Hi there, I would appreciate any feedback or guidance.
Just had a new Luxaire high efficiency (95.5%) propane gas furnace installed in a 17 year old two story home. (old ductwork with no dampers).
Replaced a 17 year old oil fired Summeraire furnace with a side vent blower exhaust that failed and could not be replaced. Decided it was time to upgrade to propane and high efficiency.
The new furnace appears to have two issues, neither of which seem to be viewed as a problem by the installer. He says it is operating 'normal.'
1. The two speed DC motor appears to be constantly searching for the correct speed. It switches back forth rapidly between speeds, sometimes every second for up to a minute before settling on low speed. This constant cycling of blower speed was continuous throughout a full heating cycle until I replaced the paper air filter with a high quality hydro-static filter. I presume this introduced a little more back pressure on the cold air return and this seems to have helped settle the cycling down during the heating phase of the start-stop cycle. The installer indicated that the constant speed cycling of the 2-speed motor is normal???? He says that Luxaire has stated the same.
Anyone have any advice?
As an aside, the installer had the furnace specially equipped with a 1200 scfm blower instead of the normal 1000 scfm that normall comes with this model.
It is definitely more noisy (air and duct noise) than the old furnace. And when it cycles between low and high speed it produces a whistle sound.
2. The furnace also seems to turn on-off more frequently than it should.
Less than a half degree celcius change on the thermostat and the furnace restarts after it shuts down. At minus 10 degrees celcius outside temp the furnace is only off for less than 5 minutes. Is this a termostat problem or a furnace controller problem/adjustment? The thermostat is a fully programmable digital unit and is less than five years old.
thanks again for any help or advice.