Hot Water cylinder timer

Forums › Home Workshop DIY › Hot Water cylinder timer

1 | 2

timmmay

20581 posts

Uber Geek

Trusted

Lifetime subscriber

#2797612 19-Oct-2021 14:15

The fairly standard digital timer I use is on my switchboard. It's been there probably five years with no issues so far. One day it will fail and we'll have no hot water, might be tomorrow, might be in 20 years. Either way I will be unpopular with the family when that happens!

johnmo

113 posts

Master Geek

#2797625 19-Oct-2021 14:32

Have 24 hour timer on switch board ($200all up to install with some other jobs). It turns on power 6pm to 6am on HW circuit and has override switch.

Showers in morning and then all day solar on roof to get max power into coldest water all day with electric top up just in time for dinner dishes on cold winter day.

That way we get max solar using the coldest water so max transfer.

We have ripple on that phase as well so only pay 11.5 cents per kwh (excl gst). Two adults and typically $10 to $15 per month excl on that "economy phase"

Never run out of HW either

OldGeek

899 posts

Ultimate Geek

ID Verified

Lifetime subscriber

#2797758 19-Oct-2021 18:10

I use this device:

Corys Advantage

The big advantage for me is that it is mounted on the switchboard using a 2-position circuit-breaker slot and comes with an android app for settings. Data connection is Bluetooth. Simple and easy, sits between your hotwater circuitbreaker and isolation switch. There is a second 'channel' available as well which I have yet to find a use for.

--

OldGeek.

Quic referal code: https://account.quic.nz/refer/581402

lenny94

5 posts

Wannabe Geek

#2805560 1-Nov-2021 16:19

SteveM2002: Hi, looking for some advice. Like most people, I’m trying to bring my power bills down and my electric hot water cylinder is one of the biggest contributors. Does anyone have any experience with the Bobbie - Smart hot water cylinder controller? Or a similar device? Lots of websites sell the device but I can only find one review, on Amazon Germany. I know it’s not a DIY project and I’d need a sparky to hard wire anything. With Contact Energy offering free power between 9pm-7am my plan would be to heat the water to max temp during those hours then no heating during the day.
Any advice or experience anyone has with hot water controllers would be much appreciated.

I have had a simple rotary timer fitted to my switchboard to control my HWC and take advantage of Contact Energy 3 hour free power deal. I have a 300 litre cylinder; partially heated by Evacuated Solar tubes. Even on a cool cloudy day I can heat the cylinder by 25 degrees in the 3 hours available. Saved about $30 in October. Haven't had the electricians bill yet by I'm expecting the payback time will be months not years.

Wheelbarrow01

1725 posts

Uber Geek

Trusted

Chorus

#2850336 14-Jan-2022 01:28

lenny94:

I have had a simple rotary timer fitted to my switchboard to control my HWC and take advantage of Contact Energy 3 hour free power deal. I have a 300 litre cylinder; partially heated by Evacuated Solar tubes. Even on a cool cloudy day I can heat the cylinder by 25 degrees in the 3 hours available. Saved about $30 in October. Haven't had the electricians bill yet by I'm expecting the payback time will be months not years.

Did you get the evacuated solar tubes installed? If so I'd be interested to hear the ballpark install cost as it's something I'm interested in.

I feel that the majority of our power usage is by way of hot water so am looking at possible solutions. Currently on an Electric Kiwi low user anytime rate of 31c per kWh so am keen to change to their new MoveMaster variable rate (34c peak, 22c shoulder and 17c overnight) and manually switch the hot water on only between 11pm and 7am for a few weeks to see if it makes much difference. If it does, I'd consider a permanent switching solution on the cylinder.

Gordy7

1906 posts

Uber Geek

ID Verified

Lifetime subscriber

#2850531 14-Jan-2022 09:50

With the focus in this thread of saving water heating power, I decided to have a look at my usage.

Paying all up approx 34c/kWh in the Eastland Network area.

Decided that water heating (controlled) may not be not worth the extra investment for savings.

Retired couple in a 3 bedroom house. Heat pump only used in winter months.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

lenny94

5 posts

Wannabe Geek

#2850665 14-Jan-2022 12:14

Wheelbarrow01:

lenny94:

I have had a simple rotary timer fitted to my switchboard to control my HWC and take advantage of Contact Energy 3 hour free power deal. I have a 300 litre cylinder; partially heated by Evacuated Solar tubes. Even on a cool cloudy day I can heat the cylinder by 25 degrees in the 3 hours available. Saved about $30 in October. Haven't had the electricians bill yet by I'm expecting the payback time will be months not years.

Did you get the evacuated solar tubes installed? If so I'd be interested to hear the ballpark install cost as it's something I'm interested in.

I feel that the majority of our power usage is by way of hot water so am looking at possible solutions. Currently on an Electric Kiwi low user anytime rate of 31c per kWh so am keen to change to their new MoveMaster variable rate (34c peak, 22c shoulder and 17c overnight) and manually switch the hot water on only between 11pm and 7am for a few weeks to see if it makes much difference. If it does, I'd consider a permanent switching solution on the cylinder.

I have had the 30 evacuated solar tubes installed for 16 years. From memory, the cost was just under $9000 but that included a 300 litre HWC, plumbing and a pump/controller to circulate the water between the tubes and the cylinder. The costs included a Rinnai gas instantaneous water heater to boost temperature as it came out of the HWC. These costs were for a new house so I'm guessing if your were retrofitting an existing house in 2022 then the costs would be much higher. Never had any problems with our system and no maintenance issues but was somewhat disappointed to find that 30 tubes only provided for about 50% of our total water heating needs and way less than that in winter.

Until a few months ago we never used electricity to heat the HWC but with 2 prices rises for bottled gas last year we decided it was time to use (free) electricity instead. Its working really well and my best guess now is that our decision to switch will save us nearly all the $700 annual cost of gas with no additional electricity charges.

I recently evaluated the SolarZero option but compared with our current system it didn't stack up and I didn't like the 20 year lease system.

If I was starting from scratch again I would probably look at a PV solution and/or heat pump technology for hot water. For the latter see: https://www.thealternativeenergycompany.co.nz/

Quic Broadband

Move to New Zealand's best fibre broadband service (affiliate link). Free setup code: R587125ERQ6VE. Note that to use Quic Broadband you must be comfortable with configuring your own router.

kotuku4

483 posts

Ultimate Geek

ID Verified

Lifetime subscriber

#2850791 14-Jan-2022 14:09

I prefer solar PV and controller to heat hot water. As opposed to thermal hot water/solar tubes.

mattyboy2

84 posts

Master Geek

#2856131 25-Jan-2022 15:06

I'm about to sign up for Contact Energy's Good Nights plan too.

In the meantime, I've been experimenting with manually switching the hot water cylinder on for 3 hours at night, and it seems to be enough to heat our hot water for the next day, at least in summer. Hot water seems to be almost half my kWh on each month's bill.

This is the sort of dumb timer I'm planning on getting. It replaces the fuse on my fusebox.

https://www.sparkydirect.com.au/p/Hager-EH010-Single-pole-timer-24-hour-16-4-amp-Analogue-No-Back-up-Battery

I harbour fantasies of one day installing a Powerwall and charging that in the 3 hours = free power the next day.

lenny94

5 posts

Wannabe Geek

#2856142 25-Jan-2022 15:25

mattyboy2:

I'm about to sign up for Contact Energy's Good Nights plan too.

In the meantime, I've been experimenting with manually switching the hot water cylinder on for 3 hours at night, and it seems to be enough to heat our hot water for the next day, at least in summer. Hot water seems to be almost half my kWh on each month's bill.

This is the sort of dumb timer I'm planning on getting. It replaces the fuse on my fusebox.

https://www.sparkydirect.com.au/p/Hager-EH010-Single-pole-timer-24-hour-16-4-amp-Analogue-No-Back-up-Battery

I harbour fantasies of one day installing a Powerwall and charging that in the 3 hours = free power the next day.

That's exactly the timer I've installed, but I was charged $200 plus labour by the electrician, who probably got it at a discount - bastards. Its simple and you can programme multiple periods to turn the HWC on and off.

I've found 3 hours of power is sufficient to heat 300 litres about 25 degrees (9-10 kWhs). In winter you might need to run the timer for longer periods and wear the extra cost.

The payback on a Powerwall is non existent. Even if you load it up with free power it will never payback its initial cost in its lifetime.

rogercruse

644 posts

Ultimate Geek

ID Verified

Lifetime subscriber

#2856209 25-Jan-2022 17:55

lenny94:... I've found 3 hours of power is sufficient to heat 300 litres about 25 degrees (9-10 kWhs). ...

Our 300 litre hot water cylinder is heated using a heat-pump and only needs an hour each day to provide all the hot water we need. Which fits nicely into the 'hour of power' supplied by Electric Kiwi.

mattyboy2

84 posts

Master Geek

#2856435 26-Jan-2022 08:45

rogercruse:

Our 300 litre hot water cylinder is heated using a heat-pump and only needs an hour each day to provide all the hot water we need. Which fits nicely into the 'hour of power' supplied by Electric Kiwi.

Thanks Roger, that's good to know. What sort of heat pump hot water system do you have?

I'm wondering how yours compares with the likes of https://www.thealternativeenergycompany.co.nz/ linked to earlier. My 1970s 2 story house has an old low pressure system which needs to be replaced.

rogercruse

644 posts

Ultimate Geek

ID Verified

Lifetime subscriber

#2856471 26-Jan-2022 09:41

mattyboy2:... What sort of heat pump hot water system do you have?...

We had an integrated home automation system installed as part of our new build. So, the one heat pump used for the heating / cooling also provides the hot water. Further details here http://www.atatouch.co.nz

The system includes 24 volts DC LED lighting and smart switches (with motion, temperature & light sensors) in every room plus remote control via a phone app.

They advertise that they can reduce the water heating bills by up to 66%... hence, only one hour for my hot water compared to three hours for yours.

1 | 2