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rws
08-04-2016, 08:39 AM
I'm planning on replacing my heat pump this fall. Using nitrogen to flow while soldering, purging and pressure testing the lines is an accepted practice for r410a. Do I have to buy a filled bottle or can this be rented? And what about a regulator, does nitrogen take a special regulator?

I know I bought the largest oxygen bottle available (ones that can readily be exchanged), I really don't need to buy a one time use bottle.

BigMike782
08-04-2016, 08:53 AM
You could rent a cylinder but the smart money is to buy one.
Nitrogen uses a CGA 580 connection. You will need a pressure regulator(as opposed to flow for welding) that has the correct delivery pressure range. A Western REB-7-5AC is what I have always sold.

JoeLee
08-04-2016, 10:27 AM
Buying or leasing / renting depends on your local supply store policy.

No special regulator needed. I use the one from my argon cylinder when I have to use the nitrogen.

JL..................

BigMike782
08-04-2016, 11:42 AM
The issue with using a flow gauge/meter is that you cannot control the pressure. It may not make a difference but I like to use the proper tool as long as it is feasible.

rws
08-04-2016, 11:59 AM
I have a regulator for my MIG, thanks! Hopefully I can get enough pressure through it to test the lines once silfossed. All this will go through the manifold gauges so I'll know what the pressure is.

JoeLee
08-04-2016, 12:36 PM
The issue with using a flow gauge/meter is that you cannot control the pressure. It may not make a difference but I like to use the proper tool as long as it is feasible. My flow meters have scales for 4 different types of gas. The cylinder pressure doesn't matter.
My argon bottles are filled to about 2500 to 2700 psi. When the pressure gets down to 500 psi the flow meter still works. So pressure isn't a big issue.

JL................

H380
08-04-2016, 03:17 PM
Buying or leasing / renting depends on your local supply store policy.

No special regulator needed. I use the one from my argon cylinder when I have to use the nitrogen.

JL..................
Yep. The gas house will require a deposit of $150 to $300.The cost of a new tank. Then you just swap out at the dock and pay only for the gas. When you are done with the bottle you get your deposit back. That way you do not need to keep your bottle certified. Also a lot of places do not fill their own bottles on site. They ship to a regional distribution center. Where every empty bottle is date and testing certified. Your personal bottle would need to go through this process and get shipped back to your branch store just for you. No gas shop will fill personal bottles around here.

BigMike782
08-04-2016, 06:03 PM
My flow meters have scales for 4 different types of gas. The cylinder pressure doesn't matter.
My argon bottles are filled to about 2500 to 2700 psi. When the pressure gets down to 500 psi the flow meter still works. So pressure isn't a big issue.

JL................
What is the working pressure of your flow meter?
Most likely 25psi. Like I said a flow gauge/meter may work but that's the same as saying I can use my drill press as a mill.

JoeLee
08-04-2016, 06:31 PM
My flow meters are made by L Tech. I can't find any pressure rating on it but the gauge goes up to 4000 psi. so I'm sure the working pressure is within that. The first one was what the welding supply store gave me when I bought my first TIG machine. I liked it so I bought a couple extra ones for other cylinders. The sight glass / CFM gage is graduated for I think four different gasses and can be rotated.

JL.................

Arcane
08-04-2016, 09:50 PM
As far as I know MIG Gas Flow Meter and Regulators will limit the pressure to a relatively low pressure (I've read that the regulators are generally set at 50psi but don't take that as gospel) for welding purposes but if testing the heat pump lines requires a higher or lower pressure than the MIG gas flow meter is able to provide then it likely will not work. MIG gas flow meters are calibrated for cubic feet per hour of gas flow at whatever pressure they are set at and aren't calibrated for output pressure. It's quite possible some are able to have the output pressure adjusted but since it's flow that is important for MIG welding and not pressure, it is likely they are preset to be safe for the average consumer to connect to all the different manufactures welders.

BigMike782
08-04-2016, 10:07 PM
25 psi is most common but there are some 50 psi.

Sparky_NY
08-04-2016, 10:34 PM
I have worked in the HVAC trade for many years. I use a pressure type regulator. For brazing the lines, I just crack the regulator adjustment open and listen with my ear to the hose for a very tiny flow. The idea is to purge the air out of the lines, if you develop any pressure it will blow the braze out of the joint and make a leak, you only need a very tiny flow.

For pressure testing, on R410a systems, I test at 300PSI. The evaporator coils are factory tested at 450psi normally. The high pressure shows up extremely tiny leaks, that the idea. The pressure is left on during the test for at least a hour.

Another important point, the OP mentioned soldering. The lines are supposed to be brazed, not soldered. Its done with 5-15% silver rod and acetylene, no flux. A propane torch is not nearly hot enough. R410a systems can hit well over 500pis under some circumstances.

Lastly, I might mention that the OP is doing a DIY install and thus the reason for not having the nitrogen setup. I hope he realizes he also needs a vacuum pump for the next step, a HVAC type deep vacuum pump (100 microns) not just any old vacuum pump. He may be intending to call in someone to evacuate (vacuum) the lines, charge the system, and start it up, in which case he will not need the pump.

rws
08-05-2016, 06:52 AM
Sparky, thanks for your input. I agree and realize the lines need to be silver soldered, not just plain solder. I mentioned silflossed in another post. Yes, the nitrogen flows through the the lines, not building pressure. And of course the vacuum. Most all manufacturers recommend a vacuum to 500 microns, some may state 350. Using nitrogen to purge the air from the lines greatly improves the vacuuming process by removing normal air and moisture. It's not rocket science as most HVAC people want you to believe. Using the proper tools and procedures it's not a problem. I installed my 13 year old r22 and have not had an issue with the refrigeration part, only replaced the condesor fan in all those years. I will have a friend/tech to evacuate my old system before I start.

Sparky_NY
08-05-2016, 08:01 AM
Sparky, thanks for your input. I agree and realize the lines need to be silver soldered, not just plain solder. I mentioned silflossed in another post. Yes, the nitrogen flows through the the lines, not building pressure. And of course the vacuum. Most all manufacturers recommend a vacuum to 500 microns, some may state 350. Using nitrogen to purge the air from the lines greatly improves the vacuuming process by removing normal air and moisture. It's not rocket science as most HVAC people want you to believe. Using the proper tools and procedures it's not a problem. I installed my 13 year old r22 and have not had an issue with the refrigeration part, only replaced the condesor fan in all those years. I will have a friend/tech to evacuate my old system before I start.

Let me add that you do not need a very big tank of nitrogen. A 40 cuft tank (2 ft tall) is enough to do about 5 residential split system installations, pressure test and all. Locally, that tank costs well under $20 to refill. I am quite curious if It is a Goodman system you plan on installing?

rws
08-05-2016, 08:35 AM
No, I think I'll get a Rheem. Goodman's are more a contractor grade unit from what I hear. Thanks for the tip on the bottle. I also don't need but less than a pound of r410a.

Highpower
08-05-2016, 10:26 AM
Purging / pressure testing A/C systems and line sets, purging fogging optics (binoculars, scopes), inflating tires....
More than one use for a nitrogen bottle hanging around. Just saying. :)

Sparky: What is your opinion on "Bluvac" equipment? I recently ordered one of the "standard" digital micron gauges (http://www.accutools.com/index.php?page=products&subpage=bluvac). Should be here today actually. Good, bad or indifferent?

boslab
08-05-2016, 10:41 AM
I've been using some for tyre inflation, seems ok
Mark

Sparky_NY
08-05-2016, 11:42 AM
Purging / pressure testing A/C systems and line sets, purging fogging optics (binoculars, scopes), inflating tires....
More than one use for a nitrogen bottle hanging around. Just saying. :)

Sparky: What is your opinion on "Bluvac" equipment? I recently ordered one of the "standard" digital micron gauges (http://www.accutools.com/index.php?page=products&subpage=bluvac). Should be here today actually. Good, bad or indifferent?

Unfortunately, I am not familiar with that brand, good or bad. They now have gauge sets with all sorts of digital functions built in that are really slick, but they are pricey.

Sparky_NY
08-05-2016, 11:45 AM
No, I think I'll get a Rheem. Goodman's are more a contractor grade unit from what I hear. Thanks for the tip on the bottle. I also don't need but less than a pound of r410a.


You hear correct. Most DIY installs are Goodman it seems, thus my question. I installed hundreds of Goodman units over the years but no longer, the quality has gone downhill severely over the years. Rheem is one of many good choices.

As you probably know, units come factory precharged with R410. Its rare that any needs to be added unless the lineset is very long, normal is a bit too much from the factory.

Maybe your friend/tech will loan you his nitrogen tank if you offer to refill it? (less than $20)

rws
08-05-2016, 01:23 PM
Sparky, I will ask him. If I can put a refundable deposit on a tank and pay for a refill, that works too.

Yes, the compressors/condenser comes with enough charge for 15 feet of line, but I'll end up with about 24-25. Seems most recommend .6oz per foot additional charge. I'll err on a bit less, then add if needed, using sub cooling as my guide.

Have you used the "Kwik Charge" unit that allows adding liquid 410a into the low side while running? Don't know how much they cost, but sure would be easy for adding 410a.

Thanks for your input here, much appreciated.

Sparky_NY
08-05-2016, 03:43 PM
Sparky, I will ask him. If I can put a refundable deposit on a tank and pay for a refill, that works too.

Yes, the compressors/condenser comes with enough charge for 15 feet of line, but I'll end up with about 24-25. Seems most recommend .6oz per foot additional charge. I'll err on a bit less, then add if needed, using sub cooling as my guide.

Have you used the "Kwik Charge" unit that allows adding liquid 410a into the low side while running? Don't know how much they cost, but sure would be easy for adding 410a.

Thanks for your input here, much appreciated.

Never heard of a Kwik Charge unit, all 410a has to be added in liquid form (tank upside down), its a blend and to maintain the proper proportions it has to be added in liquid form.

I have found that the units have a bit more than they claim from the factory, even for 25ft lines. The only time I usually have to add any is for 35ft and up. Probably varies by brand though.

Yell if I can answer any questions.

Doozer
08-05-2016, 04:30 PM
I have used argon and the flow regulator
from my welder to purge A/C lines
and do triple evacuations
because I don't do A/C work that much.
I never had a problem.
I think you are all trying to be overly
scientific about all this. (Which is rare
that I ever say this).

--Doozer

Sparky_NY
08-05-2016, 05:25 PM
I have used argon and the flow regulator
from my welder to purge A/C lines
and do triple evacuations
because I don't do A/C work that much.
I never had a problem.
I think you are all trying to be overly
scientific about all this. (Which is rare
that I ever say this).

--Doozer

Argon would probably work just fine. They use nitrogen because its so cheap no doubt. Would need a high pressure regulator still to pressure test though.

JoeLee
08-05-2016, 07:50 PM
Nitrogen acts as a dryer and removes oxides and other contaminates. It also aids in brazing.

JL................

boslab
08-06-2016, 12:26 AM
Only ever done basic AC stuff, I'm fairly ignorant however a good source of titbits I've found
http://www.harrisproductsgroup.com/en/Expert-Advice/tech-tips/nitrogen-purge-and-brazing.aspx
Mark

rws
08-06-2016, 08:36 AM
Good link, thanks boslab.