Are you sure you are talking about your heater and not your air conditioner?
We are talking specifically about the 600 Series Penguin Roof Top Air Conditioner used with Part Number 3105457 Air Distribution Box Kit which is PRE-WIRED FOR
OPTIONAL HEAT PACKAGE. (Transcribed from the front page of the A/C manual).
Section 4 of the operating instructions says:
"Heating Operation (
With Optional Heating Kit Installed).
Note: This electrical heater will not replace a furnace for heating your RV in cold weather. The intent is to remove the chill on cool days or mornings.
A. Turn the selector to Opt. Heat.
B. The heater will come on and begin heating.
C. When desired temperature level in RV is reached,
move the selector switch to the off position or fan position. (My emph).
Note: [A/C] thermostat does not control heater ON/OFF cycle."
My note: the "cycle" referred to above is the poor occupant manually working the selector switch. This is actually what amazed Luisa and caused her to post here.
Duo Therm Series 600 is an A/C model.
We know that.
I don't know of any Hi-Lo not having a thermostat for the furnace.
Yes, we do have a thermostat for the propane furnace.
The A/C unit has a temperature control mounted on it.
Yes, that is for the A/C, not the optional heater kit.
Hope this clarifies . . .
Ted and Luisa.