Geyserwise Online - Remote Control?

I looked at some of the posts here and noticed that everyone wanting to control their geysers when they have extra PV power ended up using an inline remote controlled relay and then onto a HA system and then set the Geyserwise to a long ON duration. Simple and effective.

Has anyone looked at the Geyserwise Online version to see if it’s possible to control it directly? It does have a web interface with Element On|Off function so it would be nice if there is an API interface to the element and the temperature sensors.


I did speak to Geyserwise last year. At the time there was no API for the on-line version, or any plan to add one.
You could possibly automate it through screen scraping/browser automation, but that is less than ideal.

Thanks @justinschoeman. It’s a pity as that was the deciding purchase/upgrade feature. I will have to go the other route of an additional relay to my current Geyserwise Max.

Geyserwise don’t make it easy. See:

I wonder how many tinkerers they lost due to not opening up their product just a little bit. Remote access to sensor values would be step #1, enabling the ability to set the geyser On|Off would be great, nothing more.

That said, it’s more of a challenge now…

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However one has to give Geyserwise credit for what they have done. I was first interested in their solar PV hot water system. I paid them a visit in their pondok house in Goodwood. They grew out of an electrical maintenance company realizing that much could be done to improve hot water geyser systems.
Their PV system is smart in their use of DC direct from the panels to power the PTC element.
I guess remote access isn’t high on their priorities but go knock on their door and make the request and who knows…

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Agreed, I bought four of their units already. If they added the remote features it would have been five and six. I’m just saying they could add a new market segment if they added the remote features so I will go and speak to them directly, they are around the corner from me.

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There is a “Hack” way of doing it. All you need is a DS18B20 temp sensor, 5v relay, contactor and an esp8266.
What we did was to add the contactor in series with the geyser wize and connect the temp sensor as close as possible to the geyser tank’s exposed metal (The drain cock seems to be ok). With Tasmota you can control the relay via MQTT or their HTTP protocol. You just need to “Calibrate the sensor” as there will be an offset between the side of the geyser and the middle but from my experience, it is not much, and for the need more than ample accuracy.


In layman terms this would be something like a SONOFF TH16 with the temp sensor.
This is what I bought for doing a similar project, but for my heat pump (no GeyserWise)

Not something like… that’s the exact same combination :slight_smile:

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I’m doing similar, but managed to get my DS probe in just behind the GW one, I did however change elements to a 2kw(from 3) and this has an extra jacket i can push my DS probe in. My contactor is also inline with GW and controlled atm via a shelly 1, I’m busy wiring the power button on the GW remote to an nodemcu to be able to turn that on and off as well(eventually to replace the contactor, now there for added over ride safety) I’m also splicing into the GW NTC probe to read its value(and convert) to temp so i have more data to play with. I have another DS sensor on the hot exit on the geyser so its interesting to see the temp differences between element and top of geyser.

And with the SONOFF plus relay (I have this…) you don’t then need a Geyserwise at all… If you are going to automate with Node Red for example.

I use this method and it works a treat!

Just be weary of those Fotek SSRs - most on the market are fakes (and at that price, this one almost certainly is too). You will be lucky if the actual switching device is rated at half the specified current. Fortunately, you are using it at well less than half the rated current - but still make sure you have a decent heat sink, and mount it away from anything that can burn.

Thanks Justin.

Yes I did proper research and ticked all your concerns. I got the actual model for proper price!

I also only have a 2kw geyser element so that helps. Heatsink etc all boxes ticked!


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Looks like someone built a tool for scraping the Geyserwise portal.

Did you manage to visit Geyserwise??

I was at their office today getting my MPPT checked out and asked about interfacing from 3rd party devices to their controller.
They tell me it’s on the to do list. I’m not that clued up with how this interfacing is done. I guess they need to provide an Ethernet port…

Unfortunately, they have been saying this for ages. Geyserwise online has wifi but ethernet and 3rd party access to an API would be better.

Can you confirm which 2kw element you bought thats got this ‘extra jacket’? Would love to add a TH16 with a DS18b20 probe to read the temperature without removing the existing thermostat

Looks like API access eventually happened.