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Smoke odors and retrofitted A/C
14 July 2007


Q. Is it possible for the smell of cigarette smoke in one townhome to come through the vents of an adjoining townhome? My husband and I smelled cigarette smoke in our basement tonight and I concluded that it was coming from our neighbors, who were having some kind of party at the time. My husband thought my idea was far-fetched so I'm writing you for insight!

A. Your suspicion that the smoke smell was coming from the adjacent unit is not far fetched at all but in fact, spot on. But not necessarily through the vents. Air is very mobile stuff and even the tiniest pressure differential from one space to another will cause the air to start to move to the lower pressure area.

It works on a large scale with our weather. When we have a high pressure dominant system it prevents other weather indices from entering its space. If the high pressure area moves off and replaced with a low pressure system the low pressure draws airborne moisture from wherever and we get inclement weather. Your micro townhome environment had a low pressure system in your space and it drew adjacent air in to try to equalize the pressure and it dragged the tobacco odors along with it. The cause of your personal low pressure system could have been any of a variety of causes. It could have been a kitchen vent fan, a bath fan or running the dryer or even operating your heating and cooling system. Or it could have been exterior atmospheric imbalances from one side of the building to the other-- a breeze.

I once built a three story, six unit office building in Annapolis. This building has independent HVAC systems for each unit. It also has serious fire separation between units at floors, ceilings and sidewalls. The occupant of one of the lowest units sm oked a pipe with a very distinctive smelling tobacco. You could smell it all the way up to and in the top units. After great gnashing of teeth the smoker quit. He would have lost tenants. He was the building owner.

If the problem persists and it really drives you crazy then Iíd suggest an air to air heat exchanger, also known as an energy recovery ventilator (ERV). They arenít that expensive and they bring in fresh air from the outside, heats it or cools it, whichever is needed, employing exhaust air from inside the house. It puts the fresh air into your regular HVAC air distribution system. They refresh the air in the house in fairly short order removing odors. Itís a technology that arose in response to our ever tighter building technologies and the need to get fresh air into our nearly airtight structures. I found one, the Airiva HE 150, on the web for $500-- delivered-- that on low speed will completely change the air in your townhouse twelve times a day. They claim a do-it-yourselfer can install it but my experience is that if an amateur can possibly do it wrong, they will. It involves cutting holes in the wall and into the ductwork plus powering it with electricity. Itíll take a professional about two hours to install it and that will be money well spent.

Q. We have an old house, circa 1926, with steam heat radiators and are finding it increasingly difficult to wrestle room air conditioners in and out. My husband says he saw some articles about air conditioning systems that did not need large air ducts to function adequately. We have a two-story house with five rooms downstairs and four upstairs plus 1 1/2 baths. We would greatly appreciate any information you could give us on the subject.

A. There is such a beast and it's used in old buildings and museums. It's pricey so be prepared. Last time I checked it was about twice the base cost of a traditional duct system.

It's a high velocity delivery that magically loses speed as the air enters the room. The air is piped through about 2" flex ducts and outflow openings and trim rings are about the size of a CD. The air handlers work harder than conventional systems and I hear some complaints about wind sounds that they can make but other than that they are quite well received.

You might also want to explore split wall-hung units by Sanyo or Mitsubishi. Dollar for dollar the best bang for the buck. They are quiet, unobtrusive and do a good job. The compressor sits outside so all you have in the house are the coils and the fan. They heat too so you can augment your central old fashioned radiator heat in winter.

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