Hot water boiler near piping leaking


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Old 12-01-09, 08:47 PM
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Hot water boiler near piping leaking

Hi all. I installed a Peerless WBV-04 boiler with black pipe near piping and I made the mistake of using Home Depot China elbows, tees and other fittings. Guess what; they leak! The leaks are not bad, but I have a small puddle at all times. Any suggestions to fix it short of taking it apart and using better fittings? Thanks.
 
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Old 12-02-09, 04:28 AM
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What did you use as a thread sealant ?
Where is it leaking ? Where the pipe threads into the fitting or on the fitting itself ?

Eventually small leaks will result over and seal, but that is not the intent on piping a boiler.

I am hesitant to just blame the fittings because they are made in china, if not installed properly then any fitting will not seal.
 
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Old 12-02-09, 07:15 AM
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I would recommend pipe dope rather that teflon tape. But, yes, you'll need to disconnect the leaking joints and reinstall.

Without experience, it's easy to underestimate the torque required to pull up threaded pipe connections. Here are the specs published by Crane Co. and Bell & Gossett:

1/2" 45 ft-lb
3/4" 65
1" 95
1-1/4" 130
1-1/2" 180

So, with an 18" pipe wrench, a 3/4" joint will need 65/1.5 = 43 lbs applied to the wrench. (If you use two wrenches, one on either side of the joint, you still need to apply 43 lbs to each wrench.)

I prefer U.S. fittings, but I haven't had any problem with the Chinese fittings. I have a hard time thinking that various sized fittings would all be bad - rather, I'd bet there is something wrong with your technique.

What size wrenches are you using? For 1/2" connections, I would use a 14" pipe wrench. For 3/4", I'd use an 18" wrench. For 1" connections and larger, I would use a 24" wrench. And, ideally, you should have two wrenches of each size - maybe not for the casual handyman, for sure if you're installing your own boiler.
 

Last edited by Mike Speed 30; 12-02-09 at 09:22 AM.
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Old 12-02-09, 03:33 PM
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And those torque guidelines should result in EIGHT THREADS more or less of engagement into the fittings.
 
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Old 12-02-09, 04:03 PM
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Originally Posted by NJ Trooper View Post
And those torque guidelines should result in EIGHT THREADS more or less of engagement into the fittings.
And 8 threads corresponds to 8 full turns of the pipe into the fitting.

NPT pipe threads are tapered - the leak-tightness is achieved through the physical interference of the female and male threads. Pulling up the connection takes more torque with every turn, so it seems tight enough, but it isn't.

Most people's experience is with tightening a nut and bolt enough so it won't come loose on its own. Or tlghtening a threaded plug up against a gasket, like a car's oil drain plug. Or a copper compression fitting.

Pipe threads need more torque than those examples. Pipe "sealant," such as pipe dope or teflon tape are not, strictly speaking, sealants. They are, first and foremost, lubricants - so that your can get those 8 turns, or whatever, without getting a hernia. They also help prevent the joints from freezing/rusting together - which makes disconnection difficult. They do some sealing, too, but you could achieve a perfectly leak-free joint without either dope or tape.

The 50-year-old, oil-based pipe dope worked fine, and the old joints are relatively easy to unthread. Do not try to make up for your inadequately torqued joints by buttering up the threads with dope and/or teflon tape. Use the correct wrench, and tighten, tighten. Probably the worst idea, in my opinion, is 3 wraps of teflon tape followed by a thick smear of pipe dope.

Why do I prefer pipe dope over teflon tape? Here's an example: I had some experienced, union plumbers put in a new bathroom a couple of years ago. I recently noticed that the lavatory faucet was running slowly, so I unscrewed the strainer/aerator. Guess what? Shreds of teflon tape caught in the aerator.
 

Last edited by Mike Speed 30; 12-02-09 at 05:02 PM.
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Old 12-02-09, 05:08 PM
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Doesn't anyone use wick and dope anymore? My mechanics do and we have very few problems considering the amount of work we do.
 
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Old 12-02-09, 05:08 PM
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As I posted in another forum the biggest advantage to Teflon tape is that it is clean to work with and not messy the way "dope" is. Unfortunately the biggest disadvantage to Teflon tape is that joints made up with it often leak.

...you could achieve a leak-free joint without either dope or tape.
Maybe if the threads were absolutely clean and were cut perfectly on both the male and female ends AND you had the strength of a gorilla. In the real world tapered pipe threads will almost always leak if assembled without a sealing joint compound. Mere lubrication will not be enough.

My experience over forty years is that leaking joints made up with Teflon tape likely will take years to seal on their own and of course self-sealing only applies to steel piping carrying water.
 
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Old 12-02-09, 05:14 PM
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Originally Posted by MasterPlvmber View Post
Doesn't anyone use wick and dope anymore? My mechanics do and we have very few problems considering the amount of work we do.
Do your mechanics also make up their own dope with litharge and glycerin or perhaps use white lead and linseed oil? Maybe graphite and steam-cylinder oil?

Honestly, using wicking went out at least fifty years ago except for the rare oversized female fitting or in case you have to re-use fittings that have been overstretched by a gorilla pulling on the wrench because of not using more modern sealing-type pipe thread compounds.
 
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Old 12-04-09, 11:52 AM
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Thanks for all the replies! Not all the fittings are leaking, but many are, including all the tees. I used Hercules pipe dope as a sealant, without teflon tape. I cut the threads using my rigid pipe threader that is in good shape (about five boiler jobs since new) and I used a lot of cutting oil. It is 1 1/2 black pipe and I torqued the crap out of the pipe (and have since with the leaks too, where possible) using two 24" pipe wrenches (I thought I was tightening them too much). I took apart part of the assembly and inspected the threads on the fittings and they are not great. I reinstalled a cap that was leaking with teflon and then dope, and that worked.

If it has to come apart, I will have to wait until the heating season is over. Any ideas how to achieve a seal until then?

If I have to take it apart, any suggestions on what product(s) to use for sealant?

Thanks!
 
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Old 12-27-09, 11:32 AM
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I had the exact same leak issues when adding a zone to an existing system. I made up a manifold using fittings I got at HD and every joint leaked. I used dope on each one and while it very well could have been that I didn't put enough grunt into tightening the fittings, I took the whole mess apart and reassembled with tape. No more leaks.
 
 

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