I am in the processing of adding the last section of my house which was
designed to be built in 3 parts. The first part of the house has a GE (now
with an American Standard outside unit) that has been quite satisfactory. I
have a Rudd heat pump in the 2nd part (single story, 1246 sq ft) of which
I'm not too fond. The third part of the house is 2 story (1414 down + 840
up floored + 574 up "open" sq ft). Before talking to the local hvac pros,
I'm trying to get a little background and a feeling on whether it would be
better to go with another heat pump for the 3rd section or to replace the
2nd part's Rudd with a larger Amer Std that can be zoned to handle house
part 2 & 3. General opinions?
Didn't intend to imply that changing brands would solve anything. Just
trying to convey my feeling that the unit & hvac design for the 2nd part of
the house were not 100% satisfactory and thus were potentially "fair game"
for redesign if a single unit was a reasonable option. I had that 2nd unit
installed by a man who'd been doing a good job with my a/c repairs for a
long time and I trusted his opinion. However, he was retiring & selling his
business, so he brought in the new owner to assist with the job. In
hindsight, I don't think they did a very good job with the design. Later, I
found that the new owner to be less than satisfactory with repairs. Does
make question this time whether use my very reliable repair pro with the new
work or to look at a firm that does new installations regularly... My
inclination is to go with my "regular" since he'd be the one to make repairs
later, but I'd like to go in with a little background education first.
Ignore the age of the current system. What I'm trying to determine is
whether the new 3rd section (read as "nothing there now") and the existing
2nd section should use each use a separate unit or to use a larger, single
unit with zoning for both.
It kind of sounds like you're looking for an ironclad "yes/no" answer here when
the reality is that like many things, there
are tradeoffs involved and you need to make your own choice as to what's
important to you.
A single unit with zoning has 3 primary advantages: lower cost, cheaper, and
less expensive. Both to install and maintain.
Separate units have pretty much everything else going for them. Better
performance/temperature control, redundancy (if one
unit fails you can still get heat/cool from the other), less noise when only 1
unit is operating. Installation can be easier
since the ductwork for each unit covers a smaller area. Also in a retrofit case
like yours, it means there's no modification
needed to the wiring/ductwork/etc. of the existing system.
Cost-of-operation-wise, I'm not sure which approach wins. On paper, larger
units are sometimes more efficient than smaller
ones, which would favor the zoned system. However I'm not so sure that's true
in the "real world" when the zoning-related
factors are added into the equation.
Eric, I realize there are many trade-offs and that there is probably no
clear-cut "right" answer that fits all cases. Would make the decision much
easier if it were so. Just making a stab at identifying the pros/cons &
seeing if anyone has had "real-life" experience with zoning, particularly
with a 2 story. FWIW, I'm near Austin, TX, so cooling is primary.
Thanks for your reply.
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