Attic HVAC

Things to Know About Your Attic HVAC

These are just some of the things I look for on a home inspection when assessing the HVAC installed in the attic of a home. Attic installation of the furnace is very common in San Diego because of our mild climate. It also frees up valuble floor space in the home.

The Attic Access

The first thing I need to consider is the attic access. When the furnace is located in the attic, there are some minimum standards that must be met. The actual access opening must be a minimum of 22 x 30 inches.

The typical attic access is in a closet or the hall

The typical attic access is in a closet or the hall

Required workspace for attic furnace

There are specific requirements for the attic furnace as to workspace and accessibility. 

  • If the height of the attic is less than 6 feet, then the maximum distance from the access point is 20 feet.
  • The passageway shall have a flat unobstructed floor not less than 24 inches wide.
  • A level work surface not less than 30 inches x 30 inches shall be provided in front of the appliance.
  • A permanent 120-volt receptacle and lighting fixture shall also be installed near the appliance. 
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Furnace gas shut-off

The recommended maximum length of the gas appliance connector is 36 inches. The appliance connector should not enter the appliance cabinet. The appliance connector should be connected to a gas shut-off valve. I have found on a few home inspections, the appliance connector run into the cabinet. This is incorrect and must be repaired by a qualified HVAC contractor. 

Notice the rigid gas pipe exiting the appliance cabinet.

Notice the rigid gas pipe exiting the appliance cabinet.

return air for the furnace

the return air for the attic furnace is typically located in the ceiling, in an area that is common to all of the rooms served by the unit. They are also sometimes installed on a wall.

This is a ceiling mounted return air.

This is a ceiling mounted return air.

The furnace filter

The furnace filter is typically installed behind the return air grill. Filters should be checked every three months and replaced when they reach a condition in which accumulation of particles becomes so thick that particles may be blown loose from the filter and into indoor air. Homes in areas with high indoor levels of airborne pollen or dust may need to have air filters checked and changed more frequently. Failure to change the filter when needed may result in the following problems:

·       reduced blower life due to dirt build-up on vanes, which increases operating costs;

·       reduced indoor air quality;

·       increased resistance resulting in the filter being sucked into the blower;

·       this accumulation of debris can be a potential fire hazard;

·       frost build-up on air-conditioner evaporator coils, resulting in reduced cooling efficiency and possible damage;  and reduced air-flow through the home.

This is an example of an extremely dirty air filter.

This is an example of an extremely dirty air filter.

electronic air filter

Not all air filters are disposable. Some people opt to install electronic air filters. An electronic air filter has special maintenance requirements. Failure to perform the required maintenance will result in poor filter performance and may affect the performance of the heating system or result in unhealthy conditions due to poor indoor air quality. You should read the manual for the filter to become familiar with these requirements.

This is a Honeywell electronic furnace filter.

This is a Honeywell electronic furnace filter.

Gas furnace roof exhaust

All gas furnaces, not just the one's installed in the attic, must be vented to the exterior of the home to allow the combustion gases to escape. Unless the furnace is a high-efficiency furnace, a B-vent is the most common material used to vent the furnace.

The vent should have minimum 1 inch clearance to combustibles.

The vent should have minimum 1 inch clearance to combustibles.

This home had two furnaces. 

This home had two furnaces. 

The home inspection and your furnace

The SOP's of most home inspector organizations will state what to expect from the home inspector when it comes to inspecting the HVAC system. The heating system inspection will not be as comprehensive as that performed by a qualified heating, ventilating, and air-conditioning (HVAC) system contractor. For example: identification of cracked heat exchangers requires a contractor evaluation, as does calculating the size of the system needed. Report comments are limited to identification of common requirements and deficiencies. Observed indications that further evaluation is needed will result in referral to a qualified HVAC contractor. The general home inspection does not include any type of heating system warranty or guaranty. Inspection of heating systems is limited to basic evaluation based on visual examination and operation using normal controls.

About the author: Frank Rotte is the Owner of Certified Inspection Services, LLC in Bonsall, CA. Comments are always welcome! Please visit us on Facebook at https://www.facebook.com/homeinspectionsandiego/