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Heating and cooling: Mitsubishi Ecobang

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  1.  
    • CommentAuthorunguided1
    • CommentTimeJul 28th 2010
     
    • CommentAuthorSlowmo45
    • CommentTimeJul 29th 2010
     
    Will be interesting to discover whether the unit that 'exploded' did so because of a manufacturing defect or a design defect.

    The fact that 6000 units are to be recalled in the UK and, presumably, tens of thousands more across the world, suggests Mitsi aren't certain it was an isolated incident.

    The photos that have appeared in the local press - see link below - make clear that it was fortunate nobody was close by when it did go bang.

    http://www.thisisthewestcountry.co.uk/news/8299808.Mitsubishi_recall_heat_pumps_following_Chard_explosion/
  3.  
    Interesting - I was wondering if the Ecobang was one of those new CO2-based heatpumps, but it's not, it's just R410A - though even R410A is at a much higher pressure than R22, though not as high as R744 (CO2 :) )

    Paul in Montreal.
    • CommentAuthordelboy
    • CommentTimeJul 29th 2010
     
    Mitsubishi sent over two top engineers from Japan the day after that happened. It's putting the willies up a number of house builders I know...

    However, it's possible that strong caging around the unit would mitigate the worst of the damage. But then again, what else could go wrong?
    • CommentAuthorunguided1
    • CommentTimeJul 29th 2010
     
    • CommentAuthorCWatters
    • CommentTimeJul 30th 2010
     
    I wonder why there wasn't a pressure relief valve fitted, or if there was, why it didn't operate to provide a controlled release?
    • CommentAuthorjemhayward
    • CommentTimeJul 31st 2010
     
    I now know why my original ASHP providers have not appeared to give me a quote...
    Will be looking at other providers / products.
    Anyone have any experience or opinions on Earth Save heat pumps? They are proposing using a ASHP for space heating, and a heat recovery "ecocent" cylinder for hot water duties (when the solar panels aren't up to it).
  8.  
    Posted By: CWattersI wonder why there wasn't a pressure relief valve fitted, or if there was, why it didn't operate to provide a controlled release?
    Closed refrigeration circuits (which is what a heatpump contains) will never exceed a certain pressure and you certainly don't want refrigerant escaping to the atmosphere - though with the new R744 (CO2) systems this wouldn't be a problem. The Ecobang used R410a which is a HFC and these systems operate under much higher pressure than earlier HCFC (R22) based systems. It sounds like it was a manufacturing defect in one of the components of the system. Pressures can reach around 500PSI in such systems.

    Paul in Montreal.
    • CommentAuthorCWatters
    • CommentTimeJul 31st 2010 edited
     
    Posted By: Paul in Montreal
    Posted By: CWattersI wonder why there wasn't a pressure relief valve fitted, or if there was, why it didn't operate to provide a controlled release?
    Closed refrigeration circuits (which is what a heatpump contains) will never exceed a certain pressure and you certainly don't want refrigerant escaping to the atmosphere...


    It seems to have exceeded a certain pressure this time!

    The article implies a fault in one component caused another to go bang. eg the bit that exploded wasn't faulty.

    Obviously you wouldn't want to vent refrigerant in normal use but it has to be better to have a controlled release than an explosive release. They needn't use a PVR, they could use a "Rupture" or "Burst disc" type of over pressure safety device.

    Aside: Presumably this was a gas event rather than say an electrical capacitor going bang?
  10.  
    Posted By: CWattersThe article implies a fault in one component caused another to go bang. eg the bit that exploded wasn't faulty.


    The article states this:An investigation has found that the accumulator part on the W85 unit failed under pressure due to a manufacturing fault.

    Posted By: CWattersthey could use a "Rupture" or "Burst disc" type of over pressure safety device.
    Well, the part did rupture ;) R410A-based systems do use pretty high pressures, but the new R744 (CO2)-based systems will have even higher pressures still. The maximum pressure is easy to calculate given a certain amount of refrigerant in the system so, really, there should be no need for any over-pressure devices.

    Paul in Montreal.
    • CommentAuthorCWatters
    • CommentTimeAug 1st 2010
     
    Looks like I miss read it. I thought this line...

    Mitsubishi has blamed the problem on the power receiver component in the W85 unit that failed under pressure, seriously damaging the outdoor unit.


    ...was suggesting that a manufacturing fault on one part caused another part to fail.
    • CommentAuthorRobinB
    • CommentTimeAug 1st 2010
     
    Our Ecobang is partially installed and I've just had an email to say our grant deadline for completing installation is 28th August. Hope they can make an exception and we'll get the grant and a non-exploding heat-pump.
    Fingers crossed
    Robin
    • CommentAuthorCWatters
    • CommentTimeAug 1st 2010
     
    That deadline would presumably be for completion as far as Building Control Approval is concerned. You might be able to do that without actually switching it on/commissioning? Just a thought.

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