Immersion heater

bachoo786 · November 29, 2017, 4:13pm

Hi Dave, hope you had a safe flight back. Did you have any chance to look into the schematic and the parts mate?

sparkydave · December 2, 2017, 3:17am

Hi, sorry for the delay, its been a hectic few days. Take at look at these 16A rated Sonof switches with temp sensor:

Its literally just power in and power out (active and neutral wires, with the earth bridged across. MAKE SURE THE EARTH IS CONTINUOUS!) in line with the feed to the heater element.

bachoo786 · December 2, 2017, 1:55pm

Thanks buddy.

Just a quick question. On the left of the drawing I suppose it’s the main incomer, mine is already connected to the timer do I have to remove my timer and connect the sonoff? I would like the timer to be connected in the circuit and not touch it ideally.

Secondly, I have two immersion heaters in my tank and both the cables from the heaters go straight to the timer, do I need 2 sonoff switches or 1 is enough to feed both the heaters? I suppose the wiring in the timer would be different for both the heaters.

Thanks.

sparkydave · December 3, 2017, 1:23am

Yep, that’s the isolator on the left but you can connect to the output of the timer. If both elements are 2.75 - 3kW then you will need 2 sonof switches, but this is good because it will give you more control. The second one can be the model without a temp sensor since you only need one of them for the tank. If you want to keep the timer in circuit it would be best if it can be set permanently on or in manual override so that all control is done by the sonofs and they never lose power and drop off the network

bachoo786 · December 3, 2017, 2:13am

Thanks bud.

Do I need to follow any guide on how to connect the sonoff to the Internet or?

sparkydave · December 3, 2017, 4:40am

I have never used Sonof before but what I understand is that you need to flash them with a custom firmware in order to use them with Home Assistant.

bachoo786 · January 23, 2018, 6:00pm

Hi @sparkydave @BertrumUK I have received all the parts and need to attach the sensor to the heater.

I have bought 2 sensors i.e. the AM2301 and DS18B20.

I opened up the immersion heater to see where I could attach the sensor. The photo’s below are a close up view of the heater. I need your advice as to where I fit the sensor (place with a red arrow or blue arrow on the photo) and which one?

Many thanks.

BertrumUK · January 23, 2018, 6:20pm

I would use the DS18B20 only. Not sure about the safety of placing where the blue arrow is as that is the heater so would try the red and see what readings you get. Usual H&S rules apply and you do this at your own risk.

bachoo786 · January 23, 2018, 6:34pm

Hmm thanks.

Can you please tell me what are your safety concerns if was to place where the blue arrow is?

BertrumUK · January 23, 2018, 6:49pm

You are working very near to electricity. I’m just advising caution as I would with anyone doing the same as you.

sparkydave · January 26, 2018, 1:11am

The issue with putting it near the blue arrow is more a case of getting an incorrect reading of water temp. Really both locations are too close to the element but you can use a template sensor to offset the readings to account for this i guess. I would keep it away from the element simply to try and get a more accurate reading of water temp rather than element temp. Electrically, the unit is sealed (other than the terminals for the wires) so safety “shouldnt” be an issue (disclaimer: I’m not responsible for fingers going where they shouldnt!)

bachoo786 · January 26, 2018, 6:31pm

so are you saying to insert the temperature sensor in the water in the tank rather than the element?

sparkydave · January 27, 2018, 11:57am

no, just try not to have it too close to the element as that is likely to be hotter than the water and therefore not give an accurate indication of the water temp, but like i said you can program in an offset to counter that

bachoo786 · January 27, 2018, 4:14pm

Hmm fair enough. . Where do you think I should put it then? And also can you please provide me with the offset to counter the inaccurate readings?

Thanks

sparkydave · January 30, 2018, 5:27am

well you could put it in the tank as you previously mentioned as long as you have a way of doing this while keeping it all water tight. The best way to do that would be to use a thermowell. As for the offset, you will need to do this by looking at the temperature you get back from the sensor vs the actual temperature of the water, then create a template sensor.

bachoo786 · February 20, 2018, 10:01pm

So I got everything setup with sonoff th16 and the temp probe.

I have put the temp probe near the heater it’s doing well in terms of measuring the heat. However I find that whenever I open and close the room where my heater is because of the sonoff temp sensitivity I get temperature drops.

The temp probe is covered inside the immersion heater i.e. in the white plastic…

Any solutions to this issue?

sparkydave · February 21, 2018, 10:35pm

that sounds normal if opening the door is letting heat out of the room…

bachoo786 · February 21, 2018, 11:52pm

I need to put the sensor in a better position I think… the readings are not great

bachoo786 · April 12, 2019, 1:15am

Hello guys @BertrumUK @sparkydave @GadgetUK

Just wanted to borrow your minds on replacing the sonoff th16 with a shelly 1pm?

What do you guys think? I know I will be losing out on temperature monitoring but that’s fine.

I hear shelly products are much safer. However they need to be inside a box? Is that true? Can I not just connect the mains and leave it?

Mind you I need 16Amp and shelly 1pm states it can work up to 16Amp? Is that sound?

BertrumUK · April 18, 2019, 7:46am

Hello, I have no experience of the Shelly devices so cannot give my opinion. I would look around to see if anyone else has used one for the purpose you are suggesting.