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VENTILATION in BUILDINGS
AIR BYPASS LEAKS
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AIR LEAK SEALING PROCEDURE
AIR POLLUTANTS, COMMON INDOOR
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ROOF ICE DAM LEAKS
BASEMENT CEILING VAPOR BARRIER
BASEMENT HEAT LOSS
BASEMENT LEAKS, INSPECT FOR
BLOWER DOORS & AIR INFILTRATION
BRICK WALL DRAINAGE WEEP HOLES
CATHEDRAL CEILING VENTILATION
CEILINGS, DROP or SUSPENDED PANEL
COMBUSTION AIR for TIGHT buildings
COOLING LOAD REDUCTION by ROOF VENTS
CONDENSATION on WINDOWS & SKYLIGHTS
DEW POINT CALCULATION for WALLS
FIREPLACES & HEARTHS
FLAT ROOF MOISTURE & CONDENSATION
GREEN BUILDING CONSTRUCTION
HEAT LOSS in BUILDINGS
HEAT LOSS DETECTION TOOLS
HEAT RECOVERY VENTILATORS
HOT ROOF DESIGNS: Un-Vented Roof Solutions
HOUSEWRAP AIR & VAPOR BARRIERS
HOUSE DOCTOR, how-to be
HUMIDITY LEVEL TARGET
ROOF ICE DAM LEAKS
INDOOR AIR HAZARDS TABLE
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INSULATION AIR & HEAT LEAKS
INSULATION INSPECTION & IMPROVEMENT
INSULATION R-Values & Properties
LOG HOME GUIDE
MOISTURE CONTROL in BUILDINGS
MICROWAVE OVEN VENT INSTALL
ODORS GASES SMELLS, DIAGNOSIS & CURE
ROOF VENTILATION SPECIFICATIONS
ROOF ICE DAM LEAKS
SHEATHING, FOIL FACED - VENTS
STAIN DIAGNOSIS on BUILDING INTERIORS
STUCCO WALL METHODS & INSTALLATION
SWEATING (CONDENSATION) on PIPES, TANKS
THERMAL MASS in buildings
THERMAL TRACKING Indicates Heat Loss
VAPOR BARRIERS & AIR SEALING at BAND JOISTS
VAPOR BARRIERS & HOUSEWRAP
VAPOR CONDENSATION & BUILDING SHEATHING
VENTILATION in BUILDINGS
WIND WASHING INSULATION At EAVES
WINDOWS & DOORS
Microwave oven vent installation suggestions: this article describes the venting options for built-in microwave ovens and microwave oven-vent systems typically installed above a stovetop or range. We discuss the importance of venting to the exterior, choice of vent components and materials, and we refer to microwave oven manufacturers' installation instructions.
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Reader Question: how can I stop cold drafts from the microwave oven vent I routed into the attic?
Sir, I have a installed microwave oven that is vented by an 8 inch sheet metal pipe into my attic space (no cap). how can I insulate it to stop letting my micro wave from getting all cold ? Thank you in advance for any help offered. - D.M. 1/28/2014
Reply: microwave oven vent to exterior wall: vent kits
I don't think what you described sounds like a good design - you are venting moisture into an enclosed attic space, asking for condensation, mold, lost insulation value and related trouble. Examples of this sort of problem are at
Our photo at left illustrates a side-wall vent termination for a kitchen exhaust fan. This same duct arrangement would suit a microwave oven - vent system.
[Click to enlarge any image]
If your microwave oven requires venting to the outdoors (I'd review the manufacturer's installation requirements) you would be better actually route it outside using the materials and sizes and routing recommended by the microwave appliance manufacturer.
For example a typical installation guide for a GE brand microwave describes mounting the appliance to a building wall (securing its mounting support to wall studs). The company gives three types of microwave installations:
None of these recommended installations would approve what I'd call "pseudo-venting" of the microwave via a vertical duct but terminating inside the structure.
But other than the two very general parts sketches provided by the manufacturer (adapted and shown here) the installation instructions are silent about the duct materials, sizing, length, and routing.
One could guess that's because it's pretty obvious that while the microwave may have come set up for top exhaust venting (there are instructions for converting various parts to vent out of the back of the microwave), in a retrofit installation it is going to be hell to vent a microwave out through a first floor kitchen, up through a building, and outside through a roof, soffit or gable wall. Obviously in new construction it's easier to install vent ducting before the ceilings and walls have been finished.
Actually the microwave installation instructions I reviewed presumed that the vertical duct was already in place before the microwave was mounted. The instructions simply state
If that vent has to pass through your attic but terminates outdoors, perhaps down through a soffit or out through a gable end wall to avoid having to make a hole in the roof, the exit opening will need an exhaust-air-operated vent closure (as is used on dryer vents) not only to keep cold drafts from backing down into the occupied space but also to keep critters out of the vent system.
The top-vented microwave example given assumes that the vent runs straight up through the roof (see the roof cap in the sketch above). But an alternative worth considering if it does not make the vent run too long is to vent across the attic floor and down and out through a soffit or out through a gable end wall.
For any exhaust vent that is routed through a cold or cool space (like your attic) you will want to pay attention to these considerations as well:
Kitchen Exhaust Fan Companies
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