Bit OT: Off Peak Hot Water

You don't think it's plausible? Please elaborate, without the hysterics if that's possible.

** Syliva pretty much nailed it.

Your turn..............

LOL !

... Phil

When the warm fluid rises, colder fluid has to descend, otherwise you'd end up with cavities in the fluid, which isn't going to happen.

Sylvia.

A boost element is placed at the top to provide usable hot water as quickly as possible, not to avoid a paradoxical cooling effect. What is your view on the mechanism that brings about mixing of hot & colder water?

Why do you expect thermal convection to mix the cold and hot water? What could cause the hot water to move down and mix with the cold water?

as the element heeat the cold water gets warm and rises it soon mixes with the cold water above the element and produces a slower less heated current, this continues, you won't ge whole tank circulation currents until the whole tank is essentially at the same temperature.

the element will heat all thwe water above it, if you want to heat some of the water to hot you need to mount it higher, else you'll spend the same energy heating it all he water to warm.

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A combination of different pressures resulting from the reduction in density of heated water and Rayleigh?Taylor instability. Where the heating element is not an isothermal flat plate extending the width of the tank, the latter is probably a minor effect.

Sylvia.

It's far from obvious that the mixing is that fast. Anyway, even the mixed water is warmer than its surroundings, and will ascend. Eventually it's at the same temperature as its surroundings, but it has an upward velocity, so it will rise above its proper level, in the process displacing some of the warmer water around it downwards. Throw in some more mixing, and the next parcel of warmed water will climb higher, causing yet more mixing. So even if the initial parcel of heated water cannot reach the top, these processes will ensure that it will in due course.

The tank may then indeed be essentially all at the same temperature, but that temperature will be lower than the temperature of the water that was initially at the top of the tank. Cut off the power then and you have a tank full of lukewarm water rather than a tank containing hot water at the top and cold water at the bottom.

Sylvia.

Possibly more to do with the latent heat of evaporation than conduction don't you think?

I contacted my provider: customer_enquiry With regard to off peak hot water: Does it get switched to heat the water only during night time? Or, is it possible that at some times through the day, water will also be heated? A plumber tells me this is so. He says the system takes advantage of available periods of sufficient power, even if that happens in normally peak times. Thanks

Answer: You are currently on Off Peak 1 which heats between the hours of approximately 11pm to 7am. There is a option to change to Off Peak 2 which also heats between approximately 11pm to 7am plus you receive a 5 Hour boost during the day.

Follow up question: Can you please tell me if the Off Peak 2 system gets its 5 hour boost at a regular time? Or, is there some method whereby the time varies, according to availability of adequate power?

Answer: The 5 hour boost is normally set at a fixed time during the day, but we have the facility to vary this depending on the load of our system.

Regards Jeff - Op1962 Customer Service Representative Integral Energy

*********************

So, it depends what plan you're on. At least I'm sometimes right.

** 5 hours is long enough to heat an entire tank from cold - not some " brief period " or " top up" as you falsely alluded to. Plus it is not "occasional".

Quote from you on the 24th:

" ... you'd miss on the occasional top up through the day (during brief periods when demand is also low). "

Piss off, fool.

..... Phil

I am indeed foolish to attempt sensible conversation with you. You just lost one member of your audience, genius.

Ausgrid fitted the timeswitch today.

At 11am it's letting the water heater run, which it shouldn't. So it's been programmed wrongly. How hard can it be?

Sylvia.

I decided to do the right thing, and informed Energy Australia, via their web contact page. I got a response today.

------------- Thank you for your enquiry.

The information you have provided is not sufficient for us to process your enquiry.

Please provide:

Your account number and/or address of property Your full name Date of birth Home phone number Mobile phone number:"

-------------

I did give them the address. Oh well, they've been informed. It's not my problem anymore.

Sylvia.

As long as you have hot water at op rates don't worry about their stupidity

Indeed.

Sylvia.