# Hot water pipe burst **WARNING**



## Phillip (Jul 20, 2009)

Hello,

I am currently in the process of renovating our bathroom at home, so we are using our Motorhome for showering.

Last night my wife was in the shower, I was in the MH lounge, when I heard a PSSSSSS noise comming from behind me. I looked around and saw a cloud of steam coming from the cupboard where the Truma water heater is, followed by my wife calling "Phillip! the waters gone cold!"

I quickly hit the tap button on the control panel to turn the pump off and opened the cuboard.

There was water peeing out of the side of the hot water pipe that leads away from the water heater to the taps, all over the Truma 8O 

Fortunately the burst was near the push-fit connector on the water heater and the pipe long enough to snip the burst bit off and re-connect it so wifey could finish her shower.

I've since taken the control board (printed circuit board thingy) off the water heater to dry it out and have mopped up the water as best I could with towels. Have left the cupboard open along with the roof vents to try and dry things out. I Just hope it all still works when I put the control board back in otherwise I'm guessing it could get expensive.

We have a Mobilvetta S71 (2007 reg) Truma C6002 water heater. I believe the pipes that are installed are sub-standard. They look and feel like cheap, plastic pipes.

Looking at it, it looks as if the hot water has caused it to soften to a point where the preasure of the water has forced the pipe to expand, to a point where the walls have become thin enough for the water to burst through. The pipe was lagged which I think may have compounded the problem by causing a build-up of heat in the pipe. You can see, where I have cut through the pipe, that the walls are much thinner and the pipe diameter is greater. I'm thinking it may be a good idea to remove all the lagging from the hot water pipes inside the motorhome. If it had burst behind the shower control tap thingy or under the shower (coz thats where our pipes run) it would've been a much larger job and I wouldn't have been able to fix it there and then.

I'll take some pictures later and post them here so you can the problem.


----------



## JohnsCrossMotorHomes (Jul 21, 2007)

Hi,

Is this the pc board you have removed?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=380211101718&ssPageName=STRK:MESOX:IT

Peter


----------



## Phillip (Jul 20, 2009)

JohnsCrossMotorHomes said:


> Hi,
> 
> Is this the pc board you have removed?
> 
> ...


Thanks Peter, but no 

Mines just a flat printed circuit board with a load of electronic widgets soldered onto it. No anti-static covers or metal fixing plates or anything.


----------



## vardy (Sep 1, 2006)

That's awful! - It's times like these when I'm glad that mine are probably made of lead. :werecomingforyou:


----------



## raynipper (Aug 4, 2008)

Hello Phillip.
I wonder as you are beside the house and have free access to water and drain that you both might use the van shower more like a house shower and run it much longer than usual.

Not saying that it should have burst just might have contributed to the failure.

Ray.


----------



## blondy (Aug 23, 2007)

How you described the pipe it sounds exactly like frost damage,
Have seen many over the years, especially when we used to have winters, like this year.


----------



## Phillip (Jul 20, 2009)

raynipper said:


> Hello Phillip.
> I wonder as you are beside the house and have free access to water and drain that you both might use the van shower more like a house shower and run it much longer than usual.
> 
> Not saying that it should have burst just might have contributed to the failure.
> ...


It's a good thought Ray and possibly we are, but I don't believe so. The Truma Water Heater only holds 12 litres of water which doesn't last too long in the shower anyway before it has to heat another tank full.

I firmly believe this is a fault in the quality of the pipes that Mobilvetta have installed. Am toying with the idea of replacing them with copper if I can get a fitting onto the water tank. Theres not much pipe so it shouldn't add too much weight, and it's only the hot pipes.

In my opinion, two or three people should be able to shower, one after the other, without this kind of failure being experienced.

Will see later if anything has been damaged (like the PCB which is currently drying out), and if so may start chasing Mobilvetta over it.


----------



## Phillip (Jul 20, 2009)

blondy said:


> How you described the pipe it sounds exactly like frost damage,
> Have seen many over the years, especially when we used to have winters, like this year.


Well I hope not, it was all drained down over winter, we haven't had any frost in Southampton for the past few weeks and I keep a a fan heater running inside the Motorhome (on low heat just to protect from such things :roll: ).

I'll get some pictures up here when I get home later, maybe you will be able to tell from them. Thanks.


----------



## Phillip (Jul 20, 2009)

Here are the pictures as promised:

The PCB dried out nicely, its all back together now and seems to be working fine. PHEW!


----------



## Grizzly (May 9, 2005)

Philip: Truma are a brilliant firm to deal with either in person or by phone and will, I'm sure, be able to give you advice on what sort of pipes should have been installed and if there are likely to be any problems with your circuit board.

http://www.trumauk.com/

G


----------



## Phillip (Jul 20, 2009)

Grizzly said:


> Philip: Truma are a brilliant firm to deal with either in person or by phone and will, I'm sure, be able to give you advice on what sort of pipes should have been installed and if there are likely to be any problems with your circuit board.
> 
> http://www.trumauk.com/
> 
> G


Thanks for that Grizzly. I might drop them a line to get their take on the subject.

As said I dried everything out and all seems to be working at the moment. Hopefully it'll stay that way.


----------



## rugbyken (Jan 16, 2006)

as a plumber gotta agree with blondy looks just like frost damage, the expansion of the pipe where the burst occured is the classic weakened state pre burst, the plastic probably saved it from going when it froze but the walls were weakened and when you got it up to heat and pressure finally found its way through ,
if this conjecture is correct the copper you are thinking off would probably have burst at the time, just happy for you getting of so lightly ,


----------



## plasticplumber (Nov 6, 2008)

This is a classic example of a heat burst. Plastic pipe will split in a straight line if frost damaged. 
All pipe work for use adjacent to a water heater should be classified and marked BS 7291 part2 class S which permits its use up to temperatures of 114degrees C for intermittent use. Depending on the material some plastics will withstand up to 120 degrees C.This is based on a British Standard and is irrelevant of the manufacturer. Exposure to temperature above this range will in the majority of cases result in immediate failure of the type shown in your second photo. Enlargement of the pipe close to the heat source would also be an indication of overheating together with moulded in marks from the fitting and its O ring. It is also most likely that molten flow of the plastic will be identified at the extremes of the failure and will confirm my diagnosis. Water in a sealed system can achieve this sort of temperature within pipework if the boiler thermostat fails or the boiler is not fully vented of air before operation. The burst will have occurred where there is a minute amount of contamination ether in the water or on the pipe wall as this is where the flash from water to steam will propagate from when under pressure.
I investigated plumbing failures for a living and suggest that if the pipe is correctly marked that your attention is focused on the boiler and its operation.


----------



## Phillip (Jul 20, 2009)

plasticplumber said:


> This is a classic example of a heat burst. Plastic pipe will split in a straight line if frost damaged.
> All pipe work for use adjacent to a water heater should be classified and marked BS 7291 part2 class S which permits its use up to temperatures of 114degrees C for intermittent use. Depending on the material some plastics will withstand up to 120 degrees C.This is based on a British Standard and is irrelevant of the manufacturer. Exposure to temperature above this range will in the majority of cases result in immediate failure of the type shown in your second photo. Enlargement of the pipe close to the heat source would also be an indication of overheating together with moulded in marks from the fitting and its O ring. It is also most likely that molten flow of the plastic will be identified at the extremes of the failure and will confirm my diagnosis. Water in a sealed system can achieve this sort of temperature within pipework if the boiler thermostat fails or the boiler is not fully vented of air before operation. The burst will have occurred where there is a minute amount of contamination ether in the water or on the pipe wall as this is where the flash from water to steam will propagate from when under pressure.
> I investigated plumbing failures for a living and suggest that if the pipe is correctly marked that your attention is focused on the boiler and its operation.


Thanks PlasticPlumber!

So, if I'm reading you right (it's been a long week and I'm getting a bit tired now) either:

a: The pipes are sub standard (which is what I suspect) or
b: The thermostat is dodgy and the water is getting too hot.

??


----------



## plasticplumber (Nov 6, 2008)

As in your first post you mention steam this points to the likelihood of a boiler induced fault and within this category I include both a faulty thermostat or a boiler containing residual air leaving the thermostat not reading true water temperature but the temperature of the air in the boiler. This will induce a delay in achieving the correct reading by the thermostat and also the water to heat input ratio of the boiler is upset resulting in a very quick rise in temperature and possible boiling. I think the pipe being of sub standard manufacture is probably the least likely. Is it marked as stated or is there a manufactures name? Most manufactures of pipe by raw material direct from oil companies and the manufacturing processes almost certainly precludes the pipe containing a group of duff pellets in close proximity to one another. Your pipe would appear to be a PEX derivative as it has a very glossy finish and should therefore be good to 120deg C.for more information on PEX see http://en.wikipedia.org/wiki/Cross-linked_polyethylene. Should you wish to discuss further PM me your phone No.
P.S. the lagging would make no difference to the outcome.


----------



## Mick757 (Nov 16, 2009)

Can i ask; should/do these pipe connections have the inserts, same as the ones in your home?
And, im surprised that the water in these heaters can attain such high temps. as i believe the max - again in the home, is 65 deg. C?


----------



## stuffed2 (May 9, 2005)

Problem: Burst or melted pipe.
Pipe will be distorted showing either a 'Parrot beak' look or a long opening with the edges of the pipe melted in a wave shape.
Identification: A 'Parrot beak' will have been formed by the pipe bursting due to the water freezing. If the pipe has a melted appearance it will have been subject to a temperature in excess of 128 degrees Celsius. This will have been caused by direct contact with a heat source such as a blowtorch or flue pipe or by water or steam within the system rising above safety levels.


I copied this from the speedfit site, It certainly looks a bit like a parrots beak .


----------



## Phillip (Jul 20, 2009)

Ok, so Mrs is about to call the men in white coats coz she thinks I've lost it! Photographing pipes - whatever next!

But here are some pictures of me pipes (ooer)!

Both hot and cold have the same writing on them:

"DMT PE TUBE O.D12mmXI.D9mm 70oF 170Psi NSF-51 & NSF-61 03EM14"

I get some of this O.D being Outside Diameter 12mm, I.D being Inside diameter 9mm, 170Psi being the max pressure.

I'm a bit concerned about the 70oF 8O or is it saying "at 70oF, max pressure is 170Psi" ?

Anyway the more I look at this the more I'm convinced it's heat related. So assuming the pipes are the correct grade and everything (perhaps PlasticPlumber would like to confirm this or otherwise) it must be the thermostat!

Anyone know how to test a Thermostat ??


----------



## plasticplumber (Nov 6, 2008)

The following link leads to the pipe manufactures data sheet http://www.dmfit.de/DOWNLOAD/Tube.pdf
and you are correct regarding the temperature on the pipe being 70oC at approximately 12 bar. As strength of the pipe diminishes with temperature I expect that at 3 bar 95oC should still be safe but without testing I would be unable to confirm this. Not withstanding the above if the approval is only to 70oC then anything above this is to be considerd beyond its scope of duty.
This information dramaticaly reduces the safety margin between boiler and tube but I would still consider that there has been some form of boiler malfunction as described erlier


----------



## plasticplumber (Nov 6, 2008)

I should add that 12 bar is a standard test pressure as it is regarded as the highest water pressure that should be encountered on domestic water supplies. Manufacturers therefore use this to compare products on an equal basis. Many manufactures though do go on to produce tables for temperature against pressure. i.e 12bar 20 deg,11bar 40deg,9bar 60deg, 7bar 80deg, 3 bar malfunction short term to 114deg. That table complying with class S pipe. An e-mail to the manufacturer should provide this information and clarify its maximum operational temperature.


----------

