[OT-ish] Left over right, right over left

[David WE Roberts]

Just had a visit from a very friendly plumber, about replacing an electric hob with a gas hob.

In passing, he said that he had just had to condemn an installation where a Polish person had connected the cold mains to the gas part of the boiler, and the gas to the cold mains feed. He had told them they would have to call in the gas and water boards and it would const them £7-8K to sort it all out.

My mind is still mildly boggling over the concept. [And the £7-8K; I suppose it depends on how long they had it all turned on before they realised the boiler wasn't lighting and they seemed to have a lot of air in the water system.]

I am also wondering which is going to cause more problems - mains pressure water in the gas main or mains pressure gas in the water main.

Not far from November the 5th; exploding water anyone?

"We keep putting water on the fire but it keeps getting worse and now our hose is on fire". Alternatively "The gas cooker keeps putting itself out".

Boggle, boggle, boggle. :-)

Dave R

[Dave Plowman (News)]

Didn't cost that much when we did it in the science labs at school.

[Andrew Gabriel]

The former, particularly if it's gone back into the street gas main. I would guess new meter at a minimum (even if it looks like it works, calibration would need rechecking).

Gas pressure isn't high enough (anywhere near) to get back into the water main.

[Ron Lowe]

But it won't, will it? Mains water has not been connected to the gas main.

The gas supply has been connected to the mains cold feed to the boiler. By mains cold feed, I'm assuming a combi.

That's an inlet to the boiler, and there's not going to be any back-feed from anywhere, unless someone has looped a mains supply back to the hot taps?

Since this is a DIY group, I'd just dismantle it, drain water out of where it don't belong, ( perhaps a blast of compressed air )and hope the gas valve has survived the wetting!

Re-assemble and hope for the best :-)

[dom]

Sounds like a scare story.

It's an incredibly unlikely situation where the two would be simultaneously disconnected, and then reassembled so wrongly that the incoming gas supply does a u-turn into the rising water main - and then the two get turned on simultaneously (without noticing that turning on the first hadn't produced the expected effect) so that mains pressure water is driven back through the gas supply - presumably back through the gas meter as well.

Does anyone really turn on one supply, then immediately turn on the next, before checking the first for leaks/purging etc?

They do *have* water and gas in Poland - so there's no reason why a Polish plumber is any more likely to make such a horrendous mistake than a British one.

[John Rumm]

A mixer tap would do it - but I am struggling to work out a mechanism for a major cross flow of fluids (well water into the gas being the most likely scenario).

I could well see the boiler being shagged - a dose of water in the gas valve, fan, over the PCB etc.

[Ron Lowe]

Well, possibly. But I still think it's worth the punt.

I doubt the main gas valve would have opened enough to allow enough water in to flood things that badly. The thermocouple wouldn't have allowed that.

I still say a good dismantle / blast with compressed air / dry out components in an airing cupboard overnight would have a fair chance of working.

In our work, we often get complex electronic and electo-mechanical parts flooded, with things much worse than fresh water. You'd be amazed how often a good flush in fresh water, followed by baking at a lowish temp in a drying oven can bring them back to life. Depends how much magic smoke has been alowed to leak out under fault conditions! If the engineer has been able to recognise the failure quickly, and powered-down before cooking everyting with dozens of amps, there's a fair chance of recovery.

[Jules]

Wonder if that's true today? I remember H+S being somewhat relaxed during school science classes back in the day. And a heck of a lot more fun because of it. :-)

[Heliotrope Smith]

1958 was a different world then!

[Dave Plowman (News)]

I'd say it's unlikely too. Although we might be fairly unique in using identical tube for water and gas.

[geoff]

In message , David WE Roberts writes

Sounds like bollocks to me

There is no such thing as the gas board, and while there would probably be some purging necessary of the gas main, water pressure is so much higher than gas pressure that there's little chance of any gas ending up in the water supply

Just another lying plumber

[JTM]

[snipped]

The bungalow we lived in for 30yrs was the last one to be built on the block. We were at the footof a slope with the road levelling off, but seems we were at a low spot on the gas main. Over the last few years we were there we had occasional problems with water in the gas. With a couple of appliances lit, the supply would fail, the restart with a 'pop' as it ignited on hot :coals, or pan rest, etc.

Usually it was sorted out by the engineers in a couple of hours or so, (AFTER the obligatory visit by at least 1 supervisor - even though after the first time we knew and explained what the problem was)

The gas main apparently often has water in it from leaks in the pipe and after spells ofheavy rain, this water puddles in sumps designed for its collection. One such sump was outside our home and when it couldn't cope had to be pumped out.

On the last occasion there was quite a bit of dirty water splashed around our entrance hall, where it had been emptied out of our meter. Not the cleanest ofworkers; but it was 9pm on Christmas eve! (Apparently no problem for the meter)

[Alan]

In message , geoff wrote

He probably did say that the gas and water boards needed to be called and quoted the £7k figure because he was p*****d off with people employing foreign workers at a cheaper price.

[David WE Roberts]

Presumably if the plumber had a Corgi/Gas Safe ticket then this problem would be reported back to the parent organisation to fix.

Presumably also the nationality of a non-registered plumber is irrelevant - I took this to be someone who had used an unregistered plumber (who happened to be Polish) and then had to call in a registered plumber to sort the mess out. And ended up with their system condemned.

[Jules]

Same here in the US, FWIW, at least from a sample of three houses ;)