My house has no central air, but radiant baseboard heat provided by a boiler (Weil McClain) the boiler was installed around 2005 and uses a traditional thermostat. I'm having central air installed and the installer (old guy) told me it's possible to just use one thermostat but wants to just put a separate one in for air.

I'm providing the C4 aprilaire thermostat (will do remote temperature sensor) so I rather suspect this is why he doesn't want to try and tie in the two systems.

How can this be done? It has to be possible! He's hung up on both systems having a transformer and doesn't want to tie them both in (understandable) can I just have the Tstat powered by the boiler transformer? Isn't a thermostat just a contact closure essentially when heat, air or fan is called for?

Thanks!

Current thermostat only has a wire connected to RH and W