< or > 90% efficiency oil furnace?

[paulmars]

I just bought a new thermostat for my central oil HVAC unit. Honeywell TH4110D. I can set it for oil heater <90% efficiency or >90% efficiency. I'm not sure which to set it at. I am hoping that my unit is not exactly 90%, cuz then I'm screwed. Bryant model 58cma105-12 installed in year 2001. Bryant wont help me. they insist that i pay a service tech to come here and tell me. That ain't happening.

Also, compressor cycle rate setting 3 is recommended for most compressors. I hope that is what I have.

Your thoughts?

tks,
pa

[FordMan59]

Most oil furnaces are less than 90% efficient. Given that and that the unit is an older model I vote less than <90%. The compressor cycle rate of 3 probably means the thermostat won't allow the compressor to cycle more often than every 3 minutes to protect the compressor from damage. In most instances the compressor isn't going to cycle near that often. Monitor heater used to advertise their high efficiency rating and they were only rated at 87% efficient.

[TechEditor]

I don't know about the Monitor heaters but the Toyo's are currently rated at 87% per government regulations because they don't have condensate pumps. Before the regulations, if you look back at some old Toyo advertisements for their Laser heaters, depending on the model, they were advertised at 91 - 93% efficient.