However if moisture is able to enter the unvented attic space it may lead to roofing panel issues.
Supply duct layout unvented attic.
To provide an unvented conditioned space for locating hvac equipment in the attic and or to provide a continuous thermal barrier for designs that have complex coffered ceiling planes and or numerous penetrations for lights speakers vents soffits etc which make it difficult to achieve an airtight ceiling plane.
To account for all the necessary factors many professionals use a tool called acca manual d.
Well in the comments dave roberts a senior engineer at the national renewable energy lab nrel wrote about a paper he co authored last year and included a link to it.
Choose the right duct size and layout.
Fully ducted systems are the most efficient dedicated supply ducts deliver fresh air to the living room and bedrooms while exhaust ducts pull stale air from bathrooms and the kitchen.
This building america innovations profile describes building america research showing an unvented attic insulated along the roof line provides better energy performance than a vented attic when hvac ducts are located in the attic and there are numerous pe netrations through the ceiling deck.
The design and construction guidelines in this report are the results of working with four builders and one energy consultant who routinely build homes with ducts.
Systems where condensing surface temperatures are not controlled and systems where condensing surface temperatures are controlled.
Ensure proper ductwork sealing.
Sealing ducts placing ducts in unvented attics or crawl spaces and placing the ducts in conditioned space.
Use metal flex or fiber board ducts that are insulated to code.
Remember that article i wrote about ducts installed against the roof deck and how i said it was probably the absolute worst single location for installing ducts.
Unvented attic design falls into two categories.
The duct insulation should include a vapor barrier cover.
Unfortunately most manufacturers permit duct configurations that can lead to very high energy bills.
Up against the deck may be the worst place in the attic to.
Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings.
Where all or some portion of the ducts cannot be laid on the attic floor due to truss design or some other obstacle then hang the ducts using straps or saddles to properly support the ducts.
The 1 800 square foot brick ranch in climate zone 4 dates from the 1960s but the previous owner installed both a furnace and ductwork in the attic just four years ago.
Although both the attic floor and the ductwork are insulated ted recognizes the situation isn t ideal.
The two categories essentially are the demarcation between regions where cold weather conditions occur with sufficient frequency and intensity that sufficient moisture accumulation from interior sources can occur on an uninsulated roof deck to risk mold corrosion and decay problems.
This material focuses on placing the ducts within the conditioned space.
Once all the system variables have been decided your hvac design professional can determine the most efficient ductwork design layout and calculate the correct duct size.
Ted also has inherited a powered attic ventilator.
