Attn. HVAC pros..........Is someone "blowing sunshine up my skirt"?

[Runs With Scissors]

So from what I can gather there is "supposed to be" a difference between HVAC copper fittings and Plumbing copper fittings.

I was talking to the "guy at home Depot" today, and he was like "Oh NO you can't use plumbing fittings on HVAC!! It will blow up, Satan will send the Grim Reaper and basically there will be floods and famine for 100 years if you do that, cause there is a Yuge pressure difference. There is a big difference.....one is measured in OD Vs. ID and they are thicker and stronger....blah...blah ...blah...



So I decide to order "HVAC" copper fittings for my AC/furnace project.

Well when the "HVAC" fittings show up today, I was " Hmmmm......those look a lot like the "regular copper" fittings I have from Home Depot"



So I break out the calipers, walk into the basement and grab one off the shelf, and sure enough, they are identical in every way that I can tell.

So what gives??????

Is this difference a "myth" or did I get scammed?

Here are some pics for comparison.

I realize the angle difference, but other than that what is difference and how do I know?

The oxidized one is from my basement and the shiny one is from the "HVAC kit" I just ordered.

 

[thebicman]

All hvac fittings and or pipe should be type K. K is a thicker wall copper that is the industry standard for refrigeration. Sure you could use the thinner wall copper and it may not have an issue, until it does. Say your system is using R410a and your fan fails driving the pressure up. Do you want to trust a thinner fitting with 600+ psi. I wouldn't. Been in the industry 30+ yrs and just when you think you've seen it all, someone does something stupid.

 

[Tughill Tom]

2X's what he said, K only.

 

[North Idaho Wolfman]

Yes there is a difference between the two.
Plumbing type L, M
HVAC Type K

The metallurgy is different between the two, K fittings are harder and have a higher working pressure rating.

FYI and as a side note:
The solder is different too.
Plumbing is low temp soft solder
HVAC is high temp, hard solder (Silver Solder), it's more of a brazing rod than a solder.

 

[thebicman]

Not to correct NIW as he is right. But most hvac joining of copper is done with silfos. Silver soldering is not usually required. I truley believe certain tasks should be left to the professionals. Hvac is one of them. If you don't have the tools and don't know what your doing then stop.

 

[WFM]

This is what I've used to solder copper for years. Seldom do I have a leak. I hook a washer hose to my assembly and check them with household water presser.

 

[The Evil Twin]

Put the torch down, bro.
The metallurgy between the two is different. As is the reaction to heat. ACR copper is high purity metal. Use plumbing copper and you risk rupture of the pipe. Even if that doesn't happen, the impurities in plumbing copper may not react well to the refrigeration oil and/ or refrigerant compounds.

 

[Poohbear]

2X's what he said, K only.

2 more times
Type k copper only for hvacr
K

 

[Poohbear]

Back in 1965 when I worked summers we used on new construction 15% silver on hi side & 95/5 solder on lo side. 15% on repairs.
i started my own company in 86 & my rule was 15% silver period
Did you reclaim the refrigerant in your old system or just dump it ? Got a vacume pump & micron guage ?

 

[North Idaho Wolfman]

This is what I've used to solder copper for years. Seldom do I have a leak. I hook a washer hose to my assembly and check them with household water presser.

That solder is fine for water plumbing but this is about HVAC and that solder is not applicable!

 

[jaxs]

To each his own. I use Sil-Fos15 but more importantly,purge with nitrogen while brazing. I see less than 20% technicians purging and believe that accounts for many premature system failures. Right behind no purge brazing in slipshod work is inadequate (time wise) pump down on new installations.

 

[InTheWoods]

Refrigeration tubing is 'true to size' i.e. 1/2" copper refrigeration tubing is 0.500" OD.

1/2" copper pipe for 'plumbing' is .625" OD.

 

[Mark_BX25D]

I truley believe certain tasks should be left to the professionals. Hvac is one of them. If you don't have the tools and don't know what your doing then stop.

I am an avid DIYer and I approve this message.

Where there is specialized knowledge required, the problem for the DIYer is that he doesn't know what he doesn't know.

This thread illustrates that.

 

[Runs With Scissors]

Gentlemen, I am not just going it alone on this.

I have a retired HVAC guy coming in to help with the "technical stuff".

I am just doing the "grunt work", like setting the units in place, connecting the electrical, sheetmetal work, and stuff like that. All well within my wheelhouse.

My question was to make sure that I have the right stuff for when he gets here to help me finish up.




I ordered "HVAC fittings" but I suspect that is not what I got.

So do these "K fittings" have markings on them, and do they indeed have thicker walls?

 

[The Evil Twin]

Gentlemen, I am not just going it alone on this.

I have a retired HVAC guy coming in to help with the "technical stuff".

I am just doing the "grunt work", like setting the units in place, connecting the electrical, sheetmetal work, and stuff like that. All well within my wheelhouse.

My question was to make sure that I have the right stuff for when he gets here to help me finish up.




I ordered "HVAC fittings" but I suspect that is not what I got.

So do these "K fittings" have markings on them, and do they indeed have thicker walls?

If i remember the old days, L or ACR is what you want. They may be stamped or color coded. It's been a while, but I think blue is the refrigeration identifier. ACR is just cleaned and capped L copper.

 

[InTheWoods]

I ordered "HVAC fittings" but I suspect that is not what I got.

So do these "K fittings" have markings on them, and do they indeed have thicker walls?

As noted in my post #12, measure the ID of your 3/4" fittings.

3/4" plumbing fittings will be .875".

3/4" refrigeration fittings will be .75".

 

[Dustball]

From NIBCO's product guide-

Q: Copper tubing wall thickness is designated “K,” “L” or “M.” What are the copper fittings applicable to?
A: Copper fittings’ wall thickness is determined by standards (ASME B16.22 and MSS SP-104). These standards address minimum wall thickness (per size) for the full range of copper fittings and are not intended to match tubing wall thicknesses.

If you want fittings for refrigeration, here's a catalog for Streamline-

https://www.centuryac.com/documents/copperFitting_spec.pdf

 

[thebicman]

From your first post with you showing the two fittings, the new fitting is definetily thicker wall as per your picture. Why do you suspect its not correct?

 

[WFM]

That solder is fine for water plumbing but this is about HVAC and that solder is not applicable!

Well I'm certainly not a plumber, more of a handy man really !!!!

 

[johnjk]

So shark bite fittings are out of the question????