Logan Shaw wrote
Abby Normal wrote
Rod Speed wrote
Abby Normal wrote

come back and see me when you figured out how to
get multiple systems to share common duct work rookie.

Dont have to share the same ductwork, ****wit.

okay so you are going to instal 3 systems now, three independent duct systems

I hate to say it, but I have to concur with Rod on this one. His style of
argumentation leaves a lot to be desired,

I only use that approach when some prat like this one
attempts to bull**** its way out of its predicament with
puerile **** like that one attempted.

but in this case, I agree with his conclusion.

If you are coming off setback and using a secondary heat pump to do only that,
it doesn't need duct work. If it just heats the
air in one room, the primary system will be running continuously
(or nearly) and will be circulating the air around the house anyway.

Even if the secondary heat pump heats the air in one room up to 95F in the
process, eventually that'll even out as the other system recirculates
everything.

And that isnt going to happen if it heats up the main area.

And heating the air up to such a high temperature is unlikely anyway, since by
definition when you are recovering from setback, the temperature is colder
than you'd really like it.

It could happen if you were silly enough to put it in a small room.

However, I do have to admit there could be problems if the secondary heat pump
(that's used only during recovery) is putting heat mainly into the room with
the thermostat.

Nope, not if it heats the main living area.

If the temperature in that room rises faster than in the rest of the house, it
could cause the system to think recovery has finished when it hasn't yet
gotten to that point.

Not if it heats the main living area and the primary system
spreads that heat out to the rest of the rooms. By definition
it should have been designed to do that because it needs
to do that when not coming back from the setback.

And if the secondary heat pump is too far away from the thermostat, it could
cause the system to overshoot the target and heat up the house too much. But,
those are control issues rather than duct issues, and they seem solvable.

Corse they are solvable and you dont have to use just
one thermostat either. One obvious approach is to have
a different one for the primary and secondary systems.