Fyfer Posted January 23, 2018 Share Posted January 23, 2018 Hi there, can anybody help? The ‘Truma Trumatic C3402’ Blown Air Underfloor heating in my MH has stopped working recently. I can get HOT water without a problem but whenever I flick the switch on the control panel to Heating & Hot Water, it trips after a couple of minutes, all of the usual burring and whizzing noises stop and I get a RED light on the panel. I read some years ago that some problems can be caused by fluff and dust/crud, built up over the years, in and around the blades of the fan unit. So I removed the ‘Hood’ C/W fan and cleaned & Vacuumed all of the dust/crud up. Replaced the hood and tried again, but the problem persists. Has anyone else experienced something similar? Can any of you learned MotorHomer’s shed some light on my dilemma? Any help at all would be greatly appreciated Link to comment Share on other sites More sharing options...
keninpalamos Posted January 24, 2018 Share Posted January 24, 2018 Because on space heating mode the C3402 needs a little more battery power to run the space heater blower fan motor and the combustion motor I would guess it may be your leisure battery is on its way out but if you are on EHU then it’s not that, or you can run your engine which will supply the 12v from the alternator to see if the heater runs ok to confirm it is a battery fault Link to comment Share on other sites More sharing options...
Fyfer Posted January 24, 2018 Author Share Posted January 24, 2018 Thanks for taking the time to respond Sorry I should have said MH is currently hooked up sitting on drive and both batteries reading around 13.8-14V. Batteries renewed last year. The problem arose when I was away camping wild earlier this month. The leisure battery was sitting at around 11.8V because I had left the fridge on 12V since I had parked up. I was aware of the potential low voltage problem, so I jumped into the cab and started the engine, hoping that would help solve the issue, but no luck there. Since she's been in the drive I've had her hooked up and had the HW on Gas. Hot water is HOT! But whenever I switch on the Heating it all works fine (heat being blown from the vents and exhaust blowing out external vent) for about 5-10 minutes then trips, displaying the RED light on the panel. Wondering if one of the components on the unit has developed a fault but I'm not at all sure where to start looking. :-D :-D Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 24, 2018 Share Posted January 24, 2018 Operating instructions for the C3402 appliance can be viewed via the following link, with trouble-shooting advice on Page 10. https://dealernew.truma.com/_anweisungen/Truma_Katalog/pdf_verzeichnis/30_000/34000_95000.pdf You’ll see that three suggestions are offered for the heater running OK for a while and then entering ‘fault mode’ (heater switches off and red light on control-panel is llluminated continuosly). Theseare 1: The hot-air outlets are closed/bloked, causing the appliancce to overheat. Check that all the outlets are fully open. 2: Butane gas is being used instead of propane and the weather is cold. The colder the temperature at the gas reservoir the less butane gas will vaporise and - if the vaporisation rate reduces sufficiently - the amount of gas reaching the heater will be inadequate to meet the heater’s demands. So, if you are using butane, change to propane. 3: Gas regulator icing up. This might happen in very cold weather, but there might be a fault with the regulator itself that is restricting the flow of gas to the heater. Try turning all the gas-hob burners to maximum ‘flame’ to confirm that there is a strong gas-flow downstream of the the regulator. If there is a component problemt, then (unfortunately) it could well be the heater’s printed-circuit-board (PCB) where the fault lies. This is referred to as “8 Electronic control unit” on Page 7 of the Operating Instructions document and is beneath a cover on the heater’s side. To the best of my knowledge nobody offers a repair service for Truma PCBs and replacement is far from cheap https://www.leisureshopdirect.com/gas/water/truma-heaters/trumatic-c-6002-c-3402-spare-parts/pcb-truma-c3402 The snag is that, if the PCB has developed a fault, the quickest and most certain way to prove this would be to replace it with a PCB known to be OK - but that would mean either buying a new PCB or for somebody who has one (eg. a Truma engineer) to experiment by PCB swapping. A problem that sounds similar to yours was discussed here in 2009 http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/truma-trauma/16553/ Link to comment Share on other sites More sharing options...
Fyfer Posted January 24, 2018 Author Share Posted January 24, 2018 Derek. Thank you very much indeed for your detailed response! I will check that all of the outlets are fully open. Although I think option 2 might be the problem, as I am using Butane! But had never camped in such low temperatures before. The ambient temperature is a bit warmer this week: nearly 8degC today as opposed to -2 to 2degC when the problem appeared. So will try the heating tonight when I get home. Will also make a point of changing over to Propane when I have worked my way through my current bottles of Butane and will keep my fingers crossed that it is not a faulty PCB issue Thanks very much again Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 24, 2018 Share Posted January 24, 2018 This 6-page Camping and Caravanning piece may be of interest (and not just to you ;-) ) https://www.campingandcaravanningclub.co.uk/helpandadvice/technicalhelp/datasheets/gas-caravans-motorhomes/page5/ As it says on Page 3 of the article, butane begins to produce less gas below about 4°C, so you were really pushing your luck at -2°C to 2°C It sounds like it’s the butane that’s the culprit. That the heater would run satisfactorily for several minutes suggests that the PCB is OK - if the PCB develops a fault the effect is usually more immediate. Link to comment Share on other sites More sharing options...
keninpalamos Posted January 25, 2018 Share Posted January 25, 2018 I could be wrong Derek, but if it were any problem with the gas supply or exhaust blockage then the burner and combustion motor would turn off in the water heater mode after ten minuets as well wouldn’t it? If you give Rob a call on this number I have found him to be most helpful and knows his way around the Truma Combi boiler better than most and if there is any doubt about the pcb you can send it to him and he will test/repair or exchange one for you call 07887 705480. And just s point on the fridge. You say you left it on 12v when parked, ie engine not running. If that was the case and you have a 3 way fridge that runs on gas, 12v and 230v on EHU then leaving the fridge on 12v will not flatten or discharge your leisure battery as the fridge takes its 12v power from the alternator and not the leisure battery. So I would re check your leisure battery status as the gas blown heating takes a great deal more from your leisure battery. than just using the water heater. Again I could be wrong but worth looking at again on information given. Link to comment Share on other sites More sharing options...
keninpalamos Posted January 25, 2018 Share Posted January 25, 2018 keninpalamos - 2018-01-25 4:49 AM I could be wrong Derek, but if it were any problem with the gas supply or exhaust blockage then the burner and combustion motor would turn off in the water heater mode after ten minuets as well wouldn’t it? If you give Rob a call on this number I have found him to be most helpful and knows his way around the Truma Combi boiler better than most and if there is any doubt about the pcb you can send it to him and he will test/repair or exchange one for you call 07887 705480. And just s point on the fridge. You say you left it on 12v when parked, ie engine not running. If that was the case and you have a 3 way fridge that runs on gas, 12v and 230v on EHU then leaving the fridge on 12v will not flatten or discharge your leisure battery as the fridge takes its 12v power from the alternator and not the leisure battery. So I would re check your leisure battery status as the gas blown heating takes a great deal more from your leisure battery. than just using the water heater. Again I could be wrong but worth looking at again on information given. PS As you have the same problem on EHU then it’s doubtful that this is a low 12v problem. So give Rob a call and I’m sure he will be able to help. Good luck Link to comment Share on other sites More sharing options...
Derek Uzzell Posted January 25, 2018 Share Posted January 25, 2018 keninpalamos - 2018-01-25 4:49 AM I could be wrong Derek, but if it were any problem with the gas supply or exhaust blockage then the burner and combustion motor would turn off in the water heater mode after ten minuets as well wouldn’t it? Not necessarily... When heating water a Truma C3402 appliance uses its low (2kW) gas-burner setting, and the burner will require a gas-flow rate of about 170 g/h to stay alight. However, when a C3402 is air-heating at maximum output - which it will be in cold weather when the appliance is turned on - the high (3.4kW) gas-burner setting will be in use and this requires a gas-flow rate of about 285 g/h to keep the burner lit. Butane vaporisation reduces as the temperature drops and although a reduced gas-flow may remain sufficient to meet a C3402’s gas-demand for water heating, the reduced flow may well prove inadequate to meet the demand for air heating. Running a C3402 on butane in cold weather is asking for trouble: running a C6002 (490 g/h gas-demand on 6kW burner setting) on butane would REALLY be asking for trouble. Craig’s problem has all the symptoms of butane being used in freezing temperatures and this should be straightforward for him to check now that the weather has warmed up. A Truma C3402 needs a voltage exceeding 10.5V to operate (presumably measured at the appliance). If the voltage is too low, this will be indicated by the control-panel’s red warning lamp flashing. Link to comment Share on other sites More sharing options...
keninpalamos Posted January 25, 2018 Share Posted January 25, 2018 Point taken Derek Link to comment Share on other sites More sharing options...
Fyfer Posted January 25, 2018 Author Share Posted January 25, 2018 Hi Guys Thank you both for your responses/advice Tried the heating last night, as per Derek's pointers: all vents flaps open etc and it worked. Checked it again this morning when I left for work and it was still working. Have left it on today, just to make sure. Reckon the Butane is the culprit after all. Will get myself a propane Regulator and replace the butane bottles with propane bottles when the time comes Thanks very much, once again :-D Link to comment Share on other sites More sharing options...
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