Aftermarket A/C

[Puzzigully]

With the heater, is the tap for the hoses inside the cab? That would mean you always have hot water inside? Won’t that make the cab hotter than the standard setup?

The tap is just inside the firewall so only a few inches of "heated" hose has hot water.
The tap lets the hot water circulate through the core when open
A lot neater then having it in the engine bay with maybe a little heat in the cabin - but if so, that what the A/C is for