Old boiler !

Discussion in 'OT (OFF Topic) Forums' started by Gareth Kent, Aug 15, 2017.

  1. Codger49

    Codger49 Hardcore MB Enthusiast

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    Surely maintaining your hot water cylinder at the 35,40,45 temperatures mentioned above runs the risk of bacterial infection?
     
  2. lisa110rry

    lisa110rry Hardcore MB Enthusiast

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    Wouldn't have thought so Old Codger, 40c is the default and pretty hot! 37c = 98.6f. We have turned it down to 35. But we don't make tea with it of course! Nor do we drink it. But I don't want to be scalded when using it to wipe the counters.
     
  3. lisa110rry

    lisa110rry Hardcore MB Enthusiast

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    Oh it's a new combi.
     
  4. Codger49

    Codger49 Hardcore MB Enthusiast

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    Think that makes all the difference, believe its only stored water that has to be hot enough to kill the bugs.
     
  5. Peter103

    Peter103 Hardcore MB Enthusiast

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    Old Codger,,,,,,,,,, Legionella bacteria is present in cold water, and is more likely to be got from water droplets, spray or mist, from air conditioning systems being breathed in, rather than from domestic hot water systems in housing. Indeed in schools, hospitals and care homes, hot water outlets to baths, basins and shower heads, are reduced to these sorts of lower temperatures to avoid scalding of patients and children.
     
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  6. markjay

    markjay MB Club Veteran

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    British Gas told us the water in the tank should be kept at 60 degrees because below that we could get Legionella.

    We got rid of the old water tank and fitted a combi boiler instead and never looked back :thumb:

    So I can't really say if British Gas were telling us porkies.

    We had the water tank for 15 years - but the combi is so much better. I don't fully understand why not all boilers are combi? Is there a benefit for a water tank system in a residential flat?
     
  7. Piff

    Piff Hardcore MB Enthusiast

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    Combi boilers have to be correctly sized for the household water demand. The one we took over in our previous house had only been fitted a year before we bought in a house occupied by a 98 year old lady with a single small bathroom with an old narrow cast iron bath.
    We moved in as a family of 4. The water supply to the house was a 15mm dia copper pipe and if I remember correctly the incoming flow rate was just over 10 litres a minute. The combi boiler could only supply about 8 or 9 litres a minute. Both of these numbers are less than adequate for a decent shower and the bath took about 25 minutes to fill to an acceptable level.
    We doubled the size of the house and added another bathroom so that combi boiler was inadequate.

    In our current house we have an air source heat pump which heats water to about 45/50 degrees. It cannot heat that water as fast as a gas or oil boiler so would not work on a combi set up. For heating there is a buffer tank which holds 100 litres of pre-heated water so when there is a heating demand the system has time to meet that demand.
    On the hot water side the stored hot water is at a temperature where you only need to add a little cold for a bath/shower/washing up. There is an immersion heater in the cylinder which is set to come on overnight on a Friday to raise the water temperature to 60 degrees to kill off any legionella bacteria.
     
    Last edited: Aug 17, 2017
  8. Peter103

    Peter103 Hardcore MB Enthusiast

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    Worth pointing out here that if an immersion heater fitted in the side of a hot water tank is set at 60c. the water temp toward the top half of the tank will be at a far greater temp before the heater switches off. And, if its sited in the top and its too short , you probably wouldn't get a decent bath out of it top htrs need to be 27 inch. Just saying!
     
  9. E55BOF

    E55BOF MB Club Veteran

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    Normal human body temperature is about 98.4 degrees Fahrenheit/36.6 degrees Centigrade. If your water feels hot to the touch, your thermostat's not reading correctly.
     
  10. Rory

    Rory MB Club Veteran

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    It's dormant in cold water and gets killed above 60C. Outlets even in homes now are supposed to be from mixers to limit the temperature but in public buildings it's vital that stored hot water is taken above 60C.
     
  11. 190

    190 Hardcore MB Enthusiast

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    60C water will cause serious burns. The whole legionella thing has got out of hand in my opinion.

    Open evaporative cooling towers have the prime source of legionella out breaks and they are difficult to treat consistently so most companies have just got rid of them to solve the problem. Showers are also an issue particularly emergency showers that never get used. I was never convinced that ordinary taps were a significant risk where as 60 C water is very dangerously hot if not mixed down. The cure is worse than the disease. In a similar vein to the cooling towers a common solution is get rid of large circulating hot water systems and replace with point of use electrical heaters.
     
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  12. Peter103

    Peter103 Hardcore MB Enthusiast

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    ^^^^^^ ^^^^^^^^^^ ^^^^^^^^^ ^^^^^^^^^^^ ^^^^^^^^^
    Absolutely agree with all of the above. :thumb:
     
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