Differential Thermostat Operation

SteamHeat

I am familiar with differential thermostats from Robertshaw and Aprilaire.
If you set a differential of 3.0 degrees, the boiler will switch on when the air temperature has dropped 3.0 degrees below the set point, and the boiler will run until the air temperature is 1.0 degrees above the set point.

I am trying to set a thermostat for a family member. It is a Lux PSP 511 LCa.
Lux calls the differential setting SWING. There are values from 1 to 9.
According to what I have found on the internet "1" is 0.25 degrees Fahrenheit, "2" is 0.50 degrees, ..., "9" is 2.25 degrees F.

What I cannot figure out is if you set "9" does the temp have to drop 2.25 degrees below set point to turn on the boiler
and rise 2.25 degrees above set point to turn the boiler off?
Or is turnoff just 1.0 degrees above the set point like the other manufacturers?

Anyone familiar with Lux thermostats?

TIA

Jamie Hall

Usually the swing is the range between the on and off temperatures.

SteamHeat

So, then if the set point is 70 degrees and the swing is 2.25 degrees (setting 9) then the boiler would go on at 68.875 degrees and the boiler would turn off at 71.125 degrees ?

Steamhead

That sounds right.