Truma Hot Water Problem

Susieloozy
Susieloozy Forum Participant Posts: 3
edited April 2021 in Motorhomes #1

I have a Truma Combi 4e boiler on which we have a hot water problem. Since the winter, we cannot get the hot water to work due to a constant air lock. First time we started the hot water it took the usual time to bring the water through the boiler, expel the air and get water out through the shower, bath tap and then kitchen tap. It then flows fine.

However, within a very short time of turning the hot water tap off, we have to go through the same process filling the boiler again, as though somehow air is getting in. I have replaced both the hot water drain valve and the breather valve at the top to no avail. I cannot see a non return valve between the water tank and the boiler but anyway the tank and the boiler are the same level and the cold water tank is full.

The boiler seems to be sounding as it should, and the inside heating is working very well but no hot water is coming out as though the burner is heating the air but not water.

Any suggestions gratefully received

Comments

  • DavidKlyne
    DavidKlyne Club Member Posts: 13,859 ✭✭✭
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    edited April 2021 #2

    From what you describe it almost sounds as if the tank is emptying itself. Have you checked there is no sign of water escaping under the van? Does the pump continue to run for longer than normal? Do you know what sort of pump you have, is it internal to the tank or a stand alone pump outside the tank. 

    David

  • Navigateur
    Navigateur Club Member Posts: 3,880 ✭✭✭✭✭
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    edited April 2021 #3

    Seems like the seals in the pump are gone and water is running back out to the Aquroll.   To test get it filled up. Swithch off the pump and then pull out the water connector on the side of the caravan.  If water tuns out you have the cause.    

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
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    edited April 2021 #4

    I do not have a problem with the water on my caravan, but water will escape from the side of the caravan when the pump is removed .... 🤔

  • Susieloozy
    Susieloozy Forum Participant Posts: 3
    edited April 2021 #5

    Thank you for your replies: I hope this gives some further information. It is a submersible Reich water pump which is brand new. No sign of any water leaking from under the motorhome. My latest thought is that water is running back from the boiler to the water pump but why should it suddenly start?surprised

  • DavidKlyne
    DavidKlyne Club Member Posts: 13,859 ✭✭✭
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    edited April 2021 #6

    I think this is quite a common problem on motorhomes with submersible pumps. My second Bailey has one and I often have to bleed the system which I never did with my previous Bailey which had and external to the tank pump. What I do is release the pipe going into the tank at the top which feeds the water system. See photograph below (right click on it to open a larger version in a new tab) If it is the same sort of fitting as mine it as a John Guest snap fitting which is easy enough to take apart but make sure you have a towel handy to collect any escaping water. I ease the joint apart and as soon as water starts to escape I push it back together and this usually cures the air lock. 

    David

  • Susieloozy
    Susieloozy Forum Participant Posts: 3
    edited April 2021 #7

    Update for anyone who comes to these posts in future. I have solved it by putting a non return valve in the cold water feed to the Truma. It seems weird that although the installation instructions show that with a submersible pump a NR valve should be installed, ours worked fine until I had to replace the water pump.

    In summary, if you can't get hot water to get rid of the air locks after winter, check if the non return valve is operating properly.

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited May 2021 #8

    Useful tip, thanks. Talking of hot water systems.... hopefully one day somebody will solve the mysterious workings of the Truma W 255 H error code.🤔

  • young thomas
    young thomas Forum Participant Posts: 11,356
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    edited May 2021 #9

    Bill, it occurs when the 12v supply is removed from the unit (even turning of main MH control panel) before its been properly/fully switched off.

    different (but similar) errors occur when the gas is turned off or the EHU removed before closing down the Combi...

    always turn the Combi fully OFF (hold button for 5 secs or so until OFF appears in the screen) before closing down all other power sources.

    from the Truma web site...

     

    "Warning W 255 H appears in the display of the CP plus panel – what should I do?

    The heater does not have 12 Volt power supply or there is no connection between the heater and the CP plus control panel.

    The power supply to the heater may have been interrupted by switching off the vehicle control panel (not the Truma heater control panel).

    The control panel is used to control all other functions in the vehicle and it also switches the power supply for the consumers in your vehicle on or off.

    In this case turn on the control panel in your caravan to reestablish power supply for the heater.
    Once the power supply is guaranteed and the warning is still present, check the cable connection between the heater control panel and the heater."

  • SeasideBill
    SeasideBill Forum Participant Posts: 2,112
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    edited May 2021 #10

    Thanks, do you ever get ‘App’ displayed rather than ‘off’ when turning off the control unit? I use the Truma App for iNet and remote control unit in the van.

  • young thomas
    young thomas Forum Participant Posts: 11,356
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    edited May 2021 #11

    i dont use the app, but i guess thays something to do with it. perhaps it just means under control of the 'app'?.....

    ive seen so many issues raised with the latest remote control, 'integrated solutions' like Command etc that im happy to push a button for 5 seconds.