Wondered if people here had views on the suitability of hot water in culinary preparation. I understand well why using hot water from a storage tank system is A Bad Thing, but does the same hold true for a combi boiler system, where the hot water is directly off the mains, passing through a heat exchanger on it's way to the tap?
Part of me thinks its fine, since the heat exchanger should get much hotter than ickies can live in, though there's the question of the piping (have to say, the hot water comes out close to scalding on a regular basis so can't see ickies can live in the pipework either, but hey) - but I wondered what others thought.
The cold water has to go through piping too. I use the hot water from my heat bank for cooking. I can't see why a modern combi boiler would be any different from the water's point of view. The water goes through a low water content plate heat exchanger and a flow switch.
The main difficulty will be any anti-scale or water softening. Of course, you could use a magnetic or electronic descaler. These do absolutely nothing, so the water will still be drinkable.
I think it's probably just because I've grown up with stored HW systems, but I just get past thinking it's unhygienic. I can see no obvious reason why it would be so, other than the temperature is not as high as say a kettle, but as you say above 70C should kill a lot of nasties, although not as many as 100C will :)
The only thing I do find is that hot water from the boiler tastes different to water from our (SS) kettle. I don't really know why this should be as the heating surfaces of both appliances are plate stainless steel... Unless the hot water is picking up something from the copper piping :)
Good point, although in the cold water pipework, I'd expect the chlorine to stop too many "nasties" growing :) The problem I have with the HW piping is the residual standing water, which will have had the chlorine driven off by heating, and which is nice and warm for quite a while after use... Although the "nasties" still have to get in somewhere first, before they can cause a problem :)
So this chlorine magics it way out of the pipe? I would have presumed that like the entrained air, it is forced to stay in solution until expelled by the tap.
In any case, the supplier (DPS) say I can drink the water from the heat bank, so I do. I won't be able to for long, though as I might actually get round to installing a water softener. I've put all the pipework and valves in (full bore 22mm). I'd better actually buy one before the heat exchanger freezes over. Thames water isn't known for its delicate nature.
Hmm, interesting thoughts so far, glad I raised it. I've been known to use hot water occasionally for rinsing things under the tap, but I don't use it in place of the kettle as a way to make tea ;) I *do* boil cold water in the kettle with about an inch in teh bottom of a saucepan to speed up the boiling of a pan of water, and it was partly that which started to make me wonder. The chances are I could fill a pan with hot water from the tap and get much the same time to boil - but it'd mean veggies cooking in HW water, not CW water, iyswim.
No watersoftener on my system (despite being in a very very hard water area, not my choice but the old combi boiler never had signs of furring in the 8 odd years of use), despite the fact that the water *is* clearly very hard (draining board/taps etc).
Of course, I suppose the reason why the boiler might not scale might be cos scale's coming out in the h/w as the heat-ex expands/contracts with each use and dislodges it (a boiler eng once told me this, I took it with a pinch of salt, but my flat-element kettle seems to support this theory to some extent) - not sure how I feel about veg with scale particles...
Still, glad I asked the question, and very interested to hear someone
*is* using their HW for that sort of thing (and hasn't contracted nasties from it yet!)
Thinking about it, you're right, if the system is pressurised.
Given the strong smell of chlorine whenever we run hot water, I was assuming there wasn't any left in the water...
I don't know what Thames Water have done around here, but recently the amount of scaling in the kettle and in the bath etc has dropped. Perhaps someone has installed a large magnet or HV cable close to the water main :) :)
is it just live stuff that you need to worry about? i grew up in a house where my folks suspected that there might still be lead used in some of the old piping - we never used the hot tap for drinking/cooking, i think the assumption was that hot water would dissolve much more lead than cold water...?
i don't know anything about the internal construction of HW systems nowadays, but maybe there are other metals/elements in the pipes/seals that might end up in the water?
I suspect this is because due to the heat, the chlorine is just raring to get out. A bit like the entrained air. That is why pressurised hot water comes out cloudy with bubbles, unlike the cold mains.
Only lead potentially still in existance (given the place dates from
1880's) would be the main coming in, the piping up from the main through downstairs' toilet and up into my place. I know it's all copper from the parts I can see up here. Suspect it's now all boarded in down there. Regardless, can't see any non-copper in the piping up here (and since it's combi, if the lead's on the cold main, it'll be in the drinking water as well as the hot anyway...)
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