Hot Water Cylinder at Bach, turn on/off remotely

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snowfly

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#205060 28-Oct-2016 10:26

I'm investigating options to remotely turn on/off a hot water cylinder at a bach, as sometimes it isn't used for 2-3 weeks or more.

Came across this 3g iSocket, which would allow turning a device on/off via SMS for under $300: https://www.isocket3g.com/en/

Although would require a 3 pin plug to be wired onto lead going to HWC, as its hard wired.
Waiting to here back from my sparky on this, whether that is a good/bad idea, or advised against.

Has anyone done anything similar, either had a 3 pin plug wired to the HWC (for perhaps a timer, or iSocket type device)?
Or if anyone used an alternative remote device to control HWC via SMS?

Budget is limited (otherwise may as well just leave HWC on, break even point would be too long).
Hence why I spotted the iSocket, which may work out half as much $ compared to something like the Ezy Switch, or SMS Lite

We live approx 3.5 hours drive away, which would be enough time to turn HWC on remotely before we left, and arrive to hot water (tested and it takes 4.5 hours to 100% heat HWC, after 3.5 hours its usable for showers)

Note: already wrapped HWC in insulation, cutting down daily usage from approx 2kWh to approx 1.5kWh.
Calculated via Genesis daily smart meter data while bach was empty:

property was using average 3.5kWh total per day (with HWC on cheaper controlled rate)
dropped to 3kWh per day after HWC insulation
dropped to 1.5kWh with HWC off
hence HWC = 1.5kWh, and fridge/freezer = 1.5kWh (fridge is the only other item left on)

timmmay

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#1659548 28-Oct-2016 10:33

Why not just throw the main hot water switch? Hot water tends to heat fully within 2-3 hours, so unless you MUST have instant hot water it might not be worth the bother. If it's well insulated the power use to keep it warm is likely very low.

If you turn it off I think you may be best flushing it before you use it, because of the bugs that grow in it - legionnaires? At the very least you'd have to wait until it's 100% up to temperature for maybe an hour before you use it.

It cost me $250 to have a digital timer fitted to my cylinder, but that has no remote capabilities.

cisconz

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#1659553 28-Oct-2016 10:38

Most HWC run 3kW elements, so that socket would not work as it is only 2.4kW max.

You could however have your Sparky put a relay in line that does support 3kW and then plug that into the 3g iSocket

Hmmmm

snowfly

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#1659558 28-Oct-2016 10:41

timmmay:

Why not just throw the main hot water switch? Hot water tends to heat fully within 2-3 hours, so unless you MUST have instant hot water it might not be worth the bother. If it's well insulated the power use to keep it warm is likely very low.

If you turn it off I think you may be best flushing it before you use it, because of the bugs that grow in it - legionnaires? At the very least you'd have to wait until it's 100% up to temperature for maybe an hour before you use it.

It cost me $250 to have a digital timer fitted to my cylinder, but that has no remote capabilities.

See original post, already tried turning HWC off at main switch, works fine, saves 1.5kWh per day, which equates to approx 41 cents per day (on our genesis controlled rate) for having HWC on and not being used. Considering the bach is only used primarily on weekends, and usually 2-3 weeks between visits, that is almost $9 for unused hot water, or just over $100 per year if we used the bach every weekend, and had HWC off during weekdays.

Aware of legionnaires, and the requirements (heating to 100%) via the guidelines, and could just remotely turn on a few hours before leaving so it definitely gets to 100% before we arrive.

We have kids, and arriving at the bach with hot water is the goal, baths/showers etc. Otherwise we arrive in evening on a Friday, and have to wait until the morning to have hot water.

snowfly

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#1659560 28-Oct-2016 10:43

cisconz:

Most HWC run 3kW elements, so that socket would not work as it is only 2.4kW max.

You could however have your Sparky put a relay in line that does support 3kW and then plug that into the 3g iSocket

The HWC in question is a rheem 180L low pressure, and when heating from cold, the smart meter shows approx 2kW load, suggesting only a 2kW element, so that is why I was thinking the iSocket would work.

Open to other suggestions/recommendations.

Edit: just checked specs again of iSocket, and it shows:

Power Rating

Max. rating 4000W (16A at 250VAC); continuous resistive load
Nominal rating 3600W

timmmay

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#1659570 28-Oct-2016 11:04

Could you work with a programmable timer rather than remote activation?

Honestly, for $100 per year, I'd just pay it. The cost will probably be $200 - $500 for anything that's legal and safe. If it's an old cylinder put an extra wrap on it.

Filterer

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#1659579 28-Oct-2016 11:16

A hard wired itead sonoff pow is exactly what you want and can switch 16A @240v assuming you have wifi at the batch is remotely controllable https://www.itead.cc/sonoff-pow.html

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