[zuuwk]

Hi All, This is a new install, i'm running a leak test after running line set. First pulled a vacuum then i did the leak test with soap and didn't find any noticeable leaks.. Then I left it pressurized over night and now its at the 20hr mark.. The values did change since the test was started but i'm getting a PSI increase, this can be due to temp change but not 100% sure.. I just can't seem to find the acceptable leak rate on Mitsubishi's website... This is a mini split 14000 btu cool only MR. Slim model.. Any thoughts?

 

[rider77]

That pressure test does not meet Mitsubishis requirements. I believe they require 600 psi.
Why did you pull a vacuum and put soap bubbles on the joints?

 

[buford]

Somewhere on this site , that same question has been brought up and i believe the answer is nitro will have a increased pressure as the temp goes up. Not by a bunch but i have seen it.

 

[johoff34]

That pressure test does not meet Mitsubishis requirements. I believe they require 600 psi.
Why did you pull a vacuum and put soap bubbles on the joints?

Agreed that doesn't make sense and would of been unnecessary. Also those gauges and hoses look brand new. Possible diy ?


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[zuuwk]

That pressure test does not meet Mitsubishis requirements. I believe they require 600 psi.
Why did you pull a vacuum and put soap bubbles on the joints?

Hi, I pulled a vacuum first to get all the air/moisture out that might have been in the lines, then I broke it with nitrogen pressurized @ 155 psi, then applied the soap test. I wouldn't do the soap test while the system is under vacuum, that would only pull in moisture if there was any leaks at the joints.. I've been trying to find the required PSI on the install manual but I didn't see it, so you're saying i should up it 600 psi, and if so for how long? Just started an online HVAC training class but we're far away from this stage..

I appreciate the help!

 

[rider77]

Is this for a DIY install?

 

[zuuwk]

Is this for a DIY install?

Hi,
I purchased this unit so it can help me understand my online class better. So i'm following along with the literature they provided but not everything is clear cut, and the video session with the instructor isn't for another 2 weeks... I'm trying to get a head start and better understanding from pros thus the reason for this thread.

Thanks

 

[Chris-J]

How much did it go up by, 5 PSI?
How much did the ambient temperature change inside and out?

 

[pageyjim]

Hi All, This is a new install, i'm running a leak test after running line set. First pulled a vacuum then i did the leak test with soap and didn't find any noticeable leaks.. Then I left it pressurized over night and now its at the 20hr mark.. The values did change since the test was started but i'm getting a PSI increase, this can be due to temp change but not 100% sure.. I just can't seem to find the acceptable leak rate on Mitsubishi's website... This is a mini split 14000 btu cool only MR. Slim model.. Any thoughts?

View attachment 736921

When you pressure test even with nitrogen get use to noting the temp also. There is an online calculator somewhere that shows expected increase or decrease with temp. Nitrogen is not a Noble gas.

 

[fxb80]

There is an online calculator somewhere that shows expected increase or decrease with temp.

http://www.oceanhvac.com/nitro.php

 

[pacnw]

Hi, I pulled a vacuum first to get all the air/moisture out that might have been in the lines, then I broke it with nitrogen pressurized @ 155 psi, then applied the soap test. I wouldn't do the soap test while the system is under vacuum, that would only pull in moisture if there was any leaks at the joints.. I've been trying to find the required PSI on the install manual but I didn't see it, so you're saying i should up it 600 psi, and if so for how long? Just started an online HVAC training class but we're far away from this stage..

I appreciate the help!

600 psig for 24 hours!!!

 

[zuuwk]

I appreciate the reply fellas.. I just got off the phone with testo and it appears I was doing the test incorrectly.. I had the valve on the high side closed on the gauge and was only testing the leftover PSI that was in the guage/hose. So i just performed another test with 356.6 psi and I've been reading if its done at high psi the test doesn't have to be that long, some say 10 min is enough... So now it looks like a more accurate test with a slight drop in psi.. What's your thoughts on the results? Should I test longer? It seems like joints are fine, nothing popped off, no leaks found with bubble solution at joints..
thanks

 

[zuuwk]

How much did it go up by, 5 PSI?
How much did the ambient temperature change inside and out?

It appears I did the test incorrectly.. Please see my above post with the picture... thanks

When you pressure test even with nitrogen get use to noting the temp also. There is an online calculator somewhere that shows expected increase or decrease with temp. Nitrogen is not a Noble gas.

Got it, thanks!

600 psig for 24 hours!!!

From what i've read the 600psi test is for stress testing the connections and not really needed for leak detection, maybe i got this wrong.... What is the acceptable leak rate for that much time under 600psi, Should the psi remain the same? I'm already seeing 0.4 difference (see pic above) at 356.6psi @ 11 minutes, but i found no leaks with bubble solution.

 

[buford]

You will see a initial rise or fall until the temp of the nitro equals the piping.

 

[Chris-J]

There's no better way to learn than making mistakes and understanding what went wrong.

 

[heatingman]

600 psig for 24 hours!!!

For a 14,000 btu minisplit? I think not.

For a city multi system - yes


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[pacnw]

For a 14,000 btu minisplit? I think not.

For a city multi system - yes


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I was told this from tech support, about 6 years or so ago.

I think it's in their literature, as well.

 

[Answer-Man]

zuuwk
Couple things to think about.

Look them up,Learn the terms: Pnuematic test, Pressure drop test they are not the same and many people use them interchangeably. Virtually all of your test should be a short duration pnuematic test.

What is the purpose of doing a leak check? To prove that your installation is leakfree! Having a little leak is not acceptable.

Do you think it is acceptable to tell a customer "everything is OK but I have to come back in 6 months to add refrgerant because it has just a little leak"

What is the sensitivity of you electronic leak detector? Most are 1/4 of one once in one year or better. If you can pick up a leak up with your leak detector it should be repaired. Many leaks found with a sniffer would not show up in a pneumatic test. Using snoop can get you the same sensitivity as your electronic leak detector if done correctly

What you asked is concerning a pressure drop test. Some manufacturer do have pressure drop criteria, but small units NOPE.
The following are things that can effect your pressure test.

If you have a leak you should be able to detect it at 100 psi or 600 psi a leak is a leak. At 600 psi you will have more bubbles

Yes as you add pressure to the system the pressure is trying to stretch the tubing and fittings this can create heat and the heat can cause the pressure to increase slightly. Changes in ambient temperature will cause the pressure in the system to change. Lights, heaters, fans can all cause a change. Barometric pressure can have an effect on your test pressure. So you should always record your starting pressure and temperature. You give the system a short time to stabilize and your pressure test when the T&P stop changing this is when you begin the pressure test which should be only about 10 minutes with no change in pressure or temperature.

When you do a pressure test don't forget to check your equipment for leaks also. I have seen more than one test fail due a a leak in the hose or a fitting.

I'm not asking that you believe me but do a Google or Yahoo search on Pnuematic pressure testing. You should get some hits from Various others, ASME, ANSI, RSES, ARI, these are the code authorities. Sometime the views of peers just don't match what the authority says

Good Luck in your schooling

 

[Answer-Man]

zuuwk
Couple things to think about.

Look them up,Learn the terms: Pnuematic test, Pressure drop test they are not the same and many people use them interchangeably. Virtually all of your test should be a short duration pnuematic test.

What is the purpose of doing a leak check? To prove that your installation is leakfree! Having a little leak is not acceptable.

Do you think it is acceptable to tell a customer "everything is OK but I have to come back in 6 months to add refrgerant because it has just a little leak"

What is the sensitivity of you electronic leak detector? Most are 1/4 of one once in one year or better. If you can pick up a leak up with your leak detector it should be repaired. Many leaks found with a sniffer would not show up in a pneumatic test. Using snoop can get you the same sensitivity as your electronic leak detector if done correctly

What you asked is concerning a pressure drop test. Some manufacturer do have pressure drop criteria, but small units NOPE.
The following are things that can effect your pressure test.

If you have a leak you should be able to detect it at 100 psi or 600 psi a leak is a leak. At 600 psi you will have more bubbles

Yes as you add pressure to the system the pressure is trying to stretch the tubing and fittings this can create heat and the heat can cause the pressure to increase slightly. Changes in ambient temperature will cause the pressure in the system to change. Lights, heaters, fans can all cause a change. Barometric pressure can have an effect on your test pressure. So you should always record your starting pressure and temperature. You give the system a short time to stabilize and your pressure test when the T&P stop changing this is when you begin the pressure test which should be only about 10 minutes with no change in pressure or temperature.

When you do a pressure test don't forget to check your equipment for leaks also. I have seen more than one test fail due a a leak in the hose or a fitting.

I'm not asking that you believe me but do a Google or Yahoo search on Pnuematic pressure testing. You should get some hits from Various others, ASME, ANSI, RSES, ARI, these are the code authorities. Sometime the views of peers just don't match what the authority says

Good Luck in your schooling[/QUOTE]

 

[heatingman]

I was told this from tech support, about 6 years or so ago.

I think it's in their literature, as well.

That may be true- my comment was really more - like "Im not gonna do a 24 hr holding test" on a system that small - Sort of comment


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