combustion safety - step 7 of the seven steps of building a synergy home

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Step 7 - Combustion Safety

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The 7 Steps of Building a Synergy Home

• Airtight Construction• Fresh Air Ventilation• Improved Thermal Systems• Properly Sized, Designed, Installed, and

Commissioned HVAC System• Pressure Balanced• Moisture Managed• Combustion Safety •2

• Tighter homes have made exhaust appliances compete for available air.

• Every bit of air that is exhausted to the outside must be replaced.

• Usually it is from the nearest, closest hole.• Proper planning and understanding is required

when using atmospherically vented fireplaces, furnaces, water heaters, and commercial grade cooktops.

• If gas is used, use direct-vent, sealed combustion units.

• Better yet, use all-electric appliances.•3

Exhaust Only Devices in Your Home

• Dryers are exhausting 250 – 400 cubic feet per minute (250 x 60 minutes = 15000 cubic feet per hour).

• Microwave exhaust – 300cfm• Cooktops – up to 1500cfm• Bathroom fans – 75cfm• Vented combustion appliances• Central Vacs - ???• Attic Fans

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Many times the fresh air supply is back down the exhaust pipe of a combustion appliance or a

vented fireplace. The 2/10 Warranty paid for the water heater that is located in the closet 3

separate times because the old one was inexplicably backdrafting!

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The 2009 IRC requires fresh air makeup on all vented fireplaces.

R1006.1. It also requires gasketed doors.

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Commercial grade cooktops can remove 1200 to 1600 cubic feet per minute of conditioned air from the home. The 2009

International Residential Codes now address the situation in Section M1503.4 “Exhaust hood systems capable of exhausting in excess of 400 cfm shall be provided with makeup air at a rate

approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with a means of closure and shall be

automatically controlled to start and operate simultaneously with the exhaust system.”

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These are fresh air ventilation kits for kitchen exhausts. A pressure switch wired

to the exhaust fan opens when the appliance is turned on. Makeup air on

your HVAC system is also required.

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This can be a difficult task but it is mandatory especially with a masonry fireplace nearby.

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Makeup air for a very powerful exhaust system.

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There are some great videos on Youtube.

• Alpine Fresh Air Ventilation System • Makeup Air Kit for Commercial Cooktop Exhaust• Makeup Air Kit for Wolf Cooktop

• Broan Kitchen Makeup Air Kit

• Residential Kitchen Makeup Air Webinar• Carrier ERV Video

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Many building departments require an

outside air source for factory built fireplaces.

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Do not install fresh air ventilation on a house-vented fireplace/vent-free fireplace. This short-circuits the oxygen depletion sensor and will kill

the homeowners in a tight home.

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Who is Liable For a Short-Circuited House-Vented Fireplace That Was Required by Code?

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Passive air vents do not work.

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• Low airflow through a furnace is bad because it allows the heat exchanger to get very hot.

• High temperatures can cause the “thinner” more efficient heat exchangers to crack.

• Cracked heat exchangers put off Carbon Monoxide.

• Why not use an all electric heat pump?

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Carbon monoxide monitors should be used in place of

carbon monoxide detectors.

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• Carbon monoxide monitors and smoke alarms should be installed and maintained properly.• Make sure they are properly

covered during construction because dust can ruin them.

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