The everlasting HWC

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richms

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#3298246 16-Oct-2024 20:13

tweake:

define "well insulated". i've seen claims that its "meets spec..." but they all look like very thin amount of insulation. remember that an indoor hwc also has the insulation of the house around it. also the pipes should all be insulated, including the cold as you don't want that to freeze.

the other thing is has anyone actually tested it? i bet no home owner has ever tested it. people assume its well insulated.

When they are inside, the cupboard they are in is no longer useful as an airing cupboard and stays at ambiemt if no water is used so therefore the pipes dont carry any hot water.

Richard rich.ms

tweake

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#3298269 16-Oct-2024 20:51

richms:

When they are inside, the cupboard they are in is no longer useful as an airing cupboard and stays at ambiemt if no water is used so therefore the pipes dont carry any hot water.

translation please.

the cupboard is at house temp, not outdoor ambient temp.

your saying if there is no hot water in the pipes then there is no hot water in the pipes. so ???

richms

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#3298281 16-Oct-2024 21:17

Its not warming the cupboard up, the insulation is good enough to block the transfer of any useful amount of heat from the inside to the outside. The pipes act as radiators when you are using water, but if there is no water being used, there is no useful heat being let out of it.

Sure, it will lose more in a 4 degree outdoor space compared to a 20ish degree indoor space, but its not enough to care about. Empty houses with the hot water left on have insignificant power usage when its a modern cylinder either inside or outside.

Richard rich.ms

tweake

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#3298285 16-Oct-2024 21:28

richms:

Its not warming the cupboard up, the insulation is good enough to block the transfer of any useful amount of heat from the inside to the outside. The pipes act as radiators when you are using water, but if there is no water being used, there is no useful heat being let out of it.

Sure, it will lose more in a 4 degree outdoor space compared to a 20ish degree indoor space, but its not enough to care about. Empty houses with the hot water left on have insignificant power usage when its a modern cylinder either inside or outside.

so what was the power usage of an outside hwc, in an empty house, over winter, in south island?

incidentally as i have a nice new indoor cyl, all pipes insulated and i can safely say the cupboard does warm up. clearly some heat is still coming out. which is good as i need to keep some gear dry. i could put a thermometer in there and tell you the exact temp. remind me tomorrow.

dimsim

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#3298286 16-Oct-2024 21:29

richms:

Its not warming the cupboard up, the insulation is good enough to block the transfer of any useful amount of heat from the inside to the outside. The pipes act as radiators when you are using water, but if there is no water being used, there is no useful heat being let out of it.

Sure, it will lose more in a 4 degree outdoor space compared to a 20ish degree indoor space, but its not enough to care about. Empty houses with the hot water left on have insignificant power usage when its a modern cylinder either inside or outside.

we had family staying (2-5 people) for 13 nights on our last power bill and the hot water cost (ripple meter) was $36 on a 20yo Rheem 300L indoor cylinder.

SomeoneSomewhere

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#3298316 16-Oct-2024 22:53

NZS4305 is freely available and has some information on the energy efficiency requirements of tanks and insulated piping sections. I'm not sure of how/where it's cited and whether it's superseded, but it seems unlikely the requirements have been relaxed.

A tank with a 45C differential (65C water, 25C ambient) should have about 75% of the daily losses of the same tank at 60C differential (65C water, 5C ambient).

Average the daily & yearly outdoor temperatures, rather than simply assuming worst-case winter.

pipe60

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#3298426 17-Oct-2024 11:43

Leave it alone and put a water leak alarm under it.

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richms

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#3298488 17-Oct-2024 12:24

For a leak alarm, I was able to get some tuya ones for about $5 off the choice deals on aliexpress after I had searched for some other tuya stuff it started offering me all sorts of things from them for cheap in the 3 for whaever amount deals area. I have them in the basement and by the HWC and under the sink for the next time the insinkerator decides to corrode thru.

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neb

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#3298511 17-Oct-2024 13:54

I got some Yolink ones for the same reason, they're by the HWC, in the laundry, and under the sink.

kiwigander

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#3299279 20-Oct-2024 23:21

User SomeoneSomewhere is correct. Assuming you have a vitreous-lined cylinder, you need to replace the sacrificial anode. Once you see rust in the water, it's probably too late.

An article in Silicon Chip covered this subject several years ago. Replacing a sacrificial anode is a DIY task.

The trick may be finding a replacement sacrificial anode.

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