Monday, February 16, 2015

How does a heat pump work?

If you have a Heat Pump, you may not know all you should know to make it as efficient as possible. To get the full benefits of the Heat Pump, here are some tips.

The heat pump is a very efficient piece of equipment - today’s units are over 300% efficient as compared to a very good gas heater at 95%.  It can do this because it does not burn fuel to CREATE heat - it uses much less fuel to MOVE heat.  It pumps it from outside in during the winter and from inside out during the summer.
Your Heat Pump, like any furnace, circulates and reheats room air.  Most furnaces raise the temperature of the air passing through by about 50°, giving you a 120° supply temperature with your thermostat at 70° (70°+50°=120°).  A heat pump, on the other hand, is designed to give a lower 25° boost to the air passing through, thus delivering a 95° supply (70°+25°=95°).  This lower supply temperature is high enough to heat the house, but is close to body temperature and can, at times, feel cool if you are sitting or standing in the air flow.  You can see that raising or lowering the thermostat setting also raises and lowers the supply temperature, so we suggest keeping your thermostat at 69-70° for starters so that the supply temperature is high enough to keep you comfortable.

Because the supply air temperature is lower than that of a gas or oil furnace, the Heat Pump may run longer to deliver the same amount of heat.  When it gets close to 30° outside, the Heat Pump will run almost continuously.  Remember that it is designed to do so.

You actually have two furnaces - the Heat Pump, and the back up coils that look and act just like your toaster or oven coils.  The Heat Pump is very efficient and inexpensive to run but the backup is not as efficient and is more expensive to run.  As the outside temperature drops to about 30°, the heat pump starts to need help from the backup.  Your thermostat will automatically add back up heat as needed, and that proportion increases from no back up at 30° to all back up at close to 0°.  Remember that this happens without any help on your part.  

Raising and lowering a heat pump thermostat will actually raise your bill because it forces the more expensive back up to come on when it would not normally be needed.  So be sure to set your thermostat on a comfortable temperature and not move it.

The "emergency" switch on your thermostat is for "emergencies".  It is designed to give you heat even if the Heat Pump is damaged or out of commission.  When the switch is flipped, your efficient Heat Pump is shut off and the house heats only with the not-so-efficient back up.  This will raise your heating costs, so remember only to use the "emergency" switch if your Heat Pump has a real emergency.

Your outside unit will occasionally have a frost or ice buildup.  This is normal and temporary.  If the ice or frost persists for more than an hour, call your contractor for service.

Your filter is designed to keep airborne dirt from clogging your heating coils inside the heat pump.  If the filter itself gets clogged, then the heat pump (or any furnace) can't move enough air, and it won't heat your house properly.  Check the filter every two weeks when the house is new, and then less frequently as you see it is not so dirty.  Eventually check it three times a season - both heating and cooling season.
A Heat Pump is about the least expensive way to heat your house, so consider one of these “modern marvels”. 
Advanced Heating and Air
Randall Combs
Office: (865) 933-5538

Saturday, January 4, 2014


What are air filters supposed to do anyway?

The MERV rating also indicates the percentage of particles the filter will remove from the air passing through it. In general, a MERV rating of 6 indicates that the filter will capture up to half of the particles in the air; a filter with a rating of 8 will trap 70 to 85 percent of air-born particles it encounters; and a rating of 11 or higher means that the air passing through the filter is up to 95 percent cleaner when it comes out of the filter than it was when it went into it. 

A properly sized, installed and functioning heating and air system circulates the air in your home every hour. In the process, it pulls that air through the filter. Just how much the filter cleans the air depends on the MERV rating of the filter.

MERV stands for Minimum Efficiency Reporting Value. MERV ratings indicate the size of particles that a filter can remove from the air passing through it. MERVs range from 1 to 16, with a higher number indicating a higher cleaning efficiency because it can filter smaller particles out of the air. The cheap, 1-inch (2.54-centimeter) thick, disposable filters made of jumbled fiberglass or natural fiber strands typically have a MERV rating of 1 but can go up to 4. Pleated filters made of nonwoven, disposable fabric have smaller pores, and the pleats increase the surface area of the filter so it can hold more particles than a flat surface can. These filters have MERV ratings of 3 and higher depending on the density of the fabric and the number of pleats. Some are charged with static electricity to attract and hold air-born allergens.

The particle catching efficiency actually goes up as the filter gets dirty; buildup on the fibers shrinks the openings the air passes through and allows the filter to capture more particles. This is good only up to a point. The particle-removing efficiency of the filter is inversely related to the energy efficiency of your heating and air system. A by-product of cleaning the air is a restriction of the air-flow through the system.

Think about times you've worn a dust mask while you worked on a project. It's harder to breathe through the mask than it is if you aren't wearing one. If you upgrade to the HEPA (high-efficiency particulate air) mask that filters out particles as small as 0.3 microns with up to 97 percent efficiency, it gets even harder to pull in enough air to keep you going. The same is true of your heating and air system. The denser the filter, the harder the system has to work to pull in air. A clogged filter may cause your system to run continuously, driving up your heating or cooling bills. That's why it's important to check your filters at least monthly and change them when they get dirty.

Monday, December 24, 2012

Variable Speed Motors (ECM)

How it works:

For any furnace, providing maximum comfort means achieving the proper amount of airflow. This is true for both heating and cooling operations. Unlike conventional single speed motors, a variable speed motor runs at a wide range of speeds. Using intelligent technology, it continually monitors incoming data from your heating and cooling system, and it automatically makes the adjustments necessary to meet your comfort needs. The motor varies the amount of air circulated, compensating for factors like dirty filters by increasing speed. Put simply, it delivers just the right amount of air necessary to provide the desired level of heating and cooling comfort.

--More Efficiency! Compared to a conventional single speed furnace, a variable speed furnace performs better and uses about two thirds less electricity. During cooling operation, variable speed technology typically results in an efficiency gain of 1 SEER (Seasonal Energy Efficiency Ratio). The higher the SEER, the lower
--Enhanced Humidity Control!! When moisture levels are high, there's a higher potential for mold growth and other pollutant problems. Compared to a single-speed furnace, a variable speed furnace is more effective at drawing moisture from the air for improved air quality and comfort.

Sunday, December 23, 2012

Dirty Socks Syndrome

We've had a number of questions the last couple months on unpleasant odors associated with start-ups of heating systems this season. So we thought we would share some background on an odor issue generally associated with heat pumps referred to as "Dirty Sock Syndrome," because that name approximates the smell involved.
Dirty Sock Syndrome is caused by the growth of bacteria and/or mold on the indoor coil. As the surface area of the coil becomes more compact, as it does with higher efficiency coils, the coil fin spacing is going to be tighter (more fins per inch of coil). The depth of the coil may increase as well because manufacturers want to expose a greater amount of coil surface to the air stream in order to improve coil heat exchange and in the process improve system efficiency. So as the coils grow in size, depth, and fin density, the coil is even more likely to trap bacteria and mold on its surfaces.
Heat pump environments are the most likely systems to be associated with Dirty Sock Syndrome. The reason is pretty simple. When the heat pump is in the heating mode, the heat pump heating cycle for most heat pumps is not hot enough to kill the microbes that grow on wet coils in the cooling mode. So, when the unit goes into defrost (cooling mode), the likelihood that the indoor coil is wet or moist goes up, which causes any microorganisms or bacteria that were dormant to become active again. When the heat pump goes back into the heating cycle, it only warms the microbes to a level where they off-gas their odors. And that's where the odor associated with this phenomenon come from.
When the outdoor temperature drops below the thermal balance point for the heat pump, supplemental heat for the heat pump will be energized. At that point, the discharge temperature of the system is likely hot enough to kill the microorganisms or bacteria as they move from air handler or furnace. That is why many customers will note that the odor seems to go away when they put the heat pump system in emergency heat mode.
Controlling indoor relative humidity is key to maintaining a healthy indoor environment that is less susceptible to this type of phenomenon. Anytime relative humidity gets much beyond 40% to 45% during the heating season, conditions are right for bacteria and other microorganisms to begin forming on the indoor coil. Helping your customer understand the importance of indoor relative humidity is key to solving the problem for them. Don't forget to investigate other potential sources of excessive moisture. The indoor coil drain pan can also be a source of mold and bacteria, particularly if there is a problem with the drainage and disposal of condensate from the pan.
For purposes of indoor air quality control, ultraviolet lighting is a good addition to most any HVAC system. However, because there are so many choices within this area of IAQ technology, caution must be used when selecting and installing any UV system. All UV systems are sensitive to installation location and air stream CFM. Efficiency for some UV systems changes with air temperature. UV output levels very widely from one manufacturer to the next as does air stream exposure efficiency. UV light wave length can also impact UV performance. The UVC spectrum destroys the DNA of microbial contaminants while the UVV spectrum is primarily used for oxidation, which is most often associated with neutralizing odors in the air.
The fact that a customer has a UV light system doesn't necessarily mean that particular UV system will be effective in controlling odors for their home. Some manufacturers of UV equipment make UV lights specifically designed for coil and drain pan and odor applications. Take the time to investigate several manufacturers to ensure the right choice for vour customer.

Wednesday, December 5, 2012

What does S.E.E.R rating mean for your air conditioning equipment?

We have heard it, used it, and in some cases do not know what it is, but when talking HVAC, we need to understand what S.E.E.R. means to be able to provide energy saving systems to our customers.
S.E.E.R. is an efficiency rating, much like how miles per gallon (MPG) is used to rate automobile efficiency. We all understand that if you drive 300 miles and consume exactly 20 gallons of gas, then your vehicle's fuel efficiency (MPG) is 15 miles per gallon (300 miles divided by 20 gallons). A vehicle that gets 18 MPG would be more efficient (less costly) to operate, and a 12 MPG vehicle is less efficient (more costly) to operate. For HVAC, S.E.E.R. follows the same rationale.
In 1975, there was no universal standard of measurement for HVAC energy efficiency. The Air Conditioning & Refrigeration Institute (ARI) introduced the E.E.R. (Energy Efficiency Ratio) for the purpose of rating the cooling efficiency of HVAC units. E.E.R. equaled the rated cooling output of an HVAC unit in BTU's per hour divided by the rated input of energy in watts of electricity, at specific humidity, and temperature input/output conditions.
The formal definition of Energy Efficiency Ratio is a steady state efficiency measurement of BTUH cooling output versus power (watts) input or BTUH/WATT at a specific set of indoor and outdoor dry bulb and wet bulb temperature conditions. The ARI rating point has been at 80 db./67 wb. indoor and 95 db./75 wb. outdoor temperatures.
While this sounds logical, no seasonality was taken into consideration. The climate zones across the U.S. vary, as do seasonal conditions from one zone to another. For example, Florida and Arizona have different summer conditions, which affect the performance and resulting cooling energy savings for the user of the HVAC unit. This means the seasonal conditions affect the value and must be weighed when interpreting an HVAC unit's E.E.R. rating.
Thus, in 1978 the US Congress passed a law requiring labeling of certain "appliances" (HVAC units under 65,000 btuh cooling) with an efficiency rating that took into consideration how certain variables (seasonality) affect cooling BTUH output, watts input, and an average cost of operation for the cooling side of a residential HVAC unit.
The new rating, S.E.E.R. (Seasonal Energy Efficiency Ratio), was born as an alternative to the original E.E.R., and to better approximate the actual cooling cost of operation of an "appliance" based on the installed climate zone. S.E.E.R. is a different efficiency rating than E.E.R. and is based on residential air conditioner usage patterns. S.E.E.R. includes a rating at a different temperature than E.E.R. and also includes performances such as conditions of cycling (off/on) thus includes cycling losses.
Currently all HVAC unit specification sheets are required to show only S.E.E.R. ratings.
E.E.R. and S.E.E.R. are two ways to determine the cost of operation of an HVAC unit. A 6 E.E.R. was the typical unit efficiency in 1974, and approximately 8 S.E.E.R. was predominant in the mid 80's. 10 S.E.E.R. became the first federally mandated minimum efficiency in 1992 for residential split systems and 9.7 S.E.E.R. for single package systems in 1993. Prior to 1992, individual states were free to establish their own individual minimum efficiency standards for air conditioners as well as other types of appliances. The new federal efficiency standards preempt any state standards and therefore we now have uniform efficiency standards for the entire country as opposed to a various array of different individual state standards. The minimum efficiency will increase to 12 S.E.E.R. in the US effective on Jan 23, 2006.
The higher the S.E.E.R. or E.E.R. the greater btu/h cooling delivered for the watts of electricity consumed (better miles per gallon, so to speak). You may find the chart below useful when talking with your customers about the energy savings associated with upgrading to a more efficient HVAC unit.
Cooling Operational Cost Savings (%)
This "Cooling Operational Cost Savings (%) Matrix" shows that the operational percentage savings of replacing a 6 E.E.R. unit with a (currently required) 10 S.E.E.R. unit would be 32%. Replace older HVAC units with higher S.E.E.R. (i.e. 12 S.E.E.R.) units and the customer can expect to see terrific operational savings. Include the below information when bidding new projects to inform your customers of the cost savings they can expect by upgrading to a 12 S.E.E.R. unit now.
To sum it up, the important difference is that E.E.R. is at a single rating point and more represents peak load rating while S.E.E.R. is a seasonal rating most typifying average residential usage in the US. E.E.R. is more like the highway rating of MPG on a car and S.E.E.R. is more like the city driving MPG rating of a car.