Webasto Heater WiFi control on a boat

Thread Starter

Deeplock

Joined Oct 6, 2020
4
Hi everyone
I’m a rookie so please bear with me!

I am living on a boat on the Grand Union canal with 240V shore power and also 12V DC power when I’m cruising. Most of my domestic appliances are controlled via a smart home device (MiHome/Energenie). I also have a smart relay that is fitted on a 240v pole switch for my hot water, again all Via 240v system.

I have a webasto heating system which runs via the DC system, I need some help getting this connected to my smart home system but I am finding conflicting information!


Attached pictures show the switch in question, the link to more details can be found here Webasto switch it connects to a Webasto Thermo 90 heater for which you can more details here Webasto Thermo 90 heater

What I’d like to do is control this via WiFi, I had a look at the sonoff WiFi switch solution but not sure this would work. I was planning to operate the on / off switch through the Sonoff and the diagnostics cables through the existing switch (which a number pulses flash depending on fault - see Webasto heater manual).

Any ideas or suggestions? I have seen some clever folks on eBay modify the switch so it can be controlled via a mobile phone/sim Mobile control for Webasto but nothing via WiFi which is annoying!

Many thanks
Deep (lock)

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sghioto

Joined Dec 31, 2017
1,553
I'm assuming you are trying to control the heater via wifi only when you are using shore power. Does it have to be a Sonoff controller? If so it seems like you could connect a relay to the load side of the Sonoff and wire the contacts across the Webasto switch.
SG
 

Thread Starter

Deeplock

Joined Oct 6, 2020
4
I'm assuming you are trying to control the heater via wifi only when you are using shore power. Does it have to be a Sonoff controller? If so it seems like you could connect a relay to the load side of the Sonoff and wire the contacts across the Webasto switch.
SG
Hi SG
Firstly, thank you for taking the time to reply.
You assumed correctly, ideally I only want to utilise the WiFi system whilst on shore power - only because I turn off as much AC equipment as possible so I’m not draining the batteries via the DC>AC inverter.

No, it doesn’t have to be a sonoff at all, that’s the only product/idea I was aware of hence I mentioned it.

Do you know what kind of relay would I need? I’d be grateful for any punters or recommendations on products.

many thanks
Deep
 

sghioto

Joined Dec 31, 2017
1,553
I’m going to try and get my brain around this
Sounds good. Below is the setup I'm describing using the Sonoff and the Omron relay
The L and N wires connect to the relay coil terminals 13 and 14.
Relay contacts 5 and 8 are connected together. This wire then connects to the Webasto switch terminal A
Relay contacts 9 and 12 are connected together. This wire then connects to the Webasto switch terminal B
SG
EEE Sonoff Pow R2 modification.png
 

Thread Starter

Deeplock

Joined Oct 6, 2020
4
Hi SG

thanks so much for putting the diagram together, that now makes a lot more sense to me and I think know what I need to do now! You’re very generous, thank you again!

quite excited to test out this project, it’s a big one for me and my first electrics attempt.

I shall revert with with finding!
 
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