Truma heating problem

[airwave]

How about some photos, Whale have them inside the control never see it on a Truma.

Doh , didn't take any mate , and i'm back home .

Hmmm being doing a bit of research here , and i've found a mention , ahem on the dark side , that appear's to suggest the remote sensor is a recent thing and that before that they were indeed fitted inside the control unit . I'm trying to confirm that .

 

[Lenny HB]

Remote sensor was fitted to Combi's from June 1997.

 

[airwave]

Just found a second reference , but i've found other stuff too , it seem the 3402/6002 is a redesigned second generation model , released around 1996 . It was fitted with a stainless steel boiler to replace a problematical vitreous enamelled boiler that was fitted to the original 3400/6200 . It seem's they was prone to cracking , and were impossible to repair . It also state's the 00 series should never be run without water were as the 02 series can .

This guy also state's and i quote ,

" The latest control panels no longer carry the 'room' thermostat (to simplify installation for motorhome converters this is now separate) and have an extra blown air gas-saving switch position that ignores water heating. " unquote ,

indicating they then moved to a remote sensor , but there's no indication of a date . I'm also a bit confused as to how this simplified the installation though , you have two bit's to fit instead of one .

 

[airwave]

Remote sensor was fitted to Combi's from June 1997.

Hmmm , thank's mate . Well i'm gonna have to go along with it . Evidence is mounting as to where this thing is , i'm just gonna have to rip it apart and stick me nose in . Trouble is i'm gonna have to do this , before i can get hold of a replacement .

 

[tonyidle]

As Tony says it could be a problem with the thermocouple which could mean a boiler out job to change. It won't be the heat sensor thermocouple (the black button thing) as if they go open circuit the heater runs constantly. Neither of you have mentioned if you are getting any error codes (flashing LED's on the controller or PCB).
Another possiblility is a gas flow problem, a faulty regulator.
Have you filled up with LPG in mainland europe and have a percentage of butane in your bottles. As well as butane not gassing off in cold weather, Truma Combi's don't even like butane in summer as butane can't produce sufficent flow rate for the combi's requirerment.

No - l said the thermostat (black button thing). Mine didn't fail open circuit but gave exactly the symptoms being described by the OP. Replacing it cured the fault.

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[dave newell]

Don't confuse a "thermostat" with a "temperature sensor" they are two completely different things. Many c series heaters have the (room) temperature sensor built in to the control dial (which is the actual "thermostat"). Confused yet? You will be ! Some ( mostly latee) installations will utilise a separate (room) temperature sensor, this is the 1/2" di a black " button".

D.

 

[airwave]

Confused yet?

I'm alway's confused Dave , but ya really could have done a proper job this time . Right , well to me , a thermostat does , where as a sensor tell's . So what your saying is , the thermostat i'm chasing , is actually a temperature sensor . Now if i understand you correctly , what i'm looking for , is where i think it is , in the control box . So bearing in mind this being an early installation , series released 96 , and my van is year 2000 , i won't have a separate thermostat , which is actually a sensor anyway , and probably a good reason why i can't find either in the first place .

I gotta be honest , i've alway's referred to the temperature control in the house , as a thermostat , wall or radiator .


. Why is it , the theme to a certain 80's american tv series is playing in my head , Dave .

www.youtube.com/watch?v=OSaNWYHmUvI Jump to 30 second's .


Thank's mate .

 

[tonyidle]

I'm alway's confused Dave , but ya really could have done a proper job this time . Right , well to me , a thermostat does , where as a sensor tell's . So what your saying is , the thermostat i'm chasing , is actually a temperature sensor . Now if i understand you correctly , what i'm looking for , is where i think it is , in the control box . So bearing in mind this being an early installation , series released 96 , and my van is year 2000 , i won't have a separate thermostat , which is actually a sensor anyway , and probably a good reason why i can't find either in the first place .

I gotta be honest , i've alway's referred to the temperature control in the house , as a thermostat , wall or radiator .


. Why is it , the theme to a certain 80's american tv series is playing in my head , Dave .

www.youtube.com/watch?v=OSaNWYHmUvI Jump to 30 second's .


Thank's mate .

And the button is a NTC thermister too . It's very similar to the ones used inside phone batteries to sense overheating - I know that because I used one until my replacement button arrived.

 

[Lenny HB]

I'm alway's confused

I gotta be honest , i've alway's referred to the temperature control in the house , as a thermostat , wall or radiator .

It's not hard.

A thermostat is a basically a sensor to measure the temperature combined with a switch, it can be fixed or adjustable.
e.g. The temperature of the hot water on your Truma Combi is controlled by a fixed one permanently set to 60° and it turns the boiled on and off to maintain the temperature.
The one on your house central heating is an adjustable one that can be anything fron a basic Bi-Metal strip device to a fully programmable mini computer like the Nest Thermostat.
The TVR's on your radiators are an example of a purely mechanical thermostat. i.e. It measures temperature and turns the water flow on and off.

A Sensor just measures the temperature and does not do anything else, it is connected to the controller, the two together work like a thermostat.

Clear as mud?

 

[airwave]

I know that because I used one until my replacement button arrived.

Now that's interesting Tony , can i take it you've had to replace one in the control box too . I'm trying to find out what kind of sensor this thing is , so when i pull the box apart , i can fit the new one straight away .

Clear as mud?

Hmmm , well as i said earlier , thermostat does , sensor tells , mate . The way i see it , an easier way to explain it , is with the cooling system of an engine . When the coolant get's too hot , the thermostat open's to let more water through , yet a sensor tell's you how hot the coolant actual is , via a gauge of course .

I'm learning about a new system here Lenny . I've never had to know anything about this type of tech before , so i only have limited know how . Although it's growing rapidly , with this unknown fault i've discovered . I've also discovered the unit need's regular attention , by way of cleaning , so i've been looking at schematic's , to enable me to have a rough idea , of what i'm gonna find inside when i take the lid off .

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[tonyidle]

Now that's interesting Tony , can i take it you've had to replace one in the control box too . I'm trying to find out what kind of sensor this thing is , so when i pull the box apart , i can fit the new one straight away .



Hmmm , well as i said earlier , thermostat does , sensor tells , mate . The way i see it , an easier way to explain it , is with the cooling system of an engine . When the coolant get's too hot , the thermostat open's to let more water through , yet a sensor tell's you how hot the coolant actual is , via a gauge of course .

I'm learning about a new system here Lenny . I've never had to know anything about this type of tech before , so i only have limited know how . Although it's growing rapidly , with this unknown fault i've discovered . I've also discovered the unit need's regular attention , by way of cleaning , so i've been looking at schematic's , to enable me to have a rough idea , of what i'm gonna find inside when i take the lid off .

It's a ntc thermister. And there are many different types. I tried a few I had in my junk box and the nearest I found was the one from a mobile phone battery. Is there one on the control board? I haven't delved into that circuitry - the one l changed was inside the 'button' room sensor.

 

[airwave]

It's a ntc thermister. And there are many different types. I tried a few I had in my junk box and the nearest I found was the one from a mobile phone battery. Is there one on the control board? I haven't delved into that circuitry - the one l changed was inside the 'button' room sensor.

Gotta be honest , i ent pulled it apart yet mate , so i don't know . I've done a bit of research on it and it appear's to be a ntc 10k 5% . Though it's not expensive , it does look like a solder job .