Danger : EDDI heating too much hot water and filling the cold tank the attic with hot water too?

JimmyVik · 31-05-2022 2:15pm #1

So my friend gave me a call about his attic being all steamy and like a sauna.

I called up and we had a look in his attic. The plastic cold water tank up there is full of boiling water. So much so i wouldnt be surprised if the tank is compromised.

What is happening is that the EDDI is heating his water in the main immersion tank and the valve is releasing the water that gets too hot back into his tank upstairs. The EDDI is diverting so much heat that its a near constant gushing out of boiling water into the attic tank.

Does anyone know what can be done about this or is it a matter of switching his eddi off?

You can see the eddi switching from one element in the tank to the other as the temp is reached, but both are at top temperature now.

Im worried his tank is going to soften and burst, the water in it now is that hot. Not to mention condensation all over his attic.

In the winter for sure this water will be streaming down the walls of the attic.

dmigsy · 31-05-2022 2:31pm

Sounds like the immersion thermostat is either set way too hot or it is not working. The immersion should only heat the water up to the set temperature. We have ours at 60 degrees. The eddi doesn't heat the water. It just sends solar power to the immersion if the immersion needs it.

I'd turn off the eddi until this problem is fixed. Sounds like he needs a plumber.

JimmyVik · 31-05-2022 2:34pm

https://www.boards.ie/discussion/comment/119139861#Comment_119139861

Thanks. I'll call down to him tomorrow and see if i can adjust the thermostat on his cyllinder. Good thing he spotted it before something terrible happened.

How to you turn off the eddi - just flick the switch on the wall ? Also any chance of me getting electricuted off the solar if i turn of the mains before i open up that thermostat :)

dmigsy · 31-05-2022 2:43pm

There an off switch on the eddi. I'm no electrician but I'd turn off the isolation switch on the solar as well as the mains.

JimmyVik · 31-05-2022 2:45pm

Thanks, I'll try that so. Any idea how the isolation switch for the solar is marked?

JimmyVik · 31-05-2022 3:16pm

He checked himself there no and its set at 60. But you could hear the water boiling in the tank so it was well over 60 so something not right there.

graememk · 31-05-2022 3:25pm

https://www.boards.ie/discussion/comment/119140160#Comment_119140160

Yeah thermostat on the immersion is prob dead, it's not a difficult fix though.

Can be bought at any hardware store.

Surprised the over temp in the immersion didn't click out before it boiled jnto the cold tank

You don't need to turn off the solar, switching off the eddi will be fine

JimmyVik · 31-05-2022 3:30pm

Thanks guys. Going to give it a go and try to fix it for him. Its one of those elements that has the thermostat inside the tank too. So im thinking it probably needs a new element or can you just take the thermostat out and replace it.

Ubbquittious · 31-05-2022 4:00pm

https://www.boards.ie/discussion/comment/119140229#Comment_119140229

You can take the thermostat out and replace them. There is often a second safety thermostat under the cap that has the 2 elements + thermostat. but not always

slave1 · 31-05-2022 5:27pm

Agreed, just unscrew two nut from top of temp stat (thermostat), pull it out, take to local plumber merchant and tell them to give you a new one. The temp stat is often blue and you can push it slightly in and out as there's "give" on it

tnegun · 31-05-2022 8:12pm

How long has it been installed? As others have said, it sounds like the thermostat has failed closed or has been bypassed if it's a recent install. The Eddi can be expanded to manage the temperature in the tank itself too so we would need more info and pics of the install to be certain.

spose · 31-05-2022 8:17pm

Plenty of YouTube videos on changing the thermostat if you’re not sure what you are looking at. Very straightforward change out

Jonathan · 31-05-2022 8:20pm

https://www.boards.ie/discussion/2058248219/danger-eddi-heating-too-much-hot-water-and-filling-the-cold-tank-the-attic-with-hot-water-too

Glad to hear your friend got off lightly from this episode.

I too have found that despite the stat on my immersion being set for 60°C, my Eddi does heat the water beyond this in certain circumstances. I have a a 250L dual coil cylinder with solar thermal in lower coil, boiler on top coil, and immersion about half way down.

When Eddi is boosting (full 3kW) the stat will cut out fairly sharpish at 60°C, however if the Eddi is diverting less than say 2kW, the stat doesn't cut out until the top of the tank is closer to 70°C. I'm fairly certain of those temps as I'm pulling them from the Solar Thermal controller into HA.

What size PV system does your friend have @JimmyVik ? How big is the cylinder and how much had been diverted on the day you called over? A smaller PV system is could potentially behaving similarly to mine.

the_amazing_raisin · 31-05-2022 8:51pm

https://www.boards.ie/discussion/comment/119141542#Comment_119141542

That's interesting, I wonder if it's to do with how the Eddi controls power to the immersion

IIRC it changes the voltage across the heater to control the temperature and keep the immersion within the excess solar

I wonder does that screw up the thermostat in some way 🤔

graememk · 31-05-2022 9:13pm

https://www.boards.ie/discussion/comment/119141687#Comment_119141687

It shouldn't as it's just a temperature switch.

But if it's going full bore there could be less stratification in the tank thus kicking out sooner than it being trickled in.

the_amazing_raisin · 31-05-2022 9:16pm

https://www.boards.ie/discussion/comment/119141781#Comment_119141781

Or could it be the opposite, too much stratification?

Immersion is too low in the tank and creating an overheated spot at the top of the tank?

Because there's a constant flow from the water going through the overflow it means the immersion never cuts out?

graememk · 31-05-2022 10:18pm

I wouldn't say too low, the lower the better for an eddi!

But yeah when going full bore the hot water can't get away fast enough.

tnegun · 31-05-2022 10:46pm

Re the Eddi screwing up the thermostat I would have thought it was long shot but I had to replace my thermostat recently and I just read a post on the FB group with someone claim the iBoost was burning out thermostats and they had replaced several. I wonder as the lower voltages mean higher current right it affects/damages them somehow?

Jonathan · 31-05-2022 11:00pm

https://www.boards.ie/discussion/comment/119142222#Comment_119142222

Current should be constant as that is dictated by the device. The voltage is variable (via the Eddi/iBoost). I haven't confirmed with my CT clamp, but that's the theory.

tnegun · 31-05-2022 11:03pm

I actually have a CT clamp on mine but the readings are double what they should be below 1.5kw and about right at full power 2.8-3kw . Not sure what that means though I just assumed it was the varying voltage messing with it.

graememk · 31-05-2022 11:32pm

https://www.boards.ie/discussion/comment/119142293#Comment_119142293

Is your CT before the eddi or after it (It should be before)

tnegun · 01-06-2022 10:02am

https://www.boards.ie/discussion/comment/119142399#Comment_119142399

That makes perfect sense I have it on the immersion leads so after!

graememk · 01-06-2022 10:47am

https://www.boards.ie/discussion/comment/119143166#Comment_119143166

Yeah CT only measure current, and the eddi and Iboost vary the voltage, so the current is always the same(ish) Move the CT to before the Eddi and your sorted!.

JimmyVik · 01-06-2022 11:38am

Thanks guys. I cant get over to him til the weekend now but he is leaving the eddi off for now.

Its a 210L tank with dual heating coil that goes into the top of the tank.

The eddi switches between both elements, sometimes saying heating limit has been reached, so some sort of thermostat is working alright.

Yesterday 10kwh went into it. Its a 7 kwh solar system.

Seems like an excellent setup, apart from the eddi issues. He gets grid over voltage alarms every couple of days too.

Im trying to help him to gain experience to get it installed ourselves :)

Jonathan · 02-06-2022 5:39pm

https://www.boards.ie/discussion/comment/119141542#Comment_119141542

As luck would have it, my Eddi kindly demonstrated this phenomenon for me today. It was diverting between 200W and 1kW over the course of about three hours this afternoon and managed to heat the upper half of the tank to 72°C. Immersion stat is set at 60°C, which it reached and cut out at earlier in the day.

the_amazing_raisin · 02-06-2022 9:48pm

https://www.boards.ie/discussion/comment/119150327#Comment_119150327

Yeah this is where you need to be careful about where you're measuring the temperature to control the immersion

(Tangent begins...)

A few ago my wife was working on a purified water system. As part of the purification process they had to circulate water at around 90C through the distribution pipes to sterilise them

They had temperature sensors around the network and there was some debate as to where they should measure the temperature to control the heaters, whether it should be the coldest spot or hottest spot

Eventually, after some debate, they realised they need to use the hottest spot in the network. If they used the coldest spot, then by the time it reached 90C the water in the hottest part would be boiling into steam and causing pipe to explode

(...end tangent, thanks for bearing with me 😁)

So I think what you're seeing is that the temperature setting on the immersion doesn't represent the hottest temperature in the tank.

Since I'm guessing you can use the temperature probes in the tank to control the immersion, so you'll probably need to drop the setpoint on the immersion down to compensate

That's assuming you don't want the water at 72C of course

Bloodymice · 19-10-2022 9:11am

hi. Have a PC system and having similar issues in that my water is way too hot in my immersion. reckon the thermostat in the immersion is gone. do i need a plumber or an electrician to fix this? i thought electrician but i see plumber mentioned above. many thanks.

graememk · 19-10-2022 11:03am

If the immersion is working but not stopping, it's the thermostat. So electrician.

Bloodymice · 24-10-2022 1:29pm

Thanks. Might have a look at the Eddi - didn’t know that could Control the water temp.

DownByTheGarden · 25-10-2022 1:36pm

Same issue here.

I think the issue is that the 3kwh power when boosting is going to just the top of the tank and the 1kwh boost is going to the bottom one.

I think the EDDIE or the immesion is wired wrongly. No idea how to fix it. My installer doesnt want to know since they got paid.

I just switched off the EDDI altogether and boost it with the buttons when the battery is full or there is sun out.

bullit_dodger · 25-10-2022 4:59pm

https://www.boards.ie/discussion/comment/119791057#Comment_119791057

I think the EDDIE or the immesion is wired wrongly. No idea how to fix it. My installer doesnt want to know since they got paid.

If it's just wired wrong, you can change the priority of "sink/bath" inside the menu system of the Eddi, have it so that it is heating the bottom element (even if it "thinks" that it's the top one)

Danger : EDDI heating too much hot water and filling the cold tank the attic with hot water too?

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