Permitted pressure drop, existing pipework and new appliances...

[Masood]

Your opinions, please.

I was taught that when fitting a new appliance it is permissible to leave a pressure drop unrectified as long as it existed before you fitted the appliance.

So, if you have a 1mb drop across existing pipework to an appliance, and after fitting a new appliance it is still 1mb drop, that's allowed. A friend has been taught that that is unacceptable, and any drop must be rectified.

Has anyone got a definitive answer, or can point to a TB answering this question? I'm aware that the engineer I trained with was not always as conscientious as he should have been, so some of my training has been a process of unlearning what he taught me.

Ta!

 

[leethegasman]

You are not allowed any leakage on pipework new or old you are allowed to have leaks on appliances with no smell of gas as long as the leakage rate is no more than 8 mbar E6 and 4 mbar U6

 

[GasmanxxxR1]

Your not allowed any leak on pipework, dont think your allowed a leak on new appliances.

Permissable drop if your working on the system would be changing the boiler, having a 1mb drop on say a cooker thats existing and no smell of gas, after fitting the new boiler, still 1mb drop

Thats how i see it anyway

 

[AWheating]

your knowledge of the leak is the key.

If you have investigated and found the leak to be on pipework then it must be found and repaired/made safe before you can complete your work, if you have not investigated the leaks location with existing appliances connected then you can carry on with your installation and leave the existing permissable drop as you found it.

Some engineers may want to find the leak to be sure its not on pipework, but you dont legally have to do this and you open a possible can of worms so to speak.

 

[Masood]

your knowledge of the leak is the key.

If you have investigated and found the leak to be on pipework then it must be found and repaired/made safe before you can complete your work, if you have not investigated the leaks location with existing appliances connected then you can carry on with your installation and leave the existing permissable drop as you found it.

Some engineers may want to find the leak to be sure its not on pipework, but you dont legally have to do this and you open a possible can of worms so to speak.

Thank you. Now that you explain it that rings a bell with what we were taught in college - that we ideally should isolate each appliance to determine whether the leak was on the pipework or not. It also explains why my GSR mentor never did that...

 

[mutley racers]

The guy that taught me also never bothered checking where the drop is. Test before installation and test after and if the same drop with as said, an old cooker connected, then it's acceptable. So this is the way I have been doing it.

There was a post on here about this before, think it was a 50/50 outcome

 

[AWheating]

theres no correct answer tbh, its completely up to you and a personal choice . If you want to find/ confirm the leak then great. You are not required to do it by law. You would need to consider the reason why you are there and for what you are being paid for in my eyes.

so if your doing a full heating installation and a new gas supply to the boiler then you may consider it good practice to ensure theres no leak on the propertys pipework, and more importantly you may have the money in the job to enable you to spend some time doing so.

if your there to fit a new cooker only, you may want to leave well alone and you may not want to spend the extra time for the money of just a cooker install. You may also have problems with your customer when you have to fit the new cooker and cap the gas meter.

 

[leethegasman]

The original question was can you leave a gas leak when installing a new appliance.The answer is that the pipework must be sound and if there is a pressure drop you must confirm it is on the existing appliances.other wise there is no point saying you can have permissible pressure drop on appliance and no pressure drop on pipework.unless you are going to confirm by isolating appliances and testing pipework only.there is no point just because there is a appliance fitted that we can assume the leak is on the appliance it has as much chance being on the pipework.

 

[AWheating]

The original question was can you leave a gas leak when installing a new appliance.The answer is that the pipework must be sound and if there is a pressure drop you must confirm it is on the existing appliances.other wise there is no point saying you can have permissible pressure drop on appliance and no pressure drop on pipework.unless you are going to confirm by isolating appliances and testing pipework only.there is no point just because there is a appliance fitted that we can assume the leak is on the appliance it has as much chance being on the pipework.

where does it say in the regs/IGE's/standards that you have to confirm where the leak is?

http://www.ukplumbersforums.co.uk/plumbers-arms/54116-permissible-drop-tt.html

have a read of this thread, its interesting and covers the subject and opinions well.

 

[GrahamM]

Going back to the OP's original question there are a number of variables to consider here in my opinion.
Old boiler is only gas appliance in property and is being replaced. You have a 1 MB drop before removing and replacing old boiler and still have a 1 MB drop. You then know the leak is on carcase so you must trace and repair.......thoughts?
A number of gas appliances connected is a different mater. And you will get away with the drop as long as you do not isolate the remaining appliances and carry out your drop test.

 

[leethegasman]

Testing for soundness
The Gas Safety Regulations require that new installations be installed and tested for gas tightness by a competent
person before the meter is connected. If work is to be carried out on an existing installation it must be tested before starting and any faults traced and rectified or the installation made safe. On completion of the work a further test must be carried out and if satisfactory the installation purged into service. The testing and purging of domestic installations must be carried out in accordance with BS 6891.
I may be out of date as I re take my gas again this year.

 

[GrahamM]

Testing for soundness
The Gas Safety Regulations require that new installations be installed and tested for gas tightness by a competent
person before the meter is connected. If work is to be carried out on an existing installation it must be tested before starting and any faults traced and rectified or the installation made safe. On completion of the work a further test must be carried out and if satisfactory the installation purged into service. The testing and purging of domestic installations must be carried out in accordance with BS 6891.
I may be out of date as I re take my gas again this year.

BS6891 in the installation of pipework. We are not discussing this!
It would be good practice to trace/repair any drop but as per my previous post and AWheating, technically you may be able to get away with leaving the customers nice newly laid hardwood floor in place and fit a new boiler.
A 1mb drop before removing old boiler and a 1mb drop after fitting new one. Were does it state this is not permitted?

 

[leethegasman]

This bit from previous post.
If work is to be carried out on an existing installation it must be tested before starting and any faults traced and rectified or the installation made safe.

Ask your self what is the point of permissible pressure drop if all you are going to do is test with appliances and and never prove it is the appliance.if that was the case it would say permissible pressure drop on pipework and appliances.

 

[AWheating]

Testing for soundness
The Gas Safety Regulations require that new installations be installed and tested for gas tightness by a competent
person before the meter is connected. If work is to be carried out on an existing installation it must be tested before starting and any faults traced and rectified or the installation made safe. On completion of the work a further test must be carried out and if satisfactory the installation purged into service. The testing and purging of domestic installations must be carried out in accordance with BS 6891.
I may be out of date as I re take my gas again this year.

is a permissable drop a fault? if so its not really permissable.

 

[lame plumber]

nicely put AW

 

[leethegasman]

The permissible pressure drop is allowed on appliance so you are correct it is not a fault and does not need to be rectified.
But it does say If work is to be carried out on an existing installation it must be tested before starting and any faults traced and rectified or the installation made safe.

 

[GrahamM]

The permissible pressure drop is allowed on appliance so you are correct it is not a fault and does not need to be rectified.
But it does say If work is to be carried out on an existing installation it must be tested before starting and any faults traced and rectified or the installation made safe.

As has been mentioned a permissible pressure drop of 4/8MB with no smell of gas and appliances connected is NOT A FAULT under the gas regulations.

 

[mfgs]

You don't need to trace it if other appliances connected. If you decide to trace it you will either be condemning the carcass or an appliance. The moment you find an appliance to have a leak/let by on a gas valve it becomes ID. You have no obligation to trace if its in the permissible allowance.

 

[leethegasman]

As has been mentioned a permissible pressure drop of 4/8MB with no smell of gas and appliances connected is NOT A FAULT under the gas regulations.

Correct as long as it is on the appliance

 

[GrahamM]

Correct as long as it is on the appliance

Your not interested where it is. (unless you want to be)
It can be and will be in lot of cases on pipework but as long as you don't confirm this it is not an issue.

 

[leethegasman]

You don't need to trace it if other appliances connected. If you decide to trace it you will either be condemning the carcass or an appliance. The moment you find an appliance to have a leak/let by on a gas valve it becomes ID. You have no obligation to trace if its in the permissible allowance.

I used to think the same thing I installed a Worcester boiler did all paperwork made note on paper work there was a leak think it was 1.5 mbar 2 min no smell,couple months later the boiler was playing up got gas suppler to change regulator they caped off because of leak.i re tested and put back on thinking this was ok.boiler playing up the week after fault on fan so called Worcester to replace spoke to the chap from Worcester who was replacing fan that there was a leak on system so he fitted fan but isolated gas supply,as he said you can not have a leak,spoke to the chap I have worked with for 18 years not long been on re takes and he said you have to isolate appliances to prove pipework sound,rang gas safe they confirmed no leak allowed on pipework,
Re piped gas supply as it was buried in floor screed.

 

[mfgs]

You don't have to isolate appliances to prove the pipework is sound. If there is no reported smell of gas and the drop is in the permissible drop for the type of meter fitted then it is fine. Gas safe are 100% correct in saying no leak is allowed on pipework, but you do not have to prove this every time you do a tightness test. Loads of houses have a 0.5mb leak somewhere, do you isolate all appliances to prove the pipework is ok? Once you have proved it is ok do you then check each appliance individually until you find the appliance with the leak/let by?

 

[Mike Jackson]

When you're changing an appliance and you have a permissible drop on the initial test you need to isolate that appliance to prove that the drop is elsewhere or on that appliance because you are not allowed a drop on a new appliance. If it's the only appliance you've got no choice, you'll have to prove where the leak is.

 

[Masood]

Thanks all. Glad to know that what I've been doing is not 100% wrong, and some food for thought about the best way vs. the real-life way of doing things!

 

[leethegasman]

Just to let you all know i had good chat with gas safe this morning and seams I was informed wrong in the past (from collage,worcester,and gas safe) you do not have to prove the leak is on the appliances sorry for being stubborn on this one.
I would buy you all a pint but never had a invite.
I asked if just soundness testing eg landlord and also if installing new appliance on existing system you do not have to find leak.
Do you recorded the leakage rate on your paper work or just pass or fail.