Rod Speed wrote:

RP wrote:

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, 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 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.

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. 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. 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.


It isn't going to work.


Corse it'll work.


If you raise the temp in one room to a point higher than the desired temp,


That isnt going to happen when the secondary system is
JUST used to come off the setback in a reasonable time.


then you're going to have heat losses through the exterior walls that wouldn't
have occurred with a centrally ducted system, thus defeating the purpose, at
least to some extent.


Nope.


If you feed it into an interior room then that room will simply get too hot,
no question about it.


Wrong again.


I hate to say it but it's not a very intelligent alternative.


Corse it will work fine. No reason why the secondary system
cant have a slightly lower than normal temperature set so it
recovers from the setback in a decent time and then stops and
leaves the primary system to get the temp back up to normal.
Thats going to happen fine since the temp difference is well
within its capabilitys.

Supposing that I grant your every point, what would be the point of such
a system? Wouldn't it be much easier to simply install a larger staged
system?

hvacrmedic