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Forum Index : Other Stuff : Over unity with hot water

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RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495
Posted: 07:24am 13 Feb 2010
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  Downwind said   It has been law here now for some time that all new home installations MUST have a device fitted to limit the water temp for the bathroom to 40C max. to prevent scoulding


40?? When did that change?

I thought it was a 55 degree limit in "ablution areas", unless there were children, old aged, or the infirm, in which case it was lowered to (I think) 50 deg C.

40C? Hell, in summer, even the COLD water can be over that!

Here, I have hot water heated from waste heat from the generator. I have a tempering valve in each bathroom to comply with the legislation. The kitchen and laundry get full temperature water. I have a long house, and a ring-main for the hot water with a small circulating pump so hot water is "right there" when you turn the tap on.
 
Downwind

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Joined: 09/09/2009
Location: Australia
Posts: 2333
Posted: 07:56am 13 Feb 2010
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You could well be right Ross i thought it was 40C but it may well be 55C.

Where do you need water hotter than 55C anyhow other than to keep storage size down as the temp is cut back with cold water to around 55 anyway.
Thats the advantage of a tankless system we dont need to heat the water in excess of the end temp so saving on energy.
To have a tank with 80C water in it, that we might use or might not use, is not the smartest system.
But with electric heating is about the only option.

Pete.
Sometimes it just works
 
GWatPE

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Joined: 01/09/2006
Location: Australia
Posts: 2127
Posted: 07:58am 13 Feb 2010
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  KarlJ said  we use 33l / day mains water and another 150-200 of tank water for a family of 4..


I guess the 15Hp pump is not included in thes figs.

Too low a hot water temp and nasty stuff can grow in the pipes.

We have an old house, and the solar can get the hot up to serious steaming temps. Tempering valve is still coming, so visitors get the how to do in summer.

Gordon.
become more energy aware
 
RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495
Posted: 08:47am 13 Feb 2010
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  Downwind said   Where do you need water hotter than 55C anyhow other than to keep storage size down as the temp is cut back with cold water to around 55 anyway.


Well, funnily enough - it's actually illegal (certainly where I am) for the storage tanks to be LESS than 60C (it may be higher) - to kill bacteria like legionaires. So I find it interesting that the law requires you to store "not below" a temperature that is well ABOVE the maximum temperature it's legal to dispense it at!

That said, I like to store the water nice and hot, since it makes transfer through the heat exchanger nice and quick. (I don't actually STORE any potable hot water - the water in my tanks is a horrible brew, the domestic hot water is heated indirectly via coils in the hot storage tank - so it's "instant" hot water, but using stored energy)
 
Downwind

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Joined: 09/09/2009
Location: Australia
Posts: 2333
Posted: 09:13am 13 Feb 2010
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Ross,

My point was not inregards to storage temps but more so with tankless systems heating the water to the required temp and being used rather than storing it.

The problem with bacteria is with stored hot water not water heated and used so a lesser water temp is possiable with tankless systems and energy savings to boot.

Stored water is another ball game as you have pointed out and i dont disagree with you.

The whole point behind what i was trying to make was there is little options with electric hot water except for storage tanks.
If the system in the video was as cost efficent to run as the makers claim then it would be a good option for electric tankless hot water.
Hence only heating the water to a required temp for use.

I may have given the wrong impression that i was recomending storing water at lower temps and i was not i was refereing to instant tankless systems.

Pete.
Sometimes it just works
 
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