LPG Automatic double change over problem

[Leonie]

Hi, wondering if anyone can help as have been told my issue is basically a mythical issue, as in no one has seen or heard of anything similar ever....


I’ve been on lpg since I installed the new boiler in my house 5 years ago and every year without fail at the end of the summer the regulator goes faulty. I’ve had one replaced at the end of every summer when the temperature starts to fall and we’ve not used much in the way of gas for two to three months over the summer. I’ve had different regulators fitted and they all end up leaking out of the valve. This suggest to me it’s something to do with the set up but every plumber who has been out and the Calor emergency engineer is stumped as they can last 20 or 30 years apparently? The house is south facing and the gas bottles are down the east side of the house and the boiler is a viessmann vitodens 100 if that makes any odds and it’s serviced yearly. Any ideas as to what the problem might be? I was wondering if it might be a pressure issue with the gas building up over the summer as the pressure valve always pops in the little clear bobble on top when the reg breaks?

The only suggestions are just to buy a new reg every year which seems excessive and is very frustrating as it should'nt need it or try putting some kind of shelter around the reg to help protect it perhaps?

Any help you might be able to suggest would be so helpful at this point, I'm at my wits end with it all.

 

[ShaunCorbs]

Are the bottles and reg in direct sunlight?

 

[Leonie]

Are the bottles and reg in direct sunlight?

Yes and I have asked before if that could contribute and was always told no?

 

[ShaunCorbs]

Yes and I have asked before if that could contribute and was always told no?

I'm guessing the opso has gone over pressure valve also when heated any gas expands so increases the pressure I'm guessing this is what's happening with your set up

 

[quality]

It will be a pressure increase causing the issue but its not with the gas expanding but the fact that LPG has a pressure to temperature relationship thats directly proportional

 

[Leonie]

I'm guessing the opso has gone over pressure valve also when heated any gas expands so increases the pressure I'm guessing this is what's happening with your set up

Ok so two questions if you don’t mind- 1) why hasn’t this happened either during the summer when it’s got really hot or during the spring when it’s similar temperatures as the Autumn and 2) if that is the issue how can it be fixed please? Thanks

 

[Leonie]

It will be a pressure increase causing the issue but its not with the gas expanding but the fact that LPG has a pressure to temperature relationship thats directly proportional

Umm ok, could you try and explain that for me as I don’t really understand, sorry! Any ideas on how to resolve it too? Thanks!

 

[quality]

OK
@ 10 degrees C the cylinder of lpg will be just 5.4 bar, @ 20 degrees C it will be 7.4 bar @ 30 degrees C it will be 9.8 bar C the hotter the cylinder the high the pressure.

 

[Leonie]

OK
@ 10 degrees C the cylinder of lpg will be just 5.4 bar, @ 20 degrees C it will be 7.4 bar @ 30 degrees C it will be 9.8 degrees C the hotter the cylinder the high the pressure.

Ok I get that thanks. But when it cools off the pressure would drop back down again? And again if that’s the issue why in the summer when we still have the boiler drawing for hot water (just not the central heating) isn’t this happening? It only ever blows when the weather cools off?

 

[ShaunCorbs]

It will be a pressure increase causing the issue but its not with the gas expanding but the fact that LPG has a pressure to temperature relationship thats directly proportional

Easiest way I could explain it

 

[Leonie]

Any suggestions for a fix that doesn’t involve the annual replacement of that changeover but, a week without hot water and an emergency gas leak call out?

 

[quality]

yes the pressure would drop but shauncorbs stated the safety device will have probably operated. A shelter from direct sunlight would be a start

 

[fixitflav]

The house is south facing and the gas bottles are down the east side of the house and the boiler is a viessmann vitodens 100 if that makes any odds and it’s serviced yearly. Any ideas as to what the problem might be? I was wondering if it might be a pressure issue with the gas building up over the summer as the pressure valve always pops in the little clear bobble on top when the reg breaks?

Bulk LPG tanks have design pressure 17.25barg (250psig) and the pressure relief valve set for same pressure (with maximum 10% overpressure allowed). I don't know offhand design pressure for gas bottles, but assuming the PRV is same setting, if the bottles are in full sun all day the PRV could blow off, though unlikely. Vapour pressure of liquid propane is about 17.9barg at 54°C. But if the gas is dispersed safely it wouldn't be a problem. You would expect the pressure regulator to be designed for an inlet pressure at least equal to the vessel PRV set pressure. Sounds to me like the regulators haven't been up to the job. It might be worth talking to the guy installing it, and maybe suggesting he tries a different make. There's plenty of suppliers out there.
A friend of mine has a bulk tank, tank and regulator outdoors unshaded, and had no problem.

PS just noticed your thread title. Where does the automatic double changeover come into it? Not mentioned in the post.

 

[Leonie]

The change over is attached to 15mm copper pipe that goes round the side of the house and up to the boiler. If there a specific brand of change over that is heavier duty and could cope with the location? I'm going to get a shade for it too

 

[fixitflav]

The change over is attached to 15mm copper pipe that goes round the side of the house and up to the boiler. If there a specific brand of change over that is heavier duty and could cope with the location? I'm going to get a shade for it too

OK so the changeover valve and regulator are combined. Where is it leaking from? There are plenty of regulator makers, but I don't know about auto changeover valves. I can only suggest you get on the internet. I still think it's worth having a chat with the installer. If the same make has been fitted and failed each time any other make is worth trying. Can you get a better guarantee? At least then it wouldn't be at your expense.

 

[Chalked]

Never had any problems with those.

 

[ShaunCorbs]

What's with the two hoses left dangling

 

[Chalked]

Just noticed that too.
That regulator is for 4 bottles. It can’t work as you havit set up.