Cadet makes a nice small in wall heater 220v 1000watts; the thermostat is sold separately so watch for that, amazingly stupid I know.

Once I verified everything is good working condition then I would suggest to the tenant they be put on a budget plan with the gas company and adjust the thermostat setpoint to save some money. 

On Monday, she complained that the programmable thermostat was broken. 

@Jeremy BelandIf there is Wi-Fi, you can get a Nest thermostat to monitor it and change temperatures remotely.

In the common areas and in the bathrooms, I installed Cadet Energy Plus in wall heaters, with digital thermostats. 

They were over an hour and a half late to checkout, left the thermostat at 80 degrees (the house is in Wisconsin so it's winter but 80 degrees???).

Another they turned off the thermostat and failed to turn it back on, resulting in frozen plumbing.

The HVAC person put in a split, so now there are 2 thermostats, one downstairs and one upstairs. 

I don’t need a lot of bandwidth: all I need to do is to control the locks, two thermostats and an outside camera.

Sure no heating or no cooling could be a much bigger issue, but if we're requiring and reminding tenants to be changing filters quarterly the chances of the heating issue being a quick reset on the motherboard or troubleshooting on the thermostat are high.