ronboyracer Posted February 14, 2010 Share Posted February 14, 2010 Hi Does anybody know of problems with Truma combi boilers ie the latest models 08 fit with elec back up, mine is not responding to the thermostat on the control dial 1-5, there is also a further stat fitted in the cab, so the performance is such that the blower blasts the heat out until you melt if you dont switch it off.It would be nice to know the normal operation of this unit. At the moment I am unable to solve the problem hopefully on warranty because I am in Benidorm Spain. :D :D Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 15, 2010 Share Posted February 15, 2010 Originally, the control-panel of Truma C-Series 'combination' air/water heaters had an integrated thermostat. This led to problems when the control-panel was located thoughtlessly in the motorhome (eg. at ceiling or floor height, or in a draught-prone area) and, to combat this, Truma offered a separate 'domed button-shaped' thermostat that could be positioned in a more suitable place. This small remote thermostat overrode the control-panel's integrated thermostat. The 'domed button' thermostat came with several metres of cable and, once you had installed the button where you wanted it, you just led the cable back to the heater and plugged it into a socket at the top of the heater's PCB enclosure. I had a C-3402 heater retro-fitted to my Herald in 2000 and, because the control-panel needed to be positioned close to the living-area's ceiling, I added a remote thermostat. I recall asking Truma(UK)'s technical/service manager whether many motorhome constructors fitted a remote thermostat and he told me Hymer sometimes did, hiding it inaccessibly beneath a cab seat. He said this regularly caused confusion for new owners of Hymer motorhome designs where the cab could be screened off from the living area. With the cab isolated from the living area, the heater continued to react to the cold temperature in the cab that was being sensed there by the remote thermostat, and Hymer owners couldn't understand why the heater kept blasting away even when the motorhome's living-area was well warmed up and the heater control-panel's dial was turned to its minimum setting. Around the mid-2000s, Truma removed the integrated thermostat from the control-panel used with their combination heaters and a remote 'domed button-shaped' thermostat became standard for C-Series appliances. I've no hands-on experience of Truma's latest "Combi" range, but I would have expected it to have the same 'remote-thermostat-only' arrangement. Unless your heater's Operating Instructions say otherwise, I believe your heater has no thermostat in its control-panel and, in air-heating mode, will adjust its output (and turn on and off) based on the air temperature being sensed by the thermostat located remotely in your motorhome's cab and the setting you've selected on the control-panel's 'room temperature' rotary dial. (The fact that your heater has the 230V option is, I believe, irrelevant in this instance.) If you've got the cold cab/warm living-area scenario I've mentioned above, then there may be nothing actually wrong with your heater. Conversely, it may not be reacting correctly to the thermostat in the cab. You could try to test the latter by letting the heater run for a while, turning the rotary dial to a lowish setting and then warming the thermostat. I could do this with my Herald (and with my current Hobby) by cupping my hands over the thermostat 'dome button' and breathing warmly on it. (If that's not easy to do in your case, then try using hot air from a hair drier.) If the heater fails to shut down when the thermostat is heated, then something's probably up. Link to comment Share on other sites More sharing options...
ron. Posted February 15, 2010 Share Posted February 15, 2010 Should yours be an Autocruise they installed some of these units incorrectly which gave rise to problems. On some models Autocruise did not use all the air outlets meaning one had to be blocked off. However, in the case of an outlet not being used it was important that the correct one was blocked off (either the top or bottom one, I can't remember) Unfortunately, Autocruise sometimes got this wrong which led to these kind of problems. It happed to us on a 2008 combi. If you are at Almafra campsite, we are on pitch 192 if you want further info. Nice weather we are having if you are a duck! *-) Ron Link to comment Share on other sites More sharing options...
JohnP Posted February 15, 2010 Share Posted February 15, 2010 The latest Combi has a remote thermostat. In my van it is near the habitation door. There is no thermostat in the control panel which is over the fixed bed. If as you say there is a thermostat in the cab and there are no heating outlets in the cab itself the problem may be one of insufficient warm air being circulated into the cab area. Hence hot van, cold cab. You may be able to reposition the remote thermostat. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 16, 2010 Share Posted February 16, 2010 ron. - 2010-02-15 11:12 AM Should yours be an Autocruise... Ron Having trawled back through ronboyracer's postings, evidently his vehicle is a 2008 Dethleffs motorhome that he purchased last October. He's never revealed which model it is (which doesn't help!), but it's likely that unfamiliarity with the heating system is the cause of the 'problem', rather than an actual fault. I'm fairly confident that, if someone well-versed in "Combi" usage stood behind ron when he was running the system, this would become apparent. Link to comment Share on other sites More sharing options...
JohnP Posted February 16, 2010 Share Posted February 16, 2010 The temperature control for the latest Combi's is very sensative. A fraction of a turn on the control knob can make a tremendous difference to the heat level. The highest I have run mine at is just above 3 on the control panel and this was during the recent cold weather. Suggest Ronboyracer starts at 3 to see what happens. Once up to correct temperature you should hear the fans slow down. If it is still too cold turn it up a fraction at a time. ie 3.1 3.2 etc Be gentle with it! Another thought. You say that you turn the heating off when it is to hot. Is this with the on/off switch or using the thermostat control (numbered 1 to 5? If the former, try turning the thermostat control knob down slowly. You should at some point hear the fans slow down Link to comment Share on other sites More sharing options...
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