Truma boilers......... any chance of thermal shock??

Discussion in 'Tech/Mech General' started by Chockswahay, Jan 18, 2015.

  1. Chockswahay

    Chockswahay Funster

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    With all the recent discussions about the Truma dumping water when the sensor gets below 3c I thought I would ask this question.....

    Will the boiler suffer from thermal shock (cracking?) if the unit is empty and heated up to get the sensor warm then filled with very cold water afterwards? Truman don't say anything but I do wonder.........:eek:
     
  2. GJH

    GJH Funster Life Member

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    I normally warm the sensor, gently, with a Black & Decker heat gun that I bought years ago for wallpaper stripping. I fill with water once it is warm enough to stay in place.
     
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  3. Chockswahay

    Chockswahay Funster

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    I had wondered about doing something like that, but without a heat gun I would have to point a fan heater at it LOL :LOL:
     
  4. GJH

    GJH Funster Life Member

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    Speak sweetly to the boss and borrow her hair dryer :LOL:
     
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  5. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    RTFM! If the heater is switched ON the dump valve will not operate! Assuming its a C series combined water and space heater (Ultrastore water heaters generally have manual only dump valves) you can run it without water in the tank for space heating. When the heater is switched on the dump valve is kept closed by electrickery.

    If its a later Combi with the dump valve which has a blue knob then the dump valve should be close to the heater so it will warm up with the heater, sadly not all installers follow Truma's instructions. There is an electrical heater unit available for these "blue knob" type dump valves.

    D.
     
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  6. fastpat

    fastpat Read Only Funster

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    Thermal
    Cannot imagine it having a ceramic core so thermal shock will not come into it. Your boiler would need to be operating at 500. Deg C for thermal shock to be an issue.
     
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  7. Chockswahay

    Chockswahay Funster

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    David you misread my question.......... I am referring to re-filling the system after having drained it down. In use I keep the water boiler on 24/7 in cold conditions so it is not an issue, however I have had to leave the van unoccupied for a couple of days and I have drained the water. I am concerned with the re-fill.
     
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  8. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    My apologies, I misunderstood your question and its Dave if you don't mind, only my parents call me David :)
    The answer to your question is no you won't cause a thermal shock and damage the boiler, its stainless steel and not in direct contact with the heat source (we are talking about a C series or Combi type heater aren't we?) so doesn't actually get that hot. But why not clip the dump valve shut and fill the system then switch the heater on? once it is switched on the dump valve will stay shut.

    D.
     
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  9. Chockswahay

    Chockswahay Funster

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    Thanks Dave.......... er I dunno which model without going out to the van (too cold right now....-4!) but it is a combo and less than 2 years old. I recall from a previous attempt that if the unit is too cold when I press the button on the dump valve that it won't stay in until warmer. I have put the heating on to solve this before but when filling up a couple of week s ago it occurred to me that the water was so bl@£dy cold could it do any harm?

    From what you are saying I need not worry. I am driving back to Aberdeen today from Glasgow so when I get there I will need to put the heater on to elevate the dump valve temperature before filling the fresh water tank.

    Actually it has occurred to me, do most vans have the Truma heater at or near the lowest point in the van? The problem with mine is that when it dumps it completely empties my fresh water...... I'm not too worried about the hot water to be honest.

    Just a separate question....... are you saying that the dump valve is kept shut with a solenoid? I had assumed something like a bi metal strip?

    Cheers
     
  10. Chockswahay

    Chockswahay Funster

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    @dave newell lvs your suggestion to RTFM (LOL) did make me think......

    I found the The official answer to water filling HERE on page 13 (y) (saves me going outside to get the manual haha)
     
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  11. TheCaller

    TheCaller Funster

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    Dave.

    Does your first paragraph only apply to an early Combi model?

    Mine has the dump valve with the blue knobs & having RTFM there is no suggestion of it being kept closed by anything other than the ambient temperature, whether the heater is switched on or off. No suggestion of it being held closed by electricity.

    Is this a change from earlier models?

    Everything in the manual suggests that if the dump valve won't close, you just run the heater without any water in the boiler until the air temperature is high enough for the valve to stay shut, then fill.

    As you say, there is a dump valve electric heater available as an option, should you need to speed the process up, or if the installer has put the valve in a place that will otherwise be slow to warm.
     
  12. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    Yes the first para refers to the earlier dump valve with the red knob on top, the later type with blue button and turn knob isn't kept closed electrically but there is an optional electric heater element for it, intended for when the valve is remote of the heater and not in a warm spot.

    D.
     
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