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Monday, February 26, 2018

Negative House Pressure Problems

Smoking Fireplaces & Stoves —Smelly Fireplaces—Poor Indoor Air Quality

Many homes have negative pressure problems—this is common when homes are tightly insulated, or in larger or multi-story houses.  Not enough make-up air can get in the house for all of the things that need air, like fireplaces, wood stoves, gas ranges, furnaces water heaters — and people. Sick House Syndrome can also be a result of this issue and it is more common than most people think. 

Symptoms: Fireplaces or wood stoves smoke or smell when a second fireplace is used or when a furnace kicks on - or even when none of these things happen. This is because the furnace or fireplace needs air for combustion, and takes it from the place of least resistance which is often a fireplace.  This is a house problem—not a chimney problem.

When an exhaust fan is used in the kitchen or bath, or the furnace is used, this makes the problem worse.  You may notice cold air drafts coming from fireplaces, fireplaces that smoke, Carbon Monoxide backup from the furnace, gas fireplace, or hot water heater, or leaky doors and windows. These are all symptoms of negative pressure in the house. Sometimes unexplained illness and flu like symptoms can be an indication of negative house pressure as well.

GAS appliances may backdraft Carbon Monoxide without the occupant's knowledge - CO is odorless, colorless, and tasteless. Tip: don't ignore CO alarms-if one goes off there is a reason. 

 Solutions to the problem: 

The Draw Collar has an electric element that keeps the flue heated so that draft is always established and going up and out of the chimney. In addition to reducing or eliminating smells from the flue the inducer prevents back-drafting and smoking issues when starting a fire or at the end of the fire while it is cooling down. We recommend installation of a draft inducer with every stove insert or freestanding stove on a lower level of a home. However, it does not address the rest of the appliances or house. 

Condar through the wall ventilator: The Condar ASV-90 provides the ventilation you need without the drafts, energy loss and security concerns of an open window. Open windows can give you a blast of arctic air–along with dust, noise, and security concerns. The ASV-90 delivers diffused, filtered, fresh air quietly and efficiently. This is installed in a wall in the room where an appliance does not properly draft. 

NEW: The Padgitt MHV (Make-up Air Ventilator) system brings in needed air on demand from the house, heats it during the winter months, then distributes air through the house through the cold air returns. This supplies needed combustion air for all appliances in the house including the furnace, hot water heater, and fireplaces.  It also re-supplies the house with 6 fresh air exchanges per day as recommended by the EPA for occupants to breathe. Better health is a side-effect of this installation. A handy person, HVAC Tech, or Chimney Tech can do the installation. Sized to the house. 
See more information at

Marge Padgitt is the CEO of HearthMasters, Inc. She is the publisher of Wood-Fired Magazine and and author of chimney and venting books and articles. Marge is a CSIA Certified Chimney Sweep and NFI Certified Wood-Burning Specialist. Contact Marge at