I recently bought an old house that has steam radiators. I noticed that in some places that copper piping (1 1/2″ I think) was connected to the galvanized pipe to finish a “run” to the steam radiator. My first question is this safe or allowed by code? If it is safe can you just sweat these connections like a regular copper water line or do you need special solder, etc.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Learn more about the benefits and compliance details for the DOE's new water heater energy-efficiency standards.
Featured Video
Video: Build a Fireplace, Brick by BrickHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Safe? Yeah.
Good practice? It is joining two dis-similar metals, which can be a problem if liquid water is present. Better practice would be a length of brass in between or an appropriate temp-rated di-eletric union (if condensate travels in that line). Steam only? Not a problem - gases don't carry current (ionized gases in fluorescent tubes excepted).
Yes, you sweat it like other copper pipe, but it will go easier if you throw more heat at it. Two people each with a torch works better. You don't over-bake the flux before the whole fitting is hot enough. You are not required to use lead-free solder because it is not potable water, but I would for the higher temperature rating. However, old-style 50-50 lead-tin IS easier to use, especially on those bigger fittings.
Also, very close to the galvanized, there is a big heat sink (the galv). So it can be easier to sweat the female adaptor on BEFORE joining it.
Note that in bigger copper sizes, there is both DWV copper and type K, L , etc. You need the pressure-rated stuff like for potable piping. The DWV fittings/pipe are cheaper because they are lighter but are not rated for higher pressures.
"Not a problem - gases don't carry current"
But do you ever only have gas?
When steam hits the cold pipes you will get condensation. Now I don't know how long that will last, but ???
But do you ever only have gas?
I don't know what kind of system he has. If it is the outbound pipe of a two-pipe system, it may only have steam in it. If it is the return pipe or if it is a one-pipe system (all sloped back to the boiler), then there is definitely water and steam in it and for good service and longevity, dis-similar metals should be properly isolated.
DanT mentioned bigger torches - a good idea. MAPP gas in a propane/MAPP rated torch is bit of help too. Too spendy to use routinely, but good for occasional uses.David Thomas Overlooking Cook Inlet in Kenai, Alaska
My system is a one pipe system which drains back to the boiler. I currently have a small torch with MAPP gas, would this be sufficient since it burns hotter or should I also go rent the bigger torch?
You can do it with a small torch with MAPP but keep it moving. You don't want to burn the flux in one spot before the other side is ready to suck solder.
If it is your first time sweating fittings bigger than 1", it can help to have someone else hold the solder. You keep the torch moving over the fitting. And they keep testing the coldest spot until it sucks. Then feed it about twice as much solder as you are used to.
One-pipe? Then the perferred set-up is to use a di-electric union. However steam condensate doesn't corrode as fast as potable water (steam condensate is distilled water). So if, when you open up the old fittings, they aren't very corroded, I would consider not using di-electrics.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Edited 9/13/2004 4:45 pm ET by David Thomas
> MAPP gas in a propane/MAPP rated torch is bit of help too. Too spendy to use routinely, but good for occasional uses.
Do you find that in addition to being more expensive to buy, the MAPP cylinders don't last anywhere near as long as propane? I haven't clocked it, but subjectively it seems that way.
I tried dielectric unions on the W/H once, they didn't last any longer that going directly from copper flex to galv. This time, I went copper to brass to stainless braided tube to galv, which I hope will last better. For this kind of thing, I prefer to sweat a copper thread adapter onto the copper pipe. That way you can fix it up a time or two again before you have to use a torch.
-- J.S.
"MAPP cylinders don't last anywhere near as long as propane"
Doubly so. Or maybe triply so. Or quadrupely so?
1) Yes, it seems like I go through them faster (cause propane is stored densely as a liquid?) 2) I don't keep them around in any quantity. 3) they are costly when time to replace. And 4) I refill my propane* but have to drive to get the MAPP.
*No, I don't transport the refilled cylinders across state lines, so I am not breaking any $5,000/offense federal laws. BUT, it is a good practice to toss the disposable ones unless you are really familar with all the ways by which refilling cylinders can end badly.
Yes, I like a 6-inch brass nipple for 1/2" and 3/4" runs. And no, I don't want to get into another theoretical discussion about why that shouldn't work. It does work. Brass nipples are a good transition from Cu to Fe - cheaper, reliable. And it has to do with kinetics. Yes, it makes a battery, but a very bad battery. And that is a good thing.David Thomas Overlooking Cook Inlet in Kenai, Alaska
Thanks, any idea why someone would have used the copper piping (seems to be more of an effort) than to use galvanized (which screws on easily)?
any idea why someone would have used the copper piping (seems to be more of an effort) than to use galvanized (which screws on easily)?
threading galvanized takes specialized tools. Copper uses commonly available tools.
Marine Engineer
You mention ...."Liquid water" ...is there any other kind? huh!
"You mention ...."Liquid water" ...is there any other kind? huh"
Water, like most compounds, can exist as a solid, liquid, or gas. You knew that. But since "water" can refer to the liquid state or any/all of those states, I tried to clarify. Apparently to no avail.
P.S. There are several different forms of ice (but no "ice 9"), and also a supercritical fluid that has properties of a dense gas and of a very hot liquid.David Thomas Overlooking Cook Inlet in Kenai, Alaska
The triple point.
I never met a tool I didn't like!
The preferred pipe for steam is schedule 80 with cast fittings. Most replacement work is schedule 40 with mallable fittings.
Copper tends to weaken at the joints due to expansion and contraction. 95-5 is stronger than 50-50.
Galvanized pipe would be my last choice. Threading and reaming the pipe removes the zinc, so in effect, you have black pipe.
NEVER use galvanized in a hot water heating system that has glycol, it reacts with the gylcol and does nasty things.
If your near boiler piping is correct and the mains are sloped properly, I'm willing to bet there is little corrosion at the copper to iron joints.
How do you find out if your hot water heating system has Glycol in it?
The proper way to test for glycol is to take a sample and have it tested by a good boiler chemical supplier.
I've seen properly piped systems that were built in the twenties, and some of the pipe looks like new.
"The proper way to test for glycol is to take a sample and have it tested by a good boiler chemical supplier."
I thought the proper way to test for glycol is to take a sample and have it TASTED by a good PLUMBER. <G>
Seriously, you're right. The automotive floating ball thing can give you gycol percent but the amount of anti-corrosion agents is important too.David Thomas Overlooking Cook Inlet in Kenai, Alaska
What I really need to know is what dose is lethal.
I'm afraid I might find out some day.
At least it tastes good.
But what do I know, I'm just a dumb plumber.<G>
Edited 9/15/2004 2:41 pm ET by rich1
"What I really need to know is what dose is lethal."
Lethal doses of ethylene gycol can be a low as 1/4 cup in an adult.
Much less in a child.
A tablespoon in a dog.
A larger dose can be successfully treated (by administering ethanol) if the ingestion is recognized / witnessed. Cats often don't show symptoms til they're goners.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
1/4 cup. No problem. :)
I don't know nothing about steam pipes.
But coppyer should NEVER BE CONNECTED TO GALAVANIZED WITHOUT A DILECTRIC UNION!
You will get a large amount corrosion on the inside of the galavanized pipe. DAMHIKT!
A dilectric union has a copper part solidered to the copper and galvanized part that screws into the galvanized part.
Then there is a plastic/fiber washer that goes between then and and shoulder washer that insulated the coupling nut from the copper.
Years ago I did some low pressure steam piping. The old guys (probably were my age now) that I worked with said never to use galvanized with steam. I know with water it will honeycomb shut and impede the flow. Might be the same with steam especially if it is using a return pipe.
Dave is right on the soldering of bigger pipe. You can rent a large torch that goes on a 30lb propane cylinder and that works well with up to 4". Acetylene is what we used after 3". DanT
I don't know about steam systems, but we never use dielectric fittings for joining new copper pipe to the old black pipe in the hot water systems that are common around here (MN). And yes, I have never seen galvanized pipe in these systems -- only black pipe.
I was told it has something to do with the fact it is a closed, circulating system.
About 15 years ago, we replaced the old (1903) 4" pipe running through my basement with new copper. So far there is absolutely no evidence of any telltale reactions where the new was joined to the old.
AFAIK, there's no problem joining copper to black iron/cast iron, or any other purely ferrous-type pipe. The problem occurs when you add zinc to the mix, as you do when using galvanized pipe.
Your steam radiators are probably cast iron; you should NOT repeat NOT have ANY galvanized pipe anywhere near them, copper or no copper elsewhere. You will wind up with a differential charge known as galvanic action which will corrode the zinc to very nasty rusty mud. Want to see what this looks like?
View Image
The crud you see in the pump above was caused by the one little galvanized nipple you see below. Note that nipple had been cleaned out only a few months previous to this photo being taken.
View Image
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
PS--If you want to see more graphic pix of this phenomenon, go to http://forums.taunton.com/tp-breaktime/messages?msg=43384.1
Edited 9/14/2004 6:31 pm ET by Dinosaur
A number of folks have mentioned dielectric unions. Check into it, but they may not be up to the very high temperatures of a steam system. Brass may be the better choice.
Recommend that you also take your question over to "Heatinghelp.com" to ask the steam experts.
I recall that for steam systems, there is a concern with some water sources (depends on your water, acidity or something) that can cause the copper to leach off the pipes and 'plate' the inside of your cast iron boiler, ruining it over time (Cu reacts with Fe and the cast iron rusts out).
For hot water heat systems this is not a problem because the temp is much lower.
Remember that the issue for steam piping is NOT pressure (a properly set up domestic system will never be going over 2psi, and a well balanced system will operate best at even lower than that), the concern is for heat and the things that hot steam can do over long (many years) of exposure.
Depending on your local water you may mix pipe materials with no concern, or you could ruin your boiler. One way to find out is to have a sample of your water analyzed (the people at heatinghelp can tell you where to have that done) for copper content (among other things that such analysis can tell you about your system's health).
Many things that work well for domestic water heaters (like dielectric unions) may not be a good idea for steam because there is a world of difference in the energy stored in steam vapor vs. 165~180F water, even at low pressure.
hope this helps,
Norm
Norm,
Thanks for the reference to heatinghelp.com, very informative and people were eager to help!
Thanks!