Recent Jobs For PMC Energy Services

Job completed for 60-year-old Cape Cod with Cold 2nd floor

Completion date: June 2, 2014

Why did the customer contact us?

The homeowner of a 60-year-old 2-story Cape Cod in Rochester contacted us after watching an episode of This Old House that featured Aeroseal. His second floor, especially the bedroom on the opposite end of the house from the furnace, had always been colder than the downstairs during the winter despite attempts to direct more air flow to the upstairs by closing the dampers of the ducts to the first floor registers. In addition, the house was getting dusty within days after cleaning, a symptom of leaky return ducts. After the TOH episode he realized these problems could be due to duct leakage.

Solutions provided:

Aerosealing reduced his supply duct system to 1% leakage and his return system leakage from 67% to 6%. (Commonly, returns that are comprised of panned joists and wall cavities, as opposed to fully metal ducted, leak 60% or more.) Both systems were now very tight.

We checked back with the homeowner within a week. He reported that while the air seemed cleaner the temperature stratification still existed – “The cold room seems as if it will remain the cold room”.

This got us to thinking more about his heating system. During our initial assessment, we noted that the furnace temperature was quite high – 15-20 degrees above normal – and it could not be easily reduced. Maybe the resulting high temperatures at the first floor supply registers (near the thermostat) were causing such a short heating cycle that the air temperature exiting the upstairs supply registers was still rising when the thermostat shut off the furnace. So we offered to come back, take some measurements to verify our hypothesis, and attempt to damp the ducts feeding the first floor supply registers and (now that the duct system was tight) force more heated air to the upstairs registers.

Exactly as we suspected and as the solid lines in the graph below depicts, the heating cycle, i.e. the time that furnace was heating, was brief – a mere 3 minutes – and the air temperature at the upstairs supply registers was no where near steady state when the furnace turned off.

Using our flow meter to measure the air speed at each first floor supply register, we damped the duct feeding it until the air speed was cut in half. Now when the furnace turns on, the air temperature at the upstairs registers – dashed line circles in the graph – rise much faster and the cycle extends well beyond 3 minutes. Now the upstairs is receiving much more of the furnace heat and temperatures throughout the house are more uniform. No more cold winter nights in the 60-year-old Cape Cod.

Photos & Videos:

Effect of damping first floor-supply ducts on register temp profile

Effect of damping first floor-supply ducts on register temp profile

PMC Energy Services service area
Read customer reviews