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Using hot water from a vented system for the first time in 2 years

Discussion in 'Plumbing and Central Heating' started by DIYNotIan, 21 Aug 2021.

  1. DIYNotIan

    DIYNotIan

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    Hi all

    For various reasons, we haven't used the hot water system in our house for a couple of years. It's a vented system with a tank in the loft.

    I want to try it out now but wonder whether there could be any potential problems from Legionella or anything else potentially nasty?

    I don't know whether the fact that the water has never been heated over the time means it is not a breeding ground for anything dodgy?

    And if there is a potential for nastiness, will heating the water in the cylinder make it all safe again?

    Or is the best option to run off enough water so that both the tank in the loft and the cylinder have fresh water in them (I'd rather avoid that but if it needs to happen then so be it).

    Many thanks
     
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  3. RandomGrinch

    RandomGrinch

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    There is a risk of legionella in your cylinder and more so in your loft tank. The legionella bacteria can multiply in temperatures from 20 to 45C, see:
    https://www.hse.gov.uk/healthservices/legionella.htm
    Please forgive me, all I know about this subject is how my institution dealt with the legionella risk and this is very different to a domestic situation.
    But in their case it would involve employing a pro, a chemical treatment and a flush.
    I will leave it to others with experience to offer better advice.
     
    Last edited: 21 Aug 2021
  4. DIYNotIan

    DIYNotIan

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    Many thanks for the reply.

    I wonder what happens RE legionella when the temperature is below 20C?

    And also whether the water in the loft tank ever gets above 20C?

    Ta
     
  5. RandomGrinch

    RandomGrinch

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    Below 20C the bacteria is dormant, not destroyed according to HSE. And unless your loft and tank are very well insulated, the temperature in lofts over the summer months can be extreme!
     
  6. Tigercubrider

    Tigercubrider

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    I know that at work a bloke's full time job is running the taps and logging temperatures.

    There may be some kind of liquid treatment that could be mixed into the tank after draining? Allowed to do it's stuff then throughly flushed out? Even forgetting legionella, I'd flush the system after so long.
     
  7. jeff the gasman

    jeff the gasman

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  8. RandomGrinch

    RandomGrinch

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    There may be a load of lime scale that has removed itself from the sides of the cylinder and fallen on the elements, this could cause damage to the elements when turned on.
     
  9. RandomGrinch

    RandomGrinch

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    ...and if you do drain the tank, try not to cause an aerosol. I think the HSE suggest using a face mask when draining, but I may be wrong.

    Edit: yes, HSE advise using FFP3 disposable face mask when cleaning water systems.
     
    Last edited: 21 Aug 2021
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  11. Agile

    Agile

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    If it were mine then I would drain it from the hot taps with float valve turned off.

    Then refill and add chlorine solution to the loft tank and run about 30 litres through everyday or halfday.
     
  12. DIYNotIan

    DIYNotIan

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    Took a look at the inside of the tank just now, and whilst there I thought I'd take some photos so those with a more experienced eye could say how it looks in the scheme of things. I appreciate not all nasties are visible to the eye though!

    We've got vermiculite insulation so I think that's what the white floating bits are.

    The underside of the "lid" has a coating of white mouldy stuff, so I took a snap of that too.

    Thanks to you all for taking the time to help with your replies.

    IMG_20210822_111122068.jpg

    IMG_20210822_111142904.jpg

    IMG_20210822_111152680.jpg

    IMG_20210822_111242412.jpg

    IMG_20210822_111306722.jpg
     
  13. denso13

    denso13

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    I've seen much worse storage cisterns but impossible to tell what the water might contain from photos.
     
  14. Agile

    Agile

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    I am surprised just how clean it looks!

    But it is the bacterial content that is the danger!
     
  15. DIYNotIan

    DIYNotIan

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    Well, good to hear that it at least looks clean. Taste test next... I've just baled some out and made my partner a glass of squash using it. I'll she if she notices anything untoward ;)

    On a different note, but seeing as we're talking about the tank now, when we get the plumbing work done and the system is drained, I need to have the tank disconnected so that I can change the boards underneath. I'm now wondering what my best option is. Would any plumbers mind giving a rough idea of prices/price differences on the following, to help me decide....

    OPTION1 - plumber disconnect pipework to tank, and F+E tank. I will then do the board replacement work. Plumber reconnect all pipework with the tanks in the same places.

    OPTION2 - plumber disconnect pipework to tank, and F+E tank. I will then do the board replacement work but build a higher platform for the tank for better gravity pressure. Plumber to extend current pipework for new cold water tank position (F+E wold remain in the same place) and reconnect.

    OPTION3 - as per Option 2, but fit a new tank instead of the re-using the old one (with proper lid, and an insulating jacket, plus the ball valve isn't looking great).

    Thank you so much
     
  16. Agile

    Agile

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    I would not want to drink anything from a tank like that.

    My BBC section head caught Legionella from an infected cooling tower on Broadcasting House. 43 others caught it and two others died. He lost all his sense of taste and smell and had been a keen beer drinker but did not want to drink again.

    He did not spend too much time off work but said that he had felt very bad.
     
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  17. JohnD

    JohnD

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    presumably from inhaling droplets into his lungs, rather than drinking it.

    Yours doesn't actually look very dirty, but is likely to be infected. I'd renew or replace anything in poor condition. You need a proper plastic lid, hygenic and tight-fitting, and an insulating jacket.

    I once had a grubby fibreglass CWC. I drained it through the cold bath tap, scrubbed it out and rinsed it, again draining through the cold bath tap, when it looked sparkling clean used the chlorine tablets to sterilise it. This prevented dirt and cleaning materials washing into the hot cylinder.

    It is difficult to drain a F&E tank without washing sediment into the pipes, so you need to bale it out into a bucket, then sponge it clean. You can use biocide in an F&E tank since you won't be drinking it.

    At the time we were not living in the house much, so it was no great hardship. It did have a close-fitting lid, the dirt was limescale and rust particles, with a few drowned spiders. Lids can certainly harbour micro-organisms so need to be cleaned, as does the ballcock or anything else in the tank.
     
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