What's the point of pressure testing then?

[cr0ft]

Tested a full heating system to 10 bars last week. No leaks or pressure drops. The system has been runnning for around 3 weeks now in the customers home. Now, a call - great start to a quiet week. Apparently one of the rad valve nuts is now leaking slightly.

All nuts had jointing compound applied prior to being tightened.

Makes you wonder what the point is in actually doing pressure testing to be honest!

 

[mountainman]

As has been posted before, 10 bar is way too high for a pressure test and can lead to future problems.

All new installations, even if it's just a rad change, have a settling in period and the frequent expansion and contraction of joints sometimes leads to a small leak.
That's why we give a guarantee isn't it!

 

[GQuigley67]

more pressure = leaks

 

[grahamgas]

Was the sytem copper or plastic or a mix? Tested with water or air?
I now only pressure test copper to 6 bar ,and plastic to the manufacturers spec, just to get the fittings to bite.
Had rad valve nuts leak many a time, always a few weeks after install, obviously something to do with the system bedding in etc. Just a damn nuisance

 

[GQuigley67]

i just turn the water on and fix the leaks if there is any to be honest

 

[dontknowitall]

I was taught 1½ times working pressure for an hour. In practice I pump to around 3.5bar, leave for about 5 minutes and if no drop then I'm done.

I've found by leaving it for 1/2 hour there can be a small pressure drop and you're left wondering if this was due to a seep, someone knocking something, heat in the pipe (e.g. sun on it) or some other extraeroneous thingy. Then, when you fill up/turn water on, you're spending at least 15 minutes going around checking and double checking and re-checking everything to ensure it wasn't a leak. With a five minute test, a quick grope of all the fittings and if no water or moisture you know you're done in less than 10 minutes, including the test.

(And customers and other trades have no idea about this 1½ times stuff for an hour. They think it's quite cool that you do a pressure test at all since they've never seen it done before.)

 

[cr0ft]

Hi guys. The system was plastic in the loft and copper drop-downs. Speedfit insist the systems are pressure tested to 10 bars to honour their warranties. In practise I did it to 9 bars as the radiators themselves are only tested to 10.

The drip in question was on a union nut on a lockshield valve.

It does seem like damned if you do and damned if you don't but with plastic fittings I like to make damned sure there are going to be no blow-offs down the line.

 

[cr0ft]

Oh and sorry, it was a water pressure test.

 

[mountainman]

Looked on speedfit website and it does state that pressure testing should be carried out at 2 bar for 10 minutes and 10bar for 10 minutes but it also states that other items connected to the speedfit system and not specifically rated for these pressures should be isolated to prevent damage.

So following this information logically, you may have tested part of the installation correctly but put other components under unnecessary stress thereby compromising their integrity and longevity.

 

[SimonG]

I only pressure test my first fix, then heat test and check for leaks after final fix. Also depends how heavy handed the cust is with the hoover