Green Remodel Forum

I would like to know if 2 level heating systems are efficient, and if they can be installed without all new duct work. I live in a 2 story home, and the lower level is always at least 8 degrees or more cooler than upstaird. I need a new furnace, but want to avoid new duct work.

When one part of the house is colder than another part, it is a good indication that, in the colder part of the house, either there is insufficient insulation and air sealing in the colder part, or there is insufficient supply of hot air, or both. Insufficient hot air supply can be a result of ducts being too small, or leakage in the ducts, or restriction in the ducts. The only way to find out the real cause is to conduct an audit of the house, including a duct test. Once the house leaks are sealed, ducts fixed, insulation installed, then a properly sized furnace installed. It is not uncommon that adding sealing and insulation can reduce the size of furnace by 20% or 30%. Changing out the furnace alone will not make the temperature in the house uniform.

Furnaces usually achieve optimal efficiency at only one level. A furnace running at a lower level can reduce energy consumption but will operate at a lower efficiency than the higher level. It is better to air seal and insulate the house well, then install a properly sized single level furnace. Also note that the fan speed has to match the heat output for the unit to perform optimally.

In California, according to Title 24, changing the furnace out will trigger a duct test. Duct leakage cannot be more than 15% of fan flow. Corrective action must be taken for a duct system with over 15% leakage. It is not uncommon to find leakage of 30% or higher in many older homes.

Two level heating is efficient if you insulate properly. You should definitely get you your ducts checked and make sure your windows are sealed properly. I have found though that two level is not always necessary after you get your problem areas checked out.

Our upstairs is usually hotter in the summer than our first floor. It makes sense since hot air rises. To combat that you can have automatic baffles installed that cut off or allow air to flow in the upstairs and downstairs creating two zones. You then have two thermostats that control the baffles after the furnace and . So if it is hot upstairs but the right temperature downstairs, then the baffle for the downstairs will close slightly or completely allowing all the cold air to flow upstairs to cool that zone.

To combat that you can have automatic baffles installed that cut off or allow air to flow in the upstairs and downstairs creating two zones. You then have two thermostats that control the baffles after the furnace and furnace filters. So if it is hot upstairs but the right temperature downstairs, then the baffle for the downstairs will close slightly or completely allowing all the cold air to flow upstairs to cool that zone.

It's very difficult to maintain comfort in a two-story house with one heating and air conditioning system. This is because hot air rises moving directly to the upstairs !!

In getting a way to have a systems to operate the 2 floors in designing to have a proper improvement to incorporate imagination and designing.