Seems I have an issue with my geyser. Warm water continually been thrown out of overflow pipe. For now I've turned the geyser and my mains off. Plumber is coming to look in the morning.

I think it did the same thing a few years back, and I ended up having to put a new element in.

I'm wondering about a more energy efficient upgrade, considering repairs would need to be done anyway.

My solar setup at home is relatively small, but I am mostly off-grid.

5kw inverter with 15kwh battery capacity and 8 panels.

Just my geyser that's running directly off the grid. Leaving the geyser on permanently I'm averaging around R400pm on elec, which I don't think is too bad.

Running a 1.1kw pool pump most of the day and a small aircon most summer nights.

I've considered putting 2nd inverter in, and doubling up on panels, with additional batteries. (not keen to rush this, as I have another property behind mine, where I'll likely put in a bigger system)

Wondering about the geyser options - I have plenty of space for panels. Perhaps a setup where the geyser has a few dedicated panels?

Any suggestions on a setup where the geyser will pull what it can from a few panels, and draw the balance from the grid? Not too keen to take power from the current solar setup as I am just getting by with that.

Not sure on the current geyser size - will check that in the morning.

9 hours ago, DylanP said:

I think it did the same thing a few years back, and I ended up having to put a new element in.

This sounds suspect... I'd imagine if it there is continual water coming out of the overflow, then the pressure relief valve may not be closing properly, possibly due to dirt preventing it from closing, an element can't really be the cause for water overflowing... but let me add a disclaimer, I ain't no plumber... :-)

9 hours ago, DylanP said:

I think it did the same thing a few years back, and I ended up having to put a new element in.

A new element or a new thermostat? If the overflow is kicking in there's too much water or too much pressure in the geyser. The element is a dumb device. It is controlled by the thermostat.

@Kalahari Meerkat has pointed to another problem. I suggest you treat the leak as a seperate problem and treat it first, otherwise you may spend a whole lot of money and the geyser still leaks.

1 hour ago, Kalahari Meerkat said:

then the pressure relief valve may not be closing properly

Agreed, sounds like the Latco valve, which as mentioned, might be stuck open. Else it could be the Thermostat that's stuck, i.e. your element is running non stop causing the valve to open to relieve the pressure.

Thanks for the feedback.

Plumber came around this morning. The element is still fine.

Another part he needs to replace. Doesn't sound too serious.

Am still keen to look at upgrades to this system at some point. Not too keen on going the gas geyser route. Seems a hassle to replace the large gas bottles, and I stay in a farming village, where the outdoor geysers, bottles etc tend to get stolen.

32 minutes ago, DylanP said:

Am still keen to look at upgrades to this system at some point. Not too keen on going the gas geyser route. Seems a hassle to replace the large gas bottles, and I stay in a farming village, where the outdoor geysers, bottles etc tend to get stolen.

We're using a 100l 12 Evacuated glass tube HWC here, no heating element or power otherwise... water is low pressure, fed from a Jojo tank, between 6 & 8m off the deck/ 4 to 6m above the HWC, no pumps or anything requiring electrons for this lot to work is in use... we do pump water into the Jojo tank two or three times a week, though, but the house is all low pressure & working perfectly...

So, you should consider an evacuated glass tube setup which you can augment by firing the heating element if the water isn't hot enough, with some home automation and sensors here and there you should be able to automate this mostly, I'd think... the most effective water heating is the direct heating, like with the evacuated tubes, going PV -> electrons -> element is probably only half as effective as the direct heating end...

Once or twice in winter the hot water was not quite as hot as I wold have liked it to be, I will probably look at adding in a donkey in the future, to turn warm water into hot water as it flows to the shower, by burning some wood in the donkey... only run through heating, not wanting to heat 100+l of water, after all, a complete shower is probably not more than 20l of water and no, I don't get wet, stop the water soap up and wash, then turn on water again... low pressure makes the consumption much more frugal...

Edited April 3, 20251 yr by Kalahari Meerkat
grammatik & fat fingers

Sounds like the relieve valve, had to replace one recently as well.

Regarding the upgrade what kw is your element?

For my setup I opted to rather invest the expansion into my array on my inverter than solely on the geyser. With the expansion on your inverter it adds to your total usable generation rather than just one appliance.

My approach was to replace the element that was a 3kw with a 2kw (150l geyser) (less draw longer runtime, but with the lower draw this makes that it is usually within the PV arrays capabilities and then some)

Slapped on a smart power switch and temp sensor and run the geyser once a day so I'm at about 3 to 3.5kw draw per day in summer 4 to 5 kw in the winter due to thermal losses for the geyser and only in the winter it will pull some of that power from eskom when the weather is crap otherwise my array is big enough to cover that draw. I've automated it as well with home assistant to turn on in the most optimal conditions rather than a fixed time with a failsafe at 14:30 just in case the weather is crap as mentioned.

All in that route was way less expensive than replacing the whole setup with a solar or Evacuated tube setup or plumbing in a gas backup.

Math in my head is max R 10 for eskom on those crappy that is only like maybe 20 of 30 days in a year vs R 10-20k for a full upgrade/conversion makes the ROI less attractive 🤷‍♂️ but that is just my opinion.

2 hours ago, -cK- said:

ll in that route was way less expensive than replacing the whole setup with a solar or Evacuated tube

My solar journey started with a flat solar panel geyser conversion some 8 years ago. That came with the Geyserwise controls. It worked well enough at the time.
Knowing what I know now, I should have rather done the Solar PV at the time and used those funds to expand my PV panels. Nothing beats a 230V element heating the water, especially if it's done from PV.
Now with my PV system I have the Geyserwise programmed to start at 10 till 14:30 and I always have enough hot water. It's still a 3kW element. Usually the water is at 65C within 60 to 90 mins.
On sunny days the flat panel has taken it up to 80C on the rare occasion, at which stage the pump disconnect kicks in.

Nothing beats a 230V element heating the water, especially if it's done from PV.

Perhaps nearly nothing. A heat pump using as low as 30% of an element to heat water 24/7 does do it better than the element. Total power used from PV or grid at 30-50% makes all the difference. At about 1kW the HP makes sense.

8 minutes ago, Scorp007 said:

heat pump using as low as 30% of an element to heat water 24/7 does do it better than the element.

It may do it more energy efficiently, but the cost comparison between a geyser element that has been paid for or the purchase of a new heat pump to replace it wouldn't make sense if you are using free solar energy.

1 minute ago, Scorp007 said:

Nothing beats a 230V element heating the water, especially if it's done from PV.

Perhaps nearly nothing. A heat pump using as low as 30% of an element to heat water 24/7 does do it better than the element. Total power used from PV or grid at 30-50% makes all the difference. At about 1kW the HP makes sense.

True but cost and maintenance needs to be considered when it comes to heat pumps from my research into this option. For winter needing half the power to heat the water even if it takes longer than in summer due to how the thermal exchange works could have its advantages but again for me it boils down to the ROI on the investment. When I currently only need to spend R 600 max per year for Eskom on actual usage it is harder to justify forking out 15-20k that will only show a return in 25 years but in the same breath with the way the eskom rates are being hiked this option is not completely off my consideration table.

1 hour ago, -cK- said:

True but cost and maintenance needs to be considered when it comes to heat pumps from my research into this option. For winter needing half the power to heat the water even if it takes longer than in summer due to how the thermal exchange works could have its advantages but again for me it boils down to the ROI on the investment. When I currently only need to spend R 600 max per year for Eskom on actual usage it is harder to justify forking out 15-20k that will only show a return in 25 years but in the same breath with the way the eskom rates are being hiked this option is not completely off my consideration table.

I can just share my own experience which will be for a period of 14 yrs in June with the same heat pump.

Generally the costing aspect is always second hand of what was heard and I have personally never seen a problem about the HIGH cost for maintenance from owners. After observing what was done twice during a service I decided to do the blow out of dust servicing myself. Very few times were there much to blow out but I still ensured the heat exchanger part is not blocked.

Never would anybody not have an aircon due to high service cost which could be more often than the once a year on a heat pump to keep it clean.

My experience including actual cost and savings calculated during 2022 still hold true and since 2022 I had to replace a capacitor at a massive cost of R80 which was 2 months ago. The cost for the feed pump (R2800) included a service. This cost would most probably not have been needed if the installer in 2011 installed a strainer as was the requirement from the manufacturer.

I do agree each guy will have a different ROI as it is driven by the quantity of hot water consumer. Current a 4.5kW heat pump would use about 1.2kW which is much lower than a 2kW element but the heat pump would heat in about 50% of the time the element needs. Thus the saving in PV or battery power could be used to drive other loads. With a more normal consumption of hot water as per my calculation the pay back could be 4 yrs and far from 25 yrs. Not sure with the lower power consumption and shorter time if you took that into account. I have not seen too much detail provided on forums of actual cost. Even if you subtract the annual service cost of say R1200 per year from my savings the ROI would still be I guess less than 6 yrs. But yes it is all based on what costs are used coupled to the quantity of hot water used if this was know. Few of us do have a clear handle on what this would be as well as what time of day and is it free from PV or used after sunset.

My calculation of heat pump vs element in the picture below. I did not include the cost of the 1st service as I don't have the invoice to reflect the actual cost.

A lot of times I don't even switch my heat pump on as the 2nd day the water is still at 40-42 degrees C which is fine for my water temp to shower. Daily use of power on the inverter is available to show actual power used by heat pump as it is the highest single consumption item in my household. In summer my pump never runs more than 1h to get to 56 degrees. To do dishes on the day the heat pump wasn't on I just boil 1 kettle of water to get the fat off dishes and pots and pans.

The great thing about ROI is how one can play around with figures to prove a point.

Thanks for all the replies. I'll go over them this evening.

So the geyser is gone.

Have not yet put in an insurance claim, as I'm sure they'll just replace it with a similar one. It's 150L - don't think I really needs such a big geyser. Small household.

Guess I can now consider all options.

4 hours ago, zsde said:

It may do it more energy efficiently, but the cost comparison between a geyser element that has been paid for or the purchase of a new heat pump to replace it wouldn't make sense if you are using free solar energy.

One thing about the heat pump is you can run it on the backed up side of the inverter as the draw is relatively low.

apparently insurance doesn't cover the actual geyser... so the 'like for like' geyser replacement doesn't come into play.

may as well research this properly and go with the right thing, as opposed to rushing off to buy a similar replacement tomorrow

13 hours ago, Scorp007 said:

I can just share my own experience which will be for a period of 14 yrs in June with the same heat pump.

Generally the costing aspect is always second hand of what was heard and I have personally never seen a problem about the HIGH cost for maintenance from owners. After observing what was done twice during a service I decided to do the blow out of dust servicing myself. Very few times were there much to blow out but I still ensured the heat exchanger part is not blocked.

Never would anybody not have an aircon due to high service cost which could be more often than the once a year on a heat pump to keep it clean.

My experience including actual cost and savings calculated during 2022 still hold true and since 2022 I had to replace a capacitor at a massive cost of R80 which was 2 months ago. The cost for the feed pump (R2800) included a service. This cost would most probably not have been needed if the installer in 2011 installed a strainer as was the requirement from the manufacturer.

I do agree each guy will have a different ROI as it is driven by the quantity of hot water consumer. Current a 4.5kW heat pump would use about 1.2kW which is much lower than a 2kW element but the heat pump would heat in about 50% of the time the element needs. Thus the saving in PV or battery power could be used to drive other loads. With a more normal consumption of hot water as per my calculation the pay back could be 4 yrs and far from 25 yrs. Not sure with the lower power consumption and shorter time if you took that into account. I have not seen too much detail provided on forums of actual cost. Even if you subtract the annual service cost of say R1200 per year from my savings the ROI would still be I guess less than 6 yrs. But yes it is all based on what costs are used coupled to the quantity of hot water used if this was know. Few of us do have a clear handle on what this would be as well as what time of day and is it free from PV or used after sunset.

My calculation of heat pump vs element in the picture below. I did not include the cost of the 1st service as I don't have the invoice to reflect the actual cost.

A lot of times I don't even switch my heat pump on as the 2nd day the water is still at 40-42 degrees C which is fine for my water temp to shower. Daily use of power on the inverter is available to show actual power used by heat pump as it is the highest single consumption item in my household. In summer my pump never runs more than 1h to get to 56 degrees. To do dishes on the day the heat pump wasn't on I just boil 1 kettle of water to get the fat off dishes and pots and pans.

The great thing about ROI is how one can play around with figures to prove a point.

That is if you compare what grid power would have cost you vs what you save using a heat pump.

That is not what I'm comparing, I need to look at what my actual additional savings would be if I'm do drop another 15+k into my setup (cheapest Heat pump online I could google was an ITS 3.6kw at about 15K and that is before all the bits and pieces needed plus installation). Like I said I'm spending only about R 600 per year on grid power usage due to my solar setup and yes this will vary from person to person but this changes the argument as this means I need to spend 15+k to save 600 per year and if you mention there is annual cost of 1200 that would mean I will still be spending 600 per year so then there is no financial saving only energy efficiency gains, granted if it is only blowing out dust and ensuring things are generally optimal one can do that yourself and will cost you a bit of time in an afternoons.

On the point of efficiency I would be interested in what your real world experience is with COP variances between summer and winter. Generally heat pumps are said to be rated at a COP of 3 so for 1 unit (kw) of power you get 3kw of heating so 1 hour to heat a geyser usually but as the temps drop this drops to about 2 or lower depending on the heat pump you get meaning 1 unit will be 2kw of heating (or lower) which is the same as what my element is currently (or worse) so what I will gain is only needing half the power to run the geyser vs what I'm currently using. The only thing I'm looking at is the energy efficiency gains as financially there is no incentive for me to change with my current setup which is making it a harder sell.

12 hours ago, DylanP said:

apparently insurance doesn't cover the actual geyser... so the 'like for like' geyser replacement doesn't come into play.

may as well research this properly and go with the right thing, as opposed to rushing off to buy a similar replacement tomorrow

Whatever solution you settle on, make a plan to change the anodes in the geyser(s) every 2 to 3 years. That will significantly improve geyser life.