Just replacing the kitchen gas hob for a new one. It comes with a
right-angled pipe (an elbow), one end of which goes into the hob and one end
into the copper supply pipe.
The *threaded* part of one end of the right-angled pipe is about 4mm longer
than the threaded part of the other end.
Would it be the *longer* threaded part that goes into the hob or the
*shorter* threaded part?
Since I was supplied with a rubber washer to go into the hob connection
joint, should I use gas tape on both the threaded ends of the right-angle
pipe. Thanks for advice.
And that's how the language changes!
'Hob' also common, in North America, where wood stoves were used (and
even after that when some such stoves were converted to dual fuel)
Also common expression where a kettle of hot water was kept 'on the
hob'. And as in saying "Come on in out of the cold and have a cup of
tea/coffee; the kettle is on the hob".
The term was also occasionally applied to a swinging bracket on some
stoves on which the kettle was placed after it had boiled, to keep it
hot or simmering.
Younger generations and/or the less well read, brought up with
electricity probably unlikely to be familiar with the term 'hob'.
Wife's grandmother who died at 101 in the 1970s would refer to her
wood stove as having four 'hobs'; these were the round metal sections/
covers in the heavy cast iron metal stove top that one would lift to
expose bottom of cooking pot to direct heat. She was a smart woman but
if one used a term such as 'data' or 'cyber' she wouldn't be be
Your messing with gas not knowing what you are doing probably
justifies the rules of gas fitting only being done by qualified
engineers. Do your family a favour pick up the phone and call a
"Gas safe" gas fitter.
Sounds like an elbow I have. The long side probably has a tapered
diameter and the other side has a constant diameter. If so the tapered
side screws into the black pipe and the other connects to the hob.
Picture would help?
Ooops, left out connects to hob via flexible pipe. Anyway it sounds
like the long side of the fitting is for iron pipe and the other for
flexible copper tubing via a compression fitting or a flare fitting.
This may mean the elbow was either intended to connect the supply to
the flexible copper pipe or the hob to the flexible copper pipe.
hope this helps
You probably ought to check the instructions, they might say. The end
that goes into the stove probably is not tapered thread if it has a
washer that sits under it. In that case you would not use tape. Tape
is only for "pipe" thread. Pipe thread tapers and achieves a seal by
the threads themselves. On that you do use tape or dope. If you
really have soft copper pipe coming in for the supply you may need an
adapter between the elbow and the copper so you can use a compression
fitting on the copper. If that's the case carry the elbow down to a
friendly local hardware shop and ask for help :-) Here in the states
we usually have black iron pipe for supply at it does have tapered
thread but I know you guys and the canadians use copper sometimes.
Nothing wrong with copper but your stove might be geared towards the
way we do it.
In the US, where I am. Natural gas is a low enough
presure, that the folks I work with coat the
external (male) threads with a bit of Rectorseal
#5. We do not use teflon tape on gas threads. Risk
of some of the tape flaking off, and get into the
gas valve, and create more problems.
Can't comment on the long or short ends of the
elbow. Try both -- see which works better.
Who is this "we" of whom you speak?
Honestly, every plumber I know uses teflon tape. I know there's other
stuff available, and I'm sure it works, but were does this stuff come
from all of a sudden that "nobody used teflon tape"?
Hell, use old-fashioned pipe dope for that matter. It all works.
And another thing: what's the big deal about the "correct" tape for gas
(the yellow stuff)? Again, maybe it's better, but everywhere I go I see
white tape on joints in gas piping. And none of it leaks.
You were wrong, and I'm man enough to admit it.
The yellow tape (for gas fittings) is thicker. The white is for water.
The reason is, that the white tape can suffer from osmosis, in other
words, the gas can slowly permeate through the tape.
It is only a very,very tiny leakage and probably almost undetectable
by sniffing, but that's the reason.
We means all the gas fitters I've met, and
discussed the question with. Since natural gas is
very low pressure, the teflon tape really isn't
needed. And it risks having part of the tape flake
off, and get into the gas valves. The yellow tape
is supposed to be thicker. But, with the lower gas
pressure, it's not really needed.
If a plumber showed up at one of my projects with Teflon tape in his
kit, he'd be shown the door. Same thing for a finish carpenter with
Plastic Wood in his toolbox. Sign of a competent journeyman is using
the best, not 'quickie' materials.
It comes from plugged gas valves, faucet strainers with bits of Teflon
tape stuck in the screens, and in other trades, failed engines with
bits of Teflon tape stuck in oil passages.
But the Teflon filled variety is much better.
If you had a detector similar to those used for Freon, you'd find
that, indeed, it does leak, although not to a critical extent. Local
gas company here apparently not using it, so it may not be universal.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.