> >
>

Measure Sub-cooling

#1
05-08-03, 05:44 PM
Visiting Guest
Posts: n/a
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,

#2
05-08-03, 06:01 PM
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147

you are persistant, i will give you credit for that! substitute outdoor temp for discharge line temp. ever get that refrigerant certification?

#3
05-08-03, 06:06 PM
Member
Join Date: Aug 2001
Location: NW atlanta
Posts: 3,147
subcooling

should not be used as a charging method for txv systems

#4
05-08-03, 07:18 PM
Visiting Guest
Posts: n/a
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,

#5
05-08-03, 08:33 PM
firsthvac
Visiting Guest
Posts: n/a

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
05-09-03, 05:04 AM
Visiting Guest
Posts: n/a
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.

#7
05-09-03, 06:43 PM
Visiting Guest
Posts: n/a
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.

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
05-09-03, 07:06 PM
Member
Join Date: Feb 2001
Location: sw VA
Posts: 3,100

follow ups ARE generally followed through.

Thus, you sh have posted on original thread.

fred

#9
05-09-03, 07:52 PM
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,134

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
05-09-03, 09:13 PM
Visiting Guest
Posts: n/a
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
05-10-03, 07:32 AM
firsthvac
Visiting Guest
Posts: n/a

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

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Pingbacks are Off
Refbacks are Off