An air system cleaning
A short walk through of a six hour job.
Set up starts with a walk through of the system locating all the parts and accesses. The necesary equipment is unloaded and set up. Large vacuum hoses are ready to be attached to the return side of the system or an alternate location if necessary. High pressure air hoses are brought in and located near the supply registers.
Opening the system starts by shutting down the power to the equipment. Equipment access doors are removed with all of the registers and grills. Register and grill openings are temporarily sealed with wide tape. The taped openings only allow inlet air where and when we want it.
Registers and grills are taken outside and cleaned with high power washers. Inspection may reveal rust or corrosion. This should be removed or the register replaced.
Ductwork is cleaned by vacuum in the end. But it takes high pressure air, power brushes, whips, snakes, skippers, wands and sponges to loosen the dirt that is stuck to the ducts. Different duct materials require variations in application. A 160 PSI (pounds per square inch) supply air wand for sheet metal is fine, but it may damage a flex duct. Low volume steam can be used on some deposits and ducts. Low volume is usually less then 2 GPH (gallons per hour). This won't flood the duct and cause more damage if controlled properly. Encapsulants, antimicrobials and antiallergens need to be nontoxic and only used on the spots that require it. Following manufacturers and EPA recommended practices is essential. Access doors may need to be added to do the project properly. Doors and panels are to be installed following SMACNA (Sheet Metal and Air Conditioning Contractors National Association), state and local codes. All of this is necessary to remove everything from the ducts.
Platforms and chases are special conditions. These areas are larger then the ductwork causing a drop in air velocity. Material falls out of the air stream and collects. These areas usually are open to wall cavities, cabinet bases, tub surrounds, building insulation, the attic and outside. Cleaning and sealing is required. Different blocking methods may be used to maintain the properly air speed and volume for cleaning. Sealants need to be made for duct use and not off gas harmful chemicals. Interior insulation should be the poly type rated for this use. If sound is a problem acoustic faced fiber glass can be used. This is usually only for short distances from the sound source.
Equipment can be the most time consuming part of the project. It's the same for roof mount or interior. The unit must be a least partially disassembled for access to the evaporator coil, heat exchanger, blower and housing.
Seal it properly. If the system is not sealed properly everything that was removed will get back in. Platforms, chases, duct connections and the equipment need to be sealed. Not only can debris get in, treated air can get out.
Filter location is inspected for proper fit and air leaks. Filters should have a snug fit. A loose filter will have air leaking around it. Sometimes closed cell foam may be used to fix this. The better the filter, the high the air resistance, the greater the leakage.
Reassemble the duct system. Registers and grills are adjusted and replaced. The equipment is put back together and given it's final seal. Tools are moved to the truck and work areas cleaned. Any trash is bagged as necessary and removed from the project site.
Start up and correct operation of the system is the last step. With a new filter installed the job is complete.