Hymer 640MB Starline 1998

Discussion in 'Motorhome Chat' started by holmzie1, Apr 6, 2013.

  1. holmzie1

    holmzie1 Read Only Funster

    Apr 3, 2013
    We have just purchased our first Hymer after many years with an Elddis. We are now trying to work out how everything works and how to fix all the faults "hidden" by the previous owner. Any hints and tips from Hymer owners would be most appreciated. The outside temp gauge reads -22 degrees but it is 10 degrees. Can we alter it? We also thought Hymers dumped their water when the temp was low - last night it was frosty in our driveway but the tank is still full of water? My husband just fixed the hot air system as it had been cut and we have now discovered a really narrow piece of ducting (brown with metal inside) near the water tank - what is that? Really would appreciated advice. Holmzie
  2. JeanLuc

    JeanLuc Funster

    Nov 17, 2008
    Where possible, it may help to post a photograph of any item you are trying to identify, or have a problem with.
    Regarding the water dumping issue, I am not aware that Hymers behave differently to any van with a Truma water / air heating system. There is a temperature-sensitive dump valve next to the Truma to protect it. This opens at 4ºC and dumps the water out of the Truma to prevent frost damage. It cannot be reset (pulled up to click shut) until the temperature reaches about 8ºC. This may lead to loss of water from the fresh tank too, depending on the relative height of the tank and the valve. For example, in mine, the tank is inboard under the settee and the Truma safety valve is on the floor under the wardrobe. If I travel with a full tank when the temperature has caused the Truma protection valve to open, I have a virtually empty water tank after about 150 miles of 'shaking about' on the road.

    The thin brown hot-air ducting is normally used to distribute hot air behind the fixed furniture. Larger diameter ducting (about 2 1/2 inches) is used for the main heating runs and these terminate in butterfly vents to the living area.

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