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Posted by Fins on June 4, 2007, 8:46 am
Here in FL, my centeral A/C condensor coils freeze up after running
for an hour or so.I haad a repair man check it and found the freeon
was Ok, but said the Evaporator coil was dirty and should be cleaned.
He also said the system didn't have enough return duct area. The
house is at least 25 years old and the current a/c unit is 9.5 years
old. It was working fine with the duct work it has, up until this
problem.
The repair man cleaned the coils and I still have the same problem.
Not sure if I want to let him start installing a new duct.
Any suggestions?
He is coming back this morning .
Thanks
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Posted by Lloyd E. Sponenburgh on June 4, 2007, 9:53 am
> Here in FL, my centeral A/C condensor coils freeze up after running
> for an hour or so.I haad a repair man check it and found the freeon
> was Ok, but said the Evaporator coil was dirty and should be cleaned.
> He also said the system didn't have enough return duct area. The
> house is at least 25 years old and the current a/c unit is 9.5 years
> old. It was working fine with the duct work it has, up until this
> problem.
> The repair man cleaned the coils and I still have the same problem.
>
> Not sure if I want to let him start installing a new duct.
A near ten-year-old system may not have enough evaporator _fins_ remaining
to be effective any more. That, and the swaging between fins and coil is
probably so corroded that there's poor thermal conductivity fin-to-coil.
If your return was undersized to begin with but everything else was healthy,
it might work OK. But, enter corrosion of the evap, some crud that cannot
effectively be washed out, some reduction of the size and number of fins by
un-judicious use of corrosive "Coil-Brite" type cleaners, a tired, crudded
up indoor fan, ducting so linted up inside that it's like a fur blanket,
the inevitable leaks in ducting, etc...and.... you're ready for a new
system.
I don't know where you live, but if you have sulfurous water in your home or
even nearby, the H2S gas makes the corrosion problem even worse.
Maybe its not what you wanted hear, but nothing lasts forever. On the
bright side, you'll probably enjoy the energy savings you'll get from a
decent new system. Don't just throw it in, though. Let the tech repair all
your ducting, fix leaks, replace flex duct; it can be hard and crispy, and
on the verge of failing, and the new flex has over twice the R-value of the
old material. It won't be cheap, but it's really worth it.
LLoyd
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Posted by on June 4, 2007, 10:29 am
On Mon, 4 Jun 2007 09:53:39 -0400, "Lloyd E. Sponenburgh"
>
>> Here in FL, my centeral A/C condensor coils freeze up after running
>> for an hour or so.I haad a repair man check it and found the freeon
>> was Ok, but said the Evaporator coil was dirty and should be cleaned.
>> He also said the system didn't have enough return duct area. The
>> house is at least 25 years old and the current a/c unit is 9.5 years
>> old. It was working fine with the duct work it has, up until this
>> problem.
>> The repair man cleaned the coils and I still have the same problem.
>>
>> Not sure if I want to let him start installing a new duct.
>
>A near ten-year-old system may not have enough evaporator _fins_ remaining
>to be effective any more. That, and the swaging between fins and coil is
>probably so corroded that there's poor thermal conductivity fin-to-coil.
Bwahahahaha !!!!!!
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Posted by on June 4, 2007, 11:16 am
> On Mon, 4 Jun 2007 09:53:39 -0400, "Lloyd E. Sponenburgh"
>
> >
> >> Here in FL, my centeral A/C condensor coils freeze up after running
> >> for an hour or so.I haad a repair man check it and found the freeon
> >> was Ok, but said the Evaporator coil was dirty and should be cleaned.
> >> He also said the system didn't have enough return duct area. The
> >> house is at least 25 years old and the current a/c unit is 9.5 years
> >> old. It was working fine with the duct work it has, up until this
> >> problem.
> >> The repair man cleaned the coils and I still have the same problem.
> >>
> >> Not sure if I want to let him start installing a new duct.
> >
> >A near ten-year-old system may not have enough evaporator _fins_
remaining
> >to be effective any more. That, and the swaging between fins and coil is
> >probably so corroded that there's poor thermal conductivity fin-to-coil.
>
> Bwahahahaha !!!!!!
Someone must be using sandpaper again! :-)
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Posted by Lloyd E. Sponenburgh on June 4, 2007, 12:19 pm
>> Bwahahahaha !!!!!!
>
>
> Someone must be using sandpaper again! :-)
My experience is tiny; both of you are supposed to have long experience --
but apparently not in Florida.
In my short tenure as a helper, I've seen by now dozens of systems with bare
vestiges of the evaporator fins left. Salt and sulfur corrosion are the
main culprits. Dumb-assed (read that as "experienced") technicians putting
coil-brite on full-strength is another big cause.
Don't underestimate how inefficient a coil will become when the fin-to-tube
contact rots. It can look just fine, and still not transfer heat fast
enough to work properly. You don't normally get ice on the fins when that
happens, just at the U-bends, but it screws up the ability to cool the air
stream just the same.
Laugh all you want. IIRC, Noon lives in a hot/wet locale. Maybe he can
illucidate.
LLoyd
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