What smells like gas but probably isn't gas?

Many gas appliances release unburned gas into the flue when lighting up. If the appliance is burning the gas well, you won't get enough CO in the flue to be dangerous, so there's no guarantee a CO alarm will go off when exposed to the flue.

It can be carried a long way underground in other service ducts. There was an occasional smell of gas at a road junction near me. Gas board had been along several times making small holes in the road and pavement, but obviously couldn't find the source. One day I walked past, and all the BT inspection covers were off. They were digging up about 150 yds further down the road where the leak was, but it was being carried in BTs ducting and escaping from the manholes around the junction.

Telephone exchanges have special provision to prevent any gas which has got into the ducting from leaching into the building. Sometimes you'll see a tall vent pipe outside which is venting the ducts before entry to the exchange. A couple of ones I know it's just a streetlamp column with nothing on the top of it.

I think you'll find the mercaptans they use for the smell can hang around in old pipes and in the soil around where there was a leak, even though the actual gas has long gone. Any disturbance or ground water movement can then bring them to the surface.

I remember visiting (Circa 1973) the one that led to that provision, together with a PO employee (who also posts here) a few minutes after the bang (we were queueing in the nearby chinese takeaway on the way back from the pub when the bang occured, he was the first BT employee at the scene). Gas Board person was swearing it wasn't gas (for insurance purposes) whilst his gas detector was screaming. then there was a roar from the ground which was eveloping to a crescendo of a bang. This was repeated with a louder bang, and flame from a manhole where people were digging, resulting on one being hospitalised with severe burns. For some unexplained reason, the assembled crowds retreated by several fathoms after that.

A section ofthe roof of the exchange re-appreared in the attic of a house at least a hundred yards away.

Telephone service took several months to restore with about 7 temporary exchanges located on the same site and at a neighbouring exchange.

Stench pipes started to appear at all exchanges shortly afterwards to vent the cable chamber, which then had updated seals into the building.

Hi everyone, I just wanted to update to say the problem is now solved. I thought it would be polite to do so, in case anyone finds this discussion in the future while doing a search on the same problem, so they will know how it worked out in the end!

It turns out that the mystery gas smell was in fact the fumes from the flue of my neighbour's boiler downstairs. Since it was already burned (although as discussed there's never perfect combustion) the gas detector guys and our CO alarm never picked it up, and what we smelled was just the unburned chemical additive to make the 'gas smell'. Although the flue fumes had never bothered us before, it started to do so because the boiler was situated in an outdoor shed attached to the back of our building, below where we were smelling the gas. The shed had started falling to bits, and the boiler exhaust had turned really, really rusty (the guy poked a hole in it with a biro pen to demonstrate), so the fumes were coming back inside and travelling up to our flat that way. So our neighbour is rebuilding the shed and has even arranged to get a brand new boiler installed.

So a happy ending, and thank you very much for all the help :)

Good result and thanks for the update. It's always nice to know the root of a mystery.

replying to QuackDuck, Ratman wrote: Having spent more than 21 years in the pest control industry I can assure you that the most likely cause is dead rodents. That said you should always report the smell of gas to the appropriate authority. Absolutely no doubt about it!

I can remember us getting a very strong pong of gas in our house. We knew it couldn't be mains gas because the nearest gas main is about a mile away, and it was only in our house, not outside or in a neighbour's house.

And yes, it was a dead rat in the loft. Fortunately it had died within arm's length of the edge of the floorboarding because the pillocks who had boarded our loft had glued all the 1x2 metre boards down as well as screwing them down. Since I'd no idea where the smell was coming from, I'd have had to destroy every board in turn by cutting along both sides of the rafter till I found the corpse. Luckily I found it after only searching between a few of the rafters. Dragging it out using a turned--inside-out plastic bag and then triple-wrapping it in more bags was not the nicest job in the world.

Is bottled propane and butane "scented" with similar chemicals (mercaptans, IIRC) as mains gas so leaks can be detected?

In reply to a post from 31 December 2012... can't we just ignore the crap that comes from the super crap that is Homeownershub?

Don't you think the smell would have gone away by now?

This might assist you with posting to a newsgroup, albeit through a website:

- If you are sending a reply to a message or a posting be sure you summarize the original at the top of the message, or include just enough text of the original to give a context.

Yes, the various LPGs are all odourless and have Ethyl Mercaptan added, at least in fuel applications. The Butane used in things like aerosols (since CFCs were banned) is left unodourised. I seem to recall that not everyone can smell Mercaptan. Some say it smells like rotten eggs but not I don't think so.

I suppose if someone has no sense of smell, they can't smell mercaptans, but to me they smell like a combination of rotten eggs and dogshit.

The only thing that is worse is the chemical that smells of vomit (or rather vomit contains this chemical, hence its smell - let's get cause and effect the right way round). I remember in my year off before university (thirty five years ago - time flies) I worked in a chemistry research lab, and someone was using this chemical (butyric/butanoic acid) - in a well-ventilated fume cupboard. And he dropped the vial that he was extracting it from. Even a few mls, inside a fume cupboard with a large inrush of air, managed to produce a noticeable pong in the lab. And this happened a few minutes before the MD was bringing round a group of VIPs. The MD walked in, retched at the sudden smell, as did all his guests (we'd had a few minutes to get used to it) and spluttered "Is everyone... all right... in here. Has anyone been "ill"?" and ushered the VIPs out again quickly.

As this one came from the Home owners club interface the rat is probably so old by now that its ceased to smell altogether! Brian

Why are you only now replying to a post made FIVE years ago ?.

The date shows very clearly, so you cannot miss it.

Did you suddenly feel bored one day ?.

replying to QuackDuck, Everglade wrote: This sounds EXACTLY like what we have been experiencing since moving into a completely renovated home last year. We are pretty sure the smell is coming from the cabinets in the kitchen, hallway and bathrooms. Suspect it's from the stain but not positive. As you said, when we leave windows open it quickly leaves. It has a "gassy" smell but isn't gas. It moves around the house being worse sometimes by a door, above the stove, in the hallway... We don't know if it is toxic but it sure smells like it would be. The smell is never in the two rooms of the house that have no new cabinets, so highly likely it's coming from the cabinets. Very hard to pin down because it comes and goes and moves around. If anyone knows what this might be or how to eliminate it, would love to hear.

sometimes rot smells like gas, sometimes not.

NT

The original was posted years ago. posted on December 7, 2012, 5:03 pm

So if they have not died, blown up or fixed it by now they must have gone nose blind as the commercial says.

Brian

Yeah dead animals, rot, some Fungi, . Maybe its the rotting remains of the designer of the home owners club web site? :-) Brian

They add Meracaptan to give gas the smell. Some say is smells like sulphur, others rotten eggs.

I wouldn't be surprised if the glues etc used in making the compressed chipboard have an 'interesting' collection of compounds which some people can smell.

If you notice a film on the inside of your windscreen, it contains some chemicals which have 'gassed off' from the plastics in the car- more so when the car is new, when it is hot etc. Eventually, things become brittle and crack etc. The 'new car smell' is all kinds of chemicals.

You might want to check to see if it was recently repainted with B&Q's finest Valspar made paint. They had a big problem with a batch this year that lacked a crucial antifungal agent and goes seriously mouldy with odd smells like dead cat and urine.

Other paint manufacturers are laughing all the way to the bank.