Phone head office and ask them who can repair your unit…
I did exaclty that. Hence I have a nice report. As the head office wanted it too.
The report said - Catestrophic Failure
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You use 1.5h of heating per day
Using mains power feeding the element costs 4 x R3 x 1.5 = R18 per day
Using a heat pump will cost R18 / 5 (COP5) = R3.60
Difference is R15 per day (which is a very long payback period for the heat pump replacement)
I’d rather work on a COP of 3 for a geyser heatpump.
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It doesnt seem that you use enough hot water daily to justify the expense of a heat pump (as well as the added maintenance etc).
I have a heat pump (also enerflow btw) and I am very happy with it and have been for many years. But it requires more maintenance than a normal element. If I didnt have small kids and high water usage I think I would have stuck with a normal element.
My plan if I ever go away from a heat pump is to install a smaller element (1.5kW) into two geysers in series and run them only during the day when the sun shines to store enough water for the evening.
I agree, heat pump COP is closer to 3.5 or maybe 4. Five is an optimistic number you very probably only see under perfect conditions.
Using the numbers we have already (4kWh vs 1.5kWh), the savings per day is 2.5kWh, at Cape Town rates (R3.08/kWh) is R7.70 per day. Or, if you use a lot of electricity and push into the >600kWh bracket, then times 4.27, or R10.67 per day. Let’s say R10 per day, then spending 15k on a new heat pump (probably about ballpark for a “3kW” unit right now) means 1500 days ROI, or about 4 years.
Electricity will go up though, so you could get the money back in about 3 years. Which technically is a win if the device has a warranty of 5 years and lasts at least that long… but isn’t particularly joy-inducing.
If you have decent north facing roof space I think you would be better off installing more PV (4x 560W panels ~R7k) and put all the excess energy into your geyser (via an element) so that it is still warm enough in the morning. You shouldn’t need more battery capacity for loads in the day.
In my case we only have East/West roof so more panels doesn’t help much with winter sun anyway, the heat pump however drastically reduces the kWh required to get the geyser up to temp so that it only needs a bit of a top-up in the morning (~9°C drop overnight atm), it makes much more efficient use of the PV energy available, though the old HP is limited to a 60°C max, newer ones go up to 80°C.
On the low gas pressure failure, the heat pump controller should have had a high pressure and low pressure switch input to protect it…
The ITS units raise an error for various things, but a drastic change in water pressure will trigger the error, as well as issues with gas pressure. The machine locks itself out if the error happens more than 3 times. I can’t say for sure that that means the ITS machines will not fail in the same manner, but it seems they at least tried to protect the machine.
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Thought I will come back to this thread with some feedback.
Before my heatpump broke, I already planned to expand my Solar capacity to 4.1kwp. (from 2.4kwp) to better match my battery capacity. So I did that and not replace the heatpump.
To date, I am very happy.
My 10kwh battery, starting at a 30% SoC overnight reach about 85-90% at 12:00 when the geyser comes on. PV & Battery then supplies the load, with the Battery Soc falling to 70%. Then recharges back to 100% by sunset.
A couple of times during 12:00 and 13:00 the power demand does exceed that of my inverter (5kw) capacity, so I will probably still replace the 4kw element with a 3 or 2 kw element to prevent this.
But overall happy not to have replaced my heatpump. Had a couple of fully overcast winter days now in Western Cape to experience what I know will be higher consumptions during those days, but the full month result is pleasing.
I will now rather spend the R20,000 heatpump costs on additional Solar Capacity, or bank it.
How do you heat your geyser during these times??
Municipal Supply (Eskom). So, yes I buy a bit on these days.
4kw instead of 1.5kw per hour which I would have paid if the heatpump was in order
I also have 5.45 kW of solar panels and 10 kWh of battery, never had to resort to Eskom ( so far, this winter ) to heat the geyser, I also am based in Cape Town.
So you use your batteries for hot water?
Yes, about 1.5kwh as my panels are not quite enough. But it charges back to 100% on most days.
If I do not use battery, then I loose on solar production after 14:00 as my battery will be full and my demand is then almost nothing until the evenening.
Back to my investment choices. This is where I can invest in more solar in lieu of the money I am not spending on the heatpump replacement.
It doesn’t really matter what you use it for, only whether you use them in spec. If yes, then you are using them to generate an ROI.
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Fair enough.
My research wrt the heating of hot water has indicated that heating a resistive element is quite a tall order for an inverter running off batteries…
Depends.
Way most of us do it here, it makes no difference to either the batts nor the inverter.
Using a off-grid inverter, whole new ballgame.
Not the case at all… Element size not withstanding its no different to microwave, etc. Actually better I think as the load isn’t fluctuating all the time!
I have a very similar amount of PV. If it wasn’t for the pool pump and a recent transport acquisition, I would probably have been able to say the same, but unfortunately for me, I’m now using about 900kWh from the grid. I heaped up cheap units in summer though… so so far I have not bought the expensive block. I estimate I will run out of cheap units in the last week of June.
This is the thing yes. I also use them to heat water, but with a 2 Kw element and 20Kwh worth of 1C batteries which amounts to roughly 12amps per battery.
They hardly break a sweat.
.
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