Frequently Asked Questions

Q:  My Heat Pump seems to be running to much to keep the house cool, Why?

It could be possible you have a freon leak or just low and the A/C needs more freon to create theproper temp to cool your house. This can be a very simple repair and your HVAC system needs a charge. If you leave it alone your system will have high electric costs to run.


Mechanical refrigeration is accomplished by continuously circulating, evaporating, and condensing a fixed supply of refrigerant in a closed system. Evaporation occurs at a low temperature and low pressure while condensation occurs at a high temperature and high pressure. Thus, it is possible to transfer heat from an area of low temperature (i.e., refrigerator cabinet) to an area of high temperature (i.e., kitchen).

Referring to the illustration below, beginning the cycle at the evaporator inlet (1), the low-pressure liquid expands, absorbs heat, and evaporates, changing to a low-pressure gas at the evaporator outlet (2).

The compressor (4) pumps this gas from the evaporator through the accumulator (3), increases its pressure, and discharges the high-pressure gas to the condenser (5). The accumulator is designed to protect the compressor by preventing slugs of liquid refrigerant from passing directly into the compressor. An accumulator should be included on all systems subjected to varying load conditions or frequent compressor cycling. In the condenser, heat is removed from the gas, which then condenses and becomes a high-pressure liquid. In some systems, this high-pressure liquid drains from the condenser into a liquid storage or receiver tank (6). On other systems, both the receiver and the liquid line valve (7) are omitted.

A heat exchanger (8) between the liquid line and the suction line is also an optional item, which may or may not be included in a given system design.



Illustration of the basic refrigeration cycle.




Between the condenser and the evaporator an expansion device (10) is located. Immediately preceding this device is a liquid line strainer/drier (9), which prevents plugging of the valve or tube by retaining scale, dirt, and moisture. The flow of refrigerant into the evaporator is controlled by the pressure differential across the expansion device or, in the case of a thermal expansion valve, by the degree of superheat of the suction gas. Thus, the thermal expansion valve shown requires a sensor bulb located at the evaporator outlet. In any case, the flow of refrigerant into the evaporator normally increases as the evaporator load increases.

As the high-pressure liquid refrigerant enters the evaporator, it is subjected to a much lower pressure due to the suction of the compressor and the pressure drop across the expansion device. Thus, the refrigerant tends to expand and evaporate. In order to evaporate, the liquid must absorb heat from the air passing over the evaporator.

Eventually, the desired air temperature is reached and the thermostat or cold control (11) will break the electrical circuit to the compressor motor and stop the compressor.

As the temperature of the air through the evaporator rises, the thermostat or cold control remakes the electrical circuit. The compressor starts, and the cycle continues.

In addition to the accumulator, a compressor crankcase heater (12) is included on many systems. This heater prevents accumulation of refrigerant in the compressor crankcase during the non-operating periods and prevents liquid slugging or oil pumpout on startup.

Additional protection to the compressor and system is afforded by a high- and low-pressure cutout (13). This control is set to stop the compressor in the event that the system pressures rise above or fall below the design operating range.

Other controls not indicated on the basic cycle which may be part of a system include: evaporator pressure regulators, hot gas bypass regulators, electric solenoid valves, suction pressure regulators, condenser pressure regulators, low-side or high-side float refrigerant controllers, oil separators, etc.

It is extremely important to analyze completely every system and understand the intended function of each component before attempting to determine the cause of a malfunction or failure.

Reprinted with permission from the Tecumseh Hermetic Compressor Service Handbook. For more information, visit www.tecumseh.com.

Publication date: 06/30/2003

 

Q: When should I use my Emergency Heat?
The Emergency Heat switch on a Heat Pump thermostat confuses many people. The fact of the matter is that most people don't seem to understand exactly what Emergency Heat is and when they need to use it. Many people think that Heat Pumps don't work in cold weather and they are supposed to use the emergency heat whenever it gets really cold... Wrong!



Q: What is Emergency Heat?
Simply put, all Heat Pumps in northern climates [below 35 degrees] need a supplemental heating source. Usually it is in the form of electric resistance heating. This is an all-electric Heat Pump. It can be a gas, oil, or hot-water back-up system as well. The supplemental heat is also referred to as "second-stage" or "back-up" heating, "first-stage" being the Heat Pump only. The supplemental heat is also what is used as the Emergency Heat.

Different systems have different ways of determining when the second-stage comes on to assist the heat pump but it is always done automatically. So the two stages will work together in the colder months and it is not necessary to switch your thermostat to Emergency Heat. Now we know what supplemental heat is and that it is also used for Emergency Heat.

Q: Its Cold outside. the red light on AUX/Emergency is on much of the time.  I want to slow that down.

As spoken in the above referenced paragraph explaining Heat Pumps and their auxiliary heating emergency heating mode. You have to use some logic now and some good practical thinking. Once the temperature drove drops below 37-35° engaging your auxiliary Emergency heating mode on.

Luckily for us in the Raleigh Durham area. It only gets cold, for short snaps. It is not for months at a time of brutal cold weather this morning it was 27°. When I woke up, which would clearly mean, if you had a heat pump. It would be on auxiliary heat. Good news is I get up early. By mid afternoon, we should be around 35 and above, which is a big plus for the pump so that auxiliary heat can go off. The only other way to do things is to potentially low your temperature little bit dampened some air ducts around the house in rooms that you don't necessarily stay in much of the time. This will boost airflow to the other rooms will also slow the air over the evaporator coil extracting a little bit more heat and concentrating it in those areas or she wanted near your thermostat to thermostat turns off will turn it your auxiliary heating mode off.

Tightening up dampers for gas fired furnaces for warming your house is not really recommended hired professional should really do something like this is it's more critical and has larger ramifications. You can close your dampers a little bit, but don't do it much. Just a little bit, and truly you should be having no issues with the gas furnace at this point. If in the future you see yourself having to install a new unit and replace your old unit in my be time to talk about hybrid dual fuel unit. These units are fabulous and serve both the cold weather and the really cold weather proficiently effectively and without problem call us at Enviro-NC 919-535-8422. Stay warm, be smart don't turn your thermostat down. When you leave the house, especially if you have a heat pump. And this kind of cold weather that will add up to a huge bill and it will take a long time for the pump to recover the heat.



Q: The Environmental Benefits of R-410A:
Most Air Conditioners and Heat Pumps sold around the world use a refrigerant called R-22. Emissions of R-22 are considered by some experts to be a significant factor in depleting the ozone layer that protects animals and people from harmful rays from the sun.


Q: The Cost Benefits of R-410A:
With R-22, you run the risk that it could become much more expensive or difficult to get when your system needs to be repaired in a few years. Keep in mind, R-22 will be phased out along with other ozone depleting chemicals, and both supply and demand of this chemical will be significantly affected by current and upcoming regulations.

By selecting an air conditioner or heat pump that uses R-410A, you will avoid the risk associated with purchasing a product that is destined to become obsolete.


Q: R-410A Systems Can be More Reliable than R-22 Systems:
R-410A air conditioners and heat pumps are today's "state of the art" systems, and utilize the most current technology available for efficient and reliable operation.

The heart of every air conditioner or heat pump is the compressor, and newer systems are specifically designed to use R-410A refrigerant. They often incorporate smaller, heavier-duty "scroll-type" compressors that are quieter and operate with less damaging vibration than older compressors that operate on R-22.

Since R-410A can absorb and release heat more efficiently than R-22 ever could, compressors with R-410A run cooler than R-22 systems, reducing the risk of burnout due to overheating.



Q: R-410A Uses a Synthetic Lubricant to Keep Things Moving Smoothly:
All condition systems use an oil that circulates through the inside of the system to keep all of the parts well lubricated, just like the engine of your car.

R-22 air conditioners use an oil known as "mineral oil" that has been used for decades. R-410A air conditioners use newer synthetic lubricants that are usually more soluble with the R-410A than the old mineral oils are with the older R-22 refrigerants. This means the synthetic lubricants and R-410A can mix and circulate more efficiently to keep the compressor and other moving parts lubricated, reducing wear and extending their life.

Also, just as many new cars use synthetic oils because they are less likely to break down under high stress and heat, the new synthetic oils used in R-410A air conditioners are less likely to break down under extreme conditions.



Q: Why should I perform preventive maintenance?
Heating and cooling systems work incredibly hard to perform their functions for your household. The constant stopping, starting and continual operation can wear down a machine quickly and unexpectedly if the proper care and maintenance is delayed. However, by performing preventive maintenance, or servicing your system regularly, you can maximize the lifecycle of your heating or cooling unit and guard against many unexpected failures

Preventive maintenance inspections performed on a regular basis can uncover leaks, rust, rot, soot, frayed wires and corroded electrical contacts.



Q: What equipment requires preventive maintenance?
At least once a year heat pumps and air conditioners require a professional tune-up. Because gas-fired equipment functions with greater efficiency, it only needs to be serviced every other year.

Inspections on boiler and furnace systems should include ductwork, pipes, dampers, valves, the chimney, registers, radiators, pumps, blowers, fuel lines, the gas meter, oil tank and every part of the actual furnace and boiler. Meanwhile, heat pump and conditioning unit inspections should also include inspections of the fan, compressor, indoor coils, outdoor coils and refrigerant lines.

Q: How long should my heating and Air Conditioning Unit last?

This is a question we get often. Most manufacterers have a hard time saying how long the HVAC machine will last aprox. This is due to the location of where the HVAC units are installed the sizing the demands that are being placed upon it. Upon a physical survey we can generally give a ball park figure on how long your unit might last and give some ideas to get more life from a new unit being installed. Or a existing HVAC system that you are wondering about.

Van1
Last Updated on Friday, 06 August 2010 15:30