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Boiling water tap -Hot feed


willbish
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I'm wondering if there is any reason why I shouldn't feed the tank for the boiling water tap with hot water?

My hot water is from a Sunamp and I'm expecting to have a surplus for many months of the year with diverted excess PV generation.

When the sun isn't shining the Sunamp will be charged with 1:1 electrical resistance heating element, which is the same as the small boiling water tank.

It seems to me like using hot water to fill the boiling water tank could save me some energy.

The buts ..
Replacing one or two cups of boiling water drawn off will not clear the dead leg in the hot water pipe run, unless hot water has recently been used at the kitchen tap.
This could negate a fair amount of the savings.

Are there any other reasons why I shouldn't plumb this way?
The hot water is softened but I don't consider drinking softened water an issue.
We haven't chosen a boiling water tap yet, on some that I've looked at the tank seems to be fed from the tap so no option to hot fill. Is this the case with many brands?

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5 hours ago, willbish said:

The hot water is softened but I don't consider drinking softened water an issue.

If your softener is a salt based system, you should consider this to be a big issue. The occasional cup of softened water won’t do you any harm. But making all your hot drinks from softened water is really a very bad idea. Anybody visiting your house with high blood pressure couldn’t really drink it and comply with their medical guidance to limit salt. Depending on how many cups you have a day, and how much salt you take in your diet in any case, this might tip  you over the limit. Do you want heart disease in your future?

 

Edited by Adsibob
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1 hour ago, JohnMo said:

Sounds like a not starter.  Because of the dead leg alone.

Yes you may be right.

Cuppa tea before/after washing up ?

 

37 minutes ago, Adsibob said:

But making all your hot drinks from softened water is really a very bad idea. Anybody visiting your house with high blood pressure couldn’t really drink it and comply with their medical guidance to limit salt. Depending on how many cups you have a day, and how much salt you take in your diet in any case, this might tip  you over the limit. Do you want heart disease in your future?

Sounds like someone has really put the frighteners on you @Adsibob

 

I was under the impression that water softened with salt contains no more sodium than water from naturally soft areas. There's also significantly more sodium (several 100%) in cows milk than softened water.

 

Also isn't the link between hypotension and sodium somewhat tenuous anyway?

 

Pretty sure this topic was done in depth previously and other members, after conducting their own research, chose to use softened water at their main drinking tap.

 

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8 hours ago, willbish said:
10 hours ago, JohnMo said:

Sounds like a not starter.  Because of the dead leg alone.

Yes you may be right.

Cuppa tea before/after washing up ?

 

If you have secondary return then it maybe fine? 

My Quooker combi is fed from the (softened) cold main but I have plumbing in place that I could put it in the DHW instead and draw off the secondary return from the junction with it. I have a motion sensor over the kitchen sink and a temperature probe on the pipework so easy to give the secondary a return a quick whizz when anyone is in the area if it's not at temperature.

 

Practical savings of all of this are likely nil hence I've not bothered yet, but the idea still attracts me :)

 

and yes, softened water makes for much better tea. There's a few areas where water is so hard that it's unadvised to drink it from a softener on a regular basis, but we're (just) clear of that area. It's minute levels of salt compared to one processed meal item. 

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12 hours ago, willbish said:

Yes you may be right.

Cuppa tea before/after washing up ?

 

Sounds like someone has really put the frighteners on you @Adsibob

 

I was under the impression that water softened with salt contains no more sodium than water from naturally soft areas. There's also significantly more sodium (several 100%) in cows milk than softened water.

 

Also isn't the link between hypotension and sodium somewhat tenuous anyway?

 

Pretty sure this topic was done in depth previously and other members, after conducting their own research, chose to use softened water at their main drinking tap.

 

It's pretty standard medicine that high sodium diet increases risk of hypertension and this ages blood vessels. Google atherosclerosis and sodium intake and you'll find plenty of peer reviewed articles on these risks. E.g. https://www.nature.com/articles/ejcn201540 (nature being one of the most highly respected journals in the world)

Your comparison to milk is a little inapposite as most hot drinks which are made with boiling water have a ratio of milk to water of about 1:6, although I guess a latte would have a higher milk content. Personally I don't drink cow's milk, and most of our boiling water use will be to make herbal teas. We do use oat milk (which also contains sodium) in our coffee and tea, but again this is is a very small amount (about 15ml to 20ml per cup) relative to the size of the coffee/tea cup.

Ultimately, the point is about overall sodium consumption. You can't really get sodium free milk, but you can get sodium free water, and given the amount of water drunk is typically much higher than milk, it makes sense to spare sodium from water if you can.

Edited by Adsibob
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33 minutes ago, Adsibob said:

It's pretty standard medicine that high sodium diet increases risk of hypertension and this ages blood vessels. Google atherosclerosis and sodium intake and you'll find plenty of peer reviewed articles on these risks. E.g. https://www.nature.com/articles/ejcn201540 (nature being one of the most highly respected journals in the world)

Your comparison to milk is a little inapposite as most hot drinks which are made with boiling water have a ratio of milk to water of about 1:6, although I guess a latte would have a higher milk content. Personally I don't drink cow's milk, and most of our boiling water use will be to make herbal teas. We do use oat milk (which also contains sodium) in our coffee and tea, but again this is is a very small amount (about 15ml to 20ml per cup) relative to the size of the coffee/tea cup.

Ultimately, the point is about overall sodium consumption. You can't really get sodium free milk, but you can get sodium free water, and given the amount of water drunk is typically much higher than milk, it makes sense to spare sodium from water if you can.

 

While salt is used to recharge the ion exchange resin in the water softener, the resulting softened water has increased sodium content but not salt itself.

 

Our old Quooker was on the hard cold feed and we were descaling it every year, eventually the tank seal got damaged with the repeated servicing and it failed. Quooker replaced it for £250 and we hooked the new one up to the soft cold feed.

 

Guidance is that provided the hardness does not exceed 400ppm then the residual sodium will not be an issue. We measured our hard water with a testing kit and came in below that level. 

 

I would absolutely not use soft hot water as the tanks are designed to work on a pressurised cold feed and also DHW is not potable.

 

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13 minutes ago, Bitpipe said:

 

While salt is used to recharge the ion exchange resin in the water softener, the resulting softened water has increased sodium content but not salt itself.

 

 

 

I'm afraid I don't really understand this. Yes, I accept that Sodium (Na) is not the same as salt (NaCl), but when doctors talk about restricting "salt", they mean sodium and that is why all food labels in the UK require salt levels to be published OR, if there is no added salt, "a statement indicating ‘naturally occurring sodium’ may appear in close proximity to the nutrition declaration, e.g. ‘This product contains no added salt. Salt content is due to naturally occurring sodium.’" See here for ref.

Also keep in mind that most UK tap water will have up to 0.5 mg/l of chlorine added to it, so I would guess that the sodium will bind to that to create NaCl.

Edited by Adsibob
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