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Posted by Bubba on June 28, 2007, 8:10 pm
>
>>
>> >
>> > >
>> > > >
>> > > > >
>> > > > > >
>> > > > > > > I have a Central AC system that's been around since '73. The
>> air
>> > > > > > > temperature coming out of the last register in line has
>> > consistently
>> > > > > been
>> > > > > > > 54-56F year to year even with an OAT of 90F.. My daughter has
>a
>> > new
>> > > > > system
>> > > > > > > and initially the register air temp was 70F. Service Tech
>says
>> he
>> > > > found
>> > > > > a
>> > > > > > > leak. Now, after the repair, the air temp doesn't get lower
>> than
>> > > 67F
>> > > > > and
>> > > > > > > the Tech says that's normal and everything is working OK. OAT
>> is
>> > in
>> > > > the
>> > > > > > > high 80's low 90's--Is she getting a line of bullshit??
>> > > > > > > MLD
>> > > > > >
>> > > > > >
>> > > > > > You would normally get a minimum of 12-15 degree drop. It's all
>> > going
>> > > to
>> > > > > > depend on a lot of data.
>> > > > > >
>> > > > > > So what's her temp differential?
>> > > > > >
>> > > > >
>> > > > > Don't have the exact numbers but for a ballpark evaluation--Return
>> Air
>> > > > Temp
>> > > > > (room temp)=73F with a register discharge=67F. That low a
>> > differential
>> > > (6
>> > > > > deg ) would seem to indicate that the unit still is in trouble and
>> > needs
>> > > > > help.
>> > > > > One possible explanation and it's a BIG reach-- is the fact that
>the
>> > AC
>> > > > air
>> > > > > has to travel from basement to a second level and is being heated
>as
>> > it
>> > > > > makes its way up the line--It's not that long a run, however, and
>> the
>> > > > ducts
>> > > > > that are visible are well insulated --no negative comment from the
>> > > Service
>> > > > > Tech as to this being a possible explanation. Using my own system
>> as
>> > > > > previously noted--return air temp=77F with a register air
>temp=56F.
>> > > giving
>> > > > a
>> > > > > differential of 21F which seems consistent with a good working
>> > system.
>> > > > .She
>> > > > > is dealing with the people that installed the system and based on
>> this
>> > > > > information do you think that she is being given a snow job when
>> they
>> > > tell
>> > > > > her everything is working normally?
>> > > > > MLD
>> > > >
>> > > >
>> > > > Yes, she's getting a snow job.
>> > > > Is it the air conditioners fault? Don't know, it could be a ducting
>> > issue
>> > > > (heat gain). Either way, it's not operating correctly!
>> > > >
>> > > > In order to get to the root of the problem you need to take
>> measurements
>> > > at
>> > > > the furnace or air handler. Measure the inlet and discharge air as
>> close
>> > > to
>> > > > the evaporator coils as possible and see if your differential is
>still
>> 6
>> > > > degrees. If so, this points you to the air conditioning system. If
>> it's
>> > > > 12-15 degrees, then this points you to the poorly designed ducting
>> > system.
>> > > > Another possibility is that the air handler is moving an extreme
>> amount
>> > of
>> > > > air by the evaporator. Do you have the model numbers of the
>equipment.
>> > > Lets
>> > > > see if it's a matched system or something that's been cobbled
>> together.
>> > > >
>> > > > It's best to get a second diagnosis from a service company that can
>> > > actually
>> > > > see and test this system. They should be able to diagnose the system
>> > > rather
>> > > > quickly after they gather all the required data.
>> > > >
>> > > >
>> > > Your comments are extremely helpful and appreciated. Being on the
>East
>> > > coast with the AC unit in the mid-west it's beyond my following
>through
>> on
>> > > your suggestions. However, based on your remarks it's time for the AC
>> > > company to be brought back in to do a more professional diagnosis and
>> > > troubleshooting job. Again--thanks for your input.
>> > > MLD
>> >
>> >
>> > Where in the mid-west?
>> >
>> Cincinnati
>
>
>IIRC, there's a poster here that lives there... maybe they're close and will
>reply or e-mail you?
>
WHO? :-)
Ok MLD. Spill the beans. What company? I could use a good laugh.
Bubba
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