Q. I’ve lived in this house since it was built new 18 years ago. The last HVAC tech, who came in, said the system would soon need replacement. So I’ve looked into the matter. From what I can tell, it’s significantly more expensive to buy a system that is a lot more energy-efficient in heating and cooling than the standard systems. Why on earth should I consider spending substantially more for the high-efficiency units?

The difference in energy savings between a 10 SEER air conditioner—the lowest efficiency available—and a 13 SEER is 30 percent. Typically, the installer or the local serving utility can calculate your annual energy savings and you can then make a purchase decision based on, if desired the simple savings you will realize for as long as you plan to be in the home.

You may also want to consider the environmental benefits inherent in energy efficient equipment or the fact that some manufacturers of higher efficiency equipment provide other incentives, such as a more comprehensive warranty, quieter operation, better humidity control, and other features, or that some utilities provide rebates for the installation of certain higher efficiency equipment.

Don’t too quickly overlook all the benefits of energy efficiency by focusing only on the system's first cost—think long term or life cycle, as they say in the building trade.

Q. The air in my house smells each year, at the same time of year – when I turn it on for the first heating of winter. That smell makes my family nervous. What is it?

Your furnace has been "unemployed" from early April or mid-May until late September, or even early November. You probably have not gone into the furnace on a weekly basis . . . with a feather duster.

Result: Dust accumulates on the furnace’s heat exchanger or your heat pump's resistance coils. Your nose is detecting the once-a-year odor of dust meeting high temperature. Typically, that smell disappears after two or three uses at the start of winter!

Q: How does my heating, air conditioning and ventilation (HVAC) system move air throughout my building?

Fans draw air in through grilles called returns, force air through ducts and into the conditioned space through supply registers.

Q. What are these ducts?

Most ducts are constructed of metal and installed by tradesmen called sheet metal workers. However, rigid fiberglass and flexible round ducts are also used, as well as "hollow" constructed spaces within the building – the space between floor joists is sometimes used as the return air path, for example.

Q. How can I get the right duct for my house?

Code-making bodies recognize construction standards developed by SMACNA, the leading authority on duct construction and installation. SMACNA contractors should be considered your preferred source of HVAC Expertise regarding duct selection.

Q. Should I just go with whatever the builder recommends?

The builder will not pay your future utility bills; you should take an active role in all energy-related design decisions. Regarding ducts, each material has characteristics that may favor its use in specialized applications. Sheet metal has a number of advantages – that’s why it has historically been the number one HVAC system choice and remains there today! In fact, sheet metal use in HVAC is larger than all other materials – combined.

Q. What about the environment?

Those taking all elements of the construction industry toward "green" buildings are quite pleased with sheet metal. We’re talking here about basic metals – steel and aluminum.

These materials feature high recycling rates. Your new sheet metal duct installation comes, without your specific request, with a relatively high recycled content.

When your HVAC system is upgraded, the duct system may need to be removed and replaced with a newer design. It’s a good bet that the sheet metal duct removed from your house will end up back where much of it is returned to the industry – at a metals' recycler!

Also, sheet metal ducts can be easily and more thoroughly cleaned than other duct material choices if the need should ever arise.

Q. Should I just ignore the ducts?

Ducts that are improperly constructed, sealed, or installed can leak excessive amounts of air, provide poor air distribution, and can also "pipe" noise around the home.

Additionally, ducts can become dirty if put into service before the home’s construction is complete; there’s a lot of dust and dirt around most construction sites.

What’s more, ducts in older homes can become dirty after years in service, especially if filters are not changed on a regular service basis.

Ducts play a key role in energy usage from both how much friction the fan "sees" as it moves air throughout the duct system to how well they distribute heating and cooling to keep occupants comfortable.

Q. OK – How do I reduce duct leakage?

If you are building a new structure, make sure the HVAC system designer is specifying SMACNA’s prescriptive duct sealing standards.

Our companies and workers, who have trained in this industry and gained a vast amount of HVAC expertise, recommend prescriptive sealing of ductwork as one measure that will normally lead to the most cost-effective control of leakage without the need of expensive leakage testing.

Code-making bodies nationwide recognize construction standards developed by SMACNA, the leading authority on duct construction and installation.

Q. How often should we replace the HVAC system filter?

There’s no one-size-fits-all answer. The frequency of filter changes is driven by how much your HVAC system operates, which is driven by the severity of the seasons.

In some locations the cooling system might be in use more than four months of the year – to keep heat and humidity under control. If your house is in such a hot and humid location, you should pay a lot more attention to your filter than in an area where the air conditioning is seldom used. The same logic applies to heating. If the heat is used only on especially cold days during the three or so months of winter, then filters would be checked less often.

Start by checking the HVAC system’s filters at least once a month. Hold the used filter up to the light and compare it to a clean "spare." When light is obscured by captured dust and dirt particles, the old filter should be changed. Keep a record for one year and then replace the filter on that basis. At a minimum, it is always a good idea to change filters at the start of the heating and cooling seasons and then in between according to observe need.

Q. We’re a bit put off by the problems we have heard HVAC systems have had with mold. We have two children who are relatively far apart in age, and both of their schools have been closed in the past 18 months for mold clean-outs. I’ve also heard that some of these major mold clean-ups in schools don’t work! Can the same thing happen in my house?

Mold is a "whole building" issue with moisture and the broad answer to your question is to keep moisture out of the building and control and contain moisture that is necessarily in the building.

Roofs can leak. Window flashings can leak. Pipes carrying water can leak. Anywhere you have water or excess moisture; you must control and contain it. An HVAC system’s ducts can become contaminated – but the root cause is invariably uncontrolled moisture, not the ducts. Of course, if moisture enters a building – such as your children’s schools – in excessive amounts – and mold does grow – the ductwork can convey mold and excess moisture to other parts of the building.

But the solution isn’t replacing the ductwork or turning off the ventilation system. The answer is identifying how the moisture is getting into your building or out of control from in-the-building sources and correcting the problem. This is a “moisture management” issue.

Q. We’re running tight on money and would like to avoid paying for a service call. Would you tell us how to do that?

Here are some simple things homeowners can check before calling:

1. Check your thermostat—do you have it set for heating or cooling and is the choice appropriate for the season or is it inadvertently in the "off" position?

2. Check the air filter. If it’s very dirty – if it hasn’t been changed in months and it’s clogged with dirt – your system’s working hard to get ANY air through. Replace the filter and see if the system then operates properly.

3. Check that nothing is blocking the free access of air to your outdoor unit—this applies to air conditioners and heat pumps. Shrubs and bushes can block and restrict airflow to outside units and snow can drift against outdoor heat pump coils.

4. Check your electric fuses or breakers. As you certainly know, your HVAC system uses electric power to do its job. Your load center has fuses or circuit breakers. One or more provides power to the HVAC system. You might have one for the furnace and another for the air conditioner. For a heat pump, one is usually provided for each separate piece of heat pump equipment; one for the air handler and one for the outside unit if you have a split system, for example. If the fuse is blown or the breaker has “flipped” to the “off” position, you can play with the thermostat for an extended amount of time and you won’t accomplish anything!

It is kind of wasteful to call a service person to “throw” a circuit breaker! However, that is one of the first things our service people check. And you’d be surprised how often a service call consists of not much more than resetting the circuit breaker.

Additionally, your unit might have one or more Disconnect Switches. Perhaps your home has such a switch outside the house. Perhaps a mischievous youth moved the switch from “on” to “off” without you knowing it.

Again, it will be easier for you, if you took care of this yourself. However, if you reset a circuit breaker or replace a fuse and it immediately trips or blows—call for expert service assistance.

5. HVAC experts recommend regular replacement of dirty filters. Perhaps you have done the required thing and replaced the filter very recently. Very soon after that effort, you might discover the system isn’t doing the job!

If the filter was in the HVAC equipment, go back and check that the system’s fan door is installed properly. Many heaters have a door interlock switch. Your furnace probably will not begin operating until the access door is tightly in. Others simply will not work well if the access panel is allowing air to bypass the unit.

Modulating Furnaces Set Pace for Comfort
Date: 11/19/2007
Most of us grew up with what seemed like a scary furnace that lived in the basement. It made creepy noises when it started up, and usually overheated the house before it finally shut off. And forget about energy efficiency; many furnaces manufactured before 1992 had AFUE ratings as low as 60 percent.
That has all changed. Over the last decade or so, manufacturers have incorporated numerous innovations into their furnace offerings in order to improve energy efficiency and comfort. Higher AFUEs and two-stage gas valves have ensured better energy efficiency, while variable-speed blowers have increased the level of comfort for occupants.
The latest innovation is the modulating gas furnace. Manufacturers say it maintains constant temperatures while delivering improved comfort, quieter operation, and reduced energy costs. All three of these items are extremely important for homeowners looking to invest in a premium furnace.

UNMATCHED COMFORT
York — A Johnson Controls Company, introduced its Affinity™ modulating furnaces about two years ago. The furnace features a fully modulating gas valve that circulates airflow to closely match the amount of heat needed at any given time. Unlike traditional single- or two-stage furnaces that are staged at fixed input rates and often over- or undershoot the desired temperature setup, resulting in varying temperature swings, modulating furnaces adjust the gas input, inducer speed, and blower airflow.

“The furnace modulates in 1 percent increments from 35 to 100 percent,” said Mickey Smith, York brand manager, Johnson Controls-Unitary Products. “Comfort is drastically improved due to the modulation and is extremely quiet due to the ECM blower motors. The furnace is somewhat intelligent as it continues to narrow the operating band to eventually operate at the same rate heat is leaving the home. It may run longer, but it will run longer at a reduced rate, consuming less energy.”

Several built-in safety mechanisms offer increased customer satisfaction, noted Smith. “For example, if the homeowner is away for a period of time and the product senses there is a blocked flue or some other restriction, the product automatically reduces the level of operation to a safe operating level to continue conditioning the home. Many other technologies will automatically shut off.”

In addition to being energy efficient and quiet, the Affinity modulating gas furnace is also easy to install, maintain, and operate, said Smith. “There are no additional sensors, wires, or controls needed. In fact, it may operate using a traditional single-stage one-heat/one-cool thermostat.”

The sensors and controls automatically compensate for air supply and exhaust variations, wind gusts, and long vent runs. The modulating control employs multiple feedback loops to dynamically adjust the operation of the furnace and optimize the overall temperature control.

Affinity modulating furnaces, as well as modulating furnaces from sister brands Coleman Echelon™ and Luxaire Acclimate™, are available in both a constant-speed blower configuration and a variable-speed blower configuration, and are supported in all positions (upflow, downflow and horizontal). All models within the three modulating series meet the 95 percent-AFUE level required for the Energy Policy Act of 2005 (EPACT), so the units qualify for a $150 tax credit.

New 33-Inch Modulating Gas Furnaces Achieve Up to 98 Percent AFUE

Coming on the heels of its first major product launches in four years, the Unitary Products division of Johnson Controls announced that its 33-inch, variable-speed modulating gas furnaces with electronically commutated motors (ECM) achieve up to 98 percent Annual Fuel Utilization Efficiency (AFUE).

This is the highest AFUE rating in the heating, ventilating and air conditioning industry, according to Andy Armstrong, director of marketing for Unitary Products.  He added that the other modulating ECM models in the Unitary Products line go no lower than 97.5 percent AFUE.

What’s more, Armstrong noted that all of the company’s modulating gas furnaces with permanent split capacitor (PSC) motors have a 97 percent AFUE rating – also an industry first.  In addition, all single-stage furnaces are now rated at 95.5 percent AFUE, eclipsing the previous rating of 95 percent AFUE on condensing furnaces.

“With the introduction of this new line of gas furnaces, Johnson Controls is setting the bar on energy efficiency,” Armstrong said.  “Higher AFUE ratings mean distributors and dealers now have a stronger selling proposition, and homeowners will greatly benefit from lower energy costs during the winter months.”

Johnson Controls recently launched the 33-inch gas furnaces under the York, Coleman and Luxaire brands.  The furnaces appeal to dealers and homeowners searching for efficient heating systems that are easy to install and service in tight spaces while contributing to green, sustainable home design.

The new design also includes the industry’s first fully modulating 80 percent AFUE offering that features integrated controls.  The controls provide comfort to within one degree of the thermostat set point and ensure precise modulation of the gas valve from 50 to 100 percent in 1 percent increments.  Meanwhile, the 97 percent and higher AFUE models modulate from 35 to 100 percent in 1 percent increments.

In redesigning the entire furnace line, Johnson Controls reduced the units’ height by seven inches and incorporated a variety of features, making the furnaces the ideal solution for applications where space is limited, including closets, attics and basements with low ceilings.

Multiple venting options and the multi-position design provide flexibility for all installations and applications, including up flow, down flow, and horizontal left and horizontal right.  In addition, the units’ unique condensate management system eliminates the need for external traps, which means the furnaces do not need to be elevated in horizontal applications.

Their rugged yet stylish cabinets of folded sheet metal are free of sharp edges, ensuring worry-free service.  Moreover, the units’ doors are now interchangeable between the top and bottom, based on the desired venting option, and the tool less ¼-turn latches make door removal even easier.

Operation is quiet – as low as 61 decibels (dB) for models with an 80 percent AFUE rating and 65 dB for models up to 98 percent AFUE.  All 95 percent and higher AFUE furnaces are ENERGY STAR qualified.  And with new gaskets installed around the doors, these furnaces have a reduced air leakage rate of under 1 percent.

Johnson Controls backs every York, Coleman and Luxuries 95 percent and higher AFUE gas furnace with a lifetime warranty on the heat exchanger, while high-end 80 percent AFUE models come with a limited lifetime warranty on the heat exchanger.  Every York, Coleman and Luxuries model includes a 5-year limited warranty on all other components.