Measure Sub-cooling

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  #1  
Old 05-08-03, 05:44 PM
Linkman
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Measure Sub-cooling

Hi,

Saturated temperate- Temperature = Sub-cooling

Example:

200 psig = 101 degrees - 96 degrees = 5 degrees

200 psig > Liquid line pressure reading (High Side)
101 degrees> Refrigerant temperature reading on gauge
-96 degrees > Outside ambient temperature

101-96= 5 degrees Sub-Cooling

Is that correct?

Thank you,
Linkman
 
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  #2  
Old 05-08-03, 06:01 PM
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linkman,

you are persistant, i will give you credit for that! substitute outdoor temp for discharge line temp. ever get that refrigerant certification?
 
  #3  
Old 05-08-03, 06:06 PM
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subcooling

should not be used as a charging method for txv systems
 
  #4  
Old 05-08-03, 07:18 PM
Linkman
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Thank you note

Thanks for the prompt reply guys!

I did read today about charging methods. quote "A THERMOSTATIC EXPANSION VALVE (TXV) IS CHARGED TO THE SUB-COOLING OF THE LIQUID LINE LEAVING THE CONDENSER.' by R.D. Holder........ uh! the second part of this reply is now confusing.
By the way, I am only MVAC certified but HVAC is my next goal. Yes, I am tenacious!

Thanks,
Linkman
 
  #5  
Old 05-08-03, 08:33 PM
firsthvac
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Dear Linkman--

Let's just think for a moment about thermostatic expansion valves (TXV's) and how they work. The bulb which operates the metering needle diaphragm is located near the outlet of the indoor or outdoor coil to measure the amount of refrigerant in the coil by means of a temperature above the saturated coil temperature depending on the TXV application, hence the term thermostatic (temperature changes) expansion (by means of heated expanding gas).

Now some expansion valve bulbs have a gas charge in the bulb which is equal to the sub cooling of the liquid line, therefore, the bulb charge will be more sensitive to changes in superheat from the outlet of the coil.

The point is TXV's are subject to superheats, not sub coolings.

And just a minor correction to HVAC4U's posting about subsitituting discharge line for outdoor temperature...it should be substitute "liquid line temperature" for "outdoor temperature"

In other words... Saturated Temp - Liquid Line Temp= Sub cooling (sorry bro...I know "liquid line" is what you meant )
 
  #6  
Old 05-09-03, 05:04 AM
Linkman
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Think I Got it!

Hi Guys,

Saturated temperate- Liquid Line Temperature = Sub-cooling

Example:

200 psig = 101 degrees - 96 degrees = 5 degrees

200 psig > Liquid line pressure reading (High Side)
101 degrees> Refrigerant temperature reading on gauge
-96 degrees > Liquid Line temperature

101-96= 5 degrees Sub-Cooling

Note: I would want 10 Deg to 20 Deg sub-cooling, Right?

If that's OK, I can move on to Superheat.

firsthvac: Great write up. That's the kind of answers that make rookies like me ask Less Stupid Question. Good Job...

Thank you all guys,
This is a great place & good people to learn from.
Linkman
 
  #7  
Old 05-09-03, 06:43 PM
Linkman
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Closing of a thread

Think I Got it!
Hi Guys,

Saturated temperate- Liquid Line Temperature = Sub-cooling

Example:

200 psig = 101 degrees - 96 degrees = 5 degrees

200 psig > Liquid line pressure reading (High Side)
101 degrees> Refrigerant temperature reading on gauge
-96 degrees > Liquid Line temperature

101-96= 5 degrees Sub-Cooling

Note: I would want 10 Deg to 20 Deg sub-cooling, Right?

If that's OK, I can move on to Superheat.

firsthvac: Great write up. That's the kind of answers that make rookies like me ask Less Stupid Question. Good Job...

Thank you all guys,
This is a great place & good people to learn from.
Linkman


PS: I did notice on this site that follow ups are not followed through. So I am trying this Re-Post to see what happens.

Just looking for a closing.

Thanks,
 
  #8  
Old 05-09-03, 07:06 PM
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Linkman,

follow ups ARE generally followed through.

Thus, you sh have posted on original thread.

fred
 
  #9  
Old 05-09-03, 07:52 PM
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Linkman:

I'm not exactly sure what you mean by closing.

Is it that there is some unfinished business relating to the post or is it that parting salutations were not made by the responder?

If it's the latter then I think that it would be a nice touch to make some parting comments but as long as the question is answered I would prefer to get on to the next one.
I am finding that my day job is cutting into my personal life alot lately.
Maybe it's time to ask diy.com for a raise so I can do this full time.

BTW: Thanks for the feedback.
 
  #10  
Old 05-09-03, 09:13 PM
Linkman
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Sub-Cooling

Just wanted to thank everyone who have replied. This has been a step forward for me. You have helped me and I thank you.

Till later,
Thanks Guys
 
  #11  
Old 05-10-03, 07:32 AM
firsthvac
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Linkman--

glad to be able to help you. keep up the good learning.
 
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