Exterior HVAC Duct Insulation Service

No two jobs or ducts are alike, but we can generally breakdown of the factors which impact schedule.

Demolition executes relatively quickly. A competent crew can strip, remove and dispose of old failed insulation in less than a week for most duct systems. Access to dumpsters really matters for disposal. Bags hand carried down a building and to a remote dumpster can add significant time.

Measurement can be completed for most ducts in 1-2 days, mostly depending on the distance of the job site from the installer, access to the roof and weather conditions. Add another day on the backside for translation of field measurements into computer modeling software.

Fabrication depends highly on the size and length of the duct, the amount of straight duct and the number of bends. Elbows and transitions with multiple bends or angles add time. Many ducts can be fabricated in about five to ten business days.

Staging of the materials should add one to three days, depending on the amount of material to be staged and the relative accessibility of the roof. Materials can be lifted by rope, by scaffold, by a lull or by crane in order of slowest to fastest. Use of a lull offers the best compromise between speed and cost. Delivery times depend obviously on the proximity of the job site to the factory in the Philadelphia area.

We try to minimize the time from stripping to installation to help customers avoid a fully exposed and uninsulated duct in the elements.

Installation times depend on several factors, including:

• Height of the duct off the roof
• Size of the duct
• Length of the duct
• Number of access doors in the duct
• Number of curves in the duct
• The type and size of the supports for the duct itself
• Accessibility of the roof

Let us assume that the customer needs a two-foot-high by three-foot-wide duct system. Expect the sections of Techna-duc® to come in sections four to eight feet long. A competent install crew can install two to four sections of insulation per day per technician assigned. A two-person crew could reasonably expect to install four to eight sections in a normal day, or essentially sixteen to thirty-two linear feet of duct per day in ideal conditions. Ducts that run vertically down the sides of buildings obviously take a lot longer and depend highly on access and lift availability.

Ducts high off the roof will be slightly slower. Extra access doors or excessively thick angle irons in the supports will also slow the install from extra field modification of the panels needed to accommodate these features.

The factors affecting the installation time of Dual-Tech® are like those affecting Techna-Duc®. That said, a competent install crew of two technicians should be able to install a four to eight-foot section of Dual-Tech® in 15-30 minutes per section. So, a two-person crew should be able to install roughly sixteen linear feet per hour. The size of the section (height and width) mildly affects install time, so larger ducts tend to take slightly more time than smaller ones.

Customers should not necessarily worry about uninsulated ducts killing their energy bills. Most waterlogged wrapped insulation does not help them anyway. That said, we can apply a temporary wrap or plastic option to try and provide some limited weather protection for exposed duct.

We lay down temporary protective layers over the roof, usually thin pieces of plywood, to help prevent damage to rubber roof membranes during installation.

Insulation can be disposed from a roof directly into dumpsters if available via chute, or bagged materials can be lifted or carried off the roof. Access to dumpsters and availability of lifts helps shorten schedules and drives down cost.

No duct is ever fully leak proof. Typical in-service sheet metal ducts leak somewhere between 10-20%. Engineers frequently specify new systems at 5% or less leakage. That said, both Techna-Duc® and Dual-Tech® should drive air leakage to less than 1% if installed correctly. That efficiency translates into significant energy savings for customers. A 2009 Berkley National Laboratory study identified HVAC air leakage as the number one fault causing energy inefficiency in commercial buildings, at a national cost of $2.9 billion per year.

The product manufacturer will inspect all installations prior to issuing a warranty, and repair or replace parts and labor for twenty years with limitations for exceptional circumstances (acts of God, etc).