After living without heat for a week in a house with gas and a gas
heating system, I want to change the heating system so that less
electricity is required.

Our current use hot water with 4 zones, each with a thermostat
and an electric motor, so 4 motors.

Independent of wanting we want more zones.
The 3 plumbers we spoke to say they don't want values or motor
distributed around the house, so we need to add some pipes
back to the furnace, rather than putting electrically controlled
valves in the three places where the original system was setup
in 1955 to allow for more zones.

So, rather than have a manifold with 4 motors on the push side
and a manifold with 4 "gravity" valves on the drain side,
the plumbers want to add 3 more motors.

The problems with more motors a
. not enough room
. if all 7 motors go on at once the emergency generator
would need to be too big.

Is it possible to keep the current 4 motors or even fewer,
plus electrically activated valves on the "push" side
manifold and have things work?.

Also, could we then setup things so could run without
any motors, by using electricity only for the flue vent
and the thermostatic controls? (We don't have electronic
ignition, so we don't need electricity for that. As
I've said, there are "gravity" flow valves, but the are
left over from the 1955 furnace, and haven't actually been
used as such with the current furnace, which is from about
1995.)