I have a 2008 diesel van and have the Espar 7 day timer installed on the wall for the diesel heater.
It works fine and was installed by SMBW.
After two seasons, I realize that I don't use the 7 day timer and I would much rather have a basic thermostat.
Why? The 7 day timer doesn't seem to have the function that says turn on the heater if it drops below a certain temperature, say 40 degrees. As a result, I am that function and have to jump down and turn on the heater when any sleeper in the van is cold. To make sure I turn on the heat before they get cold, the girls have given me the thinnest sleeping bag. It would seem more sensible to get a thermostat.
The 7 day timer does, as you would expect, allow you to turn on the heater at specific times for every day of the week. We aren't liveaboards so that doesn't model our usage well. SMBW only carries the 7 day timer so couldn't do a switch.
Do you have a Espar thermostat and want to trade for a 7 day? Drop me a message.
Details on the various controllers are here.
If I have no takers, I'll follow advice on the forum and replace my 7 day timer with a basic house thermostat.