Furnace Maintenance & Repair – ACE HI PLUMBING, HEATING, & AIR

Repairs and maintenance on your furnace, boiler and AC systems are essential for keeping them reliable throughout the year. Regular inspections in the spring and fall are important to help with repair costs and saving energy.

We offer 24/7 emergency when you need it. Our technicians are Nate Certified and are always continuing to be educated in the field and classroom. Don’t let the flat rate shops scare you. We do everything by the job, not by a book that was written by someone in an office. Our technicians are not driven by commission, they are here to help clients with their questions and needs.

Trust us to be there when you are in need of help. We work in Loveland, Drake, Estes Park, Greeley, Longmont, Windsor, Severance, Johnstown, and Fort Collins. We offer all services in plumbing, heating, and air when you need it the most.

Combustion Air Infiltration & Carbon Monoxide Problems – ACE HI PLUMBING, HEATING, & AIR


When a structure has a properly designed combustion air inlet system, the furnace enclosure has two dedicated vents communicating with the outside air, eliminating the need to obtain combustion inlet air from or through the living space. Residences with a non-dedicated combustion air inlet systems are the homes that are at risk. As a result of modernization, these homes may have worked fine since they were built, but can develop problems. This includes new high-efficiency window, weather stripping, and general sealing of the structure.. Anything that disturbs the pressure in the space can affect the operation of the furnace. The filtration rate may be diminished if a house is tied up for energy conservation. The house pressure drops as the furnace draws combustion air from the space and eventually the house pressure can drop enough to reduce the combustion air inlet pressure to a point that the flue will quit drafting.

Other things that can reduce combustion inlet air pressure can include the furnace blower return air drawing from the furnace enclosure, which should always be well sealed. Ductwork supply leaks can cause pressure in the structure, and the house pressure will drop, if the duct system pulls more air out of the house than it returns due to supply leaks. Closing the doors to rooms that have no dedicated return air grille can aggravate supply duct leaks. Exhaust fans drawing on the house can also reduce combustion inlet air pressure. This includes clothes dryers, bathroom fans, whole-house fans, range hoods, other gas appliances, and fireplaces. And finally, customers sometimes block furnace door vents to reduce noise, but whether a blockage of a furnace enclosure vent is intentional or unintentional, this can also cause the reduction of combustion inlet air pressure.

The Fundamentals of Carbon Monoxide- ACE HI PLUMBING, HEATING, & AIR

Safe and efficient combustion in a furnace requires a proper air-to-gas ratio. This is dependent on the availability of air(combustion inlet) and the ability to discharge oxygen-depleted air (flue gas venting). There is a potential for incomplete combustion whenever there is a malfunction of either the inlet or outlet system. This can result in carbon monoxide (CO) gases.

Residential gas heating systems with non-dedicated combustion air inlets are inside the living space without direct communication to the outside air. Many of the older homes have furnaces that draw air from the occupies space. As the air is pulled from the space, it is replenished by air infiltrating the house through the window, doors, and other obvious opening. This can create a potentially dangerous situation.

Modification done to a structure can inadvertently inhibit this flow of combustion air, causing the furnace or any other gas appliance to malfunction. Other problems in the house can turn an improperly vented furnace into a CO-generating machine.


Most residential furnaces use natural draft to drive the combustion process. Even 80%-AFUE furnaces with combustion blowers are natural-draft furnaces.The combustion blower assists the combustion gases, but the flue still operates like a natural-draft furnace. The natural pressure differential created by heating the combustion gases in the furnace is what pushes the flue gases up and out of the flue.

Combustion gases expand as they are heated which makes them less dense than the colder air entering the furnace, so they weigh less. They also exist at a lower pressure than that of the colder inlet air.

Since the combustion gases are at a lower pressure, the higher-pressure inlet gases displace them, pushing them up and out of the flue. The inlet air must always be at a higher pressure than the combustion gases so that this pressure differential can be maintained in order for the flue to operate properly. Air stops drafting through the furnace when this pressure differential is diminished by the flue pressure becoming too positive or the combustion air inlet becoming too negative. This is when CO is created and if the furnace is not drafting, the CO ends up staying in the residence.

The pressure differential needed to drive the flue gases up and out of the furnace is somewhere between 1 and 5 Pascals depending on the outdoor temperature. This means as the flue gases leave the furnace, they must be at -1 to -5 Pascals relative to atmospheric pressure. The pressure differential needed to be maintained between the inlet and outlet of the furnace’s combustion air inlet system is very delicate and can be easily disturbed. Anything that will raise the pressure in the flue or lower the pressure in the combustion air inlet system can interrupt the flow of air through the furnace and create carbon monoxide.

How to Change Your Furnace or AC Filter – ACE HI PLUMBING, HEATING, & AIR

Maintaining a clean furnace filter not only helps to keep your furnace’s interior components clean and in good operating order, but also contributes to improved air quality by reducing the amount of allergens and harmful particles in the air. All furnaces are equipped with an air filtration system designed to trap pollutants, dirt, and dust. Service technicians may replace your furnace filter during an annual inspection, but these filters are constantly working to keep the airborne pollutants out of the air you breathe and away from the operating parts of your furnace. With all of these debris piling on each and every day, frequently changing or cleaning your filter is essential to maintaining the unit’s optimal operating efficiency. This is also essential to keeping your monthly bill low. It is important to understand how to replace your filter and how often is often enough.


First, it is important to understand how filters operate and why it is so important to your HVAC system. The furnace operates through a cold and hot air return process. The process starts in the cold air vents and cold air travels through the furnace filter to start the heating process. As cold air moves through the system, hot air return begins at the furnace, travels through the heat exchanger, and then out through the vents into the home. The warm air, replaces the cooler air and the cold air is pushed back through the return vent to begin the process all over again. As the air continues to pass through the system, dust and dirt particles in the air are trapped by the filter preventing it from building up on the interior components of the unit and slowing down the operation. When the filter doesn’t get changed regularly, it becomes more difficult for the air to pass through the returns, meaning your furnace is performing overtime to keep air moving.


Air filters should be changed or cleaned every few months, before they get full. It depends on the manufacturer’s directions whether that should take place every month or every three months. Be sure to read all directions supplied with your new filter carefully. Also, you should frequently check to see if your filter should need a replacement as necessary. For example, if you have pets or if you smoke, you may find your filter turning black with pollutants sooner that you may have expected.

The location of the filter varies depending on the furnace’s make, model, and manufacturer. They generally are found near the fan motor, which is kept in the blower chamber. Filters also may be kept near the systems ductwork. Some could be exposed and easily located from the exterior of the unit, or other furnaces are manufactured with the filter inside the fan enclosure. These units require removal of an access panel to uncover the filter. Homeowners should consult their owners manual for factory instructions on how to change their individual unit’s filter.


Filters come in a variety of types, including fiberglass, HEPA, polyester, pleated, and electrostatic filters. Each has different capabilities and performance based on the size, density of the material and amount and size of particles it’s designed to filter. Filters are available in reusable or disposable options. Reusable filters require replacement every few years, but depending on the level of pollutants captured, they should be cleaned with water or a vacuum on a monthly basis. Disposable filters require a homeowner to purchase a new filter every few months, but eliminate the potential for exposure to contaminants during the cleaning process. This type of filter is regarded as more efficient at trapping smaller debris. Although reusable filters may seem more environmentally friendly, they are generally less effective at trapping small dust particles and this may reduce the overall efficiency of the unit. Regardless, all air filters are most effective when new and clean.

Once you determine the type of filter you want, it’s important to ensure you purchase the correct size. Looking at the old filter being replaced is the simplest way to determine the size of the new filter. Typically, the size is printed on the filter frame and is presented with the dimensions measuring width by height by depth. If the size is not on the frame of the filter, it can be found be measuring the dimensions with a tape measure or reading your furnace’s owner’s manual.


Both brand name and generic filters can be used in heating and cooling units. Generic filters may cost less, but often have the same specifications as brand name filters. Buying a filter in the right size will have a greater impact on performance than the brand. Installing the wrong size could allow air to bypass the filter and leak through to the blower fan, causing slow air flow, excessive dirt build-up, and a soiled blower fan. More costly repairs, cleaning, and service depends on the severity of the build-up. If you are concerned about purchasing the wrong furnace filter, don’t hesitate to talk to your maintenance technician about their recommendations for keeping your unit running in top shape year round.