Leaky fuel line connector

[jcstockdale]

Hi All,

I'm completely new to oil boilers and plumbing in general having only just bought my first house. We ran out of oil recently and when the new delivery came, there was air in the supply line. I tried bleeding it but nothing seemed to come out. So, perhaps foolishly, I started dismantling connections leading back to the tank. The oil was eventually flowing but I can't reassemble the whole line without getting a small leak at the shutoff.

The image top left shows most of the assembly. Top right shows the flared copper pipe that connects up at the right of this. Bottom left shows the end of the flexible fuel line. Bottom centre and right show each end of the shutoff valve.

What I'm wondering is whether these are all metal to metal joints or should there be some additional rubber seals or PTFE tape or anything like that. I've a feeling that the problem is with the flared copper pipe (if that's what it is). I thought that the flare nut should be pushing this up against the rubbery looking bit inside the shutoff valve but now I'm not so sure. Is there something missing here? I've cleaned up all the metal parts so there's no paste or tape there. Do I need to reapply any kind of sealant? If so, where? Or maybe parts need adding/replacing. Please help!

Thanks,
James.

 

[OnOff]

Looks like a Riello burner there like mine?

Tbh bleeding here with an Allen key should usually do it. Open it loose with Allen key in then reset the boiler a couple of times. Air, then oil should come through. Have a tray underneath in case it spurts out!





If really airlocked I suck it through with one of these. I undo the fitting the side where it disappears into the ground.

http://www.screwfix.com/p/handy-parts-hp-162-oil-change-kit-1ltr/27283

Have once had to "push" the oil in the pipe back into the tank to let it then "woosh" down the pipe again.

I just had crud in my external fire valve (I still need to change it as it's nuisance tripping tbh). The "bowl" is screwed on and crimped. I managed to undo it with a BFO pair of pump pliers though I don't think your meant to:





Worried about leaks as it's a very fine thread, when I put it back together I used Jetblue Plus (brilliant on potable water fittings too):

http://www.plumbcenter.co.uk/product/center-center-jet-blue-plus-500-g/

 

[user 28595]

Or Fernox.

cheers, Paul

 

[ruston]

In the middle picture it looks like emulsified crud drawn out of the sludge trap . If it is an olive you will clearly see where it sits amd mates , the same is true if it needs a seal.

 Nothing to stop yoy giving an olive a wrap of ptfe tape , especially if you have scored the copper.

 

[phil d]

It's a metal to metal fit, no seal or anything used in assembly, however they are designed to compress slightly and seal when they are first assembled, When I strip anything down like that I always put a single wrap of ptfe around the flared portions, I don't use any liquid sealant, if you are not careful it can end up blocking the line.

 

[ruston]

So do I . Saves the hassle of having to do it again lol, common for them to leak when they have been disturbed.

 

[jcstockdale]

Thanks everybody for your comments. I took it to a local plumbing shop and the guy suggested that I replace the flare with a compression joint. I've done that and it seems ok. Now my problem is that there's a very slow leak on either side of the shutoff valve where the reducers fit in. You can see that the PTFE tape in these two joints is stained pink by the oil. Overnight, there wasn't even enough to form a drip but when I touched it this morning, I got oil on my fingers. What do you think I've done wrong? Too tight? Not tight enough? Too much or too little PTFE? Would hemp and paste be better than tape? I really want to put this one to bed because I've been tinkering with it every night now for a week and I feel like I'm getting very close!

Cheers.

 

[ruston]

One to two wraps is enough tape , any more and it just turns off and out of the threads,

 

[user 28595]

The joint seal is made by the taper on the olive and PTFE should only be wound on the taper, not on the apex or the threads.

cheers, Paul

 

[Doc Hudson]

The joint seal is made by the taper on the olive and PTFE should only be wound on the taper, not on the apex or the threads.

cheers, Paul

If PTFE should not be used on threads, its a bit strange having "PTFE thread seal tape" written on the side then?

https://www.tapes-direct.co.uk/index.php?main_page=product_info&cPath=150&products_id=1237&zenid=atav8h8kaduvcnd8p3i47m3090

https://en.wikipedia.org/wiki/Thread_seal_tape

Doc H.

 

[phil d]

If PTFE should not be used on threads, its a bit strange having "PTFE thread seal tape" written on the side then?

https://www.tapes-direct.co.uk/index.php?main_page=product_info&cPath=150&products_id=1237&zenid=atav8h8kaduvcnd8p3i47m3090

https://en.wikipedia.org/wiki/Thread_seal_tape

Doc H.

I think he means with this type of joint, although to be honest, personally I always wrap over the entire olive, better safe than sorry. My old chap was a plumber and sometimes as a lad I'd go and help him out, tbh most of my childhood was spent helping him fit bathroom suites or heating systems. Depending on the type of pipe or joint we'd use a variety of methods to seal a joint, Steam lines, water or certain gases and Boss White, was used,other times it was PTFE tape, on Iron pipe it was either Boss White and Hemp string or Red Hermatite and Hemp string.

I don't know if you can still get the Hermatite,but thinking about it and the smell comes back to me.

I remember doing soldered joints in lead and copper,the flux was called Fluxite, by Fry's metals, I was surprised to see it is still available, but it's a lot dearer than LaCo or the other modern fluxes.Wiping a lead joint with a moleskin cloth was a work of art, I was well pleased when I learned how to do it,they don't teach it any more.

 

[jcstockdale]

Thanks Paul. I'm not sure what the apex is with respect to compression joints. I did put some tape over the olive because it didn't seal properly the first time round. I don't think it's on the threads there. My problem is only with the threaded joints on the two ends of the tap.

 

[phil d]

Thanks Paul. I'm not sure what the apex is with respect to compression joints. I did put some tape over the olive because it didn't seal properly the first time round. I don't think it's on the threads there. My problem is only with the threaded joints on the two ends of the tap.

The apex is the top of the olive, tbh I always wrap over the olive anyway, with your problem first are you wrapping the tape the correct way around the thread? if not it will loosen as you tighten the joint, another one to try if you have trouble is to wrap 3 or 4 turns of tape around the thread then just wipe a thin smear of joint paste over the top of this. I've used this method before on really problematic joints and it always works for me.

 

[jcstockdale]

The apex is the top of the olive, tbh I always wrap over the olive anyway, with your problem first are you wrapping the tape the correct way around the thread? if not it will loosen as you tighten the joint, another one to try if you have trouble is to wrap 3 or 4 turns of tape around the thread then just wipe a thin smear of joint paste over the top of this. I've used this method before on really problematic joints and it always works for me.

Thanks Phil. I haven't touched it for a couple of days because the leak is so slow. I was planning to first see if there's any room to tighten it up and see if that helps. After that, I will see about joint paste. I definitely have the tape wrapped the right way. I wrapped it the wrong way once and it was really obvious that it was coming off. At least I haven't made that mistake again!

Regarding the brass fittings, I've heard that they are relatively soft so I'm just wondering, if it's the case that one has been overtightened, does that mean that it's permanenty damaged and needs to be replaced or can you just undo it and reapply tape / paste?

Thanks again,

James.

 

[user 28595]

The tap is probably designed to have olives and you are expecting the threads to do the work. I'd use Fernox instead of PTFE, it's very effective.

cheers, Paul

 

[Lurch]

The tap is probably designed to have olives and you are expecting the threads to do the work.

No, that tap is fine as assembled.