hot water temperature

[Rosendula]

Now and again I go on a site or read a leaflet telling me how I can reduce my carbon footprint/bills. I can't remember ever reading anything helpful in any of them, as I already have loft insulation, draft proofing, low-energy light bulbs, etc., etc. But I still look occasionally to see if anyone's come up with anything new that I haven't thought of.

One thing that has always puzzled me when I read these things, though, is that they always tell us to turn our water thermostat DOWN to 60 degrees celcius. If I turned mine to 60 degrees, I'd be turning it UP. I have it around 47/47 degrees, because that's what I can comfortably use without scalding myself. If for some reason I need water hotter than that, I can boil a kettle to add to it. Such an occasion is so rare, surely this must be more eco-friendly.

So what's yours set at? And am I missing something? I was going to say 'am I a bit odd for not having really hot water?' but then I though of Annpan

[Annpan]

Glad you are thinking of me.... I dream of turning on a hot water tap

- I have been known, when visiting family, to wash my hands for an unusually long amount of time because warm water on my hands feels like such a luxury....

[Millymollymandy]

Ours is turned down too Rosendula because I can't bear scalding water coming out of the tap. We have, unfortunately, two hot water tanks heated by electricity but which heat water for different parts of the house. We really need to have hot or at least warm water in both. So one gets put on every other night and the other one about twice a week, and during our off peak hours.

[Greenbeast]

What is meant to happen is that you have your tank at above 60C to kill legionella and then use TMVs to bring the temp down so as to not scald at the outlet

My solar heats the tank to 90C but the TMV brings it down to a nice and safe 45C

[Annpan]

psst... what is TMV?

I must say, that makes sense I'd imagine that continuously handwarm water would be a perfect breeding ground for many bacterium (but Rosey, you know all about that)

[Rosendula]

psst... what is TMV?

I must say, that makes sense I'd imagine that continuously handwarm water would be a perfect breeding ground for many bacterium (but Rosey, you know all about that)

Er, no, I don't. I didn't study bacteria at Uni, just the way people go mad cleaning everything because the advertisers of cleaning products use scare tactics to make us all afraid of germs.

I know our local water company tests the water in our area 3 times a week. Someone drives around and picks houses at random, then asks the householder for samples of the water. They came to me recently. However, I don't know if they test for Legionella. I just did a Wiki and got a bit scared, so now I'm wondering if I should turn the temperature up. Like you say, Annpan, it makes sense. I've just sent an email to Yorkshire Water to ask them for their opinion, so I'll let you know.

Thanks for the advice Greenbeast. That's really why I was asking on here, because someone always knows something I don't or haven't thought of.

[Green Aura]

The legionella would be in your hot water tank Rose, not the reservoir. It breeds in warm moist situations like hot water systems that are not above 60oC and heating ducts.

So you need to heat your water above this, then have a mixer valve (TMV) to add cold water nearer the tap to make it a safe temp.

It's unfortunately one of these (fortunately few) areas where being frugal and eco could have potentially fatal consequences.

So I'd turn the temp back up but maybe heat it less often.

[Millymollymandy]

We can't heat ours above 60C anyway (I think that's the max with French electric boilers) but why on earth would I want to pay the extra electricity then cool it down again!!! Again that's (as far as I am aware) completely unknown and unavailable in France.

I drink water from the tap and it's not always on completely cold flow when I drink it - i.e. there's probably the remnants of hot water (gone cold) in the pipes and it's never affected us in 11 years of living here.

[Greenbeast]

you don't lose the extra energy you put into the tank (well apart from slightly higher loses due to bigger temperature differential) because as you add cold water to mix the temp down you aren't using as much hot as you would have been...

[Millymollymandy]

Yes good point, and at least I have modern taps which are all in one handle mixer thingies. Feel sorry for all those in the UK with separate hot and cold water taps - but then as you say you've got something in the set up which does this cooling down before it reaches the tap.

[Rosendula]

Someone from Yorkshire Water rang me back and said basically the same thing that Greenbeast said. They don't test for legionella because if it's there, it's in the immersion (or wherever) which comes after the water board have done their bit. She confirmed that 60C will kill a lot more than 47C (well, we knew that bit), but couldn't tell me any more about legionella because it's not something they deal with. Fair enough! What I'm wondering is, if it was present in my immersion, how the flip did it get there? Where does it come from if it doesn't come in through the water, and doesn't British water contain chemical nasty-killers? (bit dense on this one I'm afraid, but isn't that why some people will only drink bottled water?)

Anyhow, I decided that although we have lived here for 7.5 years and seem OK, it wouldn't do a lot of harm to turn the water up to 60C for a few hours to kill anything off that might be lurking, then turn it back down to my comfy temperature. Right now, it's horrible and I've had to tell LO not to even turn the tap on so that she doesn't scald herself.

[Green Aura]

It's a while since I've had any dealings with this, but as far as I remember it's carried in water droplets. It's not a danger to ingest, which is why drinking it won't cause any problems, but breathing in infected water vapour is the problem. Legionnaires disease is a type of pneumonia essentially.

I have no idea how it gets in, if the water board don't test or treat, then I'm guessing it comes in from the mains. I'm not sure how they would treat it - heat is the best way.

There's not been much about it recently, mainly because all the hotels etc have increased their hot water temp.

[Millymollymandy]

I'm totally confused now - so what about your cold water that you drink from the tap? If it comes from the mains we don't heat our cold water up then cool it again!

[Green Aura]

Well you don't get much vapour from cold water and I presume they need a certain temp to proliferate.

Otherwise it must come from someone coughing and sneezing - how does it get in the tank then?

[Millymollymandy]

Otherwise it must come from someone coughing and sneezing - how does it get in the tank then?

A plumber with swine flu?