Here are some answers to some frequently asked questions regarding high performance HVAC Installation Price/Time Quotes:
What is the size of the HVAC replacement sytem that you are quoting?
The size being priced is for a 3 ton – however I do not really price
by the size – because I do not know what size you will need until I do
the calculations for the sizing. Therefore if we need a 4 ton or a 5
ton I do not raise the price, as long as that is what the calculations
are telling me. I have done enough of these on similar houses to know
that it will be close to a 3 ton for your house (simple double pane windows
with typical window surface areas, 2 story, with 2300 floor area, Las Vegas at 110 degrees out).
That price is for a 16 seer two stage unit with special settings on
the thermostat so that second stage does not engage unless the
temperature starts to go up if first stage does not cut it. When we
build systems like this they only cost near 1kw per hour to run. That
is about $0.14 per hour to run and this puts the cost at around $1-2
per day to keep the house cool at 78 degrees.
I was just looking over a system yesterday, we installed two years back, that was a 3 ton on a
3300 sq ft home and the second stage had never come on – was running
on about 2 tons, since we installed it.
Why are the ducts so expensive? R8 duct does not cost that much really.
On the ducts at your home – those are going to be a challenge -
because your attic does not have much room at all. The price for the
parts, including new plenums, start collars, 90 degree elbows, new
operable curved blade grills, etc gets up to around $1000 – 1400. Then
it takes two guys about 2 days normally to do the ducts and the
plenums – but with yours it will take an extra day for sure to figure
it out and navigate and get it installed (still no guarantee it can be
done – need to have my installer look at it and think about it first -
we can have him look at it for free if you are really interested.) We
do a lot more on a duct installation than a typical contractor,
including sealing every single joint with duct mastic prior to and
with assembly – This makes the duct leakage near zero – on the stuff
we can get access to. We use metal 90 elbows at all supply registers
and at returns if we can fit them. Each run is designed for the
airflow as called for by the sizing calculations and each run has an
air balancing damper for adjusting airflow to within a set parameter.
We oversize the return ducts – so that the duct pressures are within
tolerances set by the equipment manufacturers – this means the fan
runs at about 150-350 watts on high airflow instead of around 700
watts.
Why are we adding insulation, and what are we doing exactly?
The added insulation is for making insulation repairs as the attic
gets disturbed, and as well we will then cover the ducts that we can
in insulation – putting the average r value up to near R20 for just the ducts.
Most AC energy is lost in the ducts, as typical is 30% btuh is lost in the
duct work. We reduce this by using blow in insulation and building
dikes and working to get the ducts covered as much as possible. The
latest research from testing just done in the last year tends toward
most energy is lost in the return duct work – so figuring out how to
bury and cover this duct work is key.
Other than that we bring the attic insulation up to about r40 and this has been found to be a cost
effective improvement for homes, where you can get access to the
attic. Also we are already in there and this is a good time to get it done.
Why will your work take so much longer? Other AC contractors say they can do it in half the time.
Where most contractors would be able to go in and replace an Hvac
system appliance boxes in a long day (with little care in the world about
the bad duct problems). That is easy money for those contractors – but
the disservice is to the homeowners really. Here is what we find after
we install a system – we test it several ways and spend half a day or more just
making adjustments to optimize the system – commissioning. This is a
painstaking process and the last thing an installer wants to do is fix
a system that was just installed – but needing to fix it happens a
lot. We tell the systems to do things – and when we test we find they
aren’t doing what we thought they were supposed to be doing. You cant
know this until you test it. And we find that we make a lot more
mistakes than we think we do.
But with testing and commissioning we get them fixed up and become even better installers on the next job.
