Test CH to mains pressure?

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405 TD Estate

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Oct 10, 2008, 3:42:00 AM10/10/08
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Before I tile over the bathroom floor and I have access to the
plumbing under the floor I was thinking of connecting my gravity CH
stytem to the mains pressure and that way if I have any leaks on the
bits of plumbing I've just put in I can fix them easily.

I was thinking of doing this because at some point I will change (I
won't say 'upgrade' now) to a combi boiler which I believe will run
the CH at mains pressure.

So would I just need to connect the CH drain to my hosepipe and
isolate the header tank?

If I were doing this I should also test the HW system to mains
pressure but I cannot think how to do this - any suggestions?

Andrew Gabriel

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Oct 10, 2008, 4:13:00 AM10/10/08
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In article <619508e2-e4d0-4e87...@t65g2000hsf.googlegroups.com>,

405 TD Estate <men...@yahoo.com> writes:
> Before I tile over the bathroom floor and I have access to the
> plumbing under the floor I was thinking of connecting my gravity CH
> stytem to the mains pressure and that way if I have any leaks on the
> bits of plumbing I've just put in I can fix them easily.
>
> I was thinking of doing this because at some point I will change (I
> won't say 'upgrade' now) to a combi boiler which I believe will run
> the CH at mains pressure.

No it won't. It will run at 1-2 bar, with a 3 bar pressure
relief valve. Your mains pressure could be much higher.

> So would I just need to connect the CH drain to my hosepipe and
> isolate the header tank?
>
> If I were doing this I should also test the HW system to mains
> pressure but I cannot think how to do this - any suggestions?

You can buy a pressure test kit, which is pushfit (normally)
adaptor with a tyre inlet valve and a pressure guage. You
connect it up and pump up with a bicylce pump.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Dave Plowman (News)

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Oct 10, 2008, 4:13:28 AM10/10/08
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In article
<619508e2-e4d0-4e87...@t65g2000hsf.googlegroups.com>,

I've recently converted to a sealed heating system which involved quite a
few pipework alterations and there were no leaks at mains pressure. Cold,
that is. Once it had heated up there were two... ;-)

--
*Virtual reality is its own reward*

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

405 TD Estate

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Oct 10, 2008, 4:46:54 AM10/10/08
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screwfix has this dry pressure test guage
http://www.screwfix.com/prods/72940/Hand-Tools/Plumbing-Tools/Pressure-Test-Equipment/Monument-Dry-Pressure-Test-Kit;jsessionid=YNDBCO5V4DHLWCSTHZOCFFY#

But it requires pushing onto 15mm pipe and I don't have any 'ends' to
push it onto, also wouldn't I still need to seal my header tank and if
it leaks how on earth do you know where it's leaked? I think this is
more for testing small parts of a system?

Tim S

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Oct 10, 2008, 5:31:53 AM10/10/08
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405 TD Estate coughed up some electrons that declared:

You might be adapt it to a bit of hose onto a drain cock, held with a
jubilee clip.

As to the header tank, do you have an isolator valve on the outlet to the
heating system. If you've drained the system, good time to add an isolator.
Likewise, if the hose onto a drain cock doesn't work, you could add a test
point; eg a bit of 15mm sticking out of an isolator valve somewhere.

If the system is still full of water, freezing a plug of ice in the bit of
pipe from the header tank would probably work (but make sure the boiler if
fully isolated, gas locked off, power locked off etc or bad things will
happen).

As to where the leak is - first see if you have any. Leak detection would
them be done on a dry system using a similar approach to gas, but using a
leak detector spray on each joint (or some whipped up Fairy foam). For a
wet system, look for the drips.

My static mains pressure is 7.5 bar (that's high, 4-5bar is more common).
The highest static rating I've seen for, eg a shower, is 10bar, so don't
exceed 10bar as it wouldn't be reasonable to expect the system to cope much
beyond this.

Cheers

Tim

405 TD Estate

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Oct 10, 2008, 5:58:59 AM10/10/08
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Tim -

I guess your pressures are for the HW not CH and Andrew would be
correct 1-3 bar CH for a modern combi boiler? But perhaps testing upto
10bar for the HW would be good.

This is starting to seem like a lot of effort for something I don't
have yet (the boiler) however I guess it's a lot better than waiting
until I need to put the boiler in and then hearing a leak under the
tiled bathroom floor.....

405 TD Estate

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Oct 10, 2008, 6:05:49 AM10/10/08
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Anyone know if its possible to get a wet pressure test kit? the
screwfix one specifically says dry but since I don't know how to check
for leaks with gas/air and looking for leaks would seem a lot easier,
I also wonder if a tiny air leak would be detected but water could not
escape through that air gap?

Is it normal to test the system dry? Should the system hold the
pressure indefinately or loose so much pressure in a set time period
and that's still OK? (i.e. some tiny leaks are acceptable)...

Could I some-how pump air in at the top of the system (so the guage is
dry) and therefore pressurise the water - then I only have to look for
leaks....

What is the chance my non-leaking gravity system will leak when
exposed to 10bar HW and 2-3 bar CH?

Roger Mills

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Oct 10, 2008, 6:06:41 AM10/10/08
to
In an earlier contribution to this discussion,

405 TD Estate <men...@yahoo.com> wrote:

> Before I tile over the bathroom floor and I have access to the
> plumbing under the floor I was thinking of connecting my gravity CH
> stytem to the mains pressure and that way if I have any leaks on the
> bits of plumbing I've just put in I can fix them easily.
>
> I was thinking of doing this because at some point I will change (I
> won't say 'upgrade' now) to a combi boiler which I believe will run
> the CH at mains pressure.
>

A combi *won't* run the heating at mains pressure - it will be lower.
However, the heating system - including the radiators - should certainly be
able to stand mains pressure, so you could use it to test for leaks.

> So would I just need to connect the CH drain to my hosepipe and
> isolate the header tank?

Yes. You'd have to block off *both* the pipe which feeds the system from the
F&E tank *and* the vent pipe.
>

> If I were doing this I should also test the HW system to mains
> pressure but I cannot think how to do this - any suggestions?

No!!! Under *no* circumstances should you pressurise the existing HW
system - assuming you've got a conventional HW cylinder. If you subject the
cylinder to mains pressure, it will burst! [If you switch to a combi, that
will run the HW system at mains pressure, but the cylinder won't then be
there.]
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!


The Natural Philosopher

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Oct 10, 2008, 6:16:07 AM10/10/08
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I hired a hydraulic tester to test my UFH before screeding. Cost a fiver
for a few days. Mind you that neede to have teh pipework filled, but its
a good way to check plumbing.


IIRC I went to 10 bar on the heating circuits.

I don't think my mains pressure is much above 5 bar tho.

Tim S

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Oct 10, 2008, 6:21:49 AM10/10/08
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Roger Mills coughed up some electrons that declared:


> No!!! Under *no* circumstances should you pressurise the existing HW
> system - assuming you've got a conventional HW cylinder. If you subject
> the cylinder to mains pressure, it will burst! [If you switch to a combi,
> that will run the HW system at mains pressure, but the cylinder won't then
> be there.]

Ah yes - a very good point. Sorry I overlooked the obvious.

I would add, that if anyone wished to pressure test a system with a cylinder
in place (even a little bit), do it wet, not dry. Same principle as steam
engine boilers are pressure tested full of water (aka "hydraulic testing").
If it goes pop, then it goes pop and the loss of a little bit of water
quickly reduces the pressure. Do it full of pressurised air, and it will go
bang, with health-adverse consequences.

Cheers

Tim

Tim S

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Oct 10, 2008, 6:29:57 AM10/10/08
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405 TD Estate coughed up some electrons that declared:

> Anyone know if its possible to get a wet pressure test kit? the


> screwfix one specifically says dry but since I don't know how to check
> for leaks with gas/air and looking for leaks would seem a lot easier,
> I also wonder if a tiny air leak would be detected but water could not
> escape through that air gap?

http://www.screwfix.com/prods/82412/Hand-Tools/Plumbing-Tools/Pressure-Test-Equipment/Monument-Tools-Mains-Water-Pressure-Test-Gauge

is fine wet (I've got one).

> Is it normal to test the system dry? Should the system hold the
> pressure indefinately or loose so much pressure in a set time period
> and that's still OK? (i.e. some tiny leaks are acceptable)...

If all the valves are sealing correctly it should hold up for long time.
Gate valves might be a problem with a dry test - I can see them leaking
air.

*** But please heed Roger's warning regarding HW cylinders (or any large
volume device attached to the plumbing). ****

Think you'd be better off with a wet test if you can arrange it. Or mostly
wet, with a little bit of air from a foot pump just to bring the HW pipe
pressure up to the test point for that test only.

> Could I some-how pump air in at the top of the system (so the guage is
> dry) and therefore pressurise the water - then I only have to look for
> leaks....
>
> What is the chance my non-leaking gravity system will leak when
> exposed to 10bar HW and 2-3 bar CH?

How good does the plumbing look?

Cheers

Tim


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