Cruisecontrol Posted March 25, 2021 Share Posted March 25, 2021 The reason for this is the failure of the Truma Combi to heat water when gas is selected as the power source. The van is a 2016 Burstner Nexxo Sovereign 690G. With cab air heating switched off and water heating with gas is selected the Combi fires up but switches off after 2 minutes. No fault code is displayed and the three LEDs on the boiler remain lit. Water can be heated by selecting electric. Also room temperature and water heating work on both power sources ( the water being heated by gas in this latter case is obviously due to the Combi heating the water reservoir as it heats the exchanger). Truma don't have an answer but point to a circuit board or a gas valve. The latter being unlikely due to the 2 minute cut out I'd think. The van is with Whispaire in Romsey, an excellent firm I've used before and a Truma agent. I think I'm going to need deep pockets! Has anyone experienced this or have suggestions? Link to comment Share on other sites More sharing options...
thebishbus Posted March 25, 2021 Share Posted March 25, 2021 That does sound unusual. I had mine cutting out on gas after 1 to 2 minuets, caused through debris in the in the concentric inlet/outlet pipes .I disconnected them from the outlet fitting and sucked through them with a powerful vacuum cleaner ,amazing what came out . Brian B. Link to comment Share on other sites More sharing options...
Cruisecontrol Posted March 25, 2021 Author Share Posted March 25, 2021 Thanks Brian, I'll look at that but it does work on hot air with gas selected. Weird! Link to comment Share on other sites More sharing options...
vindiboy Posted March 25, 2021 Share Posted March 25, 2021 Cruisecontrol - 2021-03-25 9:44 AM The reason for this is the failure of the Truma Combi to heat water when gas is selected as the power source. The van is a 2016 Burstner Nexxo Sovereign 690G. With cab air heating switched off and water heating with gas is selected the Combi fires up but switches off after 2 minutes. No fault code is displayed and the three LEDs on the boiler remain lit. Water can be heated by selecting electric. Also room temperature and water heating work on both power sources ( the water being heated by gas in this latter case is obviously due to the Combi heating the water reservoir as it heats the exchanger). Truma don't have an answer but point to a circuit board or a gas valve. The latter being unlikely due to the 2 minute cut out I'd think. The van is with Whispaire in Romsey, an excellent firm I've used before and a Truma agent. I think I'm going to need deep pockets! Has anyone experienced this or have suggestions? Your problem will be sorted by Whispaire in Romsey, I have used him [ Martin ] several times great service and knows his stuff , problem is he is a one man band and can get very busy, I had problems with a Combi in my ex Hymer electric collar failed and on gas the boiler was getting too hot and melting the plastic surround of the casing, he sorted all that and also the thermostat for the space heating failed , he fixed that, I also needed a new fridge freezer in my now Chausson and he did that after trying to get my old one to work but it had gone too far, I had to remove my front seats from the van and the table to get the new fridge into the van as it would not go through the habitation door , he was happy for me to that and it saved me a few hours on the labour costs , So a man I would recommend to any one, You could also stay overnight on the premises or nearby on the estate at a pinch whilst your van was in dock., he is very fair I think in what he charges too. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted March 25, 2021 Share Posted March 25, 2021 Cruisecontrol - 2021-03-25 9:44 AM ...Truma don't have an answer but point to a circuit board... As good a remote diagnosis as any. If the problem were being investigated in the Truma(UK) workshops, the logical initial step would be to try a new PCB. Link to comment Share on other sites More sharing options...
Cruisecontrol Posted April 2, 2021 Author Share Posted April 2, 2021 Tail piece The Truma 6 boiler was repaired by Whispaire of Romsey Martin, the owner, trialled replacements of the temperature sensor and the PCB - No change. Other checks made but finally the boiler was removed and the gas water heating valve was changed. Apparently the boiler, on gas selected, goes through 3 stages for air heating and 2 for water only. Stage 2 was failing on water. On air (plus water) it bypassed stage 2. So it seemed it was heating the water but in practice it would not have got completely hot. As reported before - no fault codes shown. Finally; I'm glad we maintained the MBG warranty payments. It was quite a heavty bill! We just need the freedom to use the van now - no sunny Spain this year though! Link to comment Share on other sites More sharing options...
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