Concept

Our premise is that we want to give priority heating to the Active Area. When there is less than enough heat to heat the whole house, the overall design focuses on capturing and preserving heat in the Active Area. If we have to add heat with a wood fire, it is in the Active Area. We will allow the temperature in the other areas to dip when necessary to conserve stored heat for future use.

However, there will be many days when there will be too much heat in the Active Area, whether intentional on not. On these days, the Active Area will be our "furnace." In order to distribute the heat to other areas, we have a Heat Management System.

This concept was developed based on my childhood experience growing up in a leaky old farm house with no heat to the second floor, except for floor registers that permitted some heat to migrate upward. While the old farm house worked, it wasn’t entirely satisfactory, as was evidenced by the occasional frozen glass of water and gentle drifting snow on the window sill.

The Heat Management System is composed of six inch ducts with low wattage, in-line fans connecting the Active Area (aka furnace) with the outlying bedrooms. These fans may be operated automatically or manually. The net result is the Active Area is cooled when necessary to keep it in our target comfort range and outlying areas are heated when excess heat is available.

Application

Automatic operation occurs any day when solar gains increase air temperature in the Active Area to above 76 degrees (this setting is controlled by the homeowner). The reason we set it at 76 to automatically come on is that if no one is home we would just as soon keep a little extra heat in the Active Area. When the Active Area gets up to 76 degrees, it will stay above 68 on almost any night.

When the temperature is above 76 degrees, three small fans turn on and move warm air off the Active Area ceiling into each bedroom. At the same time three other small fans draw the coolest air off the bedroom floors and send it to the Active Area. When the Active Area temperature drops two degrees, the fans stop.

The fans can also be turned on manually to warm all or any one bedroom.

This system also works with the wood stove to deliver heat to the whole or part of the house, when desired.

There will be many days when we anticipate excess heat and we can save electricity by simply opening the door to the stairs and bedrooms. While this isn’t as fast, it is effective when allowed to flow throughout the day.

In the summer, we alter the flow of the Heat Management System to exhaust the hottest air off the second floor ceiling out of the house. This is accomplished with a single 10 inch fan blowing out the west end and three ceiling inlets. At the same time, the three smaller fans draw cool air to the second floor from outside through open first floor windows. This is much like the old whole house fans, except it uses a lot less electricity and is quieter.

The external opening for the attic vent is closed during the winter and must be manually opened and closed each year. Maybe someday it will be automated, but for now this is not a big job – it takes about fifteen minutes.

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