Fresh water tank siphons

Ovy
Ovy Forum Participant Posts: 9
edited August 2017 in Motorhomes #1

Advice required please. Having changed from many years of caravanning, last year we bought our first motorhome, a new Tribute by Autotrail T615. I find that when I fill the fresh water tank until it overflows from the 2 overflow pipes on the tank it then continues to siphon out quite a lot of the water. I now keep checking the levels on the internal gauge and stop as soon as the last green light shows. This is not as convenient as waiting for it to overflow. Any suggestions please? 

Comments

  • Freedom a whitebox
    Freedom a whitebox Club Member Posts: 296 ✭✭✭
    100 Comments
    edited August 2017 #2

    Hi there, it sounds like there is a dip tube internally on the overflow.

    depnding on where the overflow connects to the tank, i.e., Top entry or side, there maybe something you can do.  It's good practice to have an air gap in a tank, but if it does have one and you can gain access to the inside, you could shorten it to reduce the amount that is syphoned off.

  • Unknown
    Unknown Forum Participant
    edited August 2017 #3
    The user and all related content has been Deleted User
  • Tammygirl
    Tammygirl Club Member Posts: 7,957 ✭✭✭
    2,500 Likes 1000 Comments
    edited August 2017 #4

    If the m/h in question is a Bailey its a common problem, the tube is too long as has been suggested in other posts. A simple adjustment is required.

  • peedee
    peedee Club Member Posts: 9,387 ✭✭✭
    2,500 Likes 1000 Comments Name Dropper
    edited August 2017 #5

    Block the overflow up and wait for water to overflow out of the filler hole, the tank will definitely be full then.

    peedee

  • Freedom a whitebox
    Freedom a whitebox Club Member Posts: 296 ✭✭✭
    100 Comments
    edited August 2017 #6

    You may find that the overflow is also the tank vent . Unless the filler is a vented one, there may be an issue filling the tank and using the water in the tank without air flowing freely into replace the water flowing out.

    Caravan and Motorhome pumps aren't that powerful, but I have seen fuel tanks implode from blocked vents!

  • peedee
    peedee Club Member Posts: 9,387 ✭✭✭
    2,500 Likes 1000 Comments Name Dropper
    edited August 2017 #7

    I take your point JC but I don't have an overflow and I haven't noticed any problems and I do not think my tank is vented because if I try to fill it too fast it can erupt out of the filler due to air trying to escape via the filler pipe.

    peedee

  • young thomas
    young thomas Forum Participant Posts: 11,356
    1000 Comments
    edited August 2017 #8

    PeeDee, im sure ours is similar, i only know when its full by water coming out of the filler....no vent or overflow that i know of.

  • Unknown
    Unknown Forum Participant
    edited August 2017 #9
    The user and all related content has been Deleted User
  • Freedom a whitebox
    Freedom a whitebox Club Member Posts: 296 ✭✭✭
    100 Comments
    edited August 2017 #10

    A little experiment to try. 

    Get a plastic bottle with an air-tight lid.

    Drill a series of hole in the bottom and one in the top.

    Fill it with water and block the top hole with your finger.

    Hold the bottle up and no water comes out of the bottom. Lift your finger and let air into the top and the water flows.

    You can try the bottle at different heights and it's still the same. Without venting, water won't flow!

     

  • peedee
    peedee Club Member Posts: 9,387 ✭✭✭
    2,500 Likes 1000 Comments Name Dropper
    edited August 2017 #11

    You can do that with a wastemaster!  wink No need to drill holes though, just open and close the caps. It leaks a bit but same principle. What does a vented cap look Like?

    peedee

  • Ovy
    Ovy Forum Participant Posts: 9
    edited August 2017 #12

    Thanks for all your useful comments. I have checked the tank and see that there are no less than 4 plastic tubes from which the water overflows. In view of the venting comments I have asked my supplying dealer to check with Autotrail as to what if anything can be done rather than me undertaking something that could give me more problems. 

Categories