I have a 2007 Sprite Alpine2. The last time we were away we had an usual humming noise coming from the Truma gas regulator when gas was in use. My local approved workshop has had a look, tested all the gas system and is stumped. There are no problems with the gas fire, fridge and water heater. The noise comes on after a while when the cooker is in use, either by itself or with the other appliances. So we are both happy that the cooker is causing the noise when pulling gas. It does not make any difference if it is 1 ring or all rings and oven. We have changed the gas bottles, tried a new Truma regulator and a Cleese regulator but none of it makes any difference. We are asking Truma and Swift for advice but does anyone else have any ideas please.
Humming Truma Gas Regulator
- Thread starter Hugh_374319267
- Start date
I get this sometimes when using the Cadac. (Might of course be at other times and i hear when out front.) I found that the gas tail is the problem and by moving it stopped the hum. I think the length is critical and the gas flow creates a vibration- called i think harmonics.
- Mar 14, 2005
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Hi Hugh,
I have come across this on occasions. Firstly let me state it is not dangerous, so don't be concerned on that count.
In my experience it has been the regulator its self which just happens to have a natural resonace caused by its intenal diaphragm and bias spring. changing the regulator is usually sufficient to cure it. every mechanical system has natural resonances and where it can become annoying it often only needs a bit of change to mover the resonance point away from the audible range, or to dislocate the energy that is feeding the resonace.
However I note that you have tried this with no joy, so my next suspect it the actual low pressure pipe work. The copper pipe work is fixed to the caravan with clips at certain points. a few extre clips may just just constrain the pipe work a bit more to prevent it vibrating. Low cost and simple to try.
Beyond that its difficult to make any suggestions without actually seeing and investigating the system.
I have come across this on occasions. Firstly let me state it is not dangerous, so don't be concerned on that count.
In my experience it has been the regulator its self which just happens to have a natural resonace caused by its intenal diaphragm and bias spring. changing the regulator is usually sufficient to cure it. every mechanical system has natural resonances and where it can become annoying it often only needs a bit of change to mover the resonance point away from the audible range, or to dislocate the energy that is feeding the resonace.
However I note that you have tried this with no joy, so my next suspect it the actual low pressure pipe work. The copper pipe work is fixed to the caravan with clips at certain points. a few extre clips may just just constrain the pipe work a bit more to prevent it vibrating. Low cost and simple to try.
Beyond that its difficult to make any suggestions without actually seeing and investigating the system.
I have been away for a while in the van. The first thing I did when on site was to release the 2 srews holding the regulator to the bulkhead, this immediately stopped the noise. I have now installed a foam rubber between the regulator and the bulkhead and all is well, no noise.
I sent a copy of my problem to Swift for their advice and a copy of their reply is below
"Thank you for your correspondence with the Swift Group.
Following up from my previous email after to having spoken with Truma from the information provided they believe it could be the unit showing early signs of seals swelling due to oil ingress however there is a possibility that it could be brooming*.
This should not cause any problems however if it is due to oil then the regulator will eventually fail to supply gas.
* - Brooming is where the diaphragm in the regulator is fluttering due to the gas flowing through it.
It us a common occurrence on bottle mounted regulators and was never noticed by the end user. Now that the regulator is mounted on the gas locker bulkhead it can be heard.
This could be due to swollen seals in the regulator restricting the gas flow. If so the only cure would be to replace the regulator"
.
So having cured the noise this may be an indication of future failure of the regulator so I propose to carry a spare.
Hugh
I sent a copy of my problem to Swift for their advice and a copy of their reply is below
"Thank you for your correspondence with the Swift Group.
Following up from my previous email after to having spoken with Truma from the information provided they believe it could be the unit showing early signs of seals swelling due to oil ingress however there is a possibility that it could be brooming*.
This should not cause any problems however if it is due to oil then the regulator will eventually fail to supply gas.
* - Brooming is where the diaphragm in the regulator is fluttering due to the gas flowing through it.
It us a common occurrence on bottle mounted regulators and was never noticed by the end user. Now that the regulator is mounted on the gas locker bulkhead it can be heard.
This could be due to swollen seals in the regulator restricting the gas flow. If so the only cure would be to replace the regulator"
.
So having cured the noise this may be an indication of future failure of the regulator so I propose to carry a spare.
Hugh
- Mar 14, 2005
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Thanks Hugh for the follow up.
You have found an interesting solution, and one to be added to the fund of useful tips.
I'm not entirely convinced the regulator is about to fail,I have had regulators making a similar noise for years in an industrial situation.
But there is certainly no harm in carrying a spare just in case.
You have found an interesting solution, and one to be added to the fund of useful tips.
I'm not entirely convinced the regulator is about to fail,I have had regulators making a similar noise for years in an industrial situation.
But there is certainly no harm in carrying a spare just in case.
"Firstly let me state it is not dangerous, so don't be concerned on that count."
without actually seeing, inspecting , measuring how do you know its not dangerous?
i have experienced a failing regulator that resulted a pressure / flow variance, poor flame quality and lead to an increase CO , this was not in a caravan but from a fixed tank installation that uses exactly the same regulator design . The only reason no one died is because the CO alarm went off.
without actually seeing, inspecting , measuring how do you know its not dangerous?
i have experienced a failing regulator that resulted a pressure / flow variance, poor flame quality and lead to an increase CO , this was not in a caravan but from a fixed tank installation that uses exactly the same regulator design . The only reason no one died is because the CO alarm went off.
- Jun 20, 2005
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10 years ago I dealt with a product recall claim for a national gas boiler manufacture whereby the gas regulator valves plastic internal pins failed causing excess CO to be admitted into the flues without warning. The problem was further compounded because the failed or failing regulators delayed ignition causing a mini explosion, sufficient to displace the flue from the boiler, allowing CO to enter various parts of the homes. The regulators still worked and apart from the occasional delayed ignition you would never have known they were faulty!
The Italian regulator manufacturers ended up paying the whole bill.
So Philspadders is absolutely right. Whilst the cause may only be a sympathetic harmonic vibration why risk your life for a few quid?
.
Fit a new regulator and sleep easy.
The Italian regulator manufacturers ended up paying the whole bill.
So Philspadders is absolutely right. Whilst the cause may only be a sympathetic harmonic vibration why risk your life for a few quid?
Fit a new regulator and sleep easy.
- Mar 14, 2005
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Hugh,
I have no problem if you want to change your regulator, what is important is that you have confidence in the safety of the equipment you use. Perhaps in my position I can understand the mechanics and risks and would be prepared to continue to use noisy regulator. You can of course ask your dealer to retest the regulator.
Phil,
We are all only as good as the information we have available, and the training and experience we have. In this case investigating LPG gas systems was part of my professional remit.
Like Hugh, I have experienced a number of Truma supplied and also a fixed LPG regulator by another manufacture that resonated with certain ranges of gas flow. Because of the effect I did some practical tests to see if there was a problem.
In fact the phenomenon was the seed of a product development programme that needed to try to understand the mechanics. The outcome clearly demonstrated that the safety of the regulator was not compromised.
That background and the fact that Hugh reported he had the system checked by a dealer, who did report a problem, but neither could find the solution, gives a high level of confidence the system remains safe.
Dusty,
Clearly I do not know what experience you have had in this field, but based on your description the mechanics of the problem are quite different. Like Phil above, the failure mode of the regulator was to change the output pressure and consequently the flame pattern and combustion.
There is nothing that indicates the needle valve affected in Hugh’s incident, thus the ability of the regulator to maintain the correct gas pressure is not in question.
I have no problem if you want to change your regulator, what is important is that you have confidence in the safety of the equipment you use. Perhaps in my position I can understand the mechanics and risks and would be prepared to continue to use noisy regulator. You can of course ask your dealer to retest the regulator.
Phil,
We are all only as good as the information we have available, and the training and experience we have. In this case investigating LPG gas systems was part of my professional remit.
Like Hugh, I have experienced a number of Truma supplied and also a fixed LPG regulator by another manufacture that resonated with certain ranges of gas flow. Because of the effect I did some practical tests to see if there was a problem.
In fact the phenomenon was the seed of a product development programme that needed to try to understand the mechanics. The outcome clearly demonstrated that the safety of the regulator was not compromised.
That background and the fact that Hugh reported he had the system checked by a dealer, who did report a problem, but neither could find the solution, gives a high level of confidence the system remains safe.
Dusty,
Clearly I do not know what experience you have had in this field, but based on your description the mechanics of the problem are quite different. Like Phil above, the failure mode of the regulator was to change the output pressure and consequently the flame pattern and combustion.
There is nothing that indicates the needle valve affected in Hugh’s incident, thus the ability of the regulator to maintain the correct gas pressure is not in question.
Damian
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Apart from Hugh and myself, everyone else is simply stabbing in the dark over this issue.
I am the engineer who services Hughs van each year and until this year there has never been a problem with the harmonics in the regulator.
This year for some inexplicable reason it (the regulator) decided to make a humming noise only when the cooker was in operation, at all other times and with all other gas equipment ON, no noise.
As soon as any of the hob burners were lit, or the grill or th eoven, in any combination or alone, the humming started.
Suspecting a possible internal fault with the regulator, I changed it for a new one, and it still did exactly the same.
I then tried a single stage regulator, and it behaved in exactly the same manner.
Back to original regulator, fully checked for oil contamination,,,none.
Fully checked for input pressure and output pressure,,,,nothing wrong at all, eveything exactly as it should be.
Pigtail checked for oil contamination,none.
System fully pressure tested, absolutely no leaks and all as it should be.
The only conclusion I can come to, having had no feedback from the sources I have asked about the problem, is that it must be something to do with pipe routing to the cooker, or the amount of gas being drawn into the cooker settting up a vibration.
Hugh, having done what he has done, has found a way of overcoming it, something I will admit never crossed my mind at the time to try, however it has not got rid of the harmonics as such,but at least it has stopped the very annoying drumming noise.
There is absolutely nothing wrong with the current regulator, pigtail or appliances, all having been checked and a flue gas analysis carried out on each appliance to ensure they are all burning correctly.
We all learn new things every day, and this is one of those learning curves which may well come in useful in the future.
I am the engineer who services Hughs van each year and until this year there has never been a problem with the harmonics in the regulator.
This year for some inexplicable reason it (the regulator) decided to make a humming noise only when the cooker was in operation, at all other times and with all other gas equipment ON, no noise.
As soon as any of the hob burners were lit, or the grill or th eoven, in any combination or alone, the humming started.
Suspecting a possible internal fault with the regulator, I changed it for a new one, and it still did exactly the same.
I then tried a single stage regulator, and it behaved in exactly the same manner.
Back to original regulator, fully checked for oil contamination,,,none.
Fully checked for input pressure and output pressure,,,,nothing wrong at all, eveything exactly as it should be.
Pigtail checked for oil contamination,none.
System fully pressure tested, absolutely no leaks and all as it should be.
The only conclusion I can come to, having had no feedback from the sources I have asked about the problem, is that it must be something to do with pipe routing to the cooker, or the amount of gas being drawn into the cooker settting up a vibration.
Hugh, having done what he has done, has found a way of overcoming it, something I will admit never crossed my mind at the time to try, however it has not got rid of the harmonics as such,but at least it has stopped the very annoying drumming noise.
There is absolutely nothing wrong with the current regulator, pigtail or appliances, all having been checked and a flue gas analysis carried out on each appliance to ensure they are all burning correctly.
We all learn new things every day, and this is one of those learning curves which may well come in useful in the future.
John , while i undestand you have experience in gas supply / regulation systems the comment was made before any other posts regarding any tests or comments from the the supplier .
I would always be very cautious in offering advice regading gas or electrical advice simply because i am not fully trained in those fields and certainly advise someon to seek professional advice and have the items professionaly inspected.
Damien , while you have inspected and tested this installation , to give the impression that " it jsut does this" is wrong. On the next ocasion someone may have a hum , thay may lead to something more serioudue to some anecdotal evidence they picked up from a forum. The post should finish with a recommendation to have the item inspected and tested by a suitably qualified person .
We are all prone to jump to conclusions when presented with problems, and on public forums such as this we are prone to offer advice based on our experience and often professional knowledge. What really worries me is that the circumstances surrounding an problem may not be described correctly, leading to an incorrect diagnosis of the problem. This of course could make matters worse, and have dire consequences.
The reason i post this is that with out the correct training and trouble shooting analytical skills most of us would never be able to identify the route cause of problems.
Damian you mention that this year only the hum has started, if it did not hum in the years before something has changed, Having inspected and changed the regulator, inspected the pigtail, has anything else changed within the van. Its use, storage, jets in the cooker, split pipe, has the cooker system been isolated from the rest of the van and pressure tested for leaks ? This is part of the trouble shooting process , i am sure John L can offer some advise on trouble shooting , or even some six sigma applications to help identify what has changed and why.
items do not start to perform differently from previous conditions unless something has changed .
I would always be very cautious in offering advice regading gas or electrical advice simply because i am not fully trained in those fields and certainly advise someon to seek professional advice and have the items professionaly inspected.
Damien , while you have inspected and tested this installation , to give the impression that " it jsut does this" is wrong. On the next ocasion someone may have a hum , thay may lead to something more serioudue to some anecdotal evidence they picked up from a forum. The post should finish with a recommendation to have the item inspected and tested by a suitably qualified person .
We are all prone to jump to conclusions when presented with problems, and on public forums such as this we are prone to offer advice based on our experience and often professional knowledge. What really worries me is that the circumstances surrounding an problem may not be described correctly, leading to an incorrect diagnosis of the problem. This of course could make matters worse, and have dire consequences.
The reason i post this is that with out the correct training and trouble shooting analytical skills most of us would never be able to identify the route cause of problems.
Damian you mention that this year only the hum has started, if it did not hum in the years before something has changed, Having inspected and changed the regulator, inspected the pigtail, has anything else changed within the van. Its use, storage, jets in the cooker, split pipe, has the cooker system been isolated from the rest of the van and pressure tested for leaks ? This is part of the trouble shooting process , i am sure John L can offer some advise on trouble shooting , or even some six sigma applications to help identify what has changed and why.
items do not start to perform differently from previous conditions unless something has changed .
- Jun 20, 2005
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This whole I know best thing has turned this sensible forum into a farce! We should be offering Newbies a balanced but sensible fail safe piece of advice. I f I am wrong in saying this then it's time I moved on.
For the sake of £50.00 or less the rule should be that unless someone like Damien has personally seen the regulator change it without all this dialogue.
Prof Jj
The diagphragms I mentioned move a plastic piece that controls the gas flows, a bit like the old SU carbs.
For the sake of £50.00 or less the rule should be that unless someone like Damien has personally seen the regulator change it without all this dialogue.
Prof Jj
The diagphragms I mentioned move a plastic piece that controls the gas flows, a bit like the old SU carbs.
Damian
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Dustydog, you are quite right, unless the problem has been investigated and the system proven to be safe, change the item.
In any event, ANY problems with gas installations shoud not be ignored or advice taken from anyone other than properly qualified LPG engineers who have seen and tested the system.
In any event, ANY problems with gas installations shoud not be ignored or advice taken from anyone other than properly qualified LPG engineers who have seen and tested the system.
when i use the external gas point connected to my Cadac i get a humming noise , but nothing when its disconnected
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