was installed by Hamstra. If your duct system was not installed by Hamstra, you should not close any registers. CLOSING OFF REGISTERS DOES NOT SAVE ENERGY! If you close off air to rooms, they will still have heat gain from the outside. This heat gain is transferred to the rest of the house through doors, walls, ceilings, etc. This heat gain will cause your unit to work just as hard as if all the registers were open. There is no energy savings to be gained from closing off registers.

Absolutely not. Never cover registers or return grills with any material. Doing this adds resistance to the system, causing your unit to work harder and your energy bills to rise. Your system was designed to operate with all registers fully open and unblocked.

Rooms in your home that have western exposure will be warmer in the afternoon than other rooms due to solar gain from the sun through windows and walls. Window coverings must be drawn in the afternoon on west facing windows to avoid these increased indoor temperatures. Your air conditioning system cannot adjust airflow throughout the day based on the movement of the sun. If you fail to draw window coverings, your rooms will get hot and your energy usage will rise. It is also a good idea to install awnings and/or plant shade trees over west facing windows.

Physics. Hot air rises, cold air falls. This is why Hamstra recommends separate systems for upstairs and downstairs or zone controls. It is impossible to have a balanced, comfortable system in a two story house with one unit and no zone control. Many heating & cooling contractors improperly install one unit on a two story home as a way to save money. While this does indeed save on the initial cost, it will lead to an uncomfortable home that is impossible to balance. We are only interested in happy and comfortable customers. This is why we will not install a single unit on a two story application unless it is equipped with an electronic zone control system.

In a typical home, a bedroom is converted into a home office. Chances are that the air conditioning system was not designed to account for the added heat loads that are associated with home offices, such as: computers, monitors, additional lighting, printers, copiers, scanners, TV’s, etc. All of these items add a great deal of heat to your office. Since your system was not designed to account for these items, the room will always be hotter than the rest of the home. You can have an air balance done to slightly help this problem, but it will not be a complete remedy. The only solution that will completely fix the problem is to have duct modifications made and, possibly, a new unit installed.

Differences: An evaporative cooler uses water to soak cooler pads and then draws outside air over the pads to cool the air. This cool moist outside air is then blown into the house to cool it. An air conditioning unit uses refrigeration inside an indoor coil to absorb heat from the air. An air conditioning system also provides dehumidification and filtration for the home while a cooler does not.


  • For years, the only real benefit of evaporative cooling over air conditioning has been cost savings. Coolers traditionally have been cheaper to operate. With the increased efficiency of air conditioning systems today, this is no longer the case. There is no longer any benefit of an evaporative cooler over an air conditioning. They cost about the same to operate and air conditioning will provide you with a more comfortable and healthy home.
  • Evaporative coolers add mold and dust to the indoor air which are serious health hazards. Everyone’s health can be negatively affected by evaporative coolers, but those with allergies, mold sensitivity and/or respiratory problems are the most effected.
  • Coolers damage ductwork by rusting it out over a short period of time.
  • Coolers require a great deal of maintenance in comparison to air conditioning. An air conditioning system needs maintenance twice yearly while a cooler needs maintenance much more frequently to operate properly due to water usage and alkaline build up.
  • Coolers leak and damage roofs and the structure below.
  • Coolers promote rusting throughout the home.

Due to the negative health effects and high risk of home damage associated with evaporative coolers, Hamstra no longer installs these machines on any home.

  • A gas heat furnace typically uses natural gas or propane to create a flame that heats metal heat exchanger plates, inside the furnace. Air from the home is then blown over these hot heat exchangers and is then returned as warm air to the home through air ducts.
  • A heat pump runs on 100% electricity. It is simply an air conditioner running in reverse. In order to supply warm air to the home, the unit reverses the normal refrigeration cycle and now transfers heat from the outdoor air to the inside of the home through the refrigeration inside the system.
  • A gas furnace will supply slightly warmer air to the home than a heat pump.
  • The price of electricity and gas, as well as the characteristics of the application, determine which type of unit will be best for you. There is really no right or wrong answer to which is better. It all depends on the situation at hand. If you would like to discuss this topic in more detail, feel free to contact our office (520) 629-9833.

SEER stands for Seasonal Energy Efficiency Ratio. It is an energy efficiency rating for air conditioning units. The higher the SEER rating, the more efficient a unit is.

  • For example, older units used to have a SEER rating of 6-10.
  • New units today must have a minimum SEER rating of 13.
  • The most efficient systems available today are about 19 SEER.

BTUh stands for British Thermal Unit Hours. It is a simple measurement of heat. One BTU represents the quantity of heat necessary to raise one pound of water one degree.

AFUE stands for Annual Fuel Utilization Efficiency. It is an efficiency rating for gas furnaces. AFUE ratings are given in percentages. This percentage represents the amount of energy input to the furnace that is actually converted into heat for the home. The remaining energy input is lost up the flue pipe. Gas furnaces of the past had AFUE ratings of about 60-75%. Today’s furnaces have ratings of 80-95%.

HSPF stands for Heating Seasonal Performance Factor. It is a heating efficiency rating for heat pumps. The HSPF scale ranges from 7.5 to 9.0 with 9 being the best possible rating.

Manual J load calculation is the only method that should be used to size heating and cooling systems. It is mandated by local codes and the Department of Energy.

Manual J calculates the heat loss and gain through walls, windows, floors, infiltration and the roof. It also accounts for internal heat loads such as people, appliances, electronics, etc.

Hamstra uses Manual J load calculation to size all of the systems we install. The design conditions that Hamstra uses for Tucson are: 104 degrees Outdoor DB (Dry bulb) with 75 degrees Indoor DB, 67degrees Indoor WB (wet bulb). These design conditions/standards are per the model energy code.

Using any other method than Manual J is incorrect and should be completely avoided.

The worst method for sizing air conditioning systems is the square footage method. This method uses a standard that 400 square feet of floor space is equal to one ton of air conditioning. So, using this method, a home that is 1600 square feet would require a four ton air conditioning machine. This is completely incorrect and is nothing more than a lazy guess. Think about it this way: I’ve got two 400 square foot buildings, one has walls eight feet high made of double masonry block and has one tiny window and one door. Then we have another building that is made of un-insulated 2×4 walls 15 feet high and has 20 – 12×3 single pane windows and a screen door. Now, do you think it is going to take the same size air conditioning unit to equally cool both buildings? The answer is no. The second building would probably need 4-5 times the cooling capacity as the first. Many HVAC contractors incorrectly use the square footage method and that is the reason why there are so many homes out there with poor air conditioning systems. It doesn’t work unless you get very lucky!

We all love the feeling of that cool air after a monsoon storm, but this is the absolute worst time to open up your doors and windows. Doing so will introduce extremely high levels of humidity into the home. This humidity gets absorbed into carpets, draperies, bedding, clothes, etc. When you fire-up your air conditioning later it is going to work extra hard for the next 24-48 hours to remove all the added humidity in the house. Yes, it takes that long to return your homes humidity back to normal. This extra work will greatly increase you energy bills. So, if you want to enjoy that cool monsoon air, go outside and have dinner on the patio. Do not completely open up your house.

Your furnace smells because dust has accumulated on the heat exchanger inside the furnace. The smell is the dust being burned off. Under normal conditions, this smell should stop coming from the furnace within 24-48 hours.

Absolutely not. You should never do this. Covering the outdoor unit will trap moisture around the unit and eventually cause it to rust.

No, never. Any covering that is close to the unit will cause recirculation of hot air around the unit. This recirculation will greatly reduce the unit’s efficiency and capacity.

Most units already have a metal coil guard that shades the condenser coil from the sun.

We have measured 120 degree inlet temperatures on 105 degree days on units that have been covered by the homeowner. Having any covering, or object close to your outdoor unit, can cause recirculation which leads to poor system performance.

Yes, pet hair and dander causes blockage of the filter and can also cause blockage of the indoor coil. Any blockage in the system will lower the systems performance and efficiency.

Doggie doors create more heat gain for the home because they have no insulation. A great deal of heat and hot air infiltration can be gained through these small doors.

Large fish tanks have been seen to increase humidity in homes therefore making the unit run longer and harder to reduce humidity levels. This leads to increased energy consumption and higher energy bills.

At least yearly with proper filter maintenance. If you do not change you filter at regular intervals your indoor coil could become clogged, which could then cause your condensate drain to clog and flood your mechanical room. Hamstra performs this cleaning during our spring tune-up.

Undersized ductwork, which is what most homes have, can greatly reduce airflow and can damage the compressor in the outdoor unit.

Undersized duct will also increase noise due the increased air velocities inside the duct.

Undersized ductwork will decrease the volume of air that can be delivered to each room, therefore decreasing comfort of the home.

Think of it this way: undersized ductwork is like a small cocktail straw. Try to blow through that straw as hard as you can and feel the amount of resistance there is. This is the same resistance a unit has to deal with when the ductwork is too small.

Undersized duct creates poor airflow. If there is not enough air flow over the indoor coil, it will ice up and could potentially flood the mechanical room and damage the home.

There are endless problems associated with wrongly sized ducts. Please feel free to call our office with any questions you might have on this subject. (520) 629-9833.

The refrigerant in your system should never have to be changed. Refrigerant is not like oil in a car. It only has to be changed if it becomes contaminated from an outside source. Even if this happens, your refrigerant can often be filtered to remove contaminants.

We recommend, at minimum, a one inch pleated filter. Do not use 3M Filtrete or Angelhair filters. From our experiences, these filter types are much too restrictive and will cause damage to your system

Washable filters are okay if they are properly maintained. However, most people fail to properly maintain their filters and this causes problems with the system. To properly clean your washable filter you should first vacuum it completely from the incoming air side. Once it is completely clean, flush with water in the opposite direction of airflow. If you flush the filter from the wrong direction, or fail to vacuum it, you will just further imbed dirt and debris into the filter. The cleaning process must be done monthly without exception.

Five inch high efficiency filter are a good upgrade to the standard one inch. They are about 20 times more effective at filtering the air inside your home.

The new PureAir filtration system from American Standard is 100 times better at filtering the indoor air than the standard one inch filter. This system is a great upgrade for those with allergies and sensitivity to other indoor pollutants. For further information on indoor air quality products, please call us directly. (520) 629-9833

Yes, it is a good idea to keep some extra fuses in case of storms or power surges.

HOWEVER, READ THE FOLLOWING CAREFULLY BEFORE YOU CHANGE OUT A FUSE ON YOUR OWN!!!! You MUST always turn off the breaker (make sure it is the correct breaker) before you change the fuse. If you fail to do so you can and will suffer major injuries. There is a lot of voltage going through your unit’s disconnect box. If you touch any part incorrectly without having the breaker off you will get hurt. ALWAYS TURN OFF THE BREAKER BEFORE CHANGING A FUSE, NO EXCEPTIONS!!!

If you have a newer unit, you do not have to oil the motor because they are sealed bearing and cannot be oiled. If your unit is older and does not have sealed bearing motors, you should oil them or have them oiled with a drop or two of oil once yearly.

There are many factors that make one brand of air conditioning equipment better or worse than another. Here is a short list of the main factors:

  • Technical support on the backend
  • Availability of parts
  • The quality and reliability of the internal components
  • Capacity of the equipment. This varies from brand to brand.
  • Available SEER ratings
  • Build quality
  • Engineering of the product
  • Call our office if you would like to discuss this topic further. (520) 629-9833

Two-stage cooling is a method of cooling that can better manage the cooling of your home while outdoor temperatures are changing. It can also better maximize indoor comfort and energy efficiency. Two-stage cooling systems are typically the most energy efficient systems available.

Two-stage cooling can be done by having one unit with two compressors, one small and one large. The small one is typically capable of putting out about 50% the capacity of the larger one. The second way to have two-stage cooling is to have a single scroll unloading compressor. This compressor can unload its capacity down to about 66% of maximum capacity. Both these methods of getting two-stage cooling allow the unit to run at a lower stage when the high stage is not needed. By doing this, energy is saved. It is the same principle that is used in car engines that have the ability to drop out cylinders when they are not needed.

Two-stage heating has the same principle as two-stage cooling. It allows the unit to adjust itself based on the amount of heating that is necessary. Two-stage heating is a good way to save on heating costs.

A heat pump system would have two different sized compressors, a small and a large one. The compressor that is used at a given time would depend upon the need. If only a small amount of heating is necessary, the smaller compressor would be used to save energy. The large compressor would only be used when a large amount of heating was needed.

A gas furnace that is two-stage has a modulating gas valve that regulates gas flow depending upon the need.

Variable speed refers to an indoor motor that changes speed. This type of motor increases speed and airflow from start up to full capacity over a span of eight minutes. This results in a quieter start-up and shut down of the system. This motor is also about five times more efficient than a conventional indoor fan motor.

Air conditioning units are sized in tons. One ton is equal to 12,000 BTU’s of total capacity. So, for example, a four-ton air conditioning unit has a total capacity of 48,000 BTU’s, while a two-ton machine only has a total capacity of 24,000 BTU’s.

Yes! Set your fan by the switch often found on motor housing. Choose the counter-clockwise direction for summer months to help blow cooler air down. Choose the clockwise direction in winter months, at a low speed, to help circulate air upwards and then throughout the room without blowing on you with a “cooling” effect.

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