At the recent service of my van, the engineer discovered that the isolation valve in the under sink cupboard wasn't working properly. It's this pictured. IMG_20201008_141020100_copy_1024x1365.jpg - Bild entfernt (keine Rechte) Seemed it only worked if the sprung centre spindle was pushed in. Strange, as it had been working fine as far as I knew. Does anyone know if this a known issue with these?

Anyway, he said it wasn't really necessary as the gas can be isolated from fridge, heater and hob by the three red gas taps and also from the gas bottle. So he said the best thing to do was remove it and put a length of copper pipe in as in this picture.IMG_20201008_111130462~2_copy_1024x1365.jpg - Bild entfernt (keine Rechte)
I thought nothing of this until today.

Since then I've been in touch with another caravan engineer. He's been looking at my van with a view to putting a hot water system in it. The one I preferred was the Truma ultrastore. He explained that the gas system is (as is usual for continental vans) fitted with steel pipes and gas regulations don't allow mixing steel and copper pipes/fittings. And there are some major problems with fitting a Truma ultrastore which requires 30mb pressure in a steel piped older caravan with unknown pressure (think I'm going to go for a 240 mains only heater say the Propex).

But I'm figuring that the length of copper pipe I had fitted by the other engineer is actually bad practice and should be steel. Apparently there can be a reaction between the two metals which can compromise the joints. Am I correct in this and what does anyone think? Advice appreciated.

Cheers, Stan

Update:
The problem with mixing copper and steel pipes is that it may cause dielectric reaction (some form of corrosion).
In the short term nothing will happen but over time, possibly many years, where the two metals come into contact, corrosion will form which may lead to a gas leak.

I’m not at all technically minded but I’m very risk averse. I’d do something about it sooner rather than later, who knows how far off one day it may leak is

Just to be precise in an otherwise correct reply its called galvanic corrosion - a dielectric is usually a low-current conducting material.

Galvanic corrosion is what many older cars suffered from when for example aluminium components were bolted to iron/steel and these joints got wet, the (non-pure) rain water acting as an electrolyte.

Electrolytic corrosion usually occurs when an external current source passes across a junction of different metals which is surrounded by an electrolyte.

Acid rain is a good electrolyte that supports both galvanic and electrolytic corrosion.

Sea spray is also a great electrolyte.