preheated water

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preheated water

Postby Jonny782 » Tue Feb 09, 2016 12:57 pm

What is the received wisdom about changing the water in boilers that has been heated and cooled? my Gaggia at work sits around all weekend, and I am thinking should i be running through a tank of fresh water on a Monday morning rather than reheating water that has been heated several times and hence deoxiginated? Ditto my plumbed in Vetrano at home - but in that case, running a fresh tank of water is going to waste a lot of hot water as you cannot run it cold, thereby contributing to global warming which I am keen not to do. Any advice gratefully received.
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Re: preheated water

Postby dr.chris » Tue Feb 09, 2016 5:35 pm

Jonny782 wrote:What is the received wisdom about changing the water in boilers that has been heated and cooled? my Gaggia at work sits around all weekend, and I am thinking should i be running through a tank of fresh water on a Monday morning rather than reheating water that has been heated several times and hence deoxiginated? Ditto my plumbed in Vetrano at home - but in that case, running a fresh tank of water is going to waste a lot of hot water as you cannot run it cold, thereby contributing to global warming which I am keen not to do. Any advice gratefully received.


The solubility of oxygen in water is highly dependent on temperature so any cycling will remove most of what little oxygen there is (and it really isn't very much). I would not have thought oxygen in the water has an impact on brewing but am open to being convinced otherwise.

Gaggias have aluminium boilers (well the one I used to have did) and I'd wonder if there was a point at which you might get some metallic taste coming through. Otherwise I really haven't bothered to empty the boiler on Anna unless she's been left for a week or two, which doesn't happen very often :)
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Re: preheated water

Postby Jonny782 » Sat Feb 13, 2016 8:41 am

Thanks for that. I have discovered from searching the web https://www.quora.com/Why-do-tea-instru ... difference that boiling water or near boiling water is by definition deoxygenated. Repeatedly heating water howeve leads to evaporation which increases the concentration of solids, although I suspect that's not the case inside a boiler where it can't escape and condenses back into the water. As I use a Britta water filter, there are may be less (fewer?) solids anyway. Probably a bigger problem is me not changing the water filter for months providing a perfect environment for bacteria to develop including the dreaded green Algae. This is probably reducing my expected lifespan on a daily basis due to meanness of not wanting to replace a £4 water filter every 6 weeks. Unfortunately, we will have our pathology, be it obsessionality in relation to coffee making (most reading this now), frittering valuable time away which could be spent reading a good book, neurotic health worries, or excessive parsimony.
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Re: preheated water

Postby dr.chris » Tue Feb 16, 2016 11:44 am

Search around here there are some good(? - detailed?) discussions on water filters.

Water quality does have a big impact on coffee and personally I am lucky enough to live in an area with excellent water (although thinking about it I should schedule in a descale). Some people do end up using bottled water.

I think you are right in thinking that the concentrations of any other elements in the water are going to appreciably change inside the boiler. You do get scale of course.
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