Immersion using 21 KW of electric

cgrj

I have a Willis attached to my immersion to heat my water. It is using 21kw to heat to full. I have had the Willis replaced as the plumber thought this was the issue. He has now told me to contact an electrician, however when I contact an electrician he says it's a plumbing issue.

The immersion will heat efficiently using the oil heating so I can't figure what the issue is...

Any guidance or suggestions would be very gratefully received

phormium

How much water are you heating with it? You say to full, do you mean you are trying to heat the full tank with it, how long is that taking? I thought they were more for just heating a little water like to do the washing up or a quick shower, not to heat a full tank for say a bath. I turn mine on for about 5 minutes to get a sink of hot water.

They are probably around 3kw so seems unlikely it would take 7 hours to heat a tank even if one tried, how did you measure the usage?

SteelyDanJalapeno

My 200 litre tank takes about 6kw to fully heat to about 45-50 degrees

blackbox

I presume you mean 21kWh or 21 Units to heat your cylinder.

Have you got an internal immersion as well as the WIllis? The Willis is rated at 2.85 kW so it will take more than 7 hours to use 21 Units if no water is being drawn off and your system is well insulated - also assuming your cylinder is big enough not to boil!

The oil heating has nothing to do with the immersion. It puts hot water through a coil in your cylinder.

10-10-20

How are you measuring the consumption of the heater/hot water?

Do a test on a day when there is nobody home. Leave the tank to go cold and then heat it using the Willis heater. Check that none of the pipes other than the Willis loop get hot.

cgrj

Thanks for the replies. I have solar panels and Eddi so that's how I am measuring ( it was using huge amounts before solar so that's not the issue). Heating a full 210 litre tank which others are also with no issue. It's taken 3kwh for 7/8 hours of the day before full, should only be taking a guesstimate of 9 max.. Not 21 units 21 kWh which is why I have an issue 🥺 and no water is been drawn off...

I know the oil heating is nothing to do with the immersion I was only trying to show the tank was functioning correctly 😀.

Thanks for reading

10-10-20

https://www.boards.ie/discussion/comment/122167530#Comment_122167530

No water might be drawn off, but you may have a thermal loop or pitching into a header tank or even an internal leak into the heating system. All these things should be checked.

TheSunIsShining

https://www.omnicalculator.com/physics/water-heating

Well something isn't adding up - 21kw is far more than required to heat 210l of water to 60 degrees.

tnegun

How hot is the water getting? How is it plumbed? Post some pictures. If it is taking 21kwh it sounds like it's heating the tank in the attic too!

John.G

The Eddi, if diverting the max 3.0kw, (immersion power), continuously, will take 8.5 hrs to reheat 210L from say 30C to 65C so unlikely to achieve this except on exceptionally sunny days like the last few?.

cgrj

Yeap , that's what's happening. It's taking all of the solar to fill the tank. When it's not as bright it just doesn't heat enough water

But problem is electrician are saying plumbing and plumbers are saying it's electrical fault and nobody wants to trouble shoot it for me .

cgrj

Have checked tanks in attic it's not heating it, so the mystery remains

cgrj

Thanks for the reply, that's the problem it's taking far too much

Shoog

https://www.boards.ie/discussion/comment/122168539#Comment_122168539

Can you not program your EDDI to restrict usage of the immersion. It will take as much electricity as it takes to heat that amount of water - and if thats to much then you need to restrict it with usage rules.

If there was an issue with the immersion heater your house would have burned down since the energy has to be going somewhere and if not the tank then it would be heat/flame.

youtheman

https://www.boards.ie/discussion/2058352643/immersion-using-21-kw-of-electric

You need to look at how many kwH it is taking (Kilow Watt Hours). KwH is total energy. Kw is just current. So 21kw for 10 minutes is completely different to 21kW for an hour.

10-10-20

I still have questions on how this is being measured. "I have solar panels and Eddi so that's how I am measuring" doesn't tell us much.

Do you have the heating system on at all, or any warm radiators around the house? One issue that I encountered was that the boiler was acting up and running the pump while trying to heat the tank, except the ignition wasn't working so the boiler was looping the water in the coil around the system for the duration of the tank heating cycle, and that drew all of the heat out of the tank. That's why I was asking about warm/hot pipes coming off the tank. So maybe check this again and be clear in your answers to the questions - we are here to help. 👍️

Wearb

https://www.boards.ie/discussion/comment/122168124#Comment_122168124

Are those figures correct John? 🤔

cgrj

Apologies, Eddi's screen shows how much power is been generated and where it is being consumed. I will attach a screenshot, this was a day when nobody was in the house ( so no hot water been used ). The Willis loops round and there are no other hot pipes (as in hit to feel) coming off the tank when water is not in use

John.G

https://www.boards.ie/discussion/comment/122169331#Comment_122169331

8.5Kwh required to heat 210L from 30Cto 65C is certainly correct, 210*(65-30)/860, 8.55Kwh, don't know if the OPs solar PV could supply this or not, it depends on the solar PV size/output, solar radiation, in houe use (apart from the immersion) etc, for example I think it was the 20th here in Cork gave a radiation output of 8.1Kwh, if one had a 6.5KWp installation and assuming 6M2/KWp then the total solar input was 6.5*6*8.1, 316Kwh, the panels in very sunny weather should (and depending on orientation) have a efficiency of ~ 15% so output 316*15%, 47.4Kwh, on a day like the 20th that 6.5Kwp might have a power output of ~ 5.8Kwh or so for hours on end. @tnegun has a solar array + a Willis, look up his thread "Fitting a Willis Immersion heater", it's very interesting.

TheSunIsShining

https://www.boards.ie/discussion/comment/122169331#Comment_122169331

The calculator I linked to above provides the various numbers

Hellrazer

Are you sure theres no boosts scheduled in the Eddi app? Its like its drawing 3kw constantly - theres something wrong somewhere - My Eddi for the entire week(Monday , Tuesday and today) has drawn 9.6 kWh and I have hot water every single day all day.

Id start by limiting the power going into the Eddi to see if it makes any difference.

Settings - Supply Grid - device limit - limit it to 5 amps and see what happens.If youre happy with that leave it at 5 amps - if you find you need more hot water try 7 amps and so on.

I suspect a setting somewhere is messing something up.

John.G

https://www.boards.ie/discussion/comment/122169579#Comment_122169579

Yes, the time required IF 3KW immersion heating available throughout, 8.55/3.0, 2.85hrs, 2 hrs 51 minutes.

Wearb

https://www.boards.ie/discussion/comment/122169727#Comment_122169727

The Eddi, if diverting the max 3.0kw, (immersion power), continuously, will take 8.5 hrs to reheat 210L from say 30C to 65C 

I'm confused by above. 3kw would take less than 3 hours. What am I missing?

10-10-20

I'm getting 12.2kWh to heat 210l of water from 15C to 65C, with a run-time of 4hr 11mins if the 3000w source is continuously run.

https://www.boards.ie/discussion/comment/122169512#Comment_122169512

I'm still suspicious of mixing/leaks. If there is no draw off the cylinder on a quiet day then none of the pipes around the wall of the hot-press should be more than tepid. And what about insulation on the tank and also on the piping to and from the Willis? Is that all complete and up to recent standards?

John.G

I said, "Yes, the time required IF 3KW immersion heating available throughout, 8.55/3.0, 2.85hrs, 2 hrs 51 minutes." so it requires 8.55Kwh to reheat 210L from 30C to 65C and a 3kw heating element will achieve this (on full power) in 2hrs 51 minutes.

CramCycle

In my old house the plumber had laid the radiator pipe next to the hot water pipe and it was siphoning heat. It done a magnificent job of taking the chill out of the air in the winter. We didn't have FIT at the time so didn't care. Are all your radiators off?

John.G

https://www.boards.ie/discussion/comment/122169512#Comment_122169512

The only explanation I can give if 20Kwh was absorbed by the cylinder is that it reached 100C and was boiling off or if it "only" reached 98C with no boil off and assuming only 20C at the beginning of heating then that would require 19Kwh, close to the logged 20Kwh. Is there any other thermostat on the Willis circuit apart from its own internal one? the stat only seemed to have cut out only once with a 3KW, 5hr, heating period.

cgrj

Afaik it only cut out to send power to washing machine other than that the Willis takes all the power .

John.G

That makes it look even more likely that the Willis stat is not cutting off the power, but if not then the cylinder should be scaldingly hot excepot that HW is leaking off somewhere.