I have a condo which Im renting out and the tenant who wants to set the temperature to over 25C - she has it at 90F. Yes I know its ridiculous but to each their own. The thermostat is not a digital one and the install happened 8 years ago (age of condo as well). The previous tenant did not mention any issues. The current tenant moved in and set the thermostat to 90F. The ambient temperature is approx 21C. The furnance seems to come on for under 5mins and then shuts off. What could be the cause of this? Does the thermostat or condo furnance have an upper limit? Im considering installing a new themrostat but want to consult the matter. The property managemnt says their are no issues to report with the heating. Any ideas are appreciated.