Boiler Line Fittings keep Breaking

ROAD3000

<span style="font-size:12pt">Okay all you boiler experts I need help </span>

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<span style="font-size:12pt">This boiler is used for heat duct only not radiant floor heat </span>

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<span style="font-size:12pt">I have a Lochinavar CHN401 gas boiler that keeps breaking fittings, fittings are copper, and I am not sure what is happing? Is it not proper expansion loops are not proper expansion tanks. The boiler sets 300 feet away from the air handlers and is 40 feet lower. </span>

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<span style="font-size:12pt">I am attaching a picture of the copper fitting break; we have had 4 breaks like this also I am attaching a picture of the piping to the boiler.</span>

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<span style="font-size:12pt">Suggestions please.</span>

ROAD3000

Opps Pictures

Pictures

Paul Fredricks_3

.

Sure looks like breaking from motion, the pipes are moving as they heat and cool. You would need some sort of stronger bracing, or a flexible connector that can take the movement.

Charlie from wmass

Basics are this

Copper likes to expand. Copper fails due to metal fatigue if exposed with out allowance for it expansion. 300 ft you need some expansion joints. Are the breaks occurring in the same location each time? Are the fittings from a certain catalog supply store? I have had brand new fitting with holes like that right out of the bag. Yours do not look like mine did but they were on the inside of the elbow like that.

Jamie Hall

Without taking a microscope...

to that break, to a certain extent I'm guessing, but... looks like low-cycle, high stress fatigue, with some stress corrosion added.  Not that unusual for copper which is being flexed.



As Paul and Charles have said, you need to set things up so that the pipe can expand and contract without putting significant stress on it.  If this were threaded, you could do it by going up 90, short nipple, then over 90, longer nipple to match the offset, then down 90, short nipple, then coming out and hooking up with what you have with another 90.  With sweat copper that won't work.  You either need a much longer expansion loop (at least 20 pipe diameters for each leg) or a real expansion joint or make the S out of flexible pipe.

Mark Eatherton

Silver soldered?

Or high temperature brazing in any case?



THe fitting I am seeing looks annealed. Actually softens the copper...



ME

icesailor

Expansion:

Absolutely, right on.

Better expansion joints or expansion allowance.

icesailor

Breaking Fittings:

Correcto again.

I once saw a heating install, PE designed, and installed by my old boss where a reverse return heat piping was done under a concrete slab and laid in sand. Screened and tamped. Uninsulated, (were talking early 1970's) and a loop kept leaking, in the same spot. In an expansion joint. The 2" copper tube would pull right out of a joint. The fittings can take the compression. They can't take the tension. Pulling apart.

Imagine the tension as opposed to the compression and you will see how to solve the problem. That is a tension crack. Compression would be crushing or a break in the back or outside of the ell.

In my case, the sand would be pushed out of the way when the pipe expanded while heated and fill in behind it. When cooling, tension came into play and the opposite tension caused by the cooling would pull the tube out of the socket.

meplumber

I agree with Mark.

Those look brazed.  Brazed fittings, when over heated, will crack.  You inadvertently anneal the fitting if you overheat it.  A 300' run should have an expansion loop in it. I believe the rule of thumb is 10 % of the total horizontal run.  Maybe Brad or one of the learned ones could tell us the rule.

Mark Eatherton

More information...

http://www.copper.org/applications/plumbing/techref/cth/cth_3design_gencon.html



ME

MikeyB

C-OF-E

Here's a good chart

ROAD3000

Okay more info on pipe

Thanks guys, pipe is copper, type L, yes fittings are silver soldered – pipe is buried 3 feet deep and no accesses to it – and yes its 300 feet long, expansion loops not installed except for offset 90 for trench position changes, pipe is wrapped in a fiberglass jacket with a plastic sleeve, breaks are random in the 300 foot length.

 

 

Okay do you think if I installed a expansion tank in the lower side and one in the upper side it would help or dig it up every hundred feet and install a 2 foot loop in the line.

 

Input

 

Thanks        

Charlie from wmass

We are not talking expansion of the fluid in the system

The pipe is expanding along its dimensions. It's length just happens to be way long then its width. the breaks may be happening as Ice said on the shrinking of the pipe and it being under tension. 300 ft under ground with brazed joints. Stock up on solder and fittings. Why not soft solder it the next time and see if it holds up better? You could also make swing joints of Brass fittings to take the movement.

Mark Eatherton

Expansion joints are virtually useless....

If installed without proper thrust blocking.



I have seen many systems that had properly sized U bend expansion joints, and STILL lost fittings due to expansion and contraction. Speaking of which, expansion joints MUST be properly cocked prior to turning it loose. For example, I did a snowmelt system in a large retail store. The longest run was 800' in length. I had 2 expansion joints located at 1/3 and 2/3's of the developed length. I thrust blocked them dead center between the expansion joints, and actually intentionally pre-cocked them into the partially compressed position. Why would a person do that?



Well, chances are pretty good that when the sensors decide that the snowmelt system needs to be on, that the slab is fairly cold, and the fluid that will be moving between the load and the source is going to cause the pipes to CONTRACT first. Hence, pre-collapsing the joints to allow for contraction first, and then expansion.



True expansion control requires the installer to think outside of the pipe. If it is going to grow, then that growth should be SENT TOWARDS the expansion joint. If left to its own devices, it WILL grow in whatever direction IT wants to grow, and it probably isn't the direction you thought or wanted it to grow.



Major changes in direction can be used to take up expansion, again, if properly thrust blocked and properly sized legs.



Thrust blocking is a science all to itself. If you don't put enough girth behind it, again, the pipes will pretty do whatever they please, and oddly enough, may change what it is that they do every time.



In lieu of silver soldering, the code allows for the use of ProPress direct burial fittings. THey have some inherent give to them and are less susceptible to redundant stress cracking at their crotch due to the copper being softened by the welding process.



We live and learn from our mistake (and yours :-)



ME

icesailor

Breaking Copper:

Another aside to this, yesterday, I turned the water in in a house. There was a broken piece of copper on the outside shower. The gooseneck for the head was galvanized steel pipe. There was a 8" piece of copper between the valve and the shower goose neck with copper adapters. A previous person installed the illegal shower valve. The valve body and arm didn't line up. So they annealed a section to bend it and make it align. The shower wasn't drained in time and the tube, split. Right where the tube was annealed. The whole section that had been exposed to high heat was split and bulged.

If copper tubing is annealed, and it is frozen and splits, it will split where the pipe is annealed. In MY experience. 

ROAD3000

Hard headed - has to be a way

Thanks Charli – I get it except not sure about the ice on the pipe part though I am in Arizona, pipe is 3 feet deep, pipe is on a boiler so I do not think it will Ice up,

 

Alright could it be possible look at picture 2 and picture 3 does the boiler piping look correct  if I compare it to the manufactures piping diagram it does not even look close the air separator and the expansion tank are in a different configuration is it possible to change this so the pipes do not move so much? If the boiler is not turned on and if the pipes are on city main water pressure they the fittings hold snug no cracks. Is it possible the expansion tank is just full of water air separator is in wrong spot??  

 

I need answers Charli stocking up on fittings and solder is not it, here is a picture of the drive way I am talking 300 feet of cobble stone pipe is under it, it would be a chore to replace and there is no way to go around the drive way.

 

This pipe was installed to the engineers specs he wanted silver soldered joints, there are 6 copper pipes going up this drive way, chiller lines, water mains, fire lines, all installed the same way same pipe same everything only the dang boiler lines keeps breaking.

 

Three has to be some way to release the motion of contraction when the pipe heats and cools.

 

Thanks’ guys           

ROAD3000

pictures

pictures

Charlie from wmass

there is a way

expansion joints set to allow the pipe to grow and shrink.

By Ic on the pipe I meant Icesailor's comment about the pipe shrinking when cooled and tension breaking the pipe. The who sized the pipe for that run? seems like a small pipe for that kind of run and that many btu's going through it.

ROAD3000

pipe size

Here is the scoop pipe is 1 ¼” engineer sized it, this system is in a house a big custom, it should not be there the A/C company installed the system they did not want to install the pipe I am a Plumber not a boiler guy I installed pipe to specs 7 years ago builder begged me to after I did not want to get involved either – every one thinks it’s a back fill issue that’s not the case are all the other pipes would be leaking. All the big boiler guys will not look at it because its on a residential house and they only work on commercial, here in Phoenix AZ hot dry claimant – boiler what’s that, you guys in the cold country see them on every other house.          

icesailor

Pipe Expansion:

You're not hard headed, the engineer didn't understand what he was doing and you did what you were told.

When pipe is heated, it expands. If it is contained at both ends, it will either buckle or bow out. When it cools, it will revert to its origonal state. You could take a pipe and hold up a house with it. The pipe is in compression. If the pipe is heated, it will exert a higher pressure while trying to "lift" the house by pushing it up. When it cools, it drops. If you cool the pipe, it will shrink. But it is still under compression.

If the pipe is in a resting state, laying in a trench, not in compression or tension, it is in flux. When it cools, it shrinks, gets shorter in it's length. It will have the same amount of force of compression while shrinking. But if it is restrained, the same force of compression becomes tension. If the pipe is buried in the ground, when it gets cold, it shrinks as it tries to compress. When the coolant stops and it reverts to its normal temperature state, it will expand into compression. But if the pipe is restrained at some point, and it can not expand in the way it decides to expand, the free part wants to go where it wants. The example I gave of the pipe holding up a house, the pipe becomes an object to lift up the house. Like putting a bridle around the house, connecting the pipe to the bridle, connecting the other end to a crane and trying to pick it up. The pipe will break at the weakest point. In my opinion, because the fittings break in the inside of the elbow, show that the pipe is in tension. It is pulled apart' If it was soldered with soft solder, it would pull out of the socket.

At least that's how I see it.

Charlie from wmass

The boiler pipes are moving more

than the other pipes. They swing from cold ground temp to 180 degrees. That is a lot of movement. I am trying to find a link to an expansion joint for you. We do not usually stick the boilers 300 feet from the house though.

MikeyB

Expansion Loop

Hoiw about trying something like this in place of your elbows, just have to pick the right one for your pressure and temp application. www.metraflex.com 

Charlie from wmass

Thanks for the web site Mikey

this is what I was referring to http://www.metraflex.com/compensators.php

They call them compensators.

Jamie Hall

Read Mark's comments carefully...

a lot of good information there (no surprise).  As I read the situation, that pipe is direct burial?  No sleeve or conduit?  Not good.  You have no idea where it is going to anchor on any given temperature cycle.  What is worse, it was my experience back in another life with continuous welded steel rail that there was a tendency for the cycling to cause the rail (or, in this case, pipe) to try to move preferentially in one direction.  The forces involved can build up to really amazing levels -- enough to snap a rail in tension, or to buckle it sideways several feet in compression.  The solution was correct anchoring, and laying the rail at the correct temperature (related to Alan's comment about prestressing the expansion joints or loops).



I honestly don't know how I would go about fixing this situation, although at the moment, at least, I can't think of any solution that doesn't involve digging the whole run up and relaying it with proper expansion joints or loops and properly done anchoring -- and setting it up so it can't possibly anchor anywhere except where it is supposed to, which pretty well means a conduit or boxed trench of some kind.

ROAD3000

expansion joints

 

Hi Guys thanks for all your comments and advice – what do you all think about this idea I need to try something –

 

1 – I have a boiler guy going to come by to check to be sure all the expansion tanks are in the right place and not holding water.

 

2 – How about if I dig up every 100 ft and install a expansion loop with a 1 ¼” braded flex line and the bottom joint install some thrust blocks, see attach drawing.   

 

 

What do you all think?

 

Jerry

ROAD3000

picture

here is the loop see picture

Dan Foley

Eco-Flex

My suggestion:  Abandon the copper and run Ecoflex



http://www.uponor-usa.com/Header/Service/For-Professionals/Products/Pre-insulated-pipe.aspx

icesailor

Expansion Joints:

I'm not an educated or trained engineer. I have only my experience to fall upon. What I say is from my experience and seeing what you are seeing with this install.

If the piping was "in the air" and supported by hangers and the pipe could go anywhere it could go, your idea might work. In fact, it should work. What you don't see or understand are the forces at play in this installation. I mentioned earlier about tension and compression. Where these two forces come into play is while buried in the sand, as the pipe is heated, it expands. Although it is moving "away", it is actually moving away in "compression". The compressive forces will push the sand away with incredible force. Forces great enough to buckle the tube if it didn't find a place to get rid of the compressive forces. While in this expanded, compressive state, sand will fall into the space that was occupied by the space while it was in flux, not moving. When the tube is then cooled, it contracts in tension. But because the sand has fallen into the void created by the previous expansion, it goes into incredible tension. Where you have those 90 degree offsets, the pressure builds to where it finally splits the fitting on the inside of the elbow. If the tube and fittings weren't silver brazed with high temperature braze rod and been done with low temperature solder, it probably would pull out of the fitting. I saw this exact same thing happen on something I was sent to fix.

Like I said, I am not an engineer. But I see things that perhaps others don't always see. If "I" were to try to solve the problem, I would NOT attempt to install those "U-Leg Expansion Joints" because that is where the failures I saw in my experience, occurred

I would instead, leave the pipes as they are, in a straight line. I would use, every 100' or less, the flexible joints you are proposing. If they are used in a straight line, the stress forces will find their way and expand and contract where they choose to. Not where you think they might want to. Someone makes expansion joints that can be used in your application. I see them as being used in a straight line. If you haven't seen buried copper pipes pull apart that were underground, and didn't figure it out, you would have no idea that it could occur.

Thrust blocks on the corners MAY be OK to force the expansion and contraction to go where you want it. But I can not prove that theory. It's just my gut feeling. I would also put expansion expansion joints in the short runs between the boiler runs and where it turns up the driveway.

Others may have better ideas than mine. That's just how I see it.

ROAD3000

Dan

Dan that’s great advice – you did not read the entire session of posting – pull up 300 feet of pavers and install pex – Yikes – I have to try expansion joints 1st  

Charlie from wmass

Jerry did you look at the compensators?

You could dig up as you planned but I would sleeve the compensators with plastic pipe. I would be concerned with the pipe grinding away over time still.

ROAD3000

Icesailor – Big thanks

Icesailor – Big thanks - okay I get it, I have been a plumber for 31 years I have installed enough pipe to wrap around the world – however not in a 300 ft boiler line – guess I am still learning all though in these 20,000 sq ft homes I have out done many and solved lots of plumbing problems in 31 years.

 

Okay sounds like my goose is cooked – I need to ditch this copper piping, chalk it up for learning, pull up a lot of pavers, install two empty conduit sleeves and pull pex piping through both one for the feed and one for the return line with some manufactured expansion joints on both ends so this pipe and say and wiggle back and forth.

 

Right  

 

Jerry     

ROAD3000

Charile

Hi Charile – yes I did, in the drawing I made I was going to add some of these at the top of the loop.

 

http://www.metraflex.com/cs_metraloop2.html

 

 

By being educated by you guys it just sounds like for one the pipe is to small for 300 feet, no expansion, protection – sounds like I am better off telling the customer, get out your check book time for a new pipe, we installed per their engineer spec so I am out of the blame loop.       

ROAD3000

Charile

Hi Charile – yes I did, in the drawing I made I was going to add some of these at the top of the loop.

 

http://www.metraflex.com/cs_metraloop2.html

 

 

By being educated by you guys it just sounds like for one the pipe is to small for 300 feet, no expansion, protection – sounds like I am better off telling the customer, get out your check book time for a new pipe, we installed per their engineer spec so I am out of the blame loop.       

Mark Eatherton

Before you start ripping and tearing,,,

PEX has a significantly HIGHER coefficient of expansion. It grows 1.1" per 100' length per 10 degrees F change in temperature.



So, your 300' long circuit, going from 60 to 180 degrees F, will grow 39.6 inches...



What ARE you going to do with all that extra unanticipated PEX?



If you anchor it in the very middle of the run, and place some 360 degree loops at the ends, allowing the growth to grow into the circular loops, then you will have control of the expansion. Otherwise, its going to control you.



I didn't say anything originally, but that size of pipe also looks undersized, based on normal engineering practices. Shouldn't make much difference in the expansion/contraction problem, but the next thing to raise its ugly head will be hydraulic erosion corrosion due to excess velocities...



Have you considered contacting the original engineer and pointing out the fact that he may have a claim against his E&O policy?



ME

Ironman

Other Issue(s)

With an 1.25 in line running 600 ft (supply + return), you would only be able to get 20 gpm max while keeping the velocity below 5 ft. pr. sec. And that's stretching it. At 20gpm, the 400k btu boiler would be running a 40 deg Delta T (180 supply, 140 return).  This too low a gpm and too high a Delta T. AHU coils are normally sized at a 20 deg Delta T, so also for the boiler. You need 2" lines or at least two sets of 1.25" lines. This doesn't even factor in the heat loss through the 600 ft. of underground piping. That would probably be another 10 - 12 deg.



A better option, if possible, would be to install a mod/con boiler near the AHU's and abandon the underground piping. That would also be much more efficient and would eliminate that huge, electricity-gulping pump.



Something to consider.

ROAD3000

High pressure low pressure loop,

High pressure low pressure loop,

 

Okay peeps; let’s see if you all can think outside the box –

 

Basically this is a big custom house 15,000 sq ft are bigger, house has a big old domestic water heater and the house hot water heater system is plumbed in a loop with a typical low flow re circ pump, this re circ pump – pumps hot water through miles of 1 ¼” tubing 24 – 7 in order for all taps to have on the demand hot water, the water temp is set to 120 degrees. This is considered a high pressure system (kind of) and there is no thought in the world even taken into expansion and contraction except for the expansion tank on top of the water heater.  Typical hot water heater system.

 

Okay back to the boiler – the boiler and feed pipes are buried in the ground 3 feet deep, boiler kicks on and off only when demanded to (right) so we get expansion and contraction when the pipe heat & cool.

 

What if………….?

 

You pipe anther short jog from the water heater throw on another low flow re circ pump place a few strategic solenoid ball valves on the boiler feed and re turn lines, this would keep the boiler lines hot 120 degrees 24 – 7 no more contraction and in turn would create a high pressure low pressure loop.

 

What do you think…..?

 

See Drawing…..?

 

I know before you throw hot tar on me – think outside the box, I think it would work, the domestic water heater is already running 24 – 7 and there would not be any noticeable energy loss.

ROAD3000

Drawing

High pressure low pressure loop



drawing

Ironman

Too Far out of the Box

You not only got out of the box with that proposal, you fell of the wagon too. No sarcasm intended. Surely, you not trying to poison the home owner, are you?



You can't mix potable and hydronic water, neither can you run potable through lines that have been used for hydronic.



And 120 deg is perfect breeding ground for legionellae! Get back closer to the box. Things that are done properly in hydronics are done that way for a reason: to protect people and the equipment.



Why not replace that water heater with  mod/con boiler and an indirect water heater? Then abandon all that underground piping. The boiler would be in the house where it belongs. Instead of exotic solutions, let proper hydronic design prevail and the problem is solved and you have a much more efficient system.

ROAD3000

Ironman

Ironman –

 

I am laughing now – it was just a crazy thought, I actually met with a 40 year exp boiler guy to at the job with the home owner, I picked his brain apart, his idea was basically dig up every 90 and put manufactured expansion joints in, he did not think the pipe size mattered nor did he think thrust blocks were needed, he was basically” in my 40 years of exp I never installed a thrust block.  

 

So after we hashed out the system and the digging up the 90’s about a hour went by, and I sprung your idea on installing a new energy efficient boiler in the garage next to the air handlers, that sprang a light bulb in every one the boiler guy and the home owner the 300 feet long run is gone – the chiller can stay down the hill that has worked great for the last 7 years. The garage mechanical room already has gas, water and drain and air vents in the doors the boiler guy just has do hang some pipe from the ceiling and push a PVC flu vent up for a vent.

 

So it looks like Iron man you do get the cake.

 

Thanks guys for all your help helping this plumber out it was a learning curve for sure for me.

 

Jerry            

Ironman

Glad to be of Help

Jerry,



That's the reason for this site: to help one another. The better educated and informed that each one of us becomes, we become a greater asset to our industry. All of us on here learn by sharing our knowledge and experience.



Keep coming back, and please, let us know how this one turns out.

Mark Eatherton

Good job Bob...

That recommendation will probably be reducing his fuel bill by at least 30%, plus eliminating the underground losses and piping system self destructing.



ME