Hi everyone,

So I have a 4kw geyser element that was working fine for a while but recently it keeps triggering my geyser timer's auto protection setting which is set to 5kw. Plumbers replaced the element which was supposedly shorting due to water leaking but that hasn't resolved the issue (which didn't occur in the past).

Did my own research and seems to me what is happening is that my voltage has been reaching 250V which causes the power draw to be 5kW and that triggers the timer's protection setting. My thinking is that I should replace it with a 3kW element but the electrician the plumbers use seems to think that it won't solve my issue and could apparently make it worse.

I'm no electrician or plumber but I know Ohms law and I know there is a relationship between power, voltage and resistance so as far as I know the reason my "4kw" element is drawing "5kw" is because it is rated to draw 4kw at 220V, and 250V it ends up drawing 5kw.

Anyone have any advice? Would a 3kw element be enough for a 200l geyser?

5 minutes ago, Carnajo said:

Would a 3kw element be enough for a 200l geyser

A 2kw will be enough... it just takes longer to heat the water.

Just now, Demo said:

A 2kw will be enough... it just takes longer to heat the water.

Thanks, makes sense, only time power will be a limiting factor is if it is losing heat to environment faster than the element can heat it.

Will it resolve my over-wattage issue though or am I not on the right track in terms of it hitting the power limit on the timer because of the high voltage?

1 minute ago, Carnajo said:

Thanks, makes sense, only time power will be a limiting factor is if it is losing heat to environment faster than the element can heat it.

Will it resolve my over-wattage issue though or am I not on the right track in terms of it hitting the power limit on the timer because of the high voltage?

I changed my Geyser wise system element to a 2kw, put a geyser blanket on and wrap all the pipes. The heat loss now is minimal - even overnight it drops ±5 degrees max.

Your issue with the over wattage is a question for a decent electrician / plumber.

Just now, Demo said:

I changed my Geyser wise system element to a 2kw, put a geyser blanket on and wrap all the pipes. The heat loss now is minimal - even overnight it drops ±5 degrees max.

Your issue with the over wattage is a question for a decent electrician / plumber.

Awesome thanks.

And yeah my problem seems to be finding a decent electrician/plumber because the first one had no idea and the second one doesn't know how to correct it either but seems to think a 3kw element will make things worse... even though they don't know why it's triggering.

43 minutes ago, Carnajo said:

Awesome thanks.

And yeah my problem seems to be finding a decent electrician/plumber because the first one had no idea and the second one doesn't know how to correct it either but seems to think a 3kw element will make things worse... even though they don't know why it's triggering.

From Deepseek :-)

If the voltage supplying your 4kW geyser increases from 230V to 250V, the geyser will indeed use more power. Here's a concise explanation:

1. Power Calculation: The geyser's power rating of 4kW (4000 watts) is at 230V. Using the formula P=V2RP=RV2, where RR is resistance, we calculate the resistance at 230V as R=23024000≈13.225R=40002302≈13.225 ohms.

2. Increased Voltage Impact: At 250V, the current becomes I=25013.225≈18.9I=13.225250≈18.9 amps. The new power consumption is P=250×18.9≈4725P=250×18.9≈4725 watts or 4.725kW, an increase of approximately 0.725kW.

3. Considerations:

   • Energy Use: The geyser may heat water faster, but total energy over time might remain similar if controlled by a thermostat.

   • Safety: Operating at a higher voltage than rated can cause overheating, reducing the geyser's lifespan.

   • Voltage Fluctuations: Consistently high voltage may require a voltage stabilizer to prevent damage.

In conclusion, the increased voltage will make the geyser use more power, potentially leading to faster heating but also safety risks. It's advisable to ensure the geyser is rated for the higher voltage or use protective measures.

Would just put a 3kw element in.

Will just take a bit longer to heat up

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Use the water heating calculator to determine how much time and energy you'll need to increase the temperature of the water.

1 hour ago, Carnajo said:

Awesome thanks.

And yeah my problem seems to be finding a decent electrician/plumber because the first one had no idea and the second one doesn't know how to correct it either but seems to think a 3kw element will make things worse... even though they don't know why it's triggering.

Any change 2 or 3will draw less current at the expense of longer heating cycle. Your 200L geyser needs 233Wh per degree increase. From this you can calculate if the 2kW might not be too long for your household lifestyle. Not all households are equal thus not easy for an outsider to give the best answer.

I will use a 3kw in order to not increase the time taken too long and it will then not trigger the power rating you set even at the higher 250V which is the problem with your setting.

Never allow the 2nd sparky close to any electrical equipment.

Edited March 13, 20251 yr by Scorp007

Thanks everyone. Yeah it’s as I thought and suspected. Just wanted to check in case I was missing something but yeah.