Jim, that's either a B or BL and I should know the difference without having to get to a book. Makes no big difference as both are quite nearly the same. Most always, they were hung on the firemans side of the boiler. Live steam was used to operate the steam pump which was the smaller diameter cylinder on the upper right hand side. If you'll look at photos, this steam pump, via a rod, ran both the cold water pump & the hot water pump. The actual heater was built into the device, so you could call it a combined feedwater heater/pump. The heater portion is on the left hand side of the device and gets exhaust steam from the front end. Before this steam reaches the heater, there is an oil separator to hopefully trap the residual steam cylinder oil that is present. So, to answer your question, the heater was not located in the smokebox or even up near the stack. Any photos of the firemans side of that loco should show the Worthington FW heater for you. Hope this helps.
As an aside, this one is one of the smallest sizes offered, there may have been an even smaller one. The ones on the Cab-Forwards & 2-10-2's were huge in comparison...they delivered more water per hour, but also used more steam.