We are looking to replace our 4 ton a/c unit in our house. Here are the
stats on the house:
1. 2200 sq ft house
2. Three attics (front, back, middle)
3. Insulation = shredded newspaper treated with flame retardant.
a. The insulation is crumbling into dust.
4. Windows on house are single paned, aluminum CHEAP windows
a. The kind used in houses in the 1960s.
5. House was built in 1964.
6. Windows are chaulked but still leak tremendous amounts of heat/cool
because, as I said, they are cheap windows. (You can feel the heat
radiating off of them right now.)
1. The a/c guy only wants to replace our 4 ton unit with another 4 ton
unit. His reason is that technology has advanced and a new 4 ton unit
will work better and cool better. Question: Will it?
2. Our contention is that (as the a/c guy explained to us) 2200sqft/500
= 4.4 tons of a/c. Question: If the equation comes out to be 4.4 tons -
shouldn't the a/c guy go to at least 4.5 tons?
3. Given all of the bad problems with the house (and yes - we should
reinsulate the house and get better windows - but I'm unemployed and we
can barely afford to get the new a/c) - Question: Should the a/c guy
blindly follow the specs he is quoting or should he realize that, given
the condition of the house, he should increase the number of tons to
compensate for the conditions?
Our outlook is that, given the conditions of the house, a larger unit
would work better. We might have to pay more for it but at least, here
in Houston, Texas - we would stay cool inside while the temperature
outside rises to over 100 degrees.
Please give me some feed back on this because we would like to be able
to present some valid arguments to the a/c person (other than what we've
already pointed out to this guy) on exactly why this blue book's
equations can not be strictly adhered to and instead need to be modified
to our needs.
Thanks in advance for any help you can give.
Please back it up, half a step. What's wrong with the old
system? I've fixed systems that other people thought were
forever dead. That said, an old sytem about to die seldom
performs to the name plate rating. So, taking out a wimpy,
pathetic, under performing system that says "4 tons" on the
name plate, replace it with one really doing 4 tons. Might
be major change.
The old system was originally put in pre 1996 (when we bought the
house). We replaced the heat exchanger (outside unit) in 1998 because
we found out that it was a 2 ton unit while the inside unit was a 4 ton
unit. So the outside unit would freeze up/trip breaker all the time.
The house came with the a/c unit and duct work all insulated (but not
the attic itself). However, the house (and unit) has gone through a lot
and the a/c now only cools to approximately 15 degrees below the outside
temperature. At over 100 degrees temperatures - we are overheating
inside of our own house (which is one of the reasons I'm answering so late).
While it is true a new 4 ton unit might work - I'm used to working in
heavily a/c'd areas (computer rooms) which range between 60 degrees and
65 degrees. Around 75 degrees I just begin to melt. Before I was
married - all of the apartments I lived in could keep the temperature
down. This house is the first house I've ever bought and the a/c, when
we bought it, seemed like it could handle the heat. Unfortunately -
that was late fall when we bought the house (in 1996). I should have
waited to buy it until summer time. Then I would have seen that the a/c
could not handle the house.
I think we actually would do better with two separate units. One for
the downstairs and one for the upstairs.
Stormin Mormon wrote:
Hey - Mark Manning:
1. The only method to determine the correct needs of a structure is to have
LOAD ENGINEERING performed by an LICENSED HVAC contractor or a LICENSED
2. It is likely that your existing system leaks air into other spaces
besides the conditioned space [your living quarters.] Most systems
installed years ago leak at a rate of about 30% or more. [I just performed
a duct test on two homes this week, the 4-ton leaked over 400 cfm and the 3-
ton leaked just under 300 cfm.] Just think of the savings if that cooled /
heated air was put where it belongs instead of in the attic. Several states
currently required duct testing as part of the permitting process.
3. Replacement equipment is more efficient than the older equipment and can
reduce your monthly utility cost. It has been determined that the higher
efficiency equipment will pay for itself through energy / utility savings.
Most utility's offer rebates reducing your initial costs.
4. Attic and wall insulation plays an important role in reducing your
utility costs and can increase your family's comfort. Have that newspaper
removed from the attic [which by the way is a fire hazard although you
believe it has flame retardant] and have insulation bates either laved or
blown in. That alone will reduce your utility costs annually. And you might
be able to get the local utility to help pay a major portion of the costs.
1. The guy is (as far as I know) a licensed HVAC person. But he is
dismissing the condition of the windows and attic. Glossing over those
problems if you will.
2. As I said - we can barely afford the new a/c unit. There are other
problems as well. Allisan flooded our house and black mold got into the
ducts as well - which is also a big incentive to replace the entire a/c
unit. (I can send/post a picture of one of our vents which has black
mold growing around the vent.) So our choice is - insulate the attic
and have black mold and bad a/c or change out the a/c, get rid of the
mold, and have great cooling. We want the latter.
3. I'll have to call Reliant and see what they say about this.
4. Yeah, I know it is a fire hazard. When Allisan came through we got
rid of it downstairs but then the contractor walked on us and took all
of the money. So we never got the upstairs re-insulated. Since then
we've been hit by one problem after another. (Funerals, extraneous
bills, IRS saying we owed them $10,000.00 because a company I had worked
for did NOT pay the taxes on the money I had made even though they DID
take it out of my paycheck, and so on.) So we are pretty much
piss-poor. So our choices are: A)Get a new a/c and forget about the
need for new insulation, or B)Get new insulation and forget about the
a/c. We can only do one or the other - not both. So we are going with
What about the equation stuff? Even a qualified HVAC person will do
some equations. The thing is - do they have to blindly follow them? Or
can they adjust them according to the situation?
I am not a HVAC contractor. Just another homeowner trying to learn
more about HVAC in order to make good decisions. So do your own
thinking about my recommendations.
I would go with the 4 ton unit. My reasoning is that you can do some
things to improve the house yourself. I would start by taking a
sample of the newspaper insulation outside and see if it will burn.
Next add insulation to your attic. The cost is likely to be a little
as the difference between the 4 ton and the 5 ton air conditioner.
Buy some caulk and caulk everywhere. $20 for caulk will probably
reduce you electric bill by $20 over the air conditioning season.
Ditto for weather stripping the doors and windows.
Buy some of those plastic sheets to insulate your windows. They tape
around the window and then you use a hair dryer to shrink them so
there are no wrinkles.
Switch to compact flouescent lamps. They use a lot less power and
will reduce the amount of air conditioning you need. Check to see if
there are other things that add heat to the inside of the house. For
example your how water heater may be inside the house. You might be
able to add insulation to it.
Ask your HVAC guy about more things you can do fairly cheaply. Maybe
better attic venting.
Think about buying a window unit just for the bedroom so you can not
air condition the whole house in order to get some sleep. Think about
ceiling fans and just ordinary fans. I use a ordinary box fan bought
at a garage sale for a couple of bucks set in the window to push out
the hot air in the second story in the evenings. It brings the
temperature down to what it is outside. Might not be any help in
Houston during the summer, but would save running the air conditioner
as much in te Spring and Fall.
1. Zyp is right! all duct joints should be checked for leaks,
2. don't rely on one contractor's input, get several inputs.
3. were the flooded walls gutted? i hope u removed any wet
if walls were opened or are still bare, u need a heat balance
performed on the house.
4. are your ducts in the walls, attic, under the floor, where? how
the floodwater get?
5. with insufficient funds to work with, a new AC and a new duct
will only partially solve your temp problem (u need major
6. pres's new ARRA (american recovery and reinvestment tax act of
a tax credit 30% of product cost (up to $1500) for energy
7. i know u probably cannot afford it, but u should talk to a cpa or
about the irs issue (i know a guy who (though an attorney) got the
re-think his unusual situation). isn't there such a thing as
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If you can get a loan or get some Fed., weatherization money, reduce the
heat-gain as much as possible!
Plug all the air infiltration places; it can be half of the heat-load.
The ductwork & airflow is the next gigantic loss of cooling BTUH of your
The install is critically important - READ & Learn what you need to know!
Make hard-copies - Print the pages linked below.
Get it all done right
On 2200-sf you ought to be able to get down to a 3.5-Ton unit.
It would work with the 4-Ton coil, - if they are a similar SEER.
There is a lot to know & learn:
WISDOM PRINCIPLED EMPOWERMENT COMMUNICATIONS -
Liberals are good at spending other peoples money, and
increasing dependance on government. What was that, about
not being a liberal?
So, you support the Constitution. Where, in there, does it
say that the Fed can take my money by force, and spend it on
fixing someone else's house?
It was Free Market Capitalism that brought down the economy, not govt
regulation, - but a lack of effective enforced govt regs.
You can't win either way, because in your mind you lose either way. If
we want a future we'll have to be willing to share, work together &
WISDOM PRINCIPLED EMPOWERMENT COMMUNICATIONS -
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