truma 6002 failed! (1 Viewer)

[bjandlin]

Good afternoon,
I'm hoping somebody may be able to offer a few words of direction please.
My heating has been playing up recently & has now stopped altogether.
The problem started with the system cycling on & off ie. Fan run, gas valve clicks in, system heats & blows hot air. After a while the gas valve & fan could be heard switching on & off,
initially this could be overcome by turning the stat up.
This happened again this morning but even with the stat fully up the system has stopped.
I have so far removed the combustion fan,which I thought may have siezed but it seems ok & free. If I turn the system on the fan runs & continues for a while after turning off, suggesting that it may be ok.
I would like to test the stat but have no idea as to which is which terminal where it plugs onto the circuit board.
If anyone could offer some help I would be very appreciative. It's a bit chilly at this time of year in Reading!
Thanks,
Barrie.

 

[bungy]

have you looked at the main pcb, it has a LED that will falsh an error code?

Did have a similar thing a year or so ago, solved by cleaning the blower fan out - it was well an truly gunked up!! and it blast air through now - supposed to be cleaned 6 monthly according to truma

 

[Lenny HB]

You could take the stat out at the other end & just short the wires out, heating should then run continually if everything else is OK.

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[bjandlin]

Thanks both, no led on pcb i'm afraid,have had the fan out & that's ok.
Taken stat out & measured across p o t & seems ok.
Will have to phone Truma on Monday.

 

[Lenny HB]

Thanks both, no led on pcb i'm afraid,have had the fan out & that's ok.
Taken stat out & measured across p o t & seems ok.
Will have to phone Truma on Monday.

Not much point they don't talk to you anymore just refer you to their service agents.

 

[hilldweller]

We often hear they are sensitive to low battery voltage.

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[ubuntu1]

Take a look at Link Removed

 

[bjandlin]

Well, despite Lennys misgivings I spoke with
Truma this morning, problem diagnosed easily to the remote temperature thermistor fitted above the door.
With this disconnected all fires up & we have masses of heat but no thermostat control.
Gets like a hot house now!
I could buy a new Truma part at an exorbitant price but could also buy just the thermistor from Maplin or RS. I wonder if anyone might know the resistance value of one please ?
Thanks for all your imputs.
Barrie.

 

[Lenny HB]

Only going by the response I got when I phoned them in December, you must have caught someone who got out of bed on the right side.

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[JeanLuc]

Is this it? Not too exorbitant at £9.45

 

[Techno]

Well, despite Lennys misgivings I spoke with
Truma this morning, problem diagnosed easily to the remote temperature thermistor fitted above the door.
With this disconnected all fires up & we have masses of heat but no thermostat control.
Gets like a hot house now!
I could buy a new Truma part at an exorbitant price but could also buy just the thermistor from Maplin or RS. I wonder if anyone might know the resistance value of one please ?
Thanks for all your imputs.
Barrie.

10k@25C my mate Tony tells me

 

[bjandlin]

Thanks Andy, have found the truma part is only £10, so have gone for that,hope that sorts it out.
Barrie

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[mitzimad]

You could take the stat out at the other end & just short the wires out, heating should then run continually if everything else is OK.

be very wary of shorting out stats nowadays unless your sure its a make and break item with electronics you can do a lot of damage to very expensive pcbs

 

[Techno]

I'm pretty certain that shorting the thermistor STOPS the heating. removing it will allow it to run unlimited.Thus no shorting required.

 

[tonyidle]

Well, despite Lennys misgivings I spoke with
Truma this morning, problem diagnosed easily to the remote temperature thermistor fitted above the door.
With this disconnected all fires up & we have masses of heat but no thermostat control.
Gets like a hot house now!
I could buy a new Truma part at an exorbitant price but could also buy just the thermistor from Maplin or RS. I wonder if anyone might know the resistance value of one please ?
Thanks for all your imputs.
Barrie.

I've just repaired mine. The thermistor is a 10K type (it's marked on it) but there's another part of the spec that complicates things. 10K(ohms) is the resistance at 25 degC and the resistance falls as temp rises and rises as temp fall. The variations in response occur either side of 25degC - the variation in resistance either side of 25degC isn't the same for all 10K thermistors. I happened to have a 10K thermistor out of a dead phone battery in my junk box (I keep surprising things) and it works perfectly. You may have to try a few different ones. The one you want will almost certainly be the cheapest and most common one in the range so pick one from one of the electronics suppliers (or eBay) and try it. Just plug the bare thermistor into the two connectors hanging out of your wall & only solder it into the housing once you're happy. The value is by no means critical & I suspect the first you try will work. All you're looking for is it to switch at a comfortable temp for you when the control is somewhere between, say, 4 and 6. Alternatively the Truma part isn't too expensive - around £15 on eBay - though a lot dearer than a simple component.

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[bjandlin]

Oh well , back to the drawing board !
Bought & fitted a new room sensor this morning,still the same, so where now ?
Both thermistors read 10.2k.
Maybe the thermostat / switch ? I'm not sure where to probe.
I don't suppose anyone has a circuit diagram or any suggestions further please ?
In anticipation, Thanks.
Barrie.

 

[tonyidle]

There is no switch - just electronics that compare the control setting to the thermistor output. If disconnecting the thermistor allows the heating to run it's likely (but not certain) that the electronics are OK. That leaves the control that sets the heating level. I could not find a circuit diagram and even the circuit boards are becoming thin on the ground. Whilst I was trying to figure mine out I replaced the thermistor with a 10K pot. I used this to mimic the action of the thermistor so I could prove that the heat control was working.

 

[bjandlin]

Thanks Tony, I'd drawn the conclusion that maybe that was where the problem is.
When the problem started (cycling on & off ) it could be overcome by turning the stat up.
It eventually died altogether. As you say with the room sensor disconnected it runs at full tilt,
plenty of heat but no regulation.
I was hoping I might have found a diagram of the multi plug wiring to put a meter on & see
whats happening.
Don't like to replace bits willy nilly, not satisfying & too costly.
Cheers.
Barrie.

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[bjandlin]

Good evening.
Thought I'd just say thanks to those of you who offered me help & advice.
I managed to sort it out, the new sensor solved it.
Not sure why it didn't work first time, I did probe the switch contacts & all seemed ok.
Maybe a bit of finger trouble on my part. Still working ok now & we have heat.
Thanks again.
Barrie.

 

[Eddystone]

Thank's for posting an update and glad it has been sorted

 

[Deleted34567]

be very wary of shorting out stats nowadays unless your sure its a make and break item with electronics you can do a lot of damage to very expensive pcbs

Ditto,
Lots of modern systems are not simple N/O or N/C switches.
They can send "signals" to modern systems to perform different roles........ so the above poster is absolutely correct.... proceed with caution and try to work to the schematic of the system.

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[Techno]

Good evening.
Thought I'd just say thanks to those of you who offered me help & advice.
I managed to sort it out, the new sensor solved it.
Not sure why it didn't work first time, I did probe the switch contacts & all seemed ok.
Maybe a bit of finger trouble on my part. Still working ok now & we have heat.
Thanks again.
Barrie.

Yes it's very strange as it should have run with the thermistor removed.

 

[bjandlin]

It did run with the thermistor disconnected Andy, on full tilt.
When I plugged the new one in it all stopped again, irrespective of the stat position.
As I say, probably finger trouble !
After this experience though I'm wondering whether to fit a switch in the line between thermistor & board connecting to give a full heat boost if we come when it's really cold.
Thanks.
Barrie.

 

[Techno]

It is normal practice to put the heater on FULL until it is going full blast before re adjusting to the desired setting. No need to fit a switch just put it on 9 or whatever your max point is.
Mine goes 0-60

This overcomes hysteresis in the system

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