Self cutting taps

[Theo]

I want to add some tees to my heating pipes, but I don't want to drain the
system down. There are things like:
https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250

but I wondered about them. In particular, apparently they cut
a flap of copper pipe where the tee goes in - does this restrict the flow in
the original pipe?

I'm also wondering what happens if that flap detaches: since it's copper I'm
not sure my magnetic filter is going to catch it, so it could get lodged
somewhere.

Any opinions as to whether they're a good idea?

Thanks
Theo

[John Rumm]

On 12/07/2022 23:50, Theo wrote:
> I want to add some tees to my heating pipes, but I don't want to drain the
> system down.

There are plenty of ways of working on CH pipework without a full drain
down. Perhaps we should do a wiki page on the various techniques?

> There are things like:
> https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250
>
> but I wondered about them. In particular, apparently they cut
> a flap of copper pipe where the tee goes in - does this restrict the flow in
> the original pipe?

Yes.

There is a type that compresses the slug of copper it takes out and
pushes it out the back into a small reservoir in the back of the
fitting. These don't restrict the flow.

They are normally only available as isolators, so you would need a
suitable branch of pipe to fit them to:

https://www.youtube.com/watch?v=MCVQ0HkxNeg&t=3s

> I'm also wondering what happens if that flap detaches: since it's copper I'm
> not sure my magnetic filter is going to catch it, so it could get lodged
> somewhere.

They cut bit tends to stay put.

However the linked above is designed for connecting washing machine
hoses, not additional fixed pipe. Something like:

https://www.screwfix.com/p/self-cutting-isolating-valve-15mm/59752

Is intended for pipe extensions.

> Any opinions as to whether they're a good idea?

IMHO, the self cutting tap type are a bit of a bodge really. The Aladdin
ones do have a real cost benefit advantage in in some circumstances though.

For mods to a typical domestic system it is little extra work to do the
job without needing them.



--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

[alan_m]

On 12/07/2022 23:50, Theo wrote:

> I want to add some tees to my heating pipes, but I don't want to drain the
> system down. There are things like:
> https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250
>

What size hole does it cut in the pipe? It could be a lot less than the
bore of the pipe you are cutting in to.

Someone removing a washing machine self cutting tap fitting.
https://youtu.be/RZBDz3oG7tY?t=183

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

[John J]

It's entirely possible to introduce a compression tee into copper pipework in an undrained system without draining down. If open vented use rubber plugs in both feed and vent pipes (these are sold as "no drain" kits). If it's a sealed system depressurize and close any auto air vents. Protect the area you are working in with a poly sheet and a highly absorbent cloth or towel. Clean up the pipe you intend to cut, use a pipeslice to cut the pipe with a suitable end to slide easily into the compression tee which has a smear of boss white in the olive and work quickly.

[Robert]

And a Wet & Dry Vacuum does wonders in sucking the water up !

[Brian]

I’d not touch them with a barge pole.

Draining downing the CH system and refilling with fresh water + inhibitor (
ideally having used a flushing cycle) every couple of years is a good idea.


That said, if you really don’t want to drain it, there are several
alternatives. Others have described some, there is also freezing - you
freeze either side of the cut using a special kit. Depending on where you
need to cut in, you could do a partial drain. Close off the rads above the
point, tie up the ball cock / turn off the feed to the header tank (
assuming a vented system). If possible, stick a cork in the exit pipe from
the header tank ( or empty it - a syphon works). You now only need to drain
the pipes above the cut in point.

If you recently filled up with inhibitor etc and don’t want to waste it,
you could always drain into a bucket and pour into the header tank before
turning the feed bank on. However, inhibitor only lasts a couple of years
and is cheap enough.

[RJH]

And close the valves on all the radiators. There was barely any pressure/water
loss when I replaced a ground floor valve recently.
--
Cheers, Rob

[Theo]

John Rumm <see.my.s...@nowhere.null> wrote:
> On 12/07/2022 23:50, Theo wrote:
> > I want to add some tees to my heating pipes, but I don't want to drain the
> > system down.
>
> There are plenty of ways of working on CH pipework without a full drain
> down. Perhaps we should do a wiki page on the various techniques?

That would be most useful - I think there's various tricks you can do that
I'm not really familiar with. Pointers to videos are also handy.

(in this case, the reason for not draining down is the system contains about
75 litres of glycol mix - so it's expensive to do a complete refill, and you
can't use pipe freezing. It's a pressurised sealed system)

> However the linked above is designed for connecting washing machine
> hoses, not additional fixed pipe. Something like:
>
> https://www.screwfix.com/p/self-cutting-isolating-valve-15mm/59752
>
> Is intended for pipe extensions.

I was also looking at that one, but it sticks out quite a lot. Also the
tiny isolation screw isn't the nicest UI for turning the extension off.
(which might be an every-few-months thing, not once-a-decade)

> IMHO, the self cutting tap type are a bit of a bodge really. The Aladdin
> ones do have a real cost benefit advantage in in some circumstances though.

That was my feeling. If I can do it without having to drain or get water
everywhere, I'm happy with that option.

> For mods to a typical domestic system it is little extra work to do the
> job without needing them.

Agreed.

Thanks
Theo

[Andrew]

Must have been sealed system then. If you have an open header tank then
I would have expected a gush of slimy black water.

There is always the "carrot in the header tank outlet connection" trick
or use a proper concentric-stepped rubber bung.

[Andrew]

On 13/07/2022 10:06, Brian wrote:
> Theo <theom...@chiark.greenend.org.uk> wrote:
>> I want to add some tees to my heating pipes, but I don't want to drain the
>> system down. There are things like:
>> https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250
>>
>> but I wondered about them. In particular, apparently they cut
>> a flap of copper pipe where the tee goes in - does this restrict the flow in
>> the original pipe?
>>
>> I'm also wondering what happens if that flap detaches: since it's copper I'm
>> not sure my magnetic filter is going to catch it, so it could get lodged
>> somewhere.
>>
>> Any opinions as to whether they're a good idea?
>>
>> Thanks
>> Theo
>>
>
> I’d not touch them with a barge pole.
>
> Draining downing the CH system and refilling with fresh water + inhibitor (
> ideally having used a flushing cycle) every couple of years is a good idea.
>
>

and also fit some full-bore 'lever' valves in strategic places too.

[Andy Burns]

Andrew wrote:

> There is always the "carrot in the header tank outlet connection" trick

I though that was mentioned in a diywiki article, but search didn't find it earlier.

[RJH]

On 13 Jul 2022 at 10:27:26 BST, Andrew wrote:

>> And close the valves on all the radiators. There was barely any pressure/water
>> loss when I replaced a ground floor valve recently.
>
> Must have been sealed system then.

Yep.
--
Cheers, Rob

[RJH]

On 13 Jul 2022 at 10:06:35 BST, Brian wrote:

> Draining downing the CH system and refilling with fresh water + inhibitor (
> ideally having used a flushing cycle) every couple of years is a good idea.

Is it? ISTR a discussion on this NG that settled on the notion that refilling
introduces more oxygen into the system, increasing the liklihood of corrosion
(or something, forget the exact details).

--
Cheers, Rob

[Clive Arthur]

On 12/07/2022 23:50, Theo wrote:

It was a long time ago, probably 35 years, but I remember a former
colleague telling me he'd used one of these. He went on to discover
that an emergency plumber on christmas day was not cheap.

--
Cheers
Clive

[Theo]

Clive Arthur <cl...@nowaytoday.co.uk> wrote:
> It was a long time ago, probably 35 years, but I remember a former
> colleague telling me he'd used one of these. He went on to discover
> that an emergency plumber on christmas day was not cheap.

As a counterexample, our dishwasher is plumbed with one of these. The
dishwasher is about 15 years old, so I assume there has not been a problem
since then (otherwise it would have been replaced with something better)

Maybe those 35 years ago weren't as good?

Theo

[Tim+]

Theo <theom...@chiark.greenend.org.uk> wrote:
> John Rumm <see.my.s...@nowhere.null> wrote:
>> On 12/07/2022 23:50, Theo wrote:
>>> I want to add some tees to my heating pipes, but I don't want to drain the
>>> system down.
>>
>> There are plenty of ways of working on CH pipework without a full drain
>> down. Perhaps we should do a wiki page on the various techniques?
>
> That would be most useful - I think there's various tricks you can do that
> I'm not really familiar with. Pointers to videos are also handy.
>
> (in this case, the reason for not draining down is the system contains about
> 75 litres of glycol mix - so it's expensive to do a complete refill, and you
> can't use pipe freezing. It's a pressurised sealed system)

If you depressurise (and turn off all the radiators as someone else
suggested) you really will lose very little water. It’s one of the big
advantages of a pressurised system.

Have a towel and/or wet & dry vacuum cleaner handy but I think you’ll find
that you’ll only see a bit of a dribble.

Tim

--
Please don't feed the trolls

[The Natural Philosopher]

On 13/07/2022 05:50, alan_m wrote:
> On 12/07/2022 23:50, Theo wrote:
>> I want to add some tees to my heating pipes, but I don't want to drain
>> the
>> system down.  There are things like:
>> https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250
>>
>
> What size hole does it cut in the pipe? It could be a lot less than the
> bore of the pipe you are cutting in to.
>
> Someone removing a washing machine self cutting tap fitting.
> https://youtu.be/RZBDz3oG7tY?t=183
>

+1 Very informative


--
In todays liberal progressive conflict-free education system, everyone
gets full Marx.

[John Rumm]

On 13/07/2022 10:17, Theo wrote:
> John Rumm <see.my.s...@nowhere.null> wrote:
>> On 12/07/2022 23:50, Theo wrote:
>>> I want to add some tees to my heating pipes, but I don't want to drain the
>>> system down.
>>
>> There are plenty of ways of working on CH pipework without a full drain
>> down. Perhaps we should do a wiki page on the various techniques?
>
> That would be most useful - I think there's various tricks you can do that
> I'm not really familiar with. Pointers to videos are also handy.

ok here is a start on the words (not proofed yet!)

I will find some pictures to add.

Some others may want to add more.

http://wiki.diyfaq.org.uk/index.php/Central_Heating_maintenance_without_draining_down?venotify=created#Isolate

[John Rumm]

That is part of the job of corrosion inhibitor - it has an oxygen
scavenger designed to mop up any dissolved oxygen.

However the point stands, that if the water is keep clean (filters /
inhibitors), then there is no need for a routine drain that often on a
sealed system since there ought not be much corrosion.

[John Rumm]

They work well enough, at least for a washing machine hose anyway. They
do occlude the pipe they are fixed to a bit though.

The main risk is probably cocking up the fitting and getting a leak then.

[Theo]

John Rumm <see.my.s...@nowhere.null> wrote:
> ok here is a start on the words (not proofed yet!)
>
> I will find some pictures to add.
>
> Some others may want to add more.
>
> http://wiki.diyfaq.org.uk/index.php/Central_Heating_maintenance_without_draining_down?venotify=created#Isolate

Thanks, that's really useful :-)

Theo

[Thomas Prufer]

On 12 Jul 2022 23:50:18 +0100 (BST), Theo <theom...@chiark.greenend.org.uk>
wrote:

>I want to add some tees to my heating pipes, but I don't want to drain the
>system down. There are things like:
>https://www.screwfix.com/p/self-cutting-tap-15mm-x/21250
>
>but I wondered about them. In particular, apparently they cut
>a flap of copper pipe where the tee goes in - does this restrict the flow in
>the original pipe?

There is one solution where the flap of pipe (copper, but also steel) is kept in
a pocket, permanently: Flamco T-Plus.

These are not cheap: they cut a full-bore hole in pressurized steel pipe,
irrespective of flow, with a plunger driven by a small explosive charge. There's
more technology in the them beyond just a T...

The first prices I googled are 100 EUR for steel cutting 1/2" teed off 1/2", 70
EUR for copper, 1/2" into 15mm. So pricey, but entirely viable in a commercial
setting where time is money, maybe less so in a diy setting.

<https://flamcogroup.com/uk-en/pageid/landingpage-tplus>



Thomas Prufer

[Andrew]

On 13/07/2022 12:36, Theo wrote:

But the worst that could happen is that a flap of copper ends up in the
dishwasher, rather than getting into the central heating circuit.

[Dave Plowman (News)]

In article <INs*Q6...@news.chiark.greenend.org.uk>,

Unless they are at the bottom of the system, you only need to partially
drain down. And you can shut off the valves to each rad to minimise the
draining down too.

If draining down and re-filling is a PITA, sort that first. You'll not
regret doing so.

I'd always use end feed solder fittings apart from where impossible.

--
*That's it! I僧 calling grandma!

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

[Theo]

"Dave Plowman (News)" <da...@davenoise.co.uk> wrote:
> Unless they are at the bottom of the system, you only need to partially
> drain down. And you can shut off the valves to each rad to minimise the
> draining down too.
>
> If draining down and re-filling is a PITA, sort that first. You'll not
> regret doing so.

A full refill would be about £150-200 for the glycol. Not going there.
Although much of that is in the buffer tank which is at the bottom of the
system and I think isolatable. Turning the rads off as well means it's only
the pipework that needs draining, so maybe that's not so bad.

I should probably work out how to repressurize it by re-injecting any fluid
that does come out.

> I'd always use end feed solder fittings apart from where impossible.

Presuming you can get the pipe dry enough to solder them if there's still
water in the loop?

Theo

[RJH]

On 14 Jul 2022 at 17:40:12 BST, Theo wrote:

>> I'd always use end feed solder fittings apart from where impossible.
>
> Presuming you can get the pipe dry enough to solder them if there's still
> water in the loop?

That's getting close to bloody mindedness. If there was ever a case for push
fit . . .
--
Cheers, Rob

[alan_m]

+1

Even with a small amount of water in the pipe a soldered joint is likely
to fail.

[Theo]

I have just discovered that copper pushfit is a thing. That makes it rather
attractive in this kind of scenario, where you want to mess with radiator
pipes but don't want ugly plastic pushfit on display. I suspect doing a
snatch with pushfit and an un-drained system (perhaps even a pressurised
one, although cutting under pressure might be difficult) might work in the
case where even a compression wouldn't.

I was previously envious of pressfit, but it doesn't make sense for DIY as
the tool is very expensive (and hiring is a faff for odd jobs) - but copper
pushfit might work.

Any recommendations on system? I see the Conex Cuprofit are demountable,
which might help in the inevitable case I get it wrong (and means I can
practice first). The Primaflow at Wickes claim to have a release tool but
every review says it doesn't work (the pictures look very similar to
Masterflow so it could be related).

Theo

[John Rumm]

On 14/07/2022 17:40, Theo wrote:
> "Dave Plowman (News)" <da...@davenoise.co.uk> wrote:
>> Unless they are at the bottom of the system, you only need to partially
>> drain down. And you can shut off the valves to each rad to minimise the
>> draining down too.
>>
>> If draining down and re-filling is a PITA, sort that first. You'll not
>> regret doing so.
>
> A full refill would be about £150-200 for the glycol. Not going there.
> Although much of that is in the buffer tank which is at the bottom of the
> system and I think isolatable. Turning the rads off as well means it's only
> the pipework that needs draining, so maybe that's not so bad.
>
> I should probably work out how to repressurize it by re-injecting any fluid
> that does come out.

I seem to recall the late great Andy Hall described exactly the process
that he used to capture and re-inject antifreeze rich CH water in these
very pages...

He had a secondary circuit that fed his workshop - and hence went
outside. I think he used a modified "pump up" garden sprayer to reload
the (sealed / pressurised) loop.

Here it is:

https://groups.google.com/g/uk.d-i-y/c/VFF0UT1i4Gk/m/4jmy7SS_aXcJ

[John Rumm]

On 14/07/2022 21:06, Theo wrote:
> RJH <patch...@gmx.com> wrote:
>> On 14 Jul 2022 at 17:40:12 BST, Theo wrote:
>>
>>>> I'd always use end feed solder fittings apart from where impossible.
>>>
>>> Presuming you can get the pipe dry enough to solder them if there's still
>>> water in the loop?
>>
>> That's getting close to bloody mindedness. If there was ever a case for push
>> fit . . .
>
> I have just discovered that copper pushfit is a thing. That makes it rather
> attractive in this kind of scenario, where you want to mess with radiator
> pipes but don't want ugly plastic pushfit on display. I suspect doing a
> snatch with pushfit and an un-drained system (perhaps even a pressurised
> one, although cutting under pressure might be difficult) might work in the
> case where even a compression wouldn't.

I did exactly that here:

http://wiki.diyfaq.org.uk/index.php/File:CuprofitPushfitOnRadTail.jpg

("Cuprofit" fitting - sealed system, with just enough water drained to
relieve the expansion vessel pressure)

> I was previously envious of pressfit, but it doesn't make sense for DIY as
> the tool is very expensive (and hiring is a faff for odd jobs) - but copper
> pushfit might work.
>
> Any recommendations on system? I see the Conex Cuprofit are demountable,
> which might help in the inevitable case I get it wrong (and means I can
> practice first). The Primaflow at Wickes claim to have a release tool but
> every review says it doesn't work (the pictures look very similar to
> Masterflow so it could be related).

IME Cuprofit are ok... I only use them in limited numbers for things
like the above. (ISTR I bought a bag of 10 a decade ago, and still have
most of em!)

[Theo]

John Rumm <see.my.s...@nowhere.null> wrote:
> I seem to recall the late great Andy Hall described exactly the process
> that he used to capture and re-inject antifreeze rich CH water in these
> very pages...
>
> He had a secondary circuit that fed his workshop - and hence went
> outside. I think he used a modified "pump up" garden sprayer to reload
> the (sealed / pressurised) loop.

Hmm, good idea. I think I have one of those somewhere...

One more question. Supposing I want to change the pipework to a ground
floor rad. I depressurise, close the valves to the rad and disconnect them.
If the system is sealed, all the water stays in the pipes. But maybe I have
an air leak somewhere - some fitting is sealed when pressurised from the
inside, but with the pressure let off maybe air can get in. Will that cause
the system to siphon everything out from my removed rad? Or will it just
amount to the run that's above my removed rad, and the ground floor room
next door would be unaffected.

One example I'm thinking of is air release valves at the top of pipe runs.
When depressurised will they let air *into* the system, or are they strictly
release only? (I think there's often a knob to close them, but curious what
happens if they aren't closed).

I *think* the siphoning would depend on where the air leak is: it would
siphon all of the pipe between the removed rad and the leak, assuming the
leak is higher up (if not, it would siphon out of the leak location
instead). But curious to know how it goes in practice, and whether this is
actually a problem.

Theo

[John Rumm]

On 15/07/2022 14:53, Theo wrote:
> John Rumm <see.my.s...@nowhere.null> wrote:
>> I seem to recall the late great Andy Hall described exactly the process
>> that he used to capture and re-inject antifreeze rich CH water in these
>> very pages...
>>
>> He had a secondary circuit that fed his workshop - and hence went
>> outside. I think he used a modified "pump up" garden sprayer to reload
>> the (sealed / pressurised) loop.
>
> Hmm, good idea. I think I have one of those somewhere...
>
> One more question. Supposing I want to change the pipework to a ground
> floor rad. I depressurise, close the valves to the rad and disconnect them.
> If the system is sealed, all the water stays in the pipes. But maybe I have

If you turn off both rad taps, then you can remove the rad and lose no
water at all.

If you then cut off one of the tails, then you will get some spillage
from the pipe. If you leave a cut end open, then air will also flow into
the cut end, and you will get ongoing slow loss of water. The key to
working on a live system, is speed - you make a cut and get it sealed
again quickly!

The lack of stored pressure, and hydraulic lock removes the torrent of
water escaping from the pipe in the "oh shit the pipe has burst!" panic.
It also limits the pressure to something that can be blocked by hand
easily. That does depending a bit on the overall height of the property
- a three storey place might have 30' of head, which will be 1 bar/15psi
of static pressure at the lowest point in the system (dynamic pressure
will be less since a good hydraulic lock will reduce that dramatically
when water is flowing))

> an air leak somewhere - some fitting is sealed when pressurised from the
> inside, but with the pressure let off maybe air can get in. Will that cause
> the system to siphon everything out from my removed rad? Or will it just
> amount to the run that's above my removed rad, and the ground floor room
> next door would be unaffected.

If there is a path for air into the system, then water will continue to
come out. A small leak as you describe is not really that relevant,
since you won't be just cutting off a pipe and leaving it for weeks.

> One example I'm thinking of is air release valves at the top of pipe runs.
> When depressurised will they let air *into* the system, or are they strictly
> release only? (I think there's often a knob to close them, but curious what
> happens if they aren't closed).

You might want to watch out if you have any automatic bleeding valves -
that may allow air to suck in when there is no pressure on the "inside"
if they are left in the open position. Normally they can be "closed" so
they are sealed completely.

> I *think* the siphoning would depend on where the air leak is: it would
> siphon all of the pipe between the removed rad and the leak, assuming the
> leak is higher up (if not, it would siphon out of the leak location
> instead). But curious to know how it goes in practice, and whether this is
> actually a problem.

Much will depend on the pipework layout, and also if you have rads open
or turned off. With all the rads turned off, you could actually drain
all/most of the pipework, while still retaining most of the system water
in the rads. (you would need to slacken a rad union nut near the top of
the system to let air into the pipes)

In places with solid ground floors, they often do all the pipework under
the first floor, and drop down to each rad. Then it is actually very
difficult to fully drain the system, since even at the lowest point
there are other independent low points that can't drain by gravity into
the bit with the drain point (hence why some systems have drain points
on most downstairs rads)

[The Natural Philosopher]

On 15/07/2022 14:53, Theo wrote:

> I*think* the siphoning would depend on where the air leak is: it would

> siphon all of the pipe between the removed rad and the leak, assuming the
> leak is higher up (if not, it would siphon out of the leak location
> instead). But curious to know how it goes in practice, and whether this is
> actually a problem.

You never know. Bubbles of air can travel upwards and along in exchange
for water travelling downwards

All you can do is drain locally , wait till the drips stop, and then do
the necessary work and bleed the system afterwards

Loops fed from above normally stay filled but the high links may not


--
“The urge to save humanity is almost always only a false face for the
urge to rule it.”
– H. L. Mencken

[Dave Plowman (News)]

In article <uSC*7g...@news.chiark.greenend.org.uk>,

Theo <theom...@chiark.greenend.org.uk> wrote:
> > I'd always use end feed solder fittings apart from where impossible.

> Presuming you can get the pipe dry enough to solder them if there's still
> water in the loop?

I often use a small compressor to blow air into the pipe. A good way to
dry it out enough to solder.

--
*What boots up must come down *