Gas Safety Question - Help

James

If you turned off your Gas supply at the mains, albeit for a very short period (less than a minute).

Q1. If lit, would you need to switch off your Gas Fire, Gas Cooker and Gas Fired Boiler first, or would residue gas in the pipes keep these lit.

Q2. If the appliances were switched off, would the pilot light(s) go out, or would residue gas keep the pilot(s) lit?

Q3. If the Cooker and Central Heating Boiler were on timer. (and I couldn't be sure what time they were due to come on) should I switch them off before turning the mains gas off, or can I leave them on timer? (Even if they do fire up during the short mains gas off period)

Thanks in advance for any replies.

Pincher

When there is no flame, so the burner is cold, the flame failure device shuts off the gas to the burner. On startup, the default position is the burner is shut off, including the pilot flame, which you need to ignite, unless it's a modern self-igniting boiler.

SYNERGY

James wrote: »

If you turned off your Gas supply at the mains, albeit for a very short period (less than a minute).

Q1. If lit, would you need to switch off your Gas Fire, Gas Cooker and Gas Fired Boiler first, or would residue gas in the pipes keep these lit.

Q2. If the appliances were switched off, would the pilot light(s) go out, or would residue gas keep the pilot(s) lit?

Q3. If the Cooker and Central Heating Boiler were on timer. (and I couldn't be sure what time they were due to come on) should I switch them off before turning the mains gas off, or can I leave them on timer? (Even if they do fire up during the short mains gas off period)

Thanks in advance for any replies.

(1) It is good practice to go round and turn off all the gas appliances before turning off the gas, the reason being that, depending on age, not all gas appliances have a flame failure device.

The FF device shuts off the gas if a flame goes out, gas will not flow until the FFD is re-set during the lighting process. Any appliance without a FFD that was turned on when the gas supply was interrupted would issue gas through the burner when the supply was re-instated. :eek:

Depending on the size of the flame / flames and the capacity / volume of the house pipe work, quickly turning on and off the main gas tap may leave the flames lit.

It's not worth taking the risk though.

(2) would the pilot light(s) go out, presuming you refer to switching off the electrical supply they should.

or would residue gas keep the pilot(s) lit? Possibly for a second or two only ( see (10))

(3) Leave the timers as they are, but see (1).

(Even if they do fire up during the short mains gas off period) This depends on the appliance, an appliance, such as some boilers, without a pilot light should fire up as normal, those with a pilot again some boilers, some gas fires etc light will need the pilot to be re-lit before they will fire.

With or without a pilot light, if pipework has been disconnected and air has entered anything lit may go out when the air in the pipe reaches the burner.

It's always wise, after turning off the gas and re-lighting pilots to go round and check them after a few mins and re-light as required.

SYNERGY

Pincher wrote: »

When there is no flame, so the burner is cold, the flame failure device shuts off the gas to the burner. On startup, the default position is the burner is shut off, including the pilot flame, which you need to ignite, unless it's a modern self-igniting boiler.

Not every gas appliance has an FFD ie many older gas fires, gas hobs and gas ovens don't have them.

The crazy aspect of this is that hobs new are available without FFD's and can be fitted in any property other than flats. :eek:
It appears that it is not acceptable if your flat and possibly your neighbours blows up due to a hob not having a FFD.

It's OK though if your nice semi and your neighbours blows up due to not having an FFD. :rotfl:

C_Mababejive

Is this a leading question...?

James

Very many thanks for all your replies.

The applicances are 'old' to say the least.

As I thought, it would appear to be common sense to switch off all appliances prior to shutting off the Gas Mains supply.

Reason I'm asking is because a 'Drop Test' (which I know little about) was done in a friends house. The Drop Test meant that the Mains Gas was turned off for a short time. Apparently the 'Drop Test' showed no drop in pressure, therefore no leaks in the house.

I was surprised that the gas engineer didn't check any of the gas appliances prior to commencing the test. In fact he didn't even know if any of them were switched on at the time. After the drop test, the gas mains was switched on and the Engineer left the premises. No appliances were checked after the switch on. He never he knew what gas appliances were in the house of if they were on or not. The house in question belonged to a very elderly neighbour

I was wondering how safe a 'Drop Test' carried out in this manner is? Is it something a Corgi Registered Engineer would do willy-nilly?

lemontart

Why was the gas safe registered engineer there? what was the purpose of his visit?

James

lemontart wrote: »

Why was the gas safe registered engineer there? what was the purpose of his visit?

Thanks - a smell of Gas reported Outside the House

bengasman

James wrote: »

I was wondering how safe a 'Drop Test' carried out in this manner is? Is it something a Corgi Registered Engineer would do willy-nilly?

1. The test is perfectly safe.
2. Corgi has stopped having anything to do with gas safety years ago.

SYNERGY

bengasman wrote: »

1. The test is perfectly safe.
2. Corgi has stopped having anything to do with gas safety years ago.

1) The tightness test may have been safe, or more correctly proved that the property meter, pipework and appliances were sound, however was it conducted correctly, see below ?

I was surprised that the gas engineer didn't check any of the gas appliances prior to commencing the test. :eek:
In fact he didn't even know if any of them were switched on at the time. After the drop test, the gas mains was switched on and the Engineer left the premises.

No appliances were checked after the switch on. He never he knew what gas appliances were in the house of if they were on or not. :eek:
The house in question belonged to a very elderly neighbour

bengasman

SYNERGY wrote: »

... however was it conducted correctly, see below ...

If it had not been conducted correctly, it would not have been safe.
Apart from that, unless you were there and followed him constantly, you don't know what he did or did not do.