Truma heating keeps blowing cold/water scolding hot. Error code W401H. (2 Viewers)

Angela12

Free Member
Nov 26, 2023
6
1
Funster No
100,054
MH
Ex library bus
HELP ! Having problems with my Truma heating. When I run the heating on combined gas/electric I get an error code come up after about 30 to 45 minutes. The boiler then blows cold air for ages and I have to wait for it to cool down before I can get heat again. The heating (cabin) temperture is set at 20 degrees. The error code is W401H which when I look it up on the Truma site it says water is overheating. I do not have the water heating on at the same time but the water is extremely hot. Could it be hot water thermostat? The boiler is well vented, hoses and breather pipes all appear clear. It’s only had a few days of use since new 3yrs ago.

D903AA18-414E-4420-A7F0-07E001D68E0A.jpeg
 
Oct 29, 2008
4,997
5,747
West Yorkshire
Funster No
4,712
MH
PVC
Exp
since 2008
You have hot water turned on , on eco setting. If you have no water it should not be turned on!!!
 
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Angela12

Angela12

Free Member
Nov 26, 2023
6
1
Funster No
100,054
MH
Ex library bus
This photo was before I turned the water off. Water is now turned off and it’s still doing it. And the water tank is full.

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Angela12

Angela12

Free Member
Nov 26, 2023
6
1
Funster No
100,054
MH
Ex library bus
It’s never been empty I have a digital display showing how much water is in tank and it’s never gone below 30%

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CAB96

LIFE MEMBER
Jan 31, 2021
592
1,289
Stockport, UK
Funster No
79,035
MH
T6 Leisuredrive
Exp
3+
It’s never been empty I have a digital display showing how much water is in tank and it’s never gone below 30%
I'm no expert, and don't have that system, but doesn't the boiler fill with water and then stay refilled from the fresh water?

In other words, it should always be 100% full in the boiler, or be refilling as you use the hot?

Or is the 30% actually the fresh water tank, not the boiler?

Anyway, hope you got it sorted, well worth paying the subs to join the forum.
 

Peter 625

Free Member
Feb 9, 2024
2
2
Funster No
101,130
MH
Autotrail Imala
I'm no expert, and don't have that system, but doesn't the boiler fill with water and then stay refilled from the fresh water?

In other words, it should always be 100% full in the boiler, or be refilling as you use the hot?

Or is the 30% actually the fresh water tank, not the boiler?

Anyway, hope you got it sorted, well worth paying the subs to join the forum.
Hi. I have been having lots of problems with the Truma system and eventually had a new pcb. I now get this same 401 code and boiling hot water even though water heating not on. Did anyone manage to resolve this as Truma were unable to make a sensible suggestion

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Oct 10, 2018
1,896
1,069
Bracklesham Bay, West Sussex
Funster No
56,646
MH
PVC
Exp
Since 2005
Peter 625 As code W401H fault shows as , Summer mode with empty water container (or,in another list , boiler reservoir is empty of water) , is it possible that the container is not filling fully or some of the water in it is draining back (faulty non return valve, ? ) allowing a smaller amount of water to get very hot.
 
Last edited:

Peter 625

Free Member
Feb 9, 2024
2
2
Funster No
101,130
MH
Autotrail Imala
Peter 625 As code W401H fault shows as , Summer mode with empty water container (or,in another list , boiler reservoir is empty of water) , is it possible that the container is not filling fully or some of the water in it is draining back (faulty non return valve, ? ) allowing a smaller amount of water to get very hot.
Sorry but tried that as the first thing we do is check the hot water system is full before we switch the truma on. Had a truma engineer check the system through prior to the pcb but he couldn't replicate the faults with the truma diagnostic programme. He did however delete over 100 fault code readings from the system prior to fitting the new pcb. This 401 code is now the only one I get. Truma told me to replace the whole system!
It's a nuisance in the winter
 

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