Truma boiler red light coming on (1 Viewer)

Sep 6, 2016
100
122
Bristol
Funster No
44,987
MH
Low-profile Coachbuilt
Exp
Since 2010
Good evening all, I have a possible problem with my Truma Combi 4 boiler/heater. After it has been on for a while (Blown air heating) a red light on the control knob starts flashing and continues to flash. The Instructions say this is due to low voltage <10.5v. However in last two weeks I had a habitation check/service and the batteries were good with no problem. When flashing the battery indicator on the van control panel reads 12.4v. This first happened a few weeks ago and I put it down to low voltage since we had not been on EHU for a week and had only driven short distances. (I do not have solar but have 2 x 85amp hab batteries). This time the van had been on EHU at home, we then drove 85 miles to Exmouth and fault started next morning. Even though red light is flashing heater still works. Any ideas please.
 

Northernraider

LIFE MEMBER
Jul 30, 2017
27,409
177,379
On the sofa ....
Funster No
49,727
MH
Mobilvetta eurayacht
Exp
On and off since 95
Yeah that's the same as mine was doing

I temporarily fixed mine by wiring straight to the battery.
But I have it wired back through the system at the minute and it seems to be fine now so I cant actually tell you what was wrong with it.

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Jul 6, 2016
1,547
1,264
West Sussex
Funster No
43,954
MH
Carthago Chic A clas
Exp
Since 1990
Could possibly be low gas pressure or a partially gummed up gas regulator.
 

TerryL

LIFE MEMBER
Mar 5, 2010
6,180
8,180
North East
Funster No
10,511
MH
Low Profile
Exp
2009
May be something as simple as poor electrical connections - how easy is it to check on your installation, some of them can be a b----r!
 
Oct 29, 2008
5,068
5,949
West Yorkshire
Funster No
4,712
MH
PVC
Exp
since 2008
12.4v at the panel, but what at the boiler?
Read the blink code at the boiler, it will tell you why it went to fault.

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OP
OP
theapples
Sep 6, 2016
100
122
Bristol
Funster No
44,987
MH
Low-profile Coachbuilt
Exp
Since 2010
Thanks for all ideas so far. I don't think it is a gas problem. I had regulator changed two weeks ago since it was 9 years old and the fault was showing before this. I'll get the volt meter out when I get home next week and get in the garage to check the fault code and check the power supply. (That should be fun)
 
Feb 24, 2022
58
76
Southampton, UK
Funster No
87,083
MH
Burstner Nexxo T620G
Exp
Actually start, 01/03/22
I currently have a similar problem, red light comes on after small fan heard to spool up. when asking for Hot water or heating,(Elect. or Gas) Is there a `Blink Code? if so, where can I get the info? (Due to nature of installation, unit is facing away from me on a shelf in the Motorhome's garage.-hence unable to get to potential fuse(s) etc.) Motorhome booked into dealer for look at (under warranty)!
 
Jul 6, 2009
1,796
2,217
Funster No
7,383
A fixed red light is a gas problem, a flashing one is low voltage. Given how some makers use thin wire to save cost then users suffer a voltage drop. If the light is a bit sensitive it will flas earlier than others?

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Apr 22, 2018
6,823
12,578
Herts.
Funster No
53,503
MH
Adria Coral lowline
I currently have a similar problem, red light comes on after small fan heard to spool up. when asking for Hot water or heating,(Elect. or Gas) Is there a `Blink Code? if so, where can I get the info? (Due to nature of installation, unit is facing away from me on a shelf in the Motorhome's garage.-hence unable to get to potential fuse(s) etc.) Motorhome booked into dealer for look at (under warranty)!
If a solid red light check your gas. Are other gas things working? If yes, it may still be gas issues and often gummed up regulator that doesn’t allow enough gas through for boiler.
 
Dec 2, 2019
4,064
9,082
South Lincolnshire
Funster No
67,140
MH
Rapido 7065+
Exp
Broken most bits now
Sometimes just resetting the main control panel works. A dumb question but is the gas turned on at the internal valve?
 
May 7, 2016
7,248
11,731
West Sussex
Funster No
42,951
MH
Carthago Compactline
Exp
Since 2003
However in last two weeks I had a habitation check/service and the batteries were good with no problem.
A hab check might cover the voltage at the time but I doubt they did a slow load test to see whether they can sustain a load in prolonged use. How old are the batteries? When batteries sulphate with age they will still charge up to a normal voltage but lose capacity i.e. what started off as a pair of 85Ah batteries might now only be capable of holding half that amount. The batteries may recover a little when the load is removed by the boiler shutting down, before recharging them try turning on lots of lights and the water pump to see if your 12.4V drops off quickly.

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