Re: [A/S] Furnace replacement

[Charlie/Betty Burke <cbburke@xxxxxxxxxxxxx>]

Dean,

The condition you suggest is excessive back pressure. It was a problem many in the 
industry got familiar with when Hydroflame tried to get 40,000 BTU's out of a very 
small box. The symptom was the burner would cycle off and on irrespective of the 
thermostat setting. What was happening was the hot air could not get out of the heat 
exchanger chamber fast enough and the hi limit switch would cut power to the gas valve 
shutting off the burner. As the blower continued to run the hi limit would cool down 
and reset. And the cycle would start all over. The higher the thermostat setting the 
longer this cycling continued. Continued use lead to scorching and deterioration of 
materials above the furnace and rapid failure of the heat exchanger. The repair 
involved reducing the BTU output, verifying clear ducting and insuring all furnace 
outlets were connected to ducting and vents.  Suburban has never had this problem on 
an original design installation. They are my source for my recommendations.
Before you alter the inlet I suggest you open up all the outlets. They are the source 
of the back pressure problem.

Charlie