Zombie Heat Pumps: The Reason Your Electric Bill Went Up

by |
13

Understanding Zombie Heat Pumps and Increased Electric Bills

 

How Zombie Heat Pumps Affect Your Electric Bill

If your air conditioning goes out in the middle of the summer, you realize it pretty fast as the house heats up.  But if your heat pump is not operating properly in the winter, you might not realize it – until the electric bill shows up!  That is because heat pumps usually use electric backup resistance heaters, which use more electricity to produce heat than the heat pump.  For an energy-efficient home, let’s explore how this works.

Heat Pump Operation and Efficiency

A heat pump takes heat from outside and moves it inside your house.  Even cold winter air contains some heat, and heat pumps can extract heat from the outside air on a cold day and transfer it indoors to maintain a comfortable temperature.  It does this by operating as a refrigeration system – essentially an air-conditioner running in reverse.  If the heat pump is taking heat from the outside air (as opposed to a geothermal ground loop), the efficiency of the heat pump decreases as the outdoor air temperature decreases. The colder it is, the harder it gets to keep your home comfortable.

The efficiency of a heat pump varies significantly with the outdoor temperature. While a heat pump may be twice as efficient as a conventional heating system at 50 degrees F, when the outdoor temperature drops to less than 30 degrees, supplemental electric resistance heating kicks in.

Electric Backup Heaters and Supplemental Heating

At very low outdoor temperatures, the heat pump compressor will shut off completely and the backup heating system takes over – using much more electricity.  Most smart thermostats support many stages of heating and cooling and can run the heat pump and auxiliary heat simultaneously to maximize comfort and reduce overall energy costs.

Smart Thermostats and Energy Optimization

In case of compressor or general system failure, many thermostats have an emergency heat switch that bypasses the thermostat and activates the supplemental heater.  You may have noticed that after a power outage, the supplemental electric resistance heater runs for a while to heat the house.  This is normal, as the system is designed to reheat the oil in the crankcase of the compressor before restarting the compressor.

Troubleshooting and Maintenance

If you notice that your system is heating but the outdoor compressor is not running, or if the emergency heat light is on, there could be several reasons for this.  The power might be off to the outdoor unit because of a blown fuse or tripped circuit breaker.  A very dirty air filter, or debris on the outside unit (such as snow) could also be the problem.  Drastic changes to the settings on the thermostat might also force the system into emergency heating mode.

If the auxiliary or emergency heat light is always on when the unit is heating, there is probably some problem with the system.  A service professional can quickly check if the system is low on refrigerant, or if there is a more serious problem.

Keep an eye on your thermostat light and your system, as well as your electric bill.  If there is an increase in electrical usage for no apparent reason, you may have a zombie heat pump running on expensive backup electric resistive heat.

Read Next: Four Steps to Keeping Your Home Comfortable and Energy Efficient This Winter

Keep your home comfortable in winter

How to Improve System Efficiency with Geothermal Heat Pumps

by |
3

Originally published on December 7, 2012

You might have read or heard about geothermal heat pumps and how they’re gaining a lot of popularity. But what does “geothermal” mean and how does this system work?

Geothermal heat pumps work along with the same principles as standard heat pump systems with a few important exceptions:

The role of the heat exchanger

The components found in a typical geothermal system closely resemble that of a heat pump system. Components like the compressor, metering device, and indoor coil all perform the same basic functions. One important exception is that the outdoor fan coil has been replaced in a geothermal system by a heat exchanger.

A heat exchanger, as the name suggests, takes heat from the system’s refrigerant and transfers it to circulating water.

Drawbacks of standard heat pumps

Standard central air heat pump systems typically consist of two parts, an indoor and outdoor unit. The indoor and outdoor sections rely on air being forced across their coils in order to transfer heat to the surrounding area.

One drawback of this design is that the system can meet limitations as the outdoor temperature reaches extremes. This is most common with a standard heat pump system in winter. As the outdoor temperature drops below 25°F, it reduces the heat pump’s ability to provide warm enough air to the home.  While the supply air is warm enough to heat your home, it may feel like “cold heat” when you feel it coming out of your vents. If you notice an increase if your electric bill due to your heat pump, it may be time to replace it.

The key difference: outside air temperature is largely irrelevant

Traditional heat pumps must absorb as much heat as possible from the cold outside air. By trading the outdoor unit with a piping loop in the ground, the outdoor ambient temperature does not affect the geothermal system’s temperatures required for heating and cooling. The ground remains at a pretty consistent temperature in the 50’s all year long.  This design allows for geothermal systems to provide warmer supply air to the house and a very high level of system efficiency, regardless of how cold it is outside.  The outside temperature now only impacts how fast or slow your home loses heat.

The geothermal heating system in action

When heating is needed, water is pumped through a series of underground pipes located externally to the house and absorbs heat from the ground.  The system’s compressor pumps refrigerant into the heat exchanger where the heat captured in the water is released to the refrigerant.  The indoor coil transfers the heat from the refrigerant to the air in the house through the ducts/vents.  Now that the refrigerant released its heat, it goes back through a metering device and returns to the heat exchanger to pick up more heat from the water.

For many facility managers, geothermal heat pumps are the key to increased comfort and efficiency in their buildings and homes. Did you know you could save so much energy getting your heating and cooling from the ground instead of the air?

Read Next: Comparing Options for Cooling Your Home

How to Troubleshoot Your Home Heating System

by |
2

As the weather turns and winter approaches, your HVAC system transitions from cooling to heating your home. Proper maintenance is key for this transition to happen smoothly–whether you use a gas furnace, electric heat or a heat pump.

But let’s say you do happen to find yourself in a situation where your house is cold and you don’t know why. While this is a frustrating situation and you’re concerned about potentially incurring a costly repair bill, below are a few key things you can check before calling your HVAC contractor.

For any traditional whole home furnace, electric heat or heat pump to work properly, the following conditions must be met:

  1. The thermostat must be calling for heat and configured properly

Thermostat Calling for Heat: Check the simplest thing first by double-checking if the thermostat is in heat mode and set to a temperature that is above the current room temperature. If not, set to heat mode, turn up the temperature by at least three degrees higher than room temperature and try again.

Thermostat Configured Properly: If you’ve verified your thermostat is in heat mode and set to a temperature that is at least three degrees higher than the current temperature, and your heat still isn’t coming on, the next thing to check is if the thermostat is configured properly. Many thermostats have settings that must be set up properly for your given system, or it will not work. Consult the user or installer manual for your thermostat and ensure the system settings match your home’s specific system configuration. For example, if your thermostat is set up to control a heat pump and electric backup heat but you haven’t configured the thermostat for auxiliary heat mode, then it may not work properly.

  1. The system must have power

Another common reason furnaces may not turn on is they simply don’t have power. Check the switch by the furnace (often looks like a light switch) and ensure it is in the “on” position. Note that the up position on the switch may not necessarily mean “ON” (nor will down always mean “OFF”). You’ll want to verify by inspecting the words on the switch itself or trying both positions before making any conclusions.

If you have a heat pump you will also want to check if the breaker outside near the condensing unit is in the “ON” position as well. Use caution when accessing those breakers as they are high voltage, and if you’re not careful, you can be severely shocked resulting in potential injury or death.

The last place to check is your main circuit breaker panel. Ensure all breakers are reset properly and in the “ON” position.

  1. Gas furnaces must have the gas source turned on

Another possible reason your furnace hasn’t come on is if the gas source has been turned off. If you check near the furnace there should be a valve on the gas line with the lever in line with the pipe (or flex pipe) leading to the furnace. If the lever is perpendicular to the line, the gas is turned off. Before turning it on, you may want to consult your gas company or contractor as to why it was turned off in the first place, as they should be left on all the time.

  1. The system must have proper airflow

Another major reason your furnace may not work properly is if it’s not getting adequate airflow. This is most often caused by covered returns, closed registers, or dirty filters. Check each of these to ensure your vents are open and your filter is in good condition.

If you’ve checked all of these and the heat is still not working properly, it’s time to call in an accredited HVAC professional.

Read Next: Winter is Coming – 5 Simple Steps to Prepare Your Furnace

Four Steps to Keeping Your Home Comfortable and Energy-Efficient This Winter

by |
1

When you think about preparing your home for the winter, what comes to mind? Maybe it’s taking care of your plants or flower beds, preparing your water lines, or draining your pool. But taking care of your HVAC system should be added to that list. After all, home heating will become pretty important to you over the coming months!

Proper care and maintenance of your home heating system can extend its lifespan and can save you money. Here are our top tips for keeping your home warm throughout the winter, and saving some money on your energy bills while you do it.

  1. Winter Maintenance of Your HVAC System

The first step is to prepare every piece of your system. Check your air filter once per month and replace them when dirty. This step alone can have an outsized impact when it comes to saving money and ensuring that your system produces its best results.

Next, clean around your system outside. Remove any sticks or other debris that might interfere with any parts of the HVAC system. Make sure to schedule a time with your HVAC system servicer to conduct routine maintenance. Do this in the fall, that way any issues can be resolved prior to you needing the system desperately. Routine maintenance will make for a healthier, more efficient system for as long as possible.

  1. Use Humidifiers Throughout the Winter

Did you know that temperature isn’t the only thing that contributes to comfort in the home? Many people face issues with humidity in the winter. As the air becomes colder, it loses the ability to hold as much water. This lack of humidity can lead to dry sinuses and skin, breathing issues, and can even make it easier for cold and flu germs to circulate.

Introducing a humidifier is a good way to alleviate these issues and maintain maximum comfort in your home. You should aim for 30-50 percent relative humidity in your home, as anything higher will make it uncomfortably stuffy, and make it easy for bacteria and mold to form and grow.

  1. Program Your Home Heating

Despite what rumors you’ve heard, there is no benefit to keeping your home heated at all times. If no one will be around for several hours or days in a row, consider turning your down. This small change will increase your energy efficiency while saving you money.

If you have a smart thermostat, you can control your home’s temperature remotely and raise it before anyone returns home. You can also program your thermostat to match your day-to-day schedule.

If you don’t have a smart thermostat, you’re not out of luck. Simply be more careful with how much you choose to adjust the thermostat. Lowering the temperature for part of the day will contribute greatly to savings.

  1. Reverse the Ceiling Fan for Heating Season

Be sure to reverse the direction of your ceiling fans between heating and cooling seasons so they can aid your heater or air conditioning’s efficiency. The ceiling fan will blow down hot air when the fan moves clockwise. This is especially important for the upstairs rooms.

Making sure air circulates properly will help to get rid of cold spots and will make it easier on your system to maintain temperatures. This simple switch will even allow you to lower the temperature by up to four degrees and feel the same heating effect.

Read Next: HVAC in the News: Should I really set my thermostat to 78 degrees?

Should I really set my thermostat to 78 degrees?

 

Benefits of a Modulating Furnace

by |
2
What Are The Benefits of a Modulating Furnace Video Overlay


Originally published on November 27, 2019

Benefits of a Modulating Furnace

When homeowners are considering the purchase of a new furnace, saving energy should be a high priority. For those seeking the greatest level of efficiency, comfort, and return on investment, a modulating furnace is often the best choice.

Designed to achieve near 100 percent efficiency, a modulating furnace is two generations ahead of the typical home heating system that homeowners are likely familiar with, the single-stage furnace, and a step above a two-stage furnace. Incorporating advanced technology, the modulating furnace is able to keep homes toasty on the most frigid of winter days, filter the air, eliminate cold spots, make the home quieter, provide incredible temperature consistency and lower utility bills.

A Furnace Evolution

To best understand the benefits of a modulating furnace, it’s important to understand how both it and previous generations of furnaces operate.

Single-Stage Furnaces

When most people think of the furnace, they likely picture the single-stage furnace. It’s what most people grew up with, and it’s still the predominant furnace type across the U.S.  A single-stage furnace has two positions, on and off. When it’s on, it’s 100 percent on and operating at full capacity with a high flame that raises the temperature inside the furnace as high as it can go. The furnace does not turn back on until the thermostat records a significant drop in the home’s temperature (usually six degrees or more) and communicates to the furnace to turn back on.

When it turns on, the cycle starts all over again, using a significant amount of natural gas, propane or fuel oil in the process. It also pumps a large volume of air through the home quickly, and homeowners can hear it start up every time it turns on thanks to the “whoosh” of air moving through the ventilation system.

Two-Stage Furnaces

The two-stage furnace is a step ahead of the single-stage furnace. Like the single-stage, it incorporates a high flame, full capacity setting used to bring a home up to temperature. However, it also operates on a second, low stage, that burns less fuel and consumes less energy. This stage is used when the temperature differential between where the house is and where the thermostat is set is not far apart. If the high flame is 100 percent, the low flame would be more like 60 percent.

The Modulating Furnace and Its Benefits

The modulating furnace is a major step forward in furnace technology. Like single- and two-stage models, a modulating furnace also has a “high” setting that’s used to bring a cold home up to temperature, but that’s where the similarities end.

Once a home has reached the thermostat’s setpoint, a modulating furnace adjusts, or modulates, its flame from low (around 40 percent) to high (100 percent) and anywhere in between to maintain the home’s temperature.

Do you really need your furnace to operate at full capacity when the temperature only needs to be maintained or raised by a degree or two?  Operating a furnace that way is wasteful, and this is where the benefits of the modulating furnace are especially apparent.

  • Energy savings – Because the furnace is not operating at 100 percent capacity (or even 60 percent capacity) every time it cycles on and off, it’s using less energy than a single- or two-stage furnace.
  • Money back – Many utility companies offer incentive programs for the installation of high-efficiency HVAC systems. By installing a modulating furnace, you may be in line for significant rebates.
  • Temperature consistency – Single- and two-stage furnaces turn on only after the interior temperature has dropped three or four degrees, then they run until the temperature reaches a degree or two above the temperature set on the thermostat, leading to wide temperature swings. A modulating furnace, on the other hand, consistently keeps the home’s temperature within one degree, or even a half a degree, of the thermostat setting at all times by adjusting the flame in the furnace.
  • Noise reduction – While a modulating furnace does cycle on and off more often, it runs much quieter than a single- or two-stage furnace because it’s not blasting a large volume of air through the system every time it turns on.
  • Air filtration – Because a modulating furnace is regularly pushing a lower volume of air through vents, it enables a more thorough filtration of air, leading to higher air quality throughout the home.
  • No more cold spots – Cold spots in the home typically occur when a single-stage furnace increases the temperature in main areas of the home rapidly, then shuts down before other areas of the home have the chance to come up to temperature. Because a modulating furnace runs longer and at a lower level, the temperature across the home has a chance to stabilize before the furnace cycles off.
  • Better sleep – Remember the noise reduction and temperature consistency? Most homeowners who switch to a modulating furnace find that they sleep better because they aren’t woken by the furnace cycling on and off, or because of large temperature swings.

If you’re in the market for a new heating system, consider the benefits of a modulating furnace. Ask your HVAC technician if a modulating furnace is right for your home.

Read next: Winter is Coming – 5 Simple Steps to Prepare Your Furnace

5 Tips to Keep Your Holiday Comfortable

by |
Reply

Is Santa Going to Adjust your Thermostat?

‘Tis the season for family gatherings and parties with friends and neighbors—and also the season for sneaking off to adjust the host’s thermostat!

According to a new survey* by Copeland, nearly 60% of respondents admitted to changing the temperature on someone else’s thermostat (or knowing someone who did) during the holidays.

Comfort during the holidays is such an issue that 50% of those surveyed said they are likely to leave a gathering early if the temperature is too hot or too cold.

Keep your home comfortable over the holidays with these tips:

  1. If you feel warm during your party—or see others start to get overheated, use the controls from your smart thermostat to discreetly change the temp from your phone app.
  2. Prior to the party, turn down your thermostat about 3-5 degrees. When your house fills up with people, they’ll be bringing the temperature back up to a comfortable level rather than overheating it.
  3. The heat from guests and food also increases humidity. If the weather outside is cold and dry, you may also want to consider opening a few windows slightly. This can help release some of the humidity, keep temperatures down and lets in the air fresh. Of course, if you do this, you should turn off the heat as long as the windows are open.
  4. The oven can really heat up your house. If possible, finish cooking before guests arrive. When you’re using the stove, make sure to turn on the exhaust fan. This can help remove the heat and humidity generated by cooking. It’s also helpful to wait until the party is over to run your dishwasher.
  5. Some types of overhead lighting put out a great deal of heat. You may want to use lamps or other light sources in those rooms and keep the overhead lights off. Or you may be able to switch out the lightbulbs in those fixtures for ones that generate less heat.

Keep your home comfortable this holiday season. Your friends, family and even Santa will appreciate your hospitality.

* Copeland commissioned Atomik Research to run an online survey of 2,004 adults in the United States in September 2019

Read Next: Three benefits of the smart thermostat

5 Steps to Prevent Frozen Pipes

by |
1

Well before the mercury ever drops below zero and winter descends across the country, experienced building owners and facility managers know the importance of taking steps to protect their buildings from frozen and burst pipes.

For most facilities, preventing damage from frozen pipes doesn’t require much beyond taking a few preventative measures. On the other hand, skipping this routine annual maintenance has the potential to cause big problems. Philadelphia Insurance Companies, one of the nation’s largest commercial insurance carriers, estimates that while the average loss related to a burst pipe claim is around $27,000, claims have been known to go as high at $1.7 million.

To prevent a potentially catastrophic event, add the following five steps to your commercial facility’s pre-winter and winter maintenance checklists to so you can minimize the potential of frozen pipes.

  1. Inspect & Service the HVAC System

Routine service and inspection visits from your HVAC professional are important to maintain the overall health of your HVAC system.

Prior to the start of the winter heating season (October or November), and again in winter (January or February), facility managers should set up inspection and service visits from their HVAC service providers. These visits not only ensure the heating system is running optimally, but also that potential service issues are found and repaired quickly.

During visits, your service technician should be conducting visual inspections of assembly systems, along with cleaning and lubricating components. Technicians should also be running diagnostics tests on electrical and mechanical components to determine parts that can be tuned up or may need replacement.

If your facility benefits from a designer air system (modulation technologies, variable speed scrolls, precise temperature control), regular service and inspection appointments are even more important to the health and longevity of your HVAC system.

  1. Audit Your Water Supply System

When was the last time you evaluated your building’s plumbing? If you’ve never conducted a water system audit, tracing from the water supply entry point through to sewage discharge, a pre-winter inspection is the time to do it. If you can’t evaluate the entire system, start with the water supply. Look for and make note of water supply lines along exterior walls or in unheated spaces and note whether those pipes are insulated or not. Check for any signs of leaks or valves that aren’t properly functioning and repair them.

Don’t overlook plumbing that services exterior or special areas of the facility either. Are the outside hose spigots on your buildings frost proof? If not, be sure that water supply to the spigots are shut off. If your property has an irrigation system, make sure the system has been drained, blown out and the water supply shut off before winter weather sets in (usually no later than late October).

If your facility has a fire suppression sprinkler system that runs through an unheated space, like an attic, consult with your system servicer for best practices. Depending on your area of the country and your fire suppression system, it may be able to withstand freezing temperatures by design.

  1. Insulate Pipes

Most buildings constructed over the last few decades are built with water supply piping located in interior walls, but that’s not always a guarantee. Sometimes, piping is located along exterior walls, in unheated spaces or even outside the building. One simple and fairly cost efficient solution is to install pipe insulation around interior pipes to protect them from freezing temperatures. For exterior pipes, make sure they are thoroughly wrapped with a sleeve or electrical heat tape.

Beyond helping to protect your facility from burst pipes, insulated plumbing minimizes plumbing noise, reduces mold growth, cuts down on heat loss from your hot water pipes and helps to save energy year-round.

  1. Inspect Unheated Spaces

Basements, crawl spaces and attics are typically areas where the space is unheated. When temperatures drop into negative territory, any plumbing running through these spaces can be vulnerable to freezing. Insulating water pipes running through these spaces is recommended. If these spaces have the capacity to be heated, keep heat in these sections of the buildings on, even if you need to lower the temperature for these sections of the building. If the pipes running through unheated spaces service outdoor spigots and irrigation systems, turn off the supply to these pipes.

  1. Check the Thermal Envelope

Inspecting walls, windows, doors, the roof and floor of your facility for cracks is something that is routinely recommended, and for good reason. A facility’s thermal envelope can dramatically impact not only how much energy and heat the building uses and retains, but also how much it loses. Should your facility lose power and heat, the consistency of your thermal envelope will determine how soon you have an emergency on your hands.

Before temperatures plummet, take the time to seal cracks and add insulation. The tighter and more insulated the building envelope, the less work your HVAC system must do and the longer your facility will retain heat in the event of a power loss or heating system failure.

Read Next: Modulation Technologies: Designing Great Commercial Spaces

Infographic: How to Improve Your HVAC Company’s Online Reviews

by |
Reply

Did you know that 64% of consumers check Google Reviews before visiting a business? Your HVAC consumers are no exception. It’s common practice for customers to browse their options online before reaching out to a contractor for an install or repair.

You’re busy servicing clients, managing employees and staying up-to-date with the latest HVAC industry regulations, so adding another task to your list may seem daunting. However, you cannot afford to ignore your company’s online reputation if you hope to attract new clients online. With that in mind, we’ve collected some quick advice that will help you maintain your reputation online while proactively attracting new customers.

HVAC Reviews Infographic

After you build a successful HVAC business, it’s important to maintain it by monitoring your reputation online. Putting this advice into action will allow you to take that a few steps further, and proactively strengthen your customer base by meeting them where they are most active online.

To download a PDF of the infographic, please click here.

Read Next: Back to School: The Contractor’s Guide to Continuing HVAC Education

HVAC Education

Comfort, Efficiency Key to Success for Facility Managers

by |
Reply

In a recent survey, more than 70% of people said that they have experienced temperature discomfort at school or work, and it has negatively affected their productivity. Whether it be at school or work this number is significant and can be very costly. But finding the perfect comfort level can be difficult.

Your customers deserve to be comfortable no matter where they are. That is why the experts at Emerson and ABM are working hard to provide high-quality solutions to all of their clients, through proactive HVAC maintenance leveraged by modern technologies to make your customers feel right at home, wherever they are.

To learn more about Emerson and ABM, see our case study.

For more information on our consumer comfort survey, download our e-book.

The Contractor’s Guide to Repairing or Replacing Flood-Damaged HVAC Systems

by |
Reply

After floodwaters have receded, damage to your building envelope can need clean-up and repair. Now is also the time to evaluate your interior components for restoration or replacement.

HVAC systems may need a complete overhaul, since floodwaters can not only corrode the physical mechanisms but also provide a breeding ground for microorganisms such as bacteria and fungi, according to the CDC. This contamination can occur in sections that were submerged and in air supply ducts above the waterline. This makes the disinfection of all components essential. Also, hurricane-force winds and the power of rushing water (and the debris it carries) can cause damage to the fins and exterior of the unit, while power surges ­– which are common during hurricanes – can adversely affect the system’s capacitator, compressor, wiring, and fuses. (https://www.hvac.com/blog/disaster-assistance-for-your-hvac-system/)

While contractors work to ensure that, once repairs are completed, the HVAC system creates a healthy indoor environment, it’s equally important that they recognize the psychological impact felt by those affected by the storm. As noted in our post, The HVAC Contractor’s Role in Disaster Recovery, HVAC contractors and technicians provide not only technical expertise but also recommendations regarding the repair-or-replace decision—advice that can be most welcome given the myriad of decisions and challenges their customers are facing in the aftermath of the disaster.

Step 1: Take adequate precautions.

Turn off the system. If areas of the building will be occupied during repairs, use temporary walls, plastic sheeting or other vapor-retarding barriers and maintain negative pressure (relative to adjacent non-construction areas) to prevent contamination from transferring to other areas or throughout the building.

Workers should wear at least an N-95 NIOSH-approved respirator to protect against airborne microorganisms and if the area is poorly ventilated, use appropriate chemical cartridges in addition to the particulate filters to guard against inhalation of chemical vapors. Auxiliary fans can also help supply clean air to the work area.

Step 2: Remove flood-contaminated materials from the system.

Any insulation in the vicinity of HVAC system components – and HVAC filter media that has been contaminated by floodwaters – must be removed and disposed of according to applicable Federal, State, and local regulations. If any HVAC system components are also contaminated and can’t be effectively cleaned and disinfected, discard and replace with new components.

AHRI recommends that duct insulation that has been in contact with floodwater is replaced since it is impossible to decontaminate. The ductwork itself should be thoroughly cleaned, dried and disinfected.

Check for any physical damage to the system (indoor and outdoor units) and to refrigerant or gas lines, electric wiring and any other connections. If either the indoor or outdoor unit of the HVAC system needs to be replaced and is rated less than 13 SEER, both parts must be replaced, according to the Air-Conditioning, Heating, and Refrigeration Institute (AHRI). Improperly matched indoor and outdoor units can increase the risk of premature failure while reducing efficiency.

Step 3: Clean and disinfect component surfaces.

Use a HEPA-filtered vacuum cleaner to remove dirt, debris, and microorganisms to clean the surfaces, including filter racks, drain pans, bends and horizontal sections of air ducts where debris can collect. Remove and service (clean, disinfect, dry thoroughly and test) the HVAC system fan and then re-install. For heavily contaminated components, use a steam or a high-pressure washer. Gasoline-powered pressure washers should be used outside away from air intakes to prevent carbon monoxide hazards.

Then disinfect with a bleach solution (1 cup of household chlorine bleach to one gallon of water), followed by a clean water rinse.

Step 4: Replace the insulation.

Once the HVAC system components are cleaned and/or replaced as needed, replace the insulation. According to the CDC, using an external (i.e., not in the air stream) smooth-surfaced insulation will help prevent debris and microorganisms from collecting in the future while upgrading to the highest efficiency filters practical is the most cost-effective way to improve the long-term quality of the indoor environment.

Step 5: Test the HVAC system and regularly check performance and condition.

Verify that all electrical components are working properly and that the HVAC system performance conforms to the recommendations in ASHRAE Standard 62.1-2016, Ventilation for Acceptable Indoor Air Quality or Standard 62.2-2016, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. Operate the system continuously at a comfortable temperature for 48 to 72 hours, checking for objectionable flood-related odors. If present, continue the flush-out process until odors are gone, then replace the HVAC filters with new ones prior to building occupancy.

Arrange for frequent inspections of the system, inspecting the HVAC system filters each time and replacing it as necessary, gradually extending the time between checks until it follows the routine operation and maintenance specifications that system.

Additional information is available from the following sources: