Geyserwise Timer on HA

Does anyone know if it is possible to switch one of these, Geyserwise TSE, timers with HA?

I would just want to turn it on/off through HA. Thinking that surely it should be possible to just open it up and link the “power” button with a relay that would trigger it?

Or have anyone done something different?

Basically I would like my geysers to come on when there’s additional capacity in the PV, and off when there isn’t. At the moment they are on from 12-14:30 (two geysers staggered) and it is typically fine, depending on the day, I can already start running them at 10:30/11:00.

I use a contact between the geyser wise and the geyser. I for a “backup” the geyser timer is setup to only come on after 9h30.Then the automation system handles the rest. So should the system fall over the geyser will at least only come on during day time rather than in the middle of the night. Been doing this now for Four years and no issues , yet


Not much you can do with the TSE. Comms protocol not available, and seems well obfuscated.
I ended out desoldering the MCU and adding my own controller to give it a modbus interface:


Thanks for the suggestions. I guess if there’s anything that needs to be changed (electrically) from the current setup, I’d rather figure out a way to get an electrician to do it. Happy to play with my pool pump, but I’d rather not mess with this stuff in my roof. That “what if I start a fire and the insurance don’t pay out” is a bit too big a “what if” for me…

I have a similar problem with my heat pump. The controller is also not accessible.

So the easiest solution I could come up with is to add 'n extra relay that you can control from HA (like the
CBI Astute or a Sonoff) in serie to the power. You then schedule the Geyserwise for a large time range and then HA will manage the extra relay.

Both have to be closed for the geyser to work. So if the Geyserwise stop (temp reached or schedule) the geyser will stop. If the HA relay stop (not enough PV) the geyser stop.
You just need to have a rule in HA to say that by 4pm the geyser is always on so that it can heat if there was not enough PV during the day.

I have not implemented this on my heat pump yet. Somewhere I read that you can’t just trip the heat pump power. It has to stop from the controller. Not sure how true that is. Still trying to get to the bottom of it.
It should no issue on a normal geyser element as that is pretty much how they work.

Jip, agreed that it should not be an issue on an element geyser. Guess I should be able to contract an electrician to install a flashed Sonoff for me.

Technically those POWs should be able to handle my Geyser’s current draw, but I’m not super comfortable with those contactors. They really put some crap push stuff into those POWs to the point where I actually don’t use the one I bought, just the basics (at least I can screw them down).

Maybe I should try and rig together something using my old pool pump timer. It has nice and fat screw-in contactors and a 30A rating. Would just need to jiffy something together to switch it… But then getting an electrician to install it would probably be out of the question as the product would not be “certified”?

Regarding your heatpump - My extremely laymans “feeling” around tripping it is that it might not be a good idea. Thinking about how an aircon “powers down”, something similar might be required. Perhaps the compressor should release or something weird like that… I just don’t like “tripping” things with moving parts.

I agree.
It should be able handle some tripping as the power can trip “normally”, but doing this potentially a few time a day might not be the best idea.

Just a point to share.

Having 2 x 150l geysers on those Geyserwise timers, I scheduled one to start heating at 10 am - heated by 12pm - the other at 1 pm - heated by 3 pm - and extended the times on both until 5 pm to keep hot due to oversupply of solar.

Geyser 1 is a verticle B+ rated outside one, the other a cheap horizontal outside geyser which loses temp. When the cheap one pops, will get a 2nd verticle B+ rated one.

Should have gone for a 400l geyser for both homes … so we learn.

Anycase, it fits 100% into my solar production, and if there is insufficient solar, well, that is just tough because hot water equates to happy females which in turn means they are not on anyone’s case … the cost (cents on the rand per month) for that precious peace becomes a negligible moot point. :wink:

The KISS principle in other words.

We have two of the Fully PV systems from Geyserwise, Just to share, I know most know this system setup, but if a newby reads. They have their own Element. Its made from a Ceramic material and not a normal electric resister. They also supply a MPPT controller that connects to this element via a DC connection. It works of a normal PV panel, Depending on size and area and size of the geyser the number of panels. So we have both, My father has 200l and I have the 150l, 200l is 2kw ac / 900w DC , 150l Has the 1.5 kw AC and 900 w DC. In winter they are working pretty well. But like any electric geyser, if you finish the hot water by night time. You need something to heat the water again. In this case its AC / Eskom. I have mine for about three years now. Would I buy again. Maybe not. I am depended on Eskom either way. What do I think I should have bought ??? GAS!!! I have been doing research and that has come a long way. And its so cost effective. We both took out the Ovens and hob for gas. A 19kg cylinder for stove / oven lasts months and months at R500 to refill … And then have a spare and you have months to fill up the empty

It’s a so-called PTC element. They increase their internal resistance as they heat up, so that it evens out at some designed temperature. They can therefore never overheat or burn out like a resistive element.

Many sellers claim that the PTC element is more efficient in heating water. To every one of them I have always said: Show me the math! It takes 1.16Wh to heat one liter of water by 1°C. Doesn’t matter what you use to get the heat, that is what it takes. If an element is said to be inefficient, then it has to be because the heat escapes without being absorbed by the water. With the element inside the water, there isn’t really anywhere else for it to go. Some of it might be conducted towards the edge of the tank along the metal of the element itself, but the vast majority ends up in the water. A resistive element is very close to 100% efficient already. What could PTC possibly bring to the table in terms of efficiency gains?

So far nobody has been able to answer me :slight_smile:


Is this sum right?
The formula to calculate the power needed to heat a specific volume of water by a given temperature rise in 1 hour.

Volume in litres x 4 x temperature rise in degrees centigrade / 3412
(4 being a factor and 3412 being a given constant)

I.e 100 liters of water to be heated from 20ºC to 50ºC, giving a temperature rise of 30ºC would give –
100 x 4 x 30 / 3412 = 3.52
Meaning that the water would be heated by 30ºC in 1 hour using 3.5kW of electricity.

Money terms:
x R2.50 - if we pay that per unit
= R8.75
= R 266.15 per month. (8.75 * 365 / 12)

Ps. Don’t laugh … I have never done this before. Minor detail, see … till I now want to educate some others in the household.

That would need 100 * 30 * 1.16 ~=3.5kWh. Your answer is right but I’m not sure where you got the x 4 from :slight_smile:

Remember though that hot water rises to the top, so while the average temperature in the tank is now 50°C, the water at the top might be way warmer, and the water at the bottom might be completely cold. So you could possibly get a hot shower out of way less than 3.5kWh, but the guy after you likely won’t :slight_smile:

Edit: Also, the energy vs temperature is linear, so you can take that 3.5kWh and divide it by your element size, and that will tell you how long it will take. So if you have a 2kW element, then 3.5/2 = 1.75 = an hour and 45 minutes.

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Got clever … some people HAVE to shower now at night, others mornings. we are now 7 people.
1 person + kitchen on 1 x 50l horizontal geyser - basta, it does what it does.
2 people on 1 x 150l horizontal geyser - heats once a day from 11am -1pm … it works.

Where I got clever:
4 people on 1 x 150l vertical geyser - heats once a day from 1pm-3pm, evening “bulk” showers are sorted.
Mornings at about 4am it goes on for 30min … morning people can shower.
Done and dusted … works… because it is vertical. :wink:

Hey TTT, You have the same problem as I do but I was pretty dumb at maths and therefore did not get it sorted for seven (7) people to want hot water at random times … :laughing: . I need training how this is done … Someone always seems to have cold water. That said. some are tenants in a cottage and a tenant knows that they can bath / Shower multiple times a day because they pay rent !! :laughing:

Hey Ryan!

Problem, I have no problem … I sorted it.
If my heating schedule results in colder or even cold showers … here, let’s have a chat … :laughing:

People who think they can do as they please, no problem, here is your new bill for that additional water and electricity you insist you have “paid” for! :wink:

Actually am dead serious … I took it one step further. We don’t “rent” space out, we have a “commune”, so we share all the costs of the property aka I’m not the “landlord”, I’m the “caretaker” see.

So if anyone wants to shower to their heart’s content, by all means, have a go, for I will sure as damn install additional meters so that “they” have to then purchase, PAYG style, water/electricity from me, the “caretaker”.

I see no reason why I need to pick up costs with the people living as they please. It is their right, yes.
But so is it their right to “k_k en betaal … die wet van Tranvaal”. :+1:

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i have the same problem with a tenant, she showers twice a day and the geyser temperature drops by 15 to 20 degrees every time she has her usual long showers, again the problem is electricity and water is included in the rent.

I’ll tell you a firsthand account of a colleague.
He wanted to cut down on usage, he figured the culprit was his hot water usage.
When he looked into it, he noted there was a habit of washing crockery as it was needed, 1 cup at a time under running hot water.
No plug in the sink.
He brought this to his housekeeper’s attention, but according to his own meter readings, (three times a day, in a little book), nothing changed.
So he started switching off the geyser every morning. He didn’t tell anyone.
There were complaints. There was no hot water when he got home after work.
But still, he claimed ignorance, it was an unexplained phenomenon.

The reason I know this story, was after a month or so he claimed victory his usage was down.
As he also happily pointed out, now there was still hot water when he got home from work as well.
Take from that story what you want.
I think that the second daily shower will either cease when the water is cold or both showers will get shorter.


@Tariqe , Its amazing the concept of its free lets use it. My latest is the cottage is a single guy, now he has a GF and I have two tenants. The use of water is later in the evening and early morning. Biggest mistake is a bath and a shower in the cottage. 200l at night an 200l in the morning. So my solar does not cater for that 9pm and 7am. Yesterday I read that @TheTerribleTriplet TTT post, and thought. You know what , he has educated you on the solution. Yesterday I installed a Change over switch to the geyser line from the DB, So when I want to be fair I will be paying but when you bring my “new” tenant rules change. Now they will be paying for the Re-heat of the geyser. Cant wait until they come and complain about the increase in electricity. Then I am going to say it will be water also that you and my “new” tenant are using soon as I am looking at water meters!!!

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Always had in the back of my mind that if ever we do rent out parts of the house, the first thing I will do is to put in PAYG meters for water AND electricity.

Cpt has water usage in kl bands, same as the electricity in units.

So for the tenants meters I will set the rates at the top rate of CoCT so that when the water/electricity consumption exceeds CoCT’s “bands” for the property, i.e. it goes top dollar, that I’m still not “out of pocket”.

IF the tenant is disciplined, and we can talk openly, the usage stays within the low bands, off course I will drop the rate.