The heater connections for the three amplifying valves are the same in your receiver as they are in the AH34, that's to say they are all connected in parallel across a common voltage source, that being one of the 4 volt secondary windings on the mains transformer.
The heater connections for the rectifier valve are connected across a separate voltage source, that being the other 4 volt winding on the mains transformer.
In the AH34, the rectified HT from the rectifier is taken via a centre tap on its heater supply winding, in your drawing showing the rectifier the rectified HT is taken directly from one side of the rectifier's heater.
If you're unsure about the meaning of parallel connections/circuits etc then take a look at this video, well worth watching:
https://www.youtube.com/watch?v=UfZu5F4u7Ns
Lawrence.