Line voltage thermostat question

I am looking for a 7 day programmable line voltage thermostat to control wall mounted 240v electric heaters in the vestibules at a church/school building. Some are 1500 watts, some are 3000 watts Currently the units are running off of the built in thermostats, but they are wasting alot of money this way.

I am looking at the Honeywell TL8230A1003. It looks like the perfect unit for my needs except for one thing. It says that it has 15 minute heating cycles? I am wondering exactly what this means. Does it mean that it will only allow one call for heat every 15 minutes? So if someone opens the door, the heater will kick on and will satisfy the temperature rather quickly. If another person comes in 5 minutes later, will the heater be allowed to run again? Or will you have to wait for 10 minues before the heater will run again? If this is the case, I'm thinking that this thermostat isn't a good idea for a vestibule that could need heat every few minutes during high traffic times.

Any help regarding this Honeywell thermostat, or other models is greatly appreciated.

If it comes down to it, I'll just build a transformer/relay box and use a 24v thermostat that is capable of more cph.

Thanks,
Michael