Suburban SF-30 to SF-35 Furnace Upgrade

Question

Can I replace a SF-30 30000 BTU Suburban furnace with a SF-35 35000 BTU unit?

My SF-30 shook extremely last night and shutdown. Now cool air blows with no heat. Since its 5 years old, I am replacing and will repair this unit as a backup. As I already have 4 interior cabin vents, can I upgrade to a SF-35? The unit is running on a 20 amp fuse and this seems like a better option for our 650 square foot space. The Suburban installation guide specs (except for vent specs) are the same for both units. Thanks. John

old-biscuit · Answer

Suburban Furnaces Service ManualSF-30 minimum vents is 3 (4")SF-35 minimum vents is 4 (4")

cholla_bob · Answer

Thanks for the info Old-Biscuit! I already have 4 vents with the SF-30, so it looks like a direct replacement for the SF-35. I would imagine the propane increase would be 1/5th more. Appreciate that Suburban manual! John

drewe · Answer

Propane usage should not change dramatically for the same heating conditions.  The rate of consumption when the furnace is working would be about a sixth again greater, but since it produces more heat it will run for a shorter period of time and the two theoretically cancel out.

cholla_bob · Answer

Good to hear. Suburban rep could not answer this question: I really appreciate the info Thanks!!!!

scottg · Answer

We only have 3 with our 35 and most of the time I shut off the bedroom vent. You should have no problems at all.

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Suburban SF-30 to SF-35 Furnace Upgrade

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