Copper vs Steel

MDNLansing

What are your thoughts on using copper air returns? I am getting ready to redo the return air lines on my vacuum system. Is steel pipe worth the extra work to cut and thread? I've got about 70 feet with 19 radiator returns connecting to it. What say ye?

Jamie Hall

I'd see no reason

not to use copper.  So long as steam doesn't get to it -- and it certainly shouldn't in this application! -- it should be fine.  Now whether I'd use sweat fittings or compression or flares, Don't really know.  Depends on which type you think you can get leak tight for vacuum most effectively!

MDNLansing

It Will See Steam

The ends of the mains vent directly into the air return using 1/4" pipes. So, it gets lots of steam. Does 200 degrees really affect the copper that much? I don't want to do this twice so if I need to use steel I certainly will.

JStar

Return

If it sees steam, use steel.

ChrisJ

Copper

My personal observation has been as long as its a straight pipe with no turns it will likely be fine.



The problem is it will still expand a lot more than steel. 

MDNLansing

Thanks Everyone

Steel it is. I looked last night and see that the box stores charge more for a 2' nipple than 10 feet of pipe. I'm not sure how they figure their costs but I won't be using prethreaded stuff. Looks like it'll be a longer job to cut and thread using steel, but I want it done right. I wouldn't want my plumber to cut corners, so I suppose I shouldn't either. Thanks again, you saved me from a mess down the road.



Happy Thanksgiving!

ChrisJ

But wait

There's more!



I bought 99% of my nipples and fittings from pexsupply.com

It was the only place I could find Ward fittings and their prices were lower than a place like homer or lowes. Even our local plumbing supply has chinese fittings.



I plan my projects ahead of time and buy whatever I can online. Then if I end up missing something or need pipe threaded I go to a local place.



Forgot to mention, copper also transfers heat a lot better than steel so there is another reason to use steal for a dry return.

vaporvac

Ditto Pexsupply

Ditto Pexsupply.com I got all my 3" fittings from them...USA made (2x more than chinese/Indian), but had read there are problems threading the latter. Still a good $. We've rented a threader/cutter for the 4"-31/2"-2" long pipe. We're using all steel except for maybe the wet return tie-in. We'll see how that goes...planning on using the steel. I HATE doing things 2x, so try to plan and save to do it best. Your place looks really nice and deserves to have it done right. You'll thank yourself later when all heats beautifully and you're giving us tours!

MDNLansing

Heat Loss

I did the heat loss calculations on the air return and I am now convinced I should not only use steel, but copper won't work. With these centrally vented vacuum systems, steam has to make it to the vent or the boiler never reaches pressure. If it cools too much, it just gets to the vent as air and water. I am pretty sure the temp will be below 130 degrees 4' from the vent using copper. I should have done this in the first place, but nonetheless copper is out of the question now.



As for the pipe, I was just assuming shipping cost of $300 worth of pipe wouldn't make sense. I've speced out materials from Grainger before and with steel the cut off point was about $800 before it made sense over buying locally. I will however check it out. I have some time if I need to wait on a delivery so that's not a big issue. It works now, but there are some restrictions in the line so it needs to be replaced. Another week or two won't matter much though.



As for fittings, is there a big difference between import and domestic fittings? I have wondered this for a long time. The cost of domestic is a lot higher around here, but I know pipe fitters specifically spec for them. There must be a reason but I haven't been able to get and answer to that. Are they such a lower quality that they become failure points? I'm replacing the boiler in 6 months and need to prepare for that. If I must use domestic fittings I need to get shopping and looking for deals now. The supply houses here in Michigan charge about 40% more for domestic. If I end up using them I'll buy early as deals and sales pop up.

ChrisJ

Shipping

Pexsupply does free shipping on orders over $300, or at least was. Double check to make sure I'm right.



There is a HUGE difference in thread quality on Ward vs the junk in stores. When we ran my natural gas line I had one leak and it was a chinese fitting we had to buy locally at the last minute. Chinese fittings will thread on maybe 1 or 2 turns before binding where the Ward fittings get many turns and slowly get tight.



With me, its not just about buying American, its about not wanting to deal with leaks.

vaporvac

Still free shipping

Free shipping still applies and they also have sales. Many people buy from them and you have some time. You can probably use some of the fittings off your current boiler and header. We've only needed to buy the 3" fittings and pipe for the risers. With planning you can really cut the cost of materials.

A friend had the same experience with the Chinese and gas fittings. NOT worth the savings as you'll lose them all in time, frustration and replacement. C

MDNLansing

Perfect

Thanks so much for the advice. I will investigate Pex and most likely order from them. I've done business with them in the past and had no issues. I'll certainly check them out. If shipping is free over $300 I'll just make sure my order is at least that. I can always start buying for my replacement now if I need a few more dollars to get free shipping. I don't currently have a header, just piped right into the mains, so I won't have any fittings to reuse really. I will however make sure to buy USA made fittings. I do not want to assemble and find leaks, especially leaks that don't show up for awhile. No way do I want to disassemble and reassemble the near boiler piping. More expensive of not, I'l do it right the first time.



Thanks again, this has been really helpful.