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Posted by dpb on December 18, 2006, 4:12 pm
smith_bp101@hotmail.com wrote:
> > > Any advice appreciated!
> >
> > More quotes on comparable systems or varying systems from same vendor
> > would be much more easily compared.
> >
> > First thing I'd ask is whether either did an actual load calculation to
> > size the unit or whether they simply looked at existing and eyeballed
> > it. Unless current system is inadequate, why the larger unit is a
> > question? Also, unless there's a distribution problem, why the
> > ductwork modification? (Perhaps it is only a transition piece though?)
> >
> > You don't give any hint as to what part of CA -- there's a world of
> > difference between requirements in CA. Unless it's a very mild area
> > needing heat very infrequently, I'd recommend against any unit as low
> > in efficiency as 80% -- just doesn't make sense in the present
> > energy-cost environment and it ain't going to get any better...
> >
> > I'm thinking you need more info and choices and definitely need more
> > info from your end to be anything more than wag's...
>
> Sorry for the lack of info.
> I'm in Stockton, CA. The first vendor did a load calculation and thus
> came up with the new ductwork size. He place a sensor in the input and
> output of the furnace. There was another quote that I didn't include
> because the vendor wanted to sell a Peron (not sure if that is correct
> spelling) system. His calculation also included installation of larger
> ducts. His price was near $10,000 so I discluded him.
>
> The second vendor ($6800 quote) did not do any load calculations.
I still think you need more or to evaluate what you've got more
thoroughly.
I know roughly where Stockton is, but would have to do a lot more work
to have any feel for the actual heating/cooling loads to comment more
than I already have on the issue of a (relatively) low-efficiency
furnace --- I still don't think that makes much sense these days.
At a minimum I would discuss the "why" of the ductwork sizing and ask
for a comparative bid on a 90+% unit from the first guy and an option
w/o the new ductwork. Then you could at least compare two nearly
equivalent systems, but a third would also be good imo.
The ductwork will only really affect the velocity and if you've had
adequate heating/cooling previously without drafts being an issue, I
don't directly follow the reasoning for the changeout w/o additional
information. Your initial post didn't provide comparative data on the
heating units, at least in a consistent format. Heating is rarely, if
ever, given in tons, so still not clear whether the furnace output was
also upgraded or not by either/both or whether the proposed units are
the same or not. While the increase from 2.5T to 3T on the A/C side
isn't all that much and, if I'm not mistaken, cooling will be your main
load, again if you weren't short of cooling previously when the system
was functioning well, it's possible you might be overcooling. That he
apparently did a load calculation and included some measurements is
somewhat reassuring, but still another for consistency's sake would
seem prudent.
I don't recognize the third vendor's system so can't comment. Unless
it were something like a ground loop or ultra-high-efficiency, would
seem quite expensive.
HTH w/ at least some things to consider...
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