# Truma boiler problem



## timtimpeggy (Aug 23, 2011)

My old Hymer again! The boiler takes ages to light, often 5 or 6 times. It seems to light more easily in windy conditions! I've had the burner blown out but still the problem goes on. It's in a 1990 Hymer Camp 65 import and has a 50mb regulator on a Gaslow gas system. Any ideas welcome
Thanks
Tim


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## runnach (Aug 24, 2011)

A 50 mbar regulator makes sense on a German impoted motorhome, But what pressure should the gaslow system run at ? typical butane would be 28 mbar propane 37 mbar so 50 mbar if this is the case is far to high.

Maybe worth checking the correct operating pressure of your gaslow system and checking the regulator falls within the parameters. also dont forget that regulators tend to run a touch higher than whats on the label.

Channa


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## timtimpeggy (Aug 31, 2011)

*thanks for the info*

thanks channa,
I'll give it a try but my Truma instructions say it runs at 50mb.


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## timtimpeggy (Aug 31, 2011)

*sorry misunderstood!*

Sounds like the Gaslow system may not be compatible with the  50mb kit in the van. I'll give gaslow a ring.
thanks again
Tim


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## Deleted member 12051 (Sep 4, 2011)

*LPG gas boiler problem*

I too have a problem with my boiler on my H reg Hymer B694. The power switch lights up then within 10 seconds the fault light comes on. The gas is firing up then stops. A gas fitter in France had a look at it, tested the LPG workings which are fine and he says it's an electrical problem. I don't have any instructions with the van but any one out there who could throw some light on this issue I would greatly appreciate your help.


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## runnach (Sep 4, 2011)

Firstly I have to say other than owning a truma boiler and mine too on occasions seems not to want to light I know little about them so cant give any specific suggestion.

However, most boilers will have a thermocouple which when the boiler is lit allows the gas control valve to remain open.

Thermocouples do seem to have a habit of burning out after a few years. It is the first thing I would check.

If a thermocouple is failed it actually is doing its job in the respect it is shutting down the Gas control valve a safety thing. replace the thermocouple and all is well.

I would expect an electrical problem only to extend to the ignition if it is a piezo. If the boiler lights temporarily then more likely to be the thermocouple 

Channa


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## activecampers (Sep 4, 2011)

This may be of help - though mine was a propex Malaga 3 heater, but the symtoms sound the same and lets be real - there are only so many ways to heat up water with gas!

Hope it may help:  Fixing Malaga 3 hot water heater ignitor/burner


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## Deleted member 12051 (Sep 5, 2011)

Many thanks to all. Your advice is invaluable and when I get back to my van I will get a thermocouple. One more question - is there different types of thermocouples or are they standard. Blonde so you can tell I'm a numptey.
Patricia


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## activecampers (Sep 5, 2011)

I'd say unique to the maker if not the boiler.
IME - the makers tech support line is VERY useful - and bits are pretty cheap....
Our flame detector isn't a typical thermocouple (as per home gas boilers)


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## runnach (Sep 6, 2011)

Doubtful thermo couples tend to either work or dont I have never know an intermittent thermocouple. The explanation is more likely as you suggest 
Butane / propane and their respective abilities to produce liquid gas in low temperatures 

Channa


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## activecampers (Sep 6, 2011)

I have known thermo couples to be intermittent, though you are right, they normally just fail.

On ours, the problem was the ignitor/flame detector (thermocouple ish!) - and, I think, the main issue was the rust between the ignitor and the burner, thus no earth continuity.  This gave intermittant problems before failing.

Gaslow is pump LPG which is typically high propane content (at least in UK)


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## Byronic (Sep 6, 2011)

activecampers said:


> I have known thermo couples to be intermittent, though you are right, they normally just fail.
> 
> Agreed.
> My Malaga W/Heater had intermittent ignition problems. Propex insisted that the
> ...


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## Russtic (Oct 3, 2011)

That could indicate a dodgy thermo-couple as propane burns hotter and therefore more likely to trigger the thermo-couple than butane.


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## runnach (Oct 4, 2011)

If the boiler cuts out intermittently but does light and stays lit I gurantee  not the theromocouple  more likely to be a blocked jet in the pilot jet.

Thermocouples either work or dont in my limited exeperience of looking after 287 gas systems 

Channa


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## Byronic (Oct 4, 2011)

Channa most of these storage boilers don't have pilot lights such as the on-demand wall type heaters eg Morco and Vaillant.
I'm not a gas engineer but this is how I understand these boilers operate, having had to dismantle half a dozen over the years. May be of some use.
They just have a Bray jet or similar supplying a burner with the sensor electrode positioned over it. When the water reaches a pre-selected heat a thermostat switch is triggered (there's also an overheat safety thermostat) which cuts off the electrical supply to a solenoid valve which cuts off the gas supply. When the water cools the thermostat closes and the solenoid valve opens, the gas flows and and a piezo electrical spark lights the gas. The thermal sensor is the safety device if it gets hot ie gas ignition takes place then the electrics will sense the heat increase and the gas solenoid will stay open, if not, then obviously for safety the soleniod remains closed.   
On a previous post I mentioned that the problem on my boiler was the bloody thermo-sensor. I also thought it was it could be anything except the thermo-sensor.
 Will be interesting to know what the ops problem turns out to be.


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## runnach (Oct 4, 2011)

[No message]


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## activecampers (Oct 5, 2011)

On the malaga, it is possible to be intermittent and for the thermocouple/ignitor to be at fault - see my link above.
HOWEVER (as I state there) it may be the theremocouple is actually working, but the cable and/or earth connection is rusty and stopping the signal getting back.  SO replacing the "intermittent" thermocouple can fix it - but mainly due to the connections being cleaned up during the refit.
Ours I'm almost certain was due to a bad earth between the thermocouple mounting and the burner (due to rust).  As the replacement was under a tenner I swapped just the thermocouple/ignitor and cleaned it up on the way back and it worked since....


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## Burtie (Mar 18, 2012)

i had a problem with my boiler its the truma ultrastore it would not light 
so i took it out and took it apart very easy job i cleaned it out and had the hoover round the jets 
but before reassembling it i put the burner part back in and connected the gas and 12 volt and tried it
it wouldnt light when i flicked the switch i could hear the gas coming through
so i used a lighter it lit and stayed lit until i flicked the switch off then when i tried the switch again it lit on its own so i took it out and reassembled it and put it back in it works every time now


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## N4ked (Mar 22, 2012)

channa said:


> A 50 mbar regulator makes sense on a German impoted motorhome, But what pressure should the gaslow system run at ? typical butane would be 28 mbar propane 37 mbar so 50 mbar if this is the case is far to high.
> 
> Maybe worth checking the correct operating pressure of your gaslow system and checking the regulator falls within the parameters. also dont forget that regulators tend to run a touch higher than whats on the label.
> 
> Channa





I am not an expert on boilers, i own a B694 Hymer in my Truma hand book it states 41 mbar as the maximum operating pressure for my truma c6002. I do have a lot of spares as recently i ended up spending nearly 2k thanks to a stupid dealer then getting a free training day at Truma UK who rectified the problem, no parts were faulty it was a broken drill bit left shorting out the electrodes. My truma will run on buta,ne lpg & propane, seems to like anything, if on butane the weather must be above 10c or my bottle freezes inside the locker. My origional problem started when someone put the Solenoid Valve in the wrong way after a service in london. I have a large posting on MHF regarding the dealer but am not allowed to post their name


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## Burtie (Mar 22, 2012)

i was weary about taking mine out but as i went along i found it quite simple
so dont know why i was weary about doing it as i rebuilt everything in my last motorhome
best to try before paying out i think


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## mitzimad (Mar 26, 2012)

ive been a domestic gas engineer for 35 years and ive not seen an intermitent fault on a thermo couple its usually pilot size/direction or bad contacts normally you can test with a multimeter one probe to the center core  and one on the outer 12mv or above obviously with the flame on the tip if need be remove and test on the cooker flame


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## romakayak (Apr 19, 2012)

mitzimad said:


> ive been a domestic gas engineer for 35 years and ive not seen an intermitent fault on a thermo couple its usually pilot size/direction or bad contacts normally you can test with a multimeter one probe to the center core  and one on the outer 12mv or above obviously with the flame on the tip if need be remove and test on the cooker flame



I have a truma boiler and when I try to switch it on there's a pause then a small/duff bang from the exhaust outlet then the red light comes on, any ideas? the butane reg is new and it usualy fires after several attemps but it's a little worrying, the bang that is.


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