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Posted by Bob Sisson on May 31, 2007, 12:57 pm
This is an extension of my question a while back out variable speed
compressors.
(Does anyone make a residential variable speed compressor in the 4 tonn
range)
(Not 2-speed or multi-compressor, true multi-speed like some of the
ductless, or commercial)
How does the expansion valve deal with variable liquid flow rates? I would
thing that at one flow you would get good expansion, but at too higher or
lower you might have problems. How do the commercial units deal with the
change if flow rates through the expansion valves, as I thought the
expansion valves were tied to the flow, which would be tied to the
compressor....
I know that several manufactures make a big deal about their expansion
"metering" values and was wondering how they fit into the grand scheme of
the system.
Bob
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Posted by Lloyd E. Sponenburgh on May 31, 2007, 1:25 pm
> How does the expansion valve deal with variable liquid flow rates? I
> would thing that at one flow you would get good expansion, but at too
> higher or lower you might have problems.
A thermostatic expansion valve releases _stored_ liquid refrigerant as
required to maintain a particular temperature at the sensing bulb, which
would be placed, say, at the exiting vapor line of the evaporator. It says
to itself, "That line is too warm, so I'll release more liquid" or it says
"that line is getting colder than I want, so I'll slow or stop the supply."
(anthropomorphizing the machine a _little_, but only a little. Some of the
new systems are pretty smart)
When the system 'knows' to slow or stop the compressor, it's because there's
a smaller demand for refrigerant. The expansion valve will release only as
much as required. All the compressor has to do is "keep up".
LLoyd
(you'd get better information by hiring a good tech for a couple of hours to
explain by Show&Tell on an actual unit)
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Posted by Bubba on May 31, 2007, 4:57 pm
On Thu, 31 May 2007 13:25:39 -0400, "Lloyd E. Sponenburgh"
>> How does the expansion valve deal with variable liquid flow rates? I
>> would thing that at one flow you would get good expansion, but at too
>> higher or lower you might have problems.
>A thermostatic expansion valve releases _stored_ liquid refrigerant as
>required to maintain a particular temperature at the sensing bulb, which
>would be placed, say, at the exiting vapor line of the evaporator. It says
>to itself, "That line is too warm, so I'll release more liquid" or it says
>"that line is getting colder than I want, so I'll slow or stop the supply."
>(anthropomorphizing the machine a _little_, but only a little. Some of the
>new systems are pretty smart)
>When the system 'knows' to slow or stop the compressor, it's because there's
>a smaller demand for refrigerant. The expansion valve will release only as
>much as required. All the compressor has to do is "keep up".
>LLoyd
>(you'd get better information by hiring a good tech for a couple of hours to
>explain by Show&Tell on an actual unit)
** Attention**
Do NOT listen to Lloyd. No matter what he thinks........
Expansion valves do NOT TALK!
Bubba :-)
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Posted by danger on May 31, 2007, 6:12 pm
bubbs! what's up you old fart?
HAHA
-Canadian Cool
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Posted by =?ISO-8859-1?Q?Tekkie=AE?= on May 31, 2007, 9:38 pm
Bubba wrote:
> On Thu, 31 May 2007 13:25:39 -0400, "Lloyd E. Sponenburgh"
>
>>> How does the expansion valve deal with variable liquid flow rates? I
>>> would thing that at one flow you would get good expansion, but at too
>>> higher or lower you might have problems.
>> A thermostatic expansion valve releases _stored_ liquid refrigerant as
>> required to maintain a particular temperature at the sensing bulb, which
>> would be placed, say, at the exiting vapor line of the evaporator. It says
>> to itself, "That line is too warm, so I'll release more liquid" or it says
>> "that line is getting colder than I want, so I'll slow or stop the supply."
>> (anthropomorphizing the machine a _little_, but only a little. Some of the
>> new systems are pretty smart)
>> When the system 'knows' to slow or stop the compressor, it's because there's
>> a smaller demand for refrigerant. The expansion valve will release only as
>> much as required. All the compressor has to do is "keep up".
>> LLoyd
>> (you'd get better information by hiring a good tech for a couple of hours to
>> explain by Show&Tell on an actual unit)
>
> ** Attention**
> Do NOT listen to Lloyd. No matter what he thinks........
> Expansion valves do NOT TALK!
> Bubba :-)
If we don't listen how do we know if they talk or not?
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> would thing that at one flow you would get good expansion, but at too
> higher or lower you might have problems.