Reducing hot water costs

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37 posts

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#3283726 18-Sep-2024 21:50

prob:
I have a Iconic Wiser / PDL / Snieder Bluetooth timer. This is standard PDL kit that any electrician can install. I get power from Z Energy and they have free power from 3 to 6 am and that's when I heat our water.

Easy to make changes from my phone using an app.

Note this timer can also use Zigbee.

https://www.kiwisparks.co.nz/products/bluetooth-hot-water-cylinder-control-kit?variant=42444211749112

Looks like a good option, so when you say it supports zigbee, I can hook this up to home assistant without any of the other hubs or anything they mention in the listing? 🤔

bfginger

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#3322313 19-Dec-2024 15:26

Maybe you could try the opposite approach and use a drain heat recovery system to reduce the quantity of hot water being used.

https://www.showerex.com/

Jase2985

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#3322457 19-Dec-2024 18:44

bfginger:

Maybe you could try the opposite approach and use a drain heat recovery system to reduce the quantity of hot water being used.

https://www.showerex.com/

Some bold claims there and its $1000.

They claim 91% ROI but i calculated it for my house, and it was only 17% so a Payback Period of 68 months

Jase2985

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#3322459 19-Dec-2024 18:45

prob:

I have a Iconic Wiser / PDL / Snieder Bluetooth timer. This is standard PDL kit that any electrician can install. I get power from Z Energy and they have free power from 3 to 6 am and that's when I heat our water.

Easy to make changes from my phone using an app.

Note this timer can also use Zigbee.

https://www.kiwisparks.co.nz/products/bluetooth-hot-water-cylinder-control-kit?variant=42444211749112

If anyone is looking for one of these, i have a brand new one im not using, Happy to let it go for less than i paid for it.

prob

239 posts

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#3327516 4-Jan-2025 18:32

I am happy with the PDL / Schneider timer setup.

Here are some graphs showing first the approximate hot water cylinder temperature (sensor running ESP Home taped to copper outlet) and power usage (from Z Energy website).

About 1/3rd of our power is used to heat the water, and this is all free using the 3 free hours that Z Energy gives on our plan.

I expect that the tank temperature is about 60 degrees Celsius.

I am puzzled by the fact that the water is heated from 3 to 6 am but the temperature starts rising at 4 am. Maybe the clock in Home Assistant is off...

jlittle

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#3327560 4-Jan-2025 21:53

Cold showers, seriously. See, for example https://www.uclahealth.org/news/article/6-cold-shower-benefits-consider

Regards, John Little

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prob

239 posts

Master Geek
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#3327563 4-Jan-2025 22:16

I will do a cold swim but not attracted to cold showers. One of my life pleasures is having an ensuit and taking as many hot showers as I like.

That and lots of fresh towels.

Regards.

PS, Z Energy really upped their game with usage stats. You can also download csv files with usage in 30 mins intervals.

DamageInc

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#3327594 5-Jan-2025 07:21

I've gone to turning off the hot water cylinder as soon as the off-peak period finishes (7am). Turn it back on when the off-peak period starts (9pm).

Pop! OS

prob

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#3327916 5-Jan-2025 21:43

Embrace your true geekiness and install a timer.

DamageInc

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#3328806 7-Jan-2025 18:16

prob:

Embrace your true geekiness and install a timer.

Isn't that expensive?

Pop! OS

Jase2985

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#3328811 7-Jan-2025 18:28

DamageInc:

prob:

Embrace your true geekiness and install a timer.

Isn't that expensive?

depends on how you define expensive, i have one of the Schneider timers I'm happy to sell for $150, and it would be about that to have a sparky to install it for you, would pay for itself in a few years and save you the time of having to do it every day.

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Spyware

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#3328814 7-Jan-2025 18:40

I had a Schneider contactor and timer (mechanical with no memory - I wouldn't have chosen if given a choice) installed, $280 + $140, and 2.5 hours of labour @ $85/hr. Total = $632.50. I thought was exorbitant.

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raytaylor

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#3328887 7-Jan-2025 21:29

My advice is not to put the timer in the hot water cupboard.
The increased temperature will kill the clock battery real quick (ive been through a few).

The reason also is that if you are on ripple controlled water, the timer would spend long periods without mains supply.

Ended up getting a din-rail wifi timer instead that (i assume) boots up, reconnects to the wifi and updates its time via NTP each time the ripple control supply returns.

Ray Taylor

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cjkbarnett

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#3328889 7-Jan-2025 21:36

I've installed a Shelly Pro 1PM in a stand alone din housing to control my hwc. Been working a treat for the last few weeks now. Turns the cylinder off and on according to our off peak rates. Our cylinder is 2.4kw.

And the device itself does not get too warm, well within its acceptable range:

Warmest i've seen it is just over 60 degrees.

larknz

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#3328891 7-Jan-2025 21:57

cjkbarnett:

I've installed a Shelly Pro 1PM in a stand alone din housing to control my hwc. Been working a treat for the last few weeks now. Turns the cylinder off and on according to our off peak rates. Our cylinder is 2.4kw.

And the device itself does not get too warm, well within its acceptable range:

Warmest i've seen it is just over 60 degrees.

The building code requires a minimum temperature of 60deg for a hot water cylinder to prevent legionella growth. The graph would indicate that you are not complying with this requirement and are creating a safety issue for your household.

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