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boiler pressure

What is a normal cycle for pressure in LR?
Recently I observed that the boiler heating stops at 1.05 (and residual heat raises it slightly more to about 1.07 or so) and start at around .82.

Is it a proper setting, I thought it was supposed to stop at 1 ?


  • Hi Lukasz

    there isnt a precise 'correct' value as it depends on the ambient temperature as that determines how much heat is radiated away to the surrounding environment

    the longer the better as it indicates a nice tight system with no leaks - a boiler cycle of 30 seconds for example would definitely indicate a leak that needed to be investigated

    my L1 (2012-16) machine had a cycle of 48 seconds and that did not have a leak

    the LR will have a longer boiler cycle than an L1 (2012-16) as the thermosiphon is running at a pressure greater than boiler pressure, typically

    you cant measure the boiler cycle time until the machine has been on for at least an hour, otherwise you will record an artificially low cycle time as the group is still heating up and is therefore drawing an elevated amount of energy out of the system

    kind regards

  • Hi Reiss,
    The cycle and measurement were done after fully heated machine (>1 hour) and ambient temperature of 22C.
    Cycle is quite long 115 seconds.

    The question is: when the heating should be switching off, when pressure reach exactly 1bar, or at 1.05bar as in my case?
    I'm not sure but I think it was switching before at 1, but I may be mistaken...

  • hi lukasz

    i wouldn't worry too much - i have measured the movement in the group surface temperature when the machine is sitting idle for an extended period of time and the wave height in the temperature response from top of pressure switch setting to bottom of pressure switch setting and back again is 0.1C, hour after hour

    the pressure switch will open at 1.0 bar and then the pressure will continue to rise for a moment or two after and during this time the pressure will rise slightly above 1.0 bar

    kind regards

  • It's also good to remember that our atmospheric pressure varies as well with low pressure (often associated with bad weather) of 990 millibar, so 0.99 bar and high pressure with mostly fair weather as high as 1040 millibar, 1.04 bar. We need instruments to measure it as we don't even feel the difference. Likewise, a temporary 0.05 bar extra measured in your boiler is practically insignificant. It's about the pressure you (barely) feel when you lower yourself into a warm bathtub. If it suddenly dropped to nearly nothing after you briefly open the steam valve, that tells one that there is a small issue that can be sorted easily and if it would suddenly overshoot an extra 500millibar that would be more intriguing.
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