lineset question

	lineset question

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Subject

Author

Date

lineset question

gofish

06-27-2007

Zephyr

Jeffrey Lebowsk...

Jeffrey Lebowsk...

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Posted by on June 27, 2007, 7:28 am

Ran across a 40+ yr old home-brew type lineset install for a 5 ton
split system. Suction is 1-3/8 & liquid is 5/8, length is around
100'. Both liquid and suction line are touching each other the
whole length, insulation if any is wrapped around both together.
About 10' is underground, direct burial.

Its a fixed orifice system. In 40 yrs, its on its third condenser,
which is 2-3 yrs old.

Other than requiring 3-4 times the amt of gas to charge such a system,
what are the ramifications of excessive subcooling and superheat?

Is this an older style technology? (pjm should know this one..) :)

Posted by Zephyr on June 27, 2007, 11:14 am

Fish;

The larger suction and liquid lines were likely for R-500 years ago. You
might also notice the fittings were "soft solder" instead of "hard solder."
Common in the 60's.

The problems:

1. Oil return. Without the correct line size the suction gas velocity may
not be up to speed to sweep the oil back to the condenser from the
evaporator. [The oversized lines may help reduce capacity losses but create
an oil return issue. It is wiser to replace an oversized suction line with
two smaller lines to overcome the distance, reduced capacity and increase
the velocity for good oil return.]

2. Buried lines cause liquid migration in the suction line and can be a
problem on start up. [In the early 60's some used a liquid line solenoid to
'pump down' the suction gas to prevent migration when the lines are lengthy
and buried.]

3. Suction and liquid lines tied together in a common bundle can increase
the superheat delivered to the compressor. This in turn causes unusually
high discharge temperatures associated with oil sludge.

4. Manufacturers today recommend the lines not be extended to far beyond
the 50 foot mark for today's equipment. There will be a reduction in
capacity [about 4% - 8%] and the issues I mentioned above.

--
Zyp

> Ran across a 40+ yr old home-brew type lineset install for a 5 ton

> split system. Suction is 1-3/8 & liquid is 5/8, length is around

> 100'. Both liquid and suction line are touching each other the

> whole length, insulation if any is wrapped around both together.

> About 10' is underground, direct burial.

> Its a fixed orifice system. In 40 yrs, its on its third condenser,

> which is 2-3 yrs old.

> Other than requiring 3-4 times the amt of gas to charge such a system,

> what are the ramifications of excessive subcooling and superheat?

> Is this an older style technology? (pjm should know this one..) :)

Posted by Jeffrey Lebowski on June 28, 2007, 2:44 am

> Ran across a 40+ yr old home-brew type lineset install for a 5 ton

> split system. Suction is 1-3/8 & liquid is 5/8, length is around

> 100'. Both liquid and suction line are touching each other the

> whole length, insulation if any is wrapped around both together.

> About 10' is underground, direct burial.

> Its a fixed orifice system. In 40 yrs, its on its third condenser,

> which is 2-3 yrs old.

> Other than requiring 3-4 times the amt of gas to charge such a system,

> what are the ramifications of excessive subcooling and superheat?

> Is this an older style technology? (pjm should know this one..) :)

Well...bring the compressor up to capacity......

Add a water coil here, another one there.

Pressures go whack, depending on where you porting them from.

Logically...in your case, it's just the losses--not in friction, but
temperature in having the lines in contact with one-another.

Suggest always ask yourself--where in blue blazes has it gone off to ?

--

Posted by Jeffrey Lebowski on June 28, 2007, 2:53 am

> > Ran across a 40+ yr old home-brew type lineset install for a 5 ton

> > split system. Suction is 1-3/8 & liquid is 5/8, length is around

> > 100'. Both liquid and suction line are touching each other the

> > whole length, insulation if any is wrapped around both together.

> > About 10' is underground, direct burial.

> >

> > Its a fixed orifice system. In 40 yrs, its on its third condenser,

> > which is 2-3 yrs old.

> >

> > Other than requiring 3-4 times the amt of gas to charge such a system,

> > what are the ramifications of excessive subcooling and superheat?

> >

> > Is this an older style technology? (pjm should know this one..) :)

> Well...bring the compressor up to capacity......

> Add a water coil here, another one there.

> Pressures go whack, depending on where you porting them from.

> Logically...in your case, it's just the losses--not in friction, but

> temperature in having the lines in contact with one-another.

> Suggest always ask yourself--where in blue blazes has it gone off to ?

Oh other thing, cant suck it all into the condensor unless it has a huge
reciever.

Probly stinks anyways and was never properly flushed and therein lies the
reason for the last compressor failure and the one before that.

Personally, I suggest shouldn't touch unless both indoor an out are
replaced.

Charge extra for the lineset flush, ( appears lineset replace is
problemmatic ) add a good filter and come back later for a to replace it.

Good luck.

--

--

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