Thanks DB Electric. I should have mentioned that this is for a greenhouse. Would this thermostat be safe to use in a greenhouse?

This thermostat is not raintight, explosion proof or weather proof it is intended to be used for wall mount baseboard type electrical heaters. Your King BPP 2406 heater is not intended for greenhouse operation it is intended for (King Electric Pic-A-Watt Garage/Workshop Heater). I would recommend that you research heaters that are intended for greenhouse operation as well as thermostats that are also rated for greenhouse operation

Here is a link for greenhouse electric heaters.

http://electricheatsource.com/Products/Commercial-Warehouse-Greenhouse 

If you have 3 phase electrical power available you can lower amperage by raising the voltage. (wattage/voltage=amperage) Example 5700 watt load on your current heater at 480 volts 5700/480=11.875 which is less than 12 amps. But your current heater is not designed for this type of voltage. If you do not have 3 phase electrical power you can still make 3 phase electrical power from single phase by using either a static phase converter or a rotary phase converter. When purchasing new heaters, light ballast or related electrical items for your greenhouse keep this advice in mind by buying 480 volt 3 phase devices.

DB Electric, that link does not work.

http://electricheatsource.com/

DB Electric, you said: "Your King BPP 2406 heater is not intended for greenhouse operation". I bought that unit from a greenhouse supply place and figured that it was intended for greenhouses. Also, other greenhouse supply vendors carry the same unit.

Than they should have the proper wall mount thermostat for the unit. My searches from Amazon and other sites call it a garage workshop heater https://www.houzz.com/discussions/need-help-with-thermostat-dsvw-vd~4525471 

None of the greenhouse vendors sell thermostats that can handle 240 V, 24 A.

That then leaves the one that I found that meets both the voltage and amperage at

https://www.platt.com/search.aspx?q=326151.

You will need to find a way to make it work in your greenhouse

Thanks, DB Electric. I will go with that.