Gas not used for 2 years

[twinkle twinkle]

Hello,

We've just bought a flat that has a gas cooker and gas heaters (these have not been used for 2 years). I tried to light the cooker yesterday, the gas is turned on and is making a noise from the one ring on the hob i tried, but this flow of gas blows out anything I try to light it with (lighter, matches etc).

We plan to get the heaters checked out before use, but I assumed I could light the cooker.

Could this be air in the pipes?

I only tried to light the cooker for about 2 minutes and I got a bit paranoid that I'd blow myself and the neigbours up :)

Any ideas?

cheers

-- t.

[the_constructor]

Get a corgi registered engineer in asap

[twinkle twinkle]

The flat isn't in the UK so it won't be a CORGI engineer, but as I mentioned I'll be getting an engineer to look at it (in the New Year).

Anyone know of a safe way to try to get the cooker lit?

The previous owner was at the place trying to light the heaters yesterday, but I stopped her as something wasn't right and I don't want to light the heaters until they have been checked out, but she was furiously clicking away at the ignition switch of the heater, so I turned off the gas.

The gas that was coming out of the cooker was extinguishing the flame from the matches and lighter so I assumed there is air in the pipes doing this, but I didn't want to leave the cooker on any longer until I checked out exactly what to do.

What is the usual method used for clearing the pipes?

-- t.

[Dave Liquorice]

Turn on an appliance an let the gas force the air out...

When you turn a gas appliance on is there a smell of gas? Is there any attempt at a flame post your ignition implement? Have you tried not having your ignition implement not in direct line of the gas flow but slightly below it? Have you tried lighting without the burning being full on?

As the pipes are remaining pressurised they must still be connected to a supply of pressure. I find it highly unlikely that this is going to be anything other than the gas supply. The pressure regulator might have failed but I would half expect them to fail safe, ie off rather than let the full supply pressure through. Is there a "hard" or "gentle" hiss when you open a valve?

[The Natural Philosopher]

Turn em on an open the windows in a breeze.

Gas burns in air. Too much or too little air and it won't.Safest is too much.

[Andy Burns]

With between 5% and 15% gas the mixture explodes.

[The Natural Philosopher]

Exactly.

So the danger is above 20% when you open the window...

Open the window first.

[Dave Liquorice]

True but not without a source of ignition, it doesn't do it spontaneously. Hence venting pipes with the windows open, you are not likely to get anywhere near the lower concentration limit.

[Roger Mills]

You've obviously got air rather than gas coming out of the nozzle! You need a decent flow of gas to clear the air out of the pipes. This may not be possible with everything connected, because there is probably a flame failure device in the cooker which only allows a trickle of gas until the pilot is lit - so you have a vicious circle.

Try this: Gas off at the meter Disconnect gas pipe where it enters cooker Open doors and windows Gas on at meter until gas rather than air comes out of the pipe Gas off at meter Reconnect pipe to cooker Gas on at meter Check with washing-up liquid that re-connected joint isn't leaking Wait a few minutes for gas in room to disperse Light cooker!

Using common sense and plenty of ventilation, you're very unlikely to end up with an explosive mixture of gas in the room. A professional would do exactly what I've described above - there's no other way to purge the pipes when a flame failure device is present.

If there *isn't* a flame failure device - i.e. if there's a good flow of (air) from the hob rings, turn all rings full on for a couple of minutes - or until you can smell neat gas coming out - with the doors and windows open. Then allow time for the gas to disperse and have another go at lighting it.

[Chris J Dixon]

When I had to call for work on my boiler [PCB :-( ] it was discovered that my gas pressure was roughly twice what it should have been. Got the regulator changed within the hour.

Chris

[Andy Wade]

The use of washing-up liquid for gas soundness testing is very strongly deprecated since the salt content can lead to corrosion, eventually causing leakage. A proprietary gas leak detection spray (available from Screwfix) should be used.

For reference the full formal gas purging procedure can be found here:

[Bill]

In message , Roger Mills writes

The definition of "unlikely" being?

I have a jar with 1000 jelly babies in it, 1 of them has cyanide in it. Would you like a jelly baby from my jar? You are unlikely to get the poisoned one.

[Ed Sirett]

FYI only look at the gas fitting FAQ. However you should leave checking over of an unused system to someone with enough experience.

[Andrew Gabriel]

In some countries (France being one), this will likely cause the gas supply to trip off, and you won't be able to reset it.

[Mungo "Two Sheds" Toadfoot]

The gas in the main pipe to the house has gone off and lost all its flammability because it's been sitting in the pipe for 2 years. You'll have to ask the engineer to rejuvinate the gas in the pipe under the street with a FreshGas tablet otherwise it'll take hours to flush out all the expired gas because the main pipe is very big, and that'll cost you a fortune.

HTH

Si

[John]

That sounds interesting - is there some sort of cut-off device that shuts off if the flow exceeds a certain volume?

This could be a life saver in areas where the theft of pipes is becoming common place.

[Mungo "Two Sheds" Toadfoot]

Zactly.

Our grill started playing up: on the low setting it lights and burns ok, if I turn the gas up even slightly, or light it and leave it on full, there's a bang that shakes the floors in the house and it blows itself out! Much fun with just a tiny amount of gas. At first I thought it was the gammon steaks I was cooking going pop until I realised that the 'pop' made the doors rattle.

We're not using it now :o)

Si

[John]

Will the "flammability" have condensed and be sitting in a highly volatile pool at a low point in the system?

(tongue in cheek)

[Mungo "Two Sheds" Toadfoot]

How do you think they make petrol? Tch! ;)

Si

[The Natural Philosopher]

I am just trying to work out what happened to all that natural fgas under the North sea, that has been there for a few million years,.

Of course. The flammability has pooled at the bottom and soaked its way to Saudi Arabia.

Its all so simple when you work it out!