Bob wrote:
"Bob" wrote in message
...
Last night our central AC/heat pump quit cooling and I found the
unit was frozen. The unit was installed when we had the house
built; it's in its eleventh year. Has generally worked reasonably
well, but have had several service calls in the last four or five
years.
We had a service man out here today. He had several issues:
- Inside air handler is not the same brand as the outside unit and
he doesn't know if they are matched. (He ought know, or find out!)
- The return air ducts are not big enough, one is 16 inches and he
said it should be at least 18 and preferably 20 inches.
For a 4-Ton system I would go for the larger Air Return.
Air Filter Rack Sizing:
For efficient operation - Gross Return Air filter grille area: 200-sq.
ins. or more per ton, is required.
Keep air velocities through the filter(s) as low as possible. Filter
Grille(s) 350-FPM.
You probably need to eliminate the too small a furnace filter, & maybe
setup two Return Air Filter Racks to get the proper FPM velocity through
the Return Air Filter(s).
ACCA Manual D specifies a maximum Return grille velocity of less than
500 ft per minute, 350-FPM is better,
and "a maximum supply outlet of less than 700 ft per minute, most use
500 or 600-FPM."
Filter mfg'ers should print the free air area of their clean filter on
the edge of the filter along with the pressure drop data.
The wrong kind of filters' as they load, can drop airflow below required
levels!
The other
in the master bedroom is 9 inches and he said that was okay.
- There is a Freon leak in the inside unit, which caused the
system to loose Freon which caused the freezing problem.
His recommendation was to replace both units and install a 20 inch
return duct from the hall filter.
He would not put Freon in our unit so it would cool because he
said it was not legal. He said he and the company he works for
could loose their license. But, if I'd give $2,000 down on a new
unit, he would put Freon in for us.
I asked if was not legal to put in Freon and he could loose his
license, why would he do it if I gave him money down. His answer,
which I believe is true was that by giving him $2,000 down, that
we would go ahead and put in the new unit. Otherwise, we might
not. That is their business policy, which they are entitled to,
but as a consumer, it just struck me wrong somehow.
As far as prices go:
A Lennox system with ten year parts and labor warranty, the new
return duct, a new thermostat and four heat strips was priced at
$7,400.
A Merit, a brand I never heard of, was $500 cheaper for the same
items but only had a two year labor and five year parts warranty.
A Maytag with a twelve / twelve warranty would run close to
$8,000.
Here is what I decided. I somehow didn't care for the attitude of
the company, although the serviceman was a heck of a nice guy. I
certainly wasn't going to commit to spending that much money
without getting some knowledgeable opinions and some other bids.
So, I was charged $149 for the one hour service call and he left.
Here are my questions:
- Is needing all these items replaced seem reasonable?
- Is his explanation of what is wrong sound reasonable?
- If I go ahead and get a new unit, what brands are best?
- Were his prices reasonable?
Sorry this is so long, but I felt I needed to explain as much as I
could so you guys could give a better opinion.
Thanks in advance for reading and any advice you can give. Bob-tx
I realized after I sent this, that I didn't mention the unit size.
It is four ton.
Also, we have had another bid on a Trane unit. This service man
said the 16 inch duct was quite sufficient. Other than that, about
the same equipment except this is an R22 Freon while the first bid
was on a unit with 410A Freon. The second bidder said they have had
a lot of problems with the 410A units due to the higher pressure.
So, I'm a little more confused than I was. I have another company
coming out this afternoon. I'll keep you posted.
Thanks again, Bob-tx
Before doing anything, have a manual J heat-gain heat-loss done so you
can size the hat & air equipment to the loads.
A 3-Ton AC might do the job, then the 16" Return would be adequate to
eliminate the duct retro expenses!
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