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I have a Nordyne KG7SA 090-24B furnace. It is oversized for current application, short cycles on airflow or high limit. I want to change orifices, which I believe are 47's and downsize around 20%. By the way, at 7000 foot elevation though furnace set up for sea level by default I think, so thought that would cut output enough, but not so. Five lobes, or am I just changing the one in the valve? Did heating work many years ago, but not now. I can do this, but need to know orifices I need and order.

Jim Kimmons

Hi Jim,

Not as simple as just changing the orifices, especially with it being over sized. For safety reasons, can only suggest you have an hvac tech come out and consult with on what is needed to be done for proper operation.

Will need National Fuel Gas Code and local codes for derating for higher altitudes. Will also need local gas heating values.

If furnace is over sized, then it needs to be sized correctly for safety reasons as well as to prevent premature failures.


Thanks,
Robert