How to pressure test the A/C unit. Part 1
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- เผยแพร่เมื่อ 5 ก.ย. 2024
- This is the first in the series on refrigerant leak detection. The pressure test.
This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.
Oh man finally this is the cleanest explanation of pressure the system on entire youtube thank you sir.
Welcome
GFM
Really good tutorial on pressure testing of a system. Take care, Brett
I am demonstrating using the highest pressure you could use on all types of equipment. some of the older units could not safely go above 150#. If the plate says 300 hi side and 150 lo side, 150 is the highest pressure without being able to separate the parts.
GFM
Great demonstration on pressure testing!!
I followed you right up to the end of the purging of the hoses to the input of the unit and this is where I've always parted company with some of you guys demonstrating this procedure.
Correct me if I'm wrong, I don't want to be the contrarian here, but the way I see it, you're simply applying a pressurized column of Nitrogen to the input of the unit and compressing the air within, because the opposite side of the system (low or high depending on which way the flow is) is closed, UNLESS, you purge the system and lines by applying pressure (as you are doing) and then loosening the opposite attached hose to purge, OR, you first pull a vacuum and then introduce the nitrogen.
kaydee457 Well, it depends on the situation. When we use nitrogen to keep the lines from oxidation while brazing, there will be nitrogen in the system before we pressurize. If we are pressurizing to find a leak, the unit will have a trace amount of refrigerant in the system unless it has been without refrigerant before the repair starts. In the latter case, we will be compressing some air with the nitrogen. In either case, the presence of air is of little consequence as the unit will be evacuated prior to charging. Have I covered what your concerns are?
GFM
grayfurnaceman Yes, but you removed the shraders and so the unit would have gone to atmosphere and therefore filled with air. I'm not criticizing your method as I've seen others do the same I'm just wondering if I'm wasting my time, and gas, when I do purge the system with dry nitrogen.
kaydee457 Well, I've watched a second time and you did mention bleeding the system. Maybe we're on the same page after all.Thanks
kaydee457 Good points. I`m not sure what good pulling the schrader does. The system will pressurize rapidly even with the schraders in. Why bother purging the entire system with nitrogen unless its going into storage or you have switched refrigerants? Like GFM said the system is going to be evacuated next so does not matter if air is in there.
Thanks for the concepts you have shared here.
Unless the high and low side are isolated by valves or by cutting out a component and brazing a line tap, do not exceed rated low side pressure. Coils can be pressurized higher when isolated, but you are taking a chance of blowing a hole in the piping.
GFM
This one is CO2 You can get them at welding supply. You will also need a regulator. You can also use nitrogen. The regulator will go higher. Hope this helps.
GFM
Thanks for posting, very informative
Welcome
GFM
Thanks
GFM
Thanks for your help.
very nice job thank's gray furnace keep up the gooood video's!!!!!!!
+jimbola77 Welcome
GFM
Awesome video
good video thanks
Your welcome
GFM
Thank you for posting this video GFM!
Thanks a lot for video!
Good job! I like.
No. That was the amount of superheat that you would have if the pressure was .1#. The temp was I believe in the 70s. I am not into torture anymore.
GFM
great tutorial. So if i am using analog gauges i just need high side?
Thank you for the video!
Great video ! Just wondering why you you only put 150 psi if the maximum is 700 ?
thanks for sharing...
Manifold gauges are a thing of the past.
if you are pressure testing with nitrogen do you really need to bleed the lines, because when your done testing you are going to release the charge
Thanks for a great video very very useful and informative. in the beginning you say pressurizing using nitrogen or co2.i understand nitrogen but, wont you be introducing the system to moisture with co2? isn't that bad? Thank You.
Dry CO2. Pressure swing will be wider as ambient temperature changes.
brilliant
Thanks for the support.
GFM
Thanks very much sir for your good work. Also sir given that we now have nitrogen in the unit, how are we going to get it out before our refrigerant recharge? Thanks
Just open the valves and dump it. Then evacuate and recharge.
GFM
Vent the N2 pressure then pull a deep vacuum.
Quick question - after brazing in new R-410A (150foot 1 1/8 line set on a 4 ton unit) the system was pressurized to 350 psi with nitro to leak check the connections. System pressure fell to 340 PSI after 30 min and to 300 PSI after 5 hours) is this a problem with a leak some where?
Yes. Even if it stopped at 300#, there is a leak. Be sure it is not in your gauge set. Methodical is the byword here. Start at one end and move to the other.
Hope this helps.
GFM
how can I track specified outdoor unit for indoor unit can you help me.
Hi Thanks for the video..I have a leak in a heat pumps system with TXV in both . I'm going to isolate the units. Do i need to pressurize both high and low sides of the line sets or just one side?
Thanks in Advance
What is the method of isolation are you using.
GFM
@@grayfurnaceman
I wil be using nitrogen to find the leak since there is no refrigerant in the system. i m going to cut the line set so i will be isolating the coil and the condenser to find out where the leak is coming from. i was wanting to know if i add nitrogen to both high and low side since the both units are using txv's and not using pistons.
Thanks
@@jtk3516 Only one side is necessary, as it will equalize.
GFM
I have a question relating to the installation of a 2.5 ton R-410 split a/c system that comes with a precharged condenser....how does one purge for brazing or pressure test the interconnecting tubing with nitrogen when there are no service ports on the evaporator?
You do not need service ports on the evap. The ports on the condenser will communicate with the lineset and the evap for pressure testing and evacuation. Hope this helps.
GFM
Why did you say bleed the low side? I thought you said not to hook up the low side. I'm using analog gauges.
I just want to pressure test some line sets, so if I hook up the high side and let pressure of 250psi, all I have to do is open the high side on my manifold analog gauges? And that will pressurized the line sets coming out of the condenser going into the air handler back to the condenser?
Thanks for the video. I need to pressure test a r22 260tr chiller evaporator shell, the tubes hv refrigerant In them. How much should be the nitrogen test pressure be for the same?? The design working pressure for tubes is 235psi and shell is 150psi.
Anish Thomas I would not exceed the design working pressure. Do not put nitrogen in the tubes with refrigerant inside. Hope this helps.GFM
Thanks for the reply. No the system is evacuated. But I need to know is there any specific pressure range for nitrogen test. The design pressure is 235. But it's I blv with r22 as with ambient nitrogen might show difference in pressure. I m Lil tensed as I don't want to put charge more that may crack the tubes or less too tat I can't detect the leak at all. As any minor leak may damage my compressor. Thanks
Anish Thomas Your design pressure for the high side is usually different than the low side. If your low side is 150#, do not exceed it. I realize the leak may be hard to find at 150#. Nitrogen is capable of very high pressures on the range of 500 to 600#. Hope this helps.GFM
So it means as my tubes are designed for 235psi, leak test with 200 will be enough?
Hey furnaceman, kind of an off topic, but i ask because i notice the same guage in most of your videos...Do you have separate guages for your 410a and your R22 installations?
marjones69 No. I generally use the sman3 for all refrigerants.
GFM
Ok cool...i have the SMAN3 too but i notice some of the other guys using a different gauge set for 410a or vice versa. Is there any chance of cross contamination? do you flush your Guage set?
what sizes will i need to connect to the gauge set?
1/4" female flare
GFM
How long do you leave the unit pressurized when doing a leak search?
It depends on the volume. There is no set rule. When I do it, I pressurize and start looking for leaks in the most obvious places. If I find none after say approximately 1/2 hour and I see a drop in pressure, may then isolate the parts of the system. Such as evaporator and line set, condenser and compressor. Hope this helps.
GFM
Very good video. I have a question that I am having trouble finding an answer to. The question is how many ounces of liquid refrigerant will a standard 1/4" refrigerant hose hold per foot? And is there much variance between refrigerants? I have search online to no avail. Thanks.
Not a whole lot. The number I have is .075 oz per foot.
GFM
I wish that a still had some R-11 and had access to a walk-in cooler. Thanks again.
After you finish the leak test...do you recover the nitrogen with a recovery machine or what..?
The nitrogen is dumped. It is, after all, 80% of the atmosphere.
GFM
ok...so just open the gages and let it out.
Michael Kokoschka 😂😂😂😂😂😂😂😂😂😂😂😂😂😂 OMG
on a R-410a system, will nitrogen be good with the refrigerant oil when you do the leak test passing tthru the compressor?
trharesco The nitrogen has no effect on the oil.
GFM
grayfurnaceman Thank you for your reply. I have one more question to ask about R-410a. when the system is in vacuum and ready to be charge with R-410a refrigerant, can you put the the whole 7 lbs of refrigerant and then turn on the compressor later ?
How many ounce of r22 do you put in unit if you do have a leak, to be able to use leak detector?
Ben Staton Sorry about the wait. You don't need much. A few ounces mixed with nitrogen. Pressure should not exceed rated pressure on the model plate.
GFM
+grayfurnaceman what would be the max pressure you would put in on a 410 evaporator coil. thanks
+Jesse James I would put the rated pressure on the model plate.
GFM
Is it possible to presurrize two units at the same time using one set of gauges on a 410a system?
+Aiveni Mila I guess you could. The low side will have to have lower pressure.
GFM
Aiveni Mila who would do that? There no reason to even want to do that.
cut the bottle off and use the pressure gauge on the bottle to see if your loosing pressure ,,you don't need the gauges,,jut don't loosen the hoses
I never trust the regulator gauge as they seem to be less accurate than the refer gauges.
GFM
How much price in this digital gug meter
They run about $100 US.
GFM
Never ever put 700 Psig on any hvac system. The compressors aren’t meant for any more than 150 psig.
To add to my other comment, a compressor can only take so much pressure before it will be dangerous and could potentially explode and could kill someone. So he says it could go to 700psi, no system works at that pressure. It’s not made to at all, not even close to that. So at about 420-450psi, the compressor could start to expand/change shape due to high pressures therefore damaging the compressor. Above 450psi, this will be when the compressor could be explosive. Please please please take my advice and only pressure test at 150PSI MAX!!
Did you actually watch the series or did you just comment?
All units can be safely tested at the model plate test pressures. Modern Tecumseh compressors can be safely tested at 360#. Copeland at #475. Look it up. All coils are capable of high side pressure test limits as they are used in both heat pumps and air conditioners. The very high test pressures I sometimes use are for isolated coils or linesets. The worst that could happen is the coil would leak.
GFM
Your gonna hurt or kill someone by telling them about 700psi pressure testing. All you need is 150psi. Look it up on let’s say a TRANE installation manual. 150psi it will tell you. Compressors will definitely expolode if you put 700psi into the system.
I still say "Did you watch the video?" The only time you use high pressure is when you isolate components. You should note that the low side pressure of a 410A system can reach that 150# pressure during high load operation. Let alone the high side pressure. Trane units have had test pressures of 300# for both high side and low side for over 30 years.
GFM
Was it really 105 F when you made this video? If so thanks for torturing yourself for us.
Never got to the point!
What were you looking for?
GFM
Thanks
GFM