I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or must
it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

the charge will be weighed in with a scale. i've seen that some units
nowadays have a pre-charged system with piercing valves that release the
refrigerant into the system,after the lines are evacuated.
"Ken" wrote in message
...
I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be checked
for optimum charge while the temperature is so low??? Or must it be
rechecked later when the temperature reaches about 80 degrees? Thanks.

On Tue, 21 Mar 2006 20:16:05 GMT, Ken wrote:

I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or

I would think it would be easier to charge a system when the temp is
low, because it wouldn't require as much pressure. (as much freon,
but not as much pressure.) Whatever they charge it from has more
pressure than the house does, summer or winter.

it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

They have formulas. Boyle's general law of gases, or something like
that.

iirc the suction formula is the ambient temp converted to psi (on a
press/temp chart) minus 30 psi.

they can also partially cover the condersor to simulate warmer conditions.
"mm" wrote in message
...
On Tue, 21 Mar 2006 20:16:05 GMT, Ken wrote:

I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or

I would think it would be easier to charge a system when the temp is
low, because it wouldn't require as much pressure. (as much freon,
but not as much pressure.) Whatever they charge it from has more
pressure than the house does, summer or winter.

it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

They have formulas. Boyle's general law of gases, or something like
that.

On Tue, 21 Mar 2006 23:43:20 -0500, mm
wrote:

On Tue, 21 Mar 2006 20:16:05 GMT, Ken wrote:

I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or

I would think it would be easier to charge a system when the temp is
low, because it wouldn't require as much pressure. (as much freon,
but not as much pressure.) Whatever they charge it from has more
pressure than the house does, summer or winter.

Actually this is completely the opposite. youi can't charge it
accurately in cold weather due to the low pressures.
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++
spam protection measure, Please remove the 33 to send e-mail

"hvactech2" wrote in message

Actually this is completely the opposite. youi can't charge it.

---------------------------------------------------
even charged with the scales,or pre-charged do you come back and double
check in warmer temps?

i did transport refrigeration straight outta tech school and my service
manager never once told me to have a recheck(not like a customer from
texas,or wherever, would travel back for a check up).

did three years with him, and never wanted to do refrigeration again....

Charging in the winter is best done by weighing in the charge, when
starting with an empty system. Most manufacturers publish pressure
charts for the winter, but they are not very accurate, due to
differences in indoor air flow and indoor and outdoor conditions. It
is best to check charge in cooling season with outdoor temps at least
75 degrees. Charging is then done done by subcooling for expansion
valve systems and by suction superheat for piston metering devices.

When charging in the winter, pressures in the system are lower, but
pressures in the refrigerant drum are also lower.

When you charge by weight, you must know the charge for the outdoor
unit and indoor coil, as well as the refrigerant line length and tubing
diameter as they affect correct charge as well as the units.

It is just best to check it in the cooling season when there is load on
the system. It is best to let it run 15 minutes to let the
temperatures and pressures stabilize.

Stretch

Stretch wrote:
Charging in the winter is best done by weighing in the charge, when
starting with an empty system. Most manufacturers publish pressure
charts for the winter, but they are not very accurate, due to
differences in indoor air flow and indoor and outdoor conditions. It
is best to check charge in cooling season with outdoor temps at least
75 degrees. Charging is then done done by subcooling for expansion
valve systems and by suction superheat for piston metering devices.

When charging in the winter, pressures in the system are lower, but
pressures in the refrigerant drum are also lower.

When you charge by weight, you must know the charge for the outdoor
unit and indoor coil, as well as the refrigerant line length and tubing
diameter as they affect correct charge as well as the units.

It is just best to check it in the cooling season when there is load on
the system. It is best to let it run 15 minutes to let the
temperatures and pressures stabilize.

Stretch

Thanks to all who responded. I thought it could be done "Roughly" in
winter via the weighing method, but to be done accurately it must be
done in warmer weather. I just like to know what the proper procedure
should be so it is done right. Thanks again.

Ken

neat... i haven't touched a residential unit since my lab class in 99.

when we did a transport unit repair or check of unit at work, we would
partially cover the condensor to raise the pressure if it was cold. if it
was a new install or complete recharge, it would be weighed in. didn't have
much use for line size or length due to everything being in one small area
,unless it had multiple evaporators. running unit in heating,then cooling
was the load like you said.


"Stretch" wrote in message
oups.com...
Charging in the winter is best done by weighing in the charge, when
starting with an empty system. Most manufacturers publish pressure
charts for the winter, but they are not very accurate, due to
differences in indoor air flow and indoor and outdoor conditions. It
is best to check charge in cooling season with outdoor temps at least
75 degrees. Charging is then done done by subcooling for expansion
valve systems and by suction superheat for piston metering devices.

When charging in the winter, pressures in the system are lower, but
pressures in the refrigerant drum are also lower.

When you charge by weight, you must know the charge for the outdoor
unit and indoor coil, as well as the refrigerant line length and tubing
diameter as they affect correct charge as well as the units.

It is just best to check it in the cooling season when there is load on
the system. It is best to let it run 15 minutes to let the
temperatures and pressures stabilize.

Stretch

Ken wrote:
I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or must
it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

The system can be charged correctly at 50º without recovering the
existing charge and weighing in.
In order to charge the system correctly at this low ambient the
condenser airflow must be restricted or reduced by some means, in order
to simulate the maximum ambient temp that will be encountered in your
area. Very few techs do this correctly however, if at all, so you'd be
better off waiting for warmer weather IMO.

Also, I advise strongly against the weigh-in method on fixed orifice
systems, since the charge is very critical on these systems. There is no
way to calculate the correct charge, since there are too many variables
to account for. You may find rules of thumb in the literature, e.g. X
lbs of refrigerant per ft of 3/8 copper tubing, etc. but these
engineering formula can only be applied reliably under lab conditions.
OTOH, a TXV metered system is much more forgiving when it comes to
refrigerant charge. On these systems weighing in the charge would
typically be adequate, but only a fool would go through the trouble of
recovering the charge to do this since setting the correct charge on a
TXV system is a simple matter of adjusting the subcooling of the liquid
line, which BTW must be checked even if you have weighed the charge in.

Richard Perry

tom&kel wrote:

iirc the suction formula is the ambient temp converted to psi (on a
press/temp chart) minus 30 psi.

Either you don't "recall correctly" or somebody pawned a bogus formula
off on you. That one is worse than a WAG.

Richard Perry


they can also partially cover the condersor to simulate warmer conditions.
"mm" wrote in message
...

On Tue, 21 Mar 2006 20:16:05 GMT, Ken wrote:


I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or

I would think it would be easier to charge a system when the temp is
low, because it wouldn't require as much pressure. (as much freon,
but not as much pressure.) Whatever they charge it from has more
pressure than the house does, summer or winter.


it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

They have formulas. Boyle's general law of gases, or something like
that.

it's been about 5years since i've put my guages on anything bigger than a
cars a/c ,so it's probably my memory. wow! did i booger this up....

the formula is in my carrier transport technician repair guide. it states
that this "rule of thumb" is acceptable; ambient temp plus 30 degrees
converted to psi for the specific refrigerant on a pt chart for an approx
discharge pressure.

the refrigerant level was checked by covering condensor untill pressure was
at 260-280 and then look at the bottom sight glass to see if it was full and
the top one was empty.

btw....what is a WAG?




"RP" wrote in message
et...


tom&kel wrote:

iirc the suction formula is the ambient temp converted to psi (on a
press/temp chart) minus 30 psi.

Either you don't "recall correctly" or somebody pawned a bogus formula off
on you. That one is worse than a WAG.

Richard Perry


they can also partially cover the condersor to simulate warmer
conditions.
"mm" wrote in message
...

On Tue, 21 Mar 2006 20:16:05 GMT, Ken wrote:


I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or

I would think it would be easier to charge a system when the temp is
low, because it wouldn't require as much pressure. (as much freon,
but not as much pressure.) Whatever they charge it from has more
pressure than the house does, summer or winter.


it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

They have formulas. Boyle's general law of gases, or something like
that.

"Ken" wrote in message
...
I am planning on having my heating/AC system replaced soon. Is
it
possible to charge the system with R22 EFFECTIVELY with the
outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system
be
checked for optimum charge while the temperature is so low???
Or must
it be rechecked later when the temperature reaches about 80
degrees?
Thanks.

The system can be charged but due to the cool temps, it may not
weigh the same in the spring. Often units get overcharged when
replaced in winter. Your installer will be happy to come out and
make an adjustment in the spring when you start using the A/C. It
doesn't have to be 80 out. 60-70 is ideal.

tom&kel wrote:
it's been about 5years since i've put my guages on anything bigger than a
cars a/c ,so it's probably my memory. wow! did i booger this up....

the formula is in my carrier transport technician repair guide. it states
that this "rule of thumb" is acceptable; ambient temp plus 30 degrees
converted to psi for the specific refrigerant on a pt chart for an approx
discharge pressure.

That method was never correct. You can't charge a system by discharge
pressure.


the refrigerant level was checked by covering condensor untill pressure was
at 260-280 and then look at the bottom sight glass to see if it was full and
the top one was empty.

btw....what is a WAG?

Maybe you can pick it out
http://www.acronymfinder.com/af-quer...ct&Acronym=WAG
You may have to scroll down the page.

Richard Perry





"RP" wrote in message
et...


tom&kel wrote:


iirc the suction formula is the ambient temp converted to psi (on a
press/temp chart) minus 30 psi.

Either you don't "recall correctly" or somebody pawned a bogus formula off
on you. That one is worse than a WAG.

Richard Perry


they can also partially cover the condersor to simulate warmer
conditions.
"mm" wrote in message
...


On Tue, 21 Mar 2006 20:16:05 GMT, Ken wrote:



I am planning on having my heating/AC system replaced soon. Is it
possible to charge the system with R22 EFFECTIVELY with the outside
temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system be
checked for optimum charge while the temperature is so low??? Or

I would think it would be easier to charge a system when the temp is
low, because it wouldn't require as much pressure. (as much freon,
but not as much pressure.) Whatever they charge it from has more
pressure than the house does, summer or winter.



it be rechecked later when the temperature reaches about 80 degrees?
Thanks.

They have formulas. Boyle's general law of gases, or something like
that.

Kathy wrote:

"Ken" wrote in message
...

I am planning on having my heating/AC system replaced soon. Is

it

possible to charge the system with R22 EFFECTIVELY with the

outside

temperature at about 50 degrees F? I realize there is a way of
calculating an amount of Freon to be loaded, but can the system

be

checked for optimum charge while the temperature is so low???

Or must

it be rechecked later when the temperature reaches about 80

degrees?

Thanks.


The system can be charged but due to the cool temps, it may not
weigh the same in the spring. Often units get overcharged when
replaced in winter.

Because it wasn't done right.

Your installer will be happy to come out and
make an adjustment in the spring when you start using the A/C. It
doesn't have to be 80 out. 60-70 is ideal.

It doesn't have to be 80 out, but I disagree with your last statement.
Why do you consider the 60-70º temp range to be ideal?

Richard Perry

"RP" wrote in message
...

Why do you consider the 60-70º temp range to be ideal?

After I clicked send I rethought that 60.
I amend my reply to say "In the 70's would be ideal".
Because it is warm enough to get the A/C to operate and not so
hot that it is constantly running.

Kathy wrote:
"RP" wrote in message
...

Why do you consider the 60-70º temp range to be ideal?


After I clicked send I rethought that 60.
I amend my reply to say "In the 70's would be ideal".
Because it is warm enough to get the A/C to operate and not so
hot that it is constantly running.

The ideal ambient temp for charging an air conditioner is the temp at
which the tech doing the work is the most comfortable

Richard Perry