"Normal" Temperature for Hot Water

28 Jan 2005
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United Kingdom
My system is what I would call the 'normal' system - Boiler downstairs heats up a tank full of water upstairs. The tank has a thermostat on it, wedged underneath one of the strings that tie the water jacket on.

I have noticed over the last two or three days (though that is not to say that it hasn't been happening for longer) that the boiler seems to be constantly fired when the hot water is on (and with or without the CH on).

The thermostat on the tank was set to 68. After a good session, when I was happy with the water temperature and the fullness of the tank, I started turning the thermostat down. It was 55 before it got to the 'click' and turned off the boiler.

Is there a proper setting for these, or is it just a matter of experimentation to find a temperature and energy consumption level that I like ? Should I just leaave it at 55 ? What is the 'normal' range for these to be set to ?
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hot water should be set at 55/60,but you can leave the stat at 75 if you want ,oaps and young children around you do not want much higher than 55/60 :LOL: :LOL:
The 'best' range for hot water temperature is quite narrow: it should be ABOVE the maximum temperature that can allow Legionella and other bacteria to grow (50 degrees or so) and BELOW scalding temperature (actually less than 55, according to the rules governing Care Homes, etc.!).

In practice, keep it in the range 55 - 60 and it will be safe enough and not contaminated. Whatever you do, don't run the hot water cylinder above 70 degrees. This will cause hard water to release large quantities of limescale which will soon fill up the cylinder!
I thought the scale thing started in the mid sixties. Too bludy hot for me at that anyway.
A really good thermal contact tween stat and tank is vital, othersisw you get a big temp difference. Make it tight and put insulation over/round it.
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In domestic situations I think you will find that the recommended temp for energy efficiency is actually 60ºC to 65ºC. Although you can set it to wherever you like.
60º Is the temperature for pastuerisation so it needs to be at least that to kill off bacteria
Over 68º is the temp where scale is more likely to form
Legionella, etc. definitely won't reproduce at 55. I don't think there's much grounds for concern about Legionella or other bacteria present in small numbers as spores or dormant. The water comes in chlorinated and potable. If it gets contaminated in the cold water tank (cold pigeon soup, anyone?!) that's a different matter - but it's not a big risk.
Blimey - Didn't realise it was such a minefield. Thanks for all the advice. I'm going to go for about 58 for the moment and see how it suits us...
Thermostats often have an operating range of +/-1º or 2º to prevent boiler cycling. Say you set it to 58ºC, it could actually come on when the temp drops to 56ºC and switch off at 60ºC.
Its not unknown for them to be out of calibration either so investing in a thermometer may be an idea.
Cos I check temps all the time I invested in one of those infra red ones for about 30 quid from Maplins. It was a proper gadget and I played with it solid for about 3 weeks testing everything, my beer, coffee temp and such. I came a cropper when I ran a bath to exactly 36.9º and jumped straight in knowing it was safe only to find that it was lukewarm :cry: :cry:

I run mine at 55 C. If we heat it up much more we always end up adding cold water for washing up etc. My view is if I need to add cold water to cool it down, why heat it up that much in the first place?

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